WorldWideScience

Sample records for absorbed light energy

  1. Energy, Electron Transfer and Photocatalytic Reactions of Visible Light Absorbing Transition Metal Complexes

    Schmehl, Russell H. [Tulane Univ., New Orleans, LA (United States)

    2016-03-02

    This is the final technical report for a project carried out at Tulane University of New Orleans that describes the development of light induced (solar) reactions geared toward decomposing water into its component elements : hydrogen and oxygen. Much of the work involved optimizing systems for absorbing visible light and undergoing light promoted reactions to generate very strong reducing agents that are capable of reacting with water to produce hydrogen. Additional portions of the research were collaborative efforts to put the strong reducing agents to work in reaction with hydrogen generation catalysts prepared elsewhere. Time resolved laser spectroscopic methods were used to evaluate the light induced reactions and characterize very reactive intermediate substances formed during the reactions.

  2. Cylinder light concentrator and absorber: theoretical description

    Kildishev, Alexander V.; Prokopeva, Ludmila J.; Narimanov, Evgenii

    2010-01-01

    We present a detailed theoretical description of a broadband omnidirectional light concentrator and absorber with cylinder geometry. The proposed optical "trap" captures nearly all the incident light within its geometric cross-section, leading to a broad range of possible applications from solar energy harvesting to thermal light emitters and optoelectronic components. We have demonstrated that an approximate lamellar black-hole with a moderate number of homogeneous layers, while giving the d...

  3. Cubic TiO2 as a potential light absorber in solar-energy conversion

    Materials are currently sought for use in the photo-induced decomposition of water on crystalline electrodes. Titanium dioxide is valuable in this respect. The electronic structural properties of cubic TiO2 polymorphs were investigated by means of first-principles methods. We demonstrate that both fluorite- and pyrite-type TiO2 have important optical absorptive transitions in the region of the visible light. A cubic TiO2 phase that can efficiently absorb the sunlight would be an important candidate material for the development of the solar cells. Also, we present results on the Ti L edges for the two different titania forms. We predict that a qualitative spectroscopic discrimination of the cubic polymorphs can be achieved by following the Ti 2p→3d x-ray transitions

  4. Photoprotection of reaction centers: thermal dissipation of absorbed light energy vs charge separation in lichens.

    Heber, Ulrich; Soni, Vineet; Strasser, Reto J

    2011-05-01

    During desiccation, fluorescence emission and stable light-dependent charge separation in the reaction centers (RCs) of photosystem II (PSII) declined strongly in three different lichens: in Parmelia sulcata with an alga as the photobiont, in Peltigera neckeri with a cyanobacterium and in the tripartite lichen Lobaria pulmonaria. Most of the decline of fluorescence was caused by a decrease in the quantum efficiency of fluorescence emission. It indicated the activation of photoprotective thermal energy dissipation. Photochemical activity of the RCs was retained even after complete desiccation. It led to light-dependent absorption changes and found expression in reversible increases in fluorescence or in fluorescence quenching. Lowering the temperature changed the direction of fluorescence responses in P. sulcata. The observations are interpreted to show that reversible light-induced increases in fluorescence emission in desiccated lichens indicate the functionality of the RCs of PSII. Photoprotection is achieved by the drainage of light energy to dissipating centers outside the RCs before stable charge separation can take place. Reversible quenching of fluorescence by strong illumination is suggested to indicate the conversion of the RCs from energy conserving to energy dissipating units. This permits them to avoid photoinactivation. On hydration, re-conversion occurs to energy-conserving RCs. PMID:21029105

  5. Cylinder light concentrator and absorber: theoretical description.

    Kildishev, Alexander V; Prokopeva, Ludmila J; Narimanov, Evgenii E

    2010-08-01

    We present a detailed theoretical description of a broadband omnidirectional light concentrator and absorber with cylinder geometry. The proposed optical "trap" captures nearly all the incident light within its geometric cross-section, leading to a broad range of possible applications--from solar energy harvesting to thermal light emitters and optoelectronic components. We have demonstrated that an approximate lamellar black-hole with a moderate number of homogeneous layers, while giving the desired ray-optical performance, can provide absorption efficiencies comparable to those of ideal devices with a smooth gradient in index. PMID:20721056

  6. Crash compatibility between cars and light trucks: benefits of lowering front-end energy-absorbing structure in SUVs and pickups.

    Baker, Bryan C; Nolan, Joseph M; O'Neill, Brian; Genetos, Alexander P

    2008-01-01

    Passenger vehicles are designed to absorb crash energy in frontal crashes through deformation or crush of energy-absorbing structures forward of the occupant compartment. In collisions between cars and light trucks (i.e., pickups and SUVs), however, the capacity of energy-absorption structures may not be fully utilized because mismatches often exist between the heights of these structures in the colliding vehicles. In 2003 automakers voluntarily committed to new design standards aimed at reducing the height mismatches between cars and light trucks. By September 2009 all new light trucks will have either the primary front structure (typically the frame rails) or a secondary structure connected to the primary structure low enough to interact with the primary structures in cars, which for most cars is about the height of the front bumper. To estimate the overall benefit of the voluntary commitment, the real-world crash experience of light trucks already meeting the height-matching criteria was compared with that of light trucks not meeting the criteria for 2000-2003 model light trucks in collisions with passenger cars during calendar years 2001-2004. The estimated benefits of lower front energy-absorbing structure were a 19 percent reduction (pcar drivers in front-to-front crashes with light trucks and a 19 percent reduction (pcar drivers in front-to-driver-side crashes with light trucks. PMID:18215539

  7. Energy-absorbing effectiveness factor

    Jones, Norman

    2010-01-01

    Abstract A study is reported on the energy-absorbing effectiveness factor which was introduced recently. The factor is defined as the quotient of the total energy, which can be absorbed in a system, to the maximum energy up to failure in a normal tensile specimen, which is made from the same volume of material. This dimensionless parameter allows comparisons to be made of the effectiveness of various geometrical shapes and of energy-absorbers made from different materials. The infl...

  8. Energy absorber for the CETA

    Wesselski, Clarence J.

    1994-01-01

    The energy absorber that was developed for the CETA (Crew Equipment and Translation Aid) on Space Station Freedom is a metal on metal frictional type and has a load regulating feature that prevents excessive stroking loads from occurring while in operation. This paper highlights some of the design and operating aspects and the testing of this energy absorber.

  9. Energy absorber for the CETA

    Wesselski, Clarence J.

    1994-05-01

    The energy absorber that was developed for the CETA (Crew Equipment and Translation Aid) on Space Station Freedom is a metal on metal frictional type and has a load regulating feature that prevents excessive stroking loads from occurring while in operation. This paper highlights some of the design and operating aspects and the testing of this energy absorber.

  10. A better energy allocation of absorbed light in photosystem II and less photooxidative damage contribute to acclimation of Arabidopsis thaliana young leaves to water deficit.

    Sperdouli, Ilektra; Moustakas, Michael

    2014-05-01

    Water deficit stress promotes excitation pressure and photooxidative damage due to an imbalance between light capture and energy use. Young leaves (YL) of Arabidopsis thaliana plants acclimate better to the onset of water deficit (OnsWD) than do mature leaves (ML). To obtain a better understanding of this differential response, we evaluated whether YL and ML of A. thaliana exposed to the OnsWD, mild water deficit (MiWD) and moderate water deficit (MoWD), show differences in their photosynthetic performance, and whether photosynthetic acclimation correlates with leaf developmental stage. Water deficit (WD) resulted in greater photooxidative damage in ML compared to YL, but the latter could not be protected under the OnsWD or MiWD, but only under MoWD. YL of A. thaliana with signs of photosynthetic acclimation under MoWD retained higher maximum quantum yield (Fv/Fm) and decreased reactive oxygen species (ROS) formation. YL under MoWD, show a reduced excitation pressure and a better balance between light capture and photochemical energy use, which contributed to their photoprotection, but only under low light intensity (LL, 130μmolphotonsm(-2)s(-1)) and not under high light (HL, 1200μmolphotonsm(-2)s(-1)). In conclusion, leaf developmental stage was correlated with photo-oxidative damage and a differential allocation of absorbed light energy in photosystem II (PSII) of Arabidopsis leaves under WD. PMID:24709149

  11. Light Absorbing Aerosols in Mexico City

    Marley, N. A.; Kelley, K. L.; Kilaparty, P. S.; Gaffney, J. S.

    2008-12-01

    The direct effects of aerosol radiative forcing has been identified by the IPCC as a major uncertainty in climate modeling. The DOE Megacity Aerosol Experiment-Mexico City (MAX-Mex), as part of the MILAGRO study in March of 2006, was undertaken to reduce these uncertainties by characterization of the optical, chemical, and physical properties of atmospheric aerosols emitted from this megacity environment. Aerosol samples collected during this study using quartz filters were characterized in the uv-visible-infrared by using surface spectroscopic techniques. These included the use of an integrating sphere approach combined with the use of Kubelka-Munk theory to obtain aerosol absorption spectra. In past work black carbon has been assumed to be the only major absorbing species in atmospheric aerosols with an broad band spectral profile that follows a simple inverse wavelength dependence. Recent work has also identified a number of other absorbing species that can also add to the overall aerosol absorption. These include primary organics from biomass and trash burning and secondary organic aerosols including nitrated PAHs and humic-like substances, or HULIS. By using surface diffuse reflection spectroscopy we have also obtained spectra in the infrared that indicate significant IR absorption in the atmospheric window-region. These data will be presented and compared to spectra of model compounds that allow for evaluation of the potential importance of these species in adding strength to the direct radiative forcing of atmospheric aerosols. This work was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-07ER64327 as part of the Atmospheric Science Program.

  12. Selective Cell Targeting with Light-Absorbing Microparticles and Nanoparticles

    Pitsillides, Costas M; Joe, Edwin K.; Wei, Xunbin; Anderson, R. Rox; Lin, Charles P.

    2003-01-01

    We describe a new method for selective cell targeting based on the use of light-absorbing microparticles and nanoparticles that are heated by short laser pulses to create highly localized cell damage. The method is closely related to chromophore-assisted laser inactivation and photodynamic therapy, but is driven solely by light absorption, without the need for photochemical intermediates (particularly singlet oxygen). The mechanism of light-particle interaction was investigated by nanosecond ...

  13. Self-Resetting Energy Absorber

    De La Fuente, Horacio M.; Nagy, Kornel; Wesselski, Clarence J.

    1992-01-01

    Device uses friction to dissipate kinetic energy. When moving mass pushes in one direction, it offers substantial friction. Pushed in opposite direction, it offers negligible friction. Built-in spring resets for another shock-absorption cycle. Used in industrial machinery, automobile bumpers and suspensions, and parachute lanyards.

  14. Can polar bear hairs absorb environmental energy?

    He Ji-Huan

    2011-01-01

    Full Text Available A polar bear (Ursus maritimus has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  15. Merits and demerits of light absorbers for ultra-shallow junction formation by green laser annealing

    Matsuno, Akira [Research Center for Nanodevices and Systems, Hiroshima University, 1-4-2 Kagamiyama, Higashihiroshima 739-8527 (Japan); Phoeton Corp., Atsugi AXT Main Tower 4F Incubation room II, Okada 3050, Atsugi, Kanagawa 243-0021 (Japan); Takii, Eisuke [Research Center for Nanodevices and Systems, Hiroshima University, 1-4-2 Kagamiyama, Higashihiroshima 739-8527 (Japan); Eto, Takanori [Research Center for Nanodevices and Systems, Hiroshima University, 1-4-2 Kagamiyama, Higashihiroshima 739-8527 (Japan); Kurobe, Ken-ichi [Research Center for Nanodevices and Systems, Hiroshima University, 1-4-2 Kagamiyama, Higashihiroshima 739-8527 (Japan); Shibahara, Kentaro [Research Center for Nanodevices and Systems, Hiroshima University, 1-4-2 Kagamiyama, Higashihiroshima 739-8527 (Japan)]. E-mail: ksshiba@hiroshima-u.ac.jp

    2005-08-01

    Ultra-shallow junction formation using an all-solid-state green laser (532 nm) has been investigated. Considering too large penetration depth of the green laser into Si, a light absorber layer was formed on a Si substrate. TiN or Mo was deposited on Si after Sb{sup +} implantation through the 2-nm screen oxide. The TiN light absorber was effective in reducing the laser energy density to activate dopant but Mo increased the required energy density. Junction depth fundamentally depended on amorphous layer depth, however, the annealing with the absorber easily led to overmelt of c-Si. Mechanisms of these results were discussed utilizing one-dimensional thermal diffusion analysis.

  16. Research on Effect of Four Natural Ultraviolet Light Absorbers on Photostabilization of Azadirachtin-A

    TAN Wei-hong; SONG Zhan-qian

    2006-01-01

    This study examined the photostabilization of Azadirachtin-A (Aza-A) when exposed to ultraviolet light in the presence of some natural absorbers. Aza-A extract solutions with and without natural UV light absorbers in methanol were applied onto the surface of glass slides. At particular intervals, the remaining concentration of Aza-A was analyzed by HPLC.Using first-order kinetic equation, the dissipation half-life values (DT50) for the degradation of Aza-A under ultraviolet radiation were obtained. It indicated that the addition of ferulic acid, gallic acid, and rutin provided moderate degree of photostabilization of Aza-A and that addition of aloin provided the best photostabilization of Aza-A, among these UV absorbers studied. Photostabilization of Aza-A by different UV light absorbers appears to be due to the competitive energy absorption of UV photons by the absorbers molecules. The dissipation half-life values of Aza-A after irradiation under ultraviolet light suggested that the addition of aloin (in 1:1 mol ratio) can provide better photostabilization of azadirachtin molecule.

  17. Exploring Light's Interactions with Bubbles and Light Absorbers in Photoelectrochemical Devices using Ray Tracing

    Stevens, John [Univ. of California, Berkeley, CA (United States)

    2013-12-01

    Ray tracing was used to perform optical optimization of arrays of photovoltaic microrods and explore the interaction between light and bubbles of oxygen gas on the surface of the microrods. The incident angle of light was varied over a wide range. The percent of incident light absorbed by the microrods and reflected by the bubbles was computed over this range. It was found that, for the 10 μm diameter, 100 μm tall SrTiO3 microrods simulated in the model, the optimal center-to-center spacing was 14 μm for a square grid. This geometry produced 75% average and 90% maximum absorbance. For a triangular grid using the same microrods, the optimal center-to-­center spacing was 14 μm. This geometry produced 67% average and 85% maximum absorbance. For a randomly laid out grid of 5 μm diameter, 100 μm tall SrTiO! microrods with an average center-­to-­center spacing of 20 μm, the average absorption was 23% and the maximum absorption was 43%. For a 50% areal coverage fraction of bubbles on the absorber surface, between 2%-20% of the incident light energy was reflected away from the rods by the bubbles, depending upon incident angle and bubble morphology.

  18. Wave energy extraction by coupled resonant absorbers.

    Evans, D V; Porter, R

    2012-01-28

    In this article, a range of problems and theories will be introduced that will build towards a new wave energy converter (WEC) concept, with the acronym 'ROTA' standing for resonant over-topping absorber. First, classical results for wave power absorption for WECs constrained to operate in a single degree of freedom will be reviewed and the role of resonance in their operation highlighted. Emphasis will then be placed on how the introduction of further resonances can improve power take-off characteristics by extending the range of frequencies over which the efficiency is close to a theoretical maximum. Methods for doing this in different types of WECs will be demonstrated. Coupled resonant absorbers achieve this by connecting a WEC device equipped with its own resonance (determined from a hydrodynamic analysis) to a new system having separate mass/spring/damper characteristics. It is shown that a coupled resonant effect can be realized by inserting a water tank into a WEC, and this idea forms the basis of the ROTA device. In essence, the idea is to exploit the coupling between the natural sloshing frequencies of the water in the internal tank and the natural resonance of a submerged buoyant circular cylinder device that is tethered to the sea floor, allowing a rotary motion about its axis of attachment. PMID:22184664

  19. Modeling the Effect of Polychromatic Light in Quantitative Absorbance Spectroscopy

    Smith, Rachel; Cantrell, Kevin

    2007-01-01

    Laboratory experiment is conducted to give the students practical experience with the principles of electronic absorbance spectroscopy. This straightforward approach creates a powerful tool for exploring many of the aspects of quantitative absorbance spectroscopy.

  20. Slow and Fast Light in an Electro-Absorber

    Öhman, Filip; Bermejo Ramirez, Andres; Sales, Salvador;

    2006-01-01

    We demonstrate controllable and large time delay in cascaded semiconductor saturable absorbers and amplifiers. The possibility of further increasing the tuneable phase shift by utilizing field screening effects in the quantum well absorber is demonstrated....

  1. Meridional gradients of light absorbing carbon over northern Europe

    In situ measurements have been made in the upper troposphere of the properties of particles containing light absorbing carbon (LAC). These measurements, made in late November 2006 over northern Europe, show that the average LAC mass concentration varies between 1 and 5 ng m-3 over a latitude range 50 deg. to 70 deg. N, with maxima at 50 deg. and 66 deg. The relative fraction of all particles larger than 0.1 μm that contain LAC decreases at higher latitudes. The derived extinction coefficient, which also increases with latitude, reaches a maximum of 1.4 Mm-1 at 66 deg. The air mass histories associated with the LAC were evaluated with back trajectory analysis using wind field analysis from the European Center for Median-Range Weather Forecast (ECMWF). A positive correlation exists between the fraction of particles containing LAC and the maximum relative humidity (RH), minimum temperature and maximum number of hours of cloud experienced by the air mass in the 5-10 days prior to being sampled by the aircraft. Air masses arriving from lower altitudes and with trajectories over North America also had larger concentration fractions of LAC. The average LAC mass is in good agreement with previous measurements made over North America for the same latitude range, and the span of values fits best with model predictions of LAC distributions that assume that the LAC transported from surface sources is hydrophobic

  2. Energy absorbing supports - an alternative piping support system

    An extensive development effort has resulted in the successful application of energy absorbers as alternative supports. Several installations of energy absorbers demonstrating the feasibility of this support concept have been successfully completed. Designed in accordance with the ASME Code Case N-420, these ductile supports undergo limited and controlled yielding under dynamic conditions, thereby dissipating energy. The design methodology determines the specific damping ratios applicable for a given piping system on the basis of the energy absorbers used. Thus, using energy absorbers permits predictable damping to be engineered into the system desing. They can be used in operating plants to replace existing snubbers. In plants under construction, they can be used in place of both snubbers and rigid supports. In both applications, fewer energy absorbers are required as compared to snubbers and rigid supports. (orig.)

  3. Energy absorbing supports - An alternative piping support system

    An extensive development effort has resulted in the successful application of energy absorbers as alternative supports. Several installations of energy absorbers demonstrating the feasibility of this support concept have been successfully completed. Designed in accordance with the ASME Code Case N-420, these ductile supports undergo limited and controlled yielding under dynamic conditions, thereby dissipating energy. The design methodology determines the specific damping ratios applicable for a given piping system on the basis of the energy absorbers used. Thus, using energy absorbers permits predictable damping to be engineered into the system design. They can be used in operating plants to replace existing snubbers. In plants under construction, they can be used in place of both snubbers and rigid supports. In both applications, fewer energy absorbers are required as compared to snubbers and rigid supports

  4. Rapid-Response Low Infrared Emission Broadband Ultrathin Plasmonic Light Absorber

    Tagliabue, Giulia; Eghlidi, Hadi; Poulikakos, Dimos

    2014-11-01

    Plasmonic nanostructures can significantly advance broadband visible-light absorption, with absorber thicknesses in the sub-wavelength regime, much thinner than conventional broadband coatings. Such absorbers have inherently very small heat capacity, hence a very rapid response time, and high light power-to-temperature sensitivity. Additionally, their surface emissivity can be spectrally tuned to suppress infrared thermal radiation. These capabilities make plasmonic absorbers promising candidates for fast light-to-heat applications, such as radiation sensors. Here we investigate the light-to-heat conversion properties of a metal-insulator-metal broadband plasmonic absorber, fabricated as a free-standing membrane. Using a fast IR camera, we show that the transient response of the absorber has a characteristic time below 13 ms, nearly one order of magnitude lower than a similar membrane coated with a commercial black spray. Concurrently, despite the small thickness, due to the large absorption capability, the achieved absorbed light power-to-temperature sensitivity is maintained at the level of a standard black spray. Finally, we show that while black spray has emissivity similar to a black body, the plasmonic absorber features a very low infra-red emissivity of almost 0.16, demonstrating its capability as selective coating for applications with operating temperatures up to 400°C, above which the nano-structure starts to deform.

  5. Sources of light-absorbing aerosol in arctic snow and their seasonal variation

    Hegg, D.A.; Warren, S. G.; Grenfell, T. C.; Doherty, S. J.; A. D. Clarke

    2010-01-01

    Two data sets consisting of measurements of light absorbing aerosols (LAA) in arctic snow together with suites of other corresponding chemical constituents are presented; the first from Siberia, Greenland and near the North Pole obtained in 2008, and the second from the Canadian arctic obtained in 2009. A preliminary differentiation of the LAA into black carbon (BC) and non-BC LAA is done. Source attribution of the light absorbing aerosols was done using a positive matrix factorization (PMF) ...

  6. Removal of fluorescence and ultraviolet absorbance of dissolved organic matter in reclaimed water by solar light.

    Wu, Qianyuan; Li, Chao; Wang, Wenlong; He, Tao; Hu, Hongying; Du, Ye; Wang, Ting

    2016-05-01

    Storing reclaimed water in lakes is a widely used method of accommodating changes in the consumption of reclaimed water during wastewater reclamation and reuse. Solar light serves as an important function in degrading pollutants during storage, and its effect on dissolved organic matter (DOM) was investigated in this study. Solar light significantly decreased the UV254 absorbance and fluorescence (FLU) intensity of reclaimed water. However, its effect on the dissolved organic carbon (DOC) value of reclaimed water was very limited. The decrease in the UV254 absorbance intensity and FLU excitation-emission matrix regional integration volume (FLU volume) of reclaimed water during solar light irradiation was fit with pseudo-first order reaction kinetics. The decrease of UV254 absorbance was much slower than that of the FLU volume. Ultraviolet light in solar light had a key role in decreasing the UV254 absorbance and FLU intensity during solar light irradiation. The light fluence-based removal kinetic constants of the UV254 and FLU intensity were independent of light intensity. The peaks of the UV254 absorbance and FLU intensity with an apparent molecular weight (AMW) of 100Da to 2000Da decreased after solar irradiation, whereas the DOC value of the major peaks did not significantly change. PMID:27155416

  7. Energy deposition and radiological studies for the LBNF Hadron Absorber

    Rakhno, I. L.; Mokhov, N. V.; Tropin, I.S.; Eidelman, Y. I.

    2015-01-01

    Results of detailed Monte Carlo energy deposition and radiological studies performed for the LBNF hadron absorber with the MARS15 code are described. The model of the entire facility, that includes a pion-production target, focusing horns, target chase, decay channel, hadron absorber system - all with corresponding radiation shielding - was developed using the recently implemented ROOT-based geometry option in the MARS15 code. Both normal operation and accidental conditions were studied. Resu...

  8. Quasinormal modes of black holes absorbing dark energy

    He, Xi; Bin WANG; Wu, Shao-Feng; Lin, Chi-Yong

    2008-01-01

    We study perturbations of black holes absorbing dark energy. Due to the accretion of dark energy, the black hole mass changes. We observe distinct perturbation behaviors for absorption of different forms of dark energy into the black holes. This provides the possibility of extracting information whether dark energy lies above or below the cosmological constant boundary $w=-1$. In particular, we find in the late time tail analysis that, differently from the other dark energy models, the accret...

  9. Absorbance Based Light Emitting Diode Optical Sensors and Sensing Devices

    Dermot Diamond; Martina O’Toole

    2008-01-01

    The ever increasing demand for in situ monitoring of health, environment and security has created a need for reliable, miniaturised sensing devices. To achieve this, appropriate analytical devices are required that possess operating characteristics of reliability, low power consumption, low cost, autonomous operation capability and compatibility with wireless communications systems. The use of light emitting diodes (LEDs) as light sources is one strategy, which has been successfully applied i...

  10. Ultrathin Semiconductor Perfect Light Absorbers with High Spectral, Polarization, and Angle Selectivity for Arbitrary Wavelengths

    Huang, Lujun; Cao, Linyou

    2014-01-01

    Enabling perfect light absorption in ultrathin materials promises the development of exotic photonic devices. Here we demonstrate new strategies that can provide capabilities to rationally design ultrathin (thickness < {\\lambda}/10~{\\lambda}/5) semiconductor perfect absorbers for arbitrary wavelengths, including those at which the intrinsic absorption of the semiconductor is weak, e.g. Si for near-IR wavelengths. This is in stark contrast with the existing studies on ultrathin perfect absorbers, which have focused on metallic materials or highly-absorptive semiconductors. Our design strategies are built upon an intuitive model, coupled leaky mode theory that we recently developed and can turn the design for perfect absorbers to the design for leaky modes. The designed absorber is featured with extraordinary absorption enhancement, miniaturized dimension, and high selectivity for the wavelength, polarization, and angle of incident light. It can enable the development of flexible, light-weight, high-performa...

  11. Energy deposition studies for the LBNE beam absorber

    Rakhno, Igor L; Tropin, Igor S

    2015-01-01

    Results of detailed Monte Carlo energy deposition studies performed for the LBNE absorber core and the surrounding shielding with the MARS15 code are described. The model of the entire facility, that includes a pion-production target, focusing horns, target chase, decay channel, hadron absorber system -- all with corresponding radiation shielding -- was developed using the recently implemented ROOT-based geometry option in the MARS15 code. This option provides substantial flexibility and automation when developing complex geometry models. Both normal operation and accidental conditions were studied. Various design options were considered, in particular the following: (i) filling the decay pipe with air or helium; (ii) the absorber mask material and shape; (iii) the beam spoiler material and size. Results of detailed thermal calculations with the ANSYS code helped to select the most viable absorber design options.

  12. Energy deposition studies for the LBNE beam absorber

    Rakhno, Igor L.; Mokhov, Nikolai V.; Tropin, Igor S.

    2015-01-29

    Results of detailed Monte Carlo energy deposition studies performed for the LBNE absorber core and the surrounding shielding with the MARS15 code are described. The model of the entire facility, that includes a pion-production target, focusing horns, target chase, decay channel, hadron absorber system – all with corresponding radiation shielding – was developed using the recently implemented ROOT-based geometry option in the MARS15 code. This option provides substantial flexibility and automation when developing complex geometry models. Both normal operation and accidental conditions were studied. Various design options were considered, in particular the following: (i) filling the decay pipe with air or helium; (ii) the absorber mask material and shape; (iii) the beam spoiler material and size. Results of detailed thermal calculations with the ANSYS code helped to select the most viable absorber design options.

  13. Open-Cell Aluminium Foams with Graded Coatings as Passively Controllable Energy Absorbers

    Jung, Anne; Beex, Lars; Diebels, Stefan; Bordas, Stéphane

    2015-01-01

    Compared to most bulk materials, open-cell aluminium (Al) foams (OCAFs) are light-weight and can absorb a significant amount of energy in compression, e.g. during impact.When coatedwith nickel (Ni), OCAFs can absorb even more energy, making them more appropriate for impacts at higher velocities than uncoated OCAFs. When Ni-coated OCAFs experience low-velocity impact however, the stopping distance during the impact is small compared to that of uncoated OCAFs and hence, deceleration occurs fast...

  14. An energy model for the acoustic insulation of absorbing materials

    Díaz Cereceda, Cristina; Poblet-Puig, Jordi; Rodríguez Ferran, Antonio

    2013-01-01

    In this work an energy model for the acoustic insulation of absorbing ma- terials is shown. This model is an extension of Statistical Energy Analysis (SEA) [1] in order to account for the effect of non-conservative connections [2, 3]. The energy-based approach allows to solve sound insulation problems in large domains (such as those in building acoustics) in an efficient way for the whole frequency range required by regulations (50-5000 Hz). In particular, this approach is appl...

  15. Numerical Modeling of a Wave Energy Point Absorber

    Hernandez, Lorenzo Banos; Frigaard, Peter; Kirkegaard, Poul Henning

    The present study deals with numerical modelling of the Wave Star Energy WSE device. Hereby, linear potential theory is applied via a BEM code on the wave hydrodynamics exciting the floaters. Time and frequency domain solutions of the floater response are determined for regular and irregular seas....... Furthermore, these results are used to estimate the power and the energy absorbed by a single oscillating floater. Finally, a latching control strategy is analysed in open-loop configuration for energy maximization....

  16. Energy-harvesting shock absorber with a mechanical motion rectifier

    Energy-harvesting shock absorbers are able to recover the energy otherwise dissipated in the suspension vibration while simultaneously suppressing the vibration induced by road roughness. They can work as a controllable damper as well as an energy generator. An innovative design of regenerative shock absorbers is proposed in this paper, with the advantage of significantly improving the energy harvesting efficiency and reducing the impact forces caused by oscillation. The key component is a unique motion mechanism, which we called ‘mechanical motion rectifier (MMR)’, to convert the oscillatory vibration into unidirectional rotation of the generator. An implementation of a MMR-based harvester with high compactness is introduced and prototyped. A dynamic model is created to analyze the general properties of the motion rectifier by making an analogy between mechanical systems and electrical circuits. The model is capable of analyzing electrical and mechanical components at the same time. Both simulation and experiments are carried out to verify the modeling and the advantages. The prototype achieved over 60% efficiency at high frequency, much better than conventional regenerative shock absorbers in oscillatory motion. Furthermore, road tests are done to demonstrate the feasibility of the MMR shock absorber, in which more than 15 Watts of electricity is harvested while driving at 15 mph on a smooth paved road. The MMR-based design can also be used for other applications of vibration energy harvesting, such as from tall buildings or long bridges. (paper)

  17. Energy-harvesting shock absorber with a mechanical motion rectifier

    Li, Zhongjie; Zuo, Lei; Kuang, Jian; Luhrs, George

    2013-02-01

    Energy-harvesting shock absorbers are able to recover the energy otherwise dissipated in the suspension vibration while simultaneously suppressing the vibration induced by road roughness. They can work as a controllable damper as well as an energy generator. An innovative design of regenerative shock absorbers is proposed in this paper, with the advantage of significantly improving the energy harvesting efficiency and reducing the impact forces caused by oscillation. The key component is a unique motion mechanism, which we called ‘mechanical motion rectifier (MMR)’, to convert the oscillatory vibration into unidirectional rotation of the generator. An implementation of a MMR-based harvester with high compactness is introduced and prototyped. A dynamic model is created to analyze the general properties of the motion rectifier by making an analogy between mechanical systems and electrical circuits. The model is capable of analyzing electrical and mechanical components at the same time. Both simulation and experiments are carried out to verify the modeling and the advantages. The prototype achieved over 60% efficiency at high frequency, much better than conventional regenerative shock absorbers in oscillatory motion. Furthermore, road tests are done to demonstrate the feasibility of the MMR shock absorber, in which more than 15 Watts of electricity is harvested while driving at 15 mph on a smooth paved road. The MMR-based design can also be used for other applications of vibration energy harvesting, such as from tall buildings or long bridges.

  18. Enhancing Localized Evaporation through Separated Light Absorbing Centers and Scattering Centers

    Zhao, Dengwu; Duan, Haoze; Yu, Shengtao; Zhang, Yao; He, Jiaqing; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

    2015-11-01

    This report investigates the enhancement of localized evaporation via separated light absorbing particles (plasmonic absorbers) and scattering particles (polystyrene nanoparticles). Evaporation has been considered as one of the most important phase-change processes in modern industries. To improve the efficiency of evaporation, one of the most feasible methods is to localize heat at the top water layer rather than heating the bulk water. In this work, the mixture of purely light absorptive plasmonic nanostructures such as gold nanoparticles and purely scattering particles (polystyrene nanoparticles) are employed to confine the incident light at the top of the solution and convert light to heat. Different concentrations of both the light absorbing centers and the light scattering centers were evaluated and the evaporation performance can be largely enhanced with the balance between absorbing centers and scattering centers. The findings in this study not only provide a new way to improve evaporation efficiency in plasmonic particle-based solution, but also shed lights on the design of new solar-driven localized evaporation systems.

  19. Energy deposition and radiological studies for the LBNF Hadron Absorber

    Rakhno, I L; Tropin, I S; Eidelman, Y I

    2015-01-01

    Results of detailed Monte Carlo energy deposition and radiological studies performed for the LBNF hadron absorber with the MARS15 code are described. The model of the entire facility, that includes a pion-production target, focusing horns, target chase, decay channel, hadron absorber system - all with corresponding radiation shielding - was developed using the recently implemented ROOT-based geometry option in the MARS15 code. Both normal operation and accidental conditions were studied. Results of detailed thermal calculations with the ANSYS code helped to select the most viable design options.

  20. Energy Deposition and Radiological Studies for the LBNF Hadron Absorber

    Rakhno, I. L. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Mokhov, N. V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Tropin, I. S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Eidelman, Y. I. [Euclid Techlabs LLC., Cleveland, OH (United States)

    2015-06-25

    Results of detailed Monte Carlo energy deposition and radiological studies performed for the LBNF hadron absorber with the MARS15 code are described. The model of the entire facility, that includes a pion-production target, focusing horns, target chase, decay channel, hadron absorber system – all with corresponding radiation shielding – was developed using the recently implemented ROOT-based geometry option in the MARS15 code. Both normal operation and accidental conditions were studied. Results of detailed thermal calculations with the ANSYS code helped to select the most viable design options.

  1. Rigorous modelling of light's intensity angular-profile in Abbe refractometers with absorbing homogeneous fluids

    We derive an optical model for the light intensity distribution around the critical angle in a standard Abbe refractometer when used on absorbing homogenous fluids. The model is developed using rigorous electromagnetic optics. The obtained formula is very simple and can be used suitably in the analysis and design of optical sensors relying on Abbe type refractometry.

  2. Light-absorbing aldol condensation products in acidic aerosols: Spectra, kinetics, and contribution to the absorption index

    Nozière, Barbara; Esteve, William

    The radiative properties of aerosols that are transparent to light in the near-UV and visible, such as sulfate aerosols, can be dramatically modified when mixed with absorbing material such as soot. In a previous work we had shown that the aldol condensation of carbonyl compounds produces light-absorbing compounds in sulfuric acid solutions. In this work we report the spectroscopic and kinetic parameters necessary to estimate the effects of these reactions on the absorption index of sulfuric acid aerosols in the atmosphere. The absorption spectra obtained from the reactions of six different carbonyl compounds (acetaldehyde, acetone, propanal, butanal, 2-butanone, and trifluoroacetone) and their mixtures were compared over 190-1100 nm. The results indicated that most carbonyl compounds should be able to undergo aldol condensation. The products are oligomers absorbing light in the 300-500 nm region where few other compounds absorb, making them important for the radiative properties of aerosols. Kinetic experiments in 96-75 wt% H 2SO 4 solutions and between 273 and 314 K gave an activation energy for the rate constant of formation of the aldol products of acetaldehyde of -(70±15) kJ mol -1 in 96 wt% solution and showed that the effect of acid concentration was exponential. A complete expression for this rate constant is proposed where the absolute value in 96 wt% H 2SO 4 and at 298 K is scaled to the Henry's law coefficient for acetaldehyde and the absorption cross-section for the aldol products assumed in this work. The absorption index of stratospheric sulfuric acid aerosols after a 2-year residence time was estimated to 2×10 -4, optically equivalent to a content of 0.5% of soot and potentially significant for the radiative forcing of these aerosols and for satellite observations in channels where the aldol products absorb.

  3. Study of absorbed dose distribution to high energy electron beams

    The depth absorbed dose distribution by electron beams was studied. The influence of the beam energy, the energy spread, field size and design characteristics of the accelerator was relieved. Three accelerators with different scattering and collimation systems were studied leading todifferent depth dose distributions. A theoretical model was constructed in order to explain the increase in the depth dose in the build-up region with the increase of the energy. The model utilizes a three-dimensional formalism based on the Fermi-Eyges multiple scattering theory, with the introduction of modifications that takes into account the criation of secondary electrons. (Author)

  4. Quasinormal modes of black holes absorbing dark energy

    We study perturbations of black holes absorbing dark energy. Due to the accretion of dark energy, the black hole mass changes. We observe distinct perturbation behaviors for absorption of different forms of dark energy onto the black holes. This provides the possibility of extracting information whether dark energy lies above or below the cosmological constant boundary w=-1. In particular, we find in the late time tail analysis that, differently from the other dark energy models, the accretion of phantom energy exhibits a growing mode in the perturbation tail. The instability behavior found in this work is consistent with the Big Rip scenario, in which all of the bound objects are torn apart with the presence of the phantom dark energy

  5. The conservation of light's energy, mass, and momentum

    Mortenson, Juliana H. J.

    2011-09-01

    An advance in the foundations of quantum mechanics was presented at the previous "Nature of Light" meeting which brings new insights to the conservation of light's energy, mass and momentum. Those discoveries suggest that the "photon" is a time-based collection of sub-photonic elementary light particles. Incorporation of this new understanding into quantum mechanics has allowed the determination of universal constants for the energy, mass, and momentum of light. The energy constant for light is 6.626 X 10-34 J/osc, meaning the energy of a single oscillation of light is constant irrespective of the light's frequency or wavelength. Likewise, the mass and momentum of a single oscillation of light are constant, regardless of changes to either time or space. A realistic understanding of the conservation of energy, mass and momentum for both matter and light in a single conservation law is now possible. When a body with mass absorbs or emits light, its energy, mass and momentum change in quantized amounts according to the relationship: Δ E = Nh~ = Nm0c2 = Nρ0c where "N" is the number of oscillations absorbed absorbed or emitted by the body and h~, m0, and ρ0 are the constant energy, mass and momentum of an oscillation. Implications extend from general relativity and gravity to space sails and light driven nanomotors.

  6. Femtosecond laser energy deposition in strongly absorbing cluster gases diagnosed by blast wave trajectory analysis

    An intense ultrafast laser pulse can be very strongly absorbed in a moderate density gas composed of van der Waals bonded clusters. In this paper, the deposition of the energy of intense 30 fs light pulses in a gas of deuterium clusters has been diagnosed using a technique based on analysis of the trajectories of the resulting cylindrically symmetric blast waves. Using the well-known relation between blast wave velocity and energy deposition in gas, the laser energy deposited per unit length as a function of distance in gas jet plume was measured. These measurements were conducted in jets containing either deuterium clusters or simple deuterium molecules

  7. Fabrication of chalcopyrite light-absorbing layers based on nanoparticle and nanowire networks

    Ren, Yuhang; Luo, Paifeng; Gao, Bo; Cevher, Zehra; Sun, Chivin

    2013-03-01

    We report on a method of preparing chalcopyrite, CuInGaSe2 (CIGS) light-absorbing layers using low cost air stable ink based on semiconductor nanoparticle and nanowires. The nanoparticles and nanowires are prepared from metal salts such as metal chloride and acetate at room temperature without inert gas protection. A uniform and non-aggregation CIGS precursor layer is fabricated with the formation of nanoparticle and nanowire networks utilizing ultrasonic spaying technique. We obtain a high quality CIGS absorber by cleaning the residue salts and carbon agents at an increased temperature and through selenizing the pretreated CIGS precursors. Our results offer an opportunity for the low-cost deposition of chalcopyrite absorber materials at large scale with high throughput. This work was partially sponsored by Sun Harmonics Ltd. and by NYSTAR through the Photonics Center for Applied Technology at the City University of New York.

  8. Performance evaluation and parameter sensitivity of energy-harvesting shock absorbers on different vehicles

    Guo, Sijing; Liu, Yilun; Xu, Lin; Guo, Xuexun; Zuo, Lei

    2016-07-01

    Traditional shock absorbers provide favourable ride comfort and road handling by dissipating the suspension vibration energy into heat waste. In order to harvest this dissipated energy and improve the vehicle fuel efficiency, many energy-harvesting shock absorbers (EHSAs) have been proposed in recent years. Among them, two types of EHSAs have attracted much attention. One is a traditional EHSA which converts the oscillatory vibration into bidirectional rotation using rack-pinion, ball-screw or other mechanisms. The other EHSA is equipped with a mechanical motion rectifier (MMR) that transforms the bidirectional vibration into unidirectional rotation. Hereinafter, they are referred to as NonMMR-EHSA and MMR-EHSA, respectively. This paper compares their performances with the corresponding traditional shock absorber by using closed-form analysis and numerical simulations on various types of vehicles, including passenger cars, buses and trucks. Results suggest that MMR-EHSA provides better ride performances than NonMMR-EHSA, and that MMR-EHSA is able to improve both the ride comfort and road handling simultaneously over the traditional shock absorber when installed on light-damped, heavy-duty vehicles. Additionally, the optimal parameters of MMR-EHSA are obtained for ride comfort. The optimal solutions ('Pareto-optimal solutions') are also obtained by considering the trade-off between ride comfort and road handling.

  9. The Investigation of Property of Radiation and Absorbed of Infrared Lights of the Biological Tissues

    Pang, Xiao-Feng; Deng, Bo; Xiao, He-Lan; Cai, Guo-Ping

    2010-04-01

    The properties of absorption of infrared light for collagen, hemoglobin, bivine serum albumen (BSA) protein molecules with α- helix structure and water in the living systems as well as the infrared transmission spectra for person’s skins and finger hands of human body in the region of 400-4000 cm-1 (i.e., wavelengths of 2-20 μm) have been collected and determined by using a Nicolet Nexus 670 FT-IR Spectrometer, a Perkin Elmer GX FT-IR spectrometer, an OMA (optical multichannel analysis) and an infrared probe systems, respectively. The experimental results obtained show that the protein molecules and water can all absorb the infrared lights in the ranges of 600-1900 cm-1 and 2900-3900 cm-l, but their properties of absorption are somewhat different due to distinctions of their structure and conformation and molecular weight. We know from the transmission spectra of person’s finger hands and skin that the infrared lights with wavelengths of 2 μm-7 μm can not only transmit over the person’s skin and finger hands, but also be absorbed by the above proteins and water in the living systems. Thus, we can conclude from this study that the human beings and animals can absorb the infrared lights with wavelengths of 2 μm-7 μm.

  10. On Two Models of the Light Pulse Delay in a Saturable Absorber

    Zapasskii, V S

    2011-01-01

    A comparative analysis of two approaches to description of the light modulation pulse delay in a saturable absorber is presented. According to the simplest model, the delay of the optical pulse is a result of distortion of its shape due to absorption self-modulation in the nonlinear medium. The second model of the effect, proposed at the beginning of our century, connects the pulse delay with the so-called "slow light" resulting from the group velocity reduction under conditions of the coherent population oscillations. It is shown that all the known experimental data on the light pulse delay in saturable absorbers can be comprehensively described in the framework of the simplest model of saturable absorber and do not require invoking the effect of coherent population oscillations with spectral hole-burning and anomalous modifications of the light group velocity. It is concluded that the effect of group velocity reduction under conditions of coherent population oscillations has not received so far any experime...

  11. Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

    M. O. Andreae

    2006-05-01

    Full Text Available Although the definition and measurement methods of atmospheric ''black carbon'' (''BC'' have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black (''brown carbon, Cbrown'' makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC in the atmosphere. Evidence for the atmospheric presence of Cbrown comes directly from aerosol absorption measurements near specific combustion sources, from observations of spectral properties of water extracts of continental aerosol, from laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that these species may severely bias measurements of ''BC'' and ''EC'' over vast parts of the troposphere, where mass concentration of Cbrown is high relative to that of combustion soot. We also imply that due to the strongly skewed absorption of Cbrown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. The possible consequences of these effects on our understanding of tropospheric processes are discussed.

  12. Light-absorbing Particles in Snow and Ice: Measurement and Modeling of Climatic and Hydrological Impact

    Qian, Yun; Yasunari, Teppei J.; Doherty, Sarah J.; Flanner, M. G.; Lau, William K.; Ming, J.; Wang, Hailong; Wang, Mo; Warren, Stephen G.; Zhang, Rudong

    2015-01-01

    Light absorbing particles (LAP, e.g., black carbon, brown carbon, and dust) influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric heating by absorption of solar radiation and interactions with clouds, LAP in snow on land and ice can reduce the surface reflectance (a.k.a., surface darkening), which is likely to accelerate the snow aging process and further reduces snow albedo and increases the speed of snowpack melt. LAP in snow and ice (LAPSI) has been identified as one of major forcings affecting climate change, e.g. in the fourth and fifth assessment reports of IPCC. However, the uncertainty level in quantifying this effect remains very high. In this review paper, we document various technical methods of measuring LAPSI and review the progress made in measuring the LAPSI in Arctic, Tibetan Plateau and other mid-latitude regions. We also report the progress in modeling the mass concentrations, albedo reduction, radiative forcing, andclimatic and hydrological impact of LAPSI at global and regional scales. Finally we identify some research needs for reducing the uncertainties in the impact of LAPSI on global and regional climate and the hydrological cycle.

  13. Mixed Ge/Pb perovskite light absorbers with an ascendant efficiency explored from theoretical view.

    Sun, Ping-Ping; Li, Quan-Song; Feng, Shuai; Li, Ze-Sheng

    2016-06-01

    Organic-inorganic methylammonium lead halide perovskites have recently attracted great interest emerging as promising photovoltaic materials with a high 20.8% efficiency, but lead pollution is still a problem that may hinder the development and wide spread of MAPbI3 perovskites. To reduce the use of lead, we investigated the structures, electronic and optical properties of mixed MAGexPb(1-x)I3 theoretically by using density functional theory methods at different calculation levels. Results show that the mixed Ge/Pb perovskites exhibit a monotonic decrease evolution in band energy to push the band gap deeper in the near-infrared region and have a red shift optical absorption with an increased proportion of Ge. The results also indicate that lattice distortion and spin-orbit coupling (SOC) strength play important roles in the band gap behavior of MAGexPb(1-x)I3 by affecting the bandwidths of CBM and VBM. The calculations for short circuit current density, open circuit voltage, and theoretical power conversion efficiency suggest that mixed Ge/Pb perovskite solar cells (PSCs) with efficiency over 22% are superior to MAPbI3 and MAGeI3. And notably, MAGe0.75Pb0.25I3 is a promising harmless material for solar cells absorber with the highest theoretical efficiency of 24.24%. These findings are expected to be helpful for further rational design of nontoxic light absorption layer for high-performance PSCs. PMID:27171746

  14. Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

    M. O. Andreae

    2006-01-01

    Full Text Available Although the definition and measurement techniques for atmospheric 'black carbon' ('BC' or 'elemental carbon'' ('EC' have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black ('brown carbon, Cbrown' makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC in the atmosphere. Evidence for the atmospheric presence of Cbrown comes from (1 spectral aerosol light absorption measurements near specific combustion sources, (2 observations of spectral properties of water extracts of continental aerosol, (3 laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and (4 indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that brown carbon may severely bias measurements of 'BC' and 'EC' over vast parts of the troposphere, especially those strongly polluted by biomass burning, where the mass concentration of Cbrown is high relative to that of soot carbon. Chemical measurements to determine 'EC' are biased by the refractory nature of Cbrown as well as by complex matrix interferences. Optical measurements of 'BC' suffer from a number of problems: (1 many of the presently used instruments introduce a substantial bias into the determination of aerosol light absorption, (2 there is no unique conversion factor between light absorption and 'EC' or 'BC' concentration in ambient aerosols, and (3 the difference in spectral properties between the different types of LAC, as well as the chemical complexity of Cbrown, lead to several conceptual as well as practical complications. We also suggest that due to the sharply increasing absorption of Cbrown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. We discuss the possible consequences of these effects for our

  15. Total absorption of visible light in ultra-thin weakly-absorbing semiconductor gratings

    Sturmberg, Björn C P; Choi, Duk-Yong; White, Thomas P; Botten, Lindsay C; Dossou, Kokou B; Poulton, Christopher G; Catchpole, Kylie R; McPhedran, Ross C; de Sterke, C Martijn

    2016-01-01

    The perfect absorption of light in subwavelength thickness layers generally relies on exotic materials, metamaterials or thick metallic gratings. Here we demonstrate that total light absorption can be achieved in ultra-thin gratings composed of conventional materials, including relatively weakly-absorbing semiconductors, which are compatible with optoelectronic applications such as photodetectors and optical modulators. We fabricate a 41 nm thick antimony sulphide grating structure that has a measured absorptance of A = 99.3% at a visible wavelength of 591 nm, in excellent agreement with theory. We infer that the absorption within the grating is A = 98.7%, with only A = 0.6% within the silver mirror. A planar reference sample absorbs A = 7.7% at this wavelength.

  16. Infrared light-absorbing gold/gold sulfide nanoparticles induce cell death in esophageal adenocarcinoma

    Li Y; Gobin AM; Dryden GW; Kang X; Xiao D; Li SP; Zhang G; Martin RCG

    2013-01-01

    Yan Li,1 Andre M Gobin,2 Gerald W Dryden,3 Xinqin Kang,1 Deyi Xiao,1 Su Ping Li,1 Guandong Zhang,2 Robert CG Martin11Department of Surgery, 2Department of Bioengineering, 3Division of Medicine, University of Louisville School of Medicine, Louisville, KY, USAAbstract: Gold nanoparticles and near infrared-absorbing light are each innocuous to tissue but when combined can destroy malignant tissue while leaving healthy tissue unharmed. This study investigated the feasibility of photothermal ablat...

  17. Triazolobithiophene Light Absorbing Self-Assembled Monolayers: Synthesis and Mass Spectrometry Applications

    Denis Séraphin

    2011-10-01

    Full Text Available The synthesis of five light absorbing triazolobithiophenic thiols, which were utilized for producing self-assembled monolayers (SAMs on gold surfaces, is presented. The monolayer formation was monitored by cyclic voltammetry, indicating excellent surface coverage. The new triazolobithiophenic compounds exhibited an absorption maximum around 340 nm, which is close to the emission wavelength of a standard nitrogen laser. Consequently these compounds could be used to aid ionization in laser desorption mass spectrometry (MS.

  18. Literature search on Light Water Reactor (LWR) fuel and absorber rod fabrication, 1960--1976

    A literature search was conducted to provide information supporting the design of a conceptual Light Water Reactor (LWR) Fuel Fabrication plant. Emphasis was placed on fuel processing and pin bundle fabrication, effects of fuel impurities and microstructure on performance and densification, quality assurance, absorber and poison rod fabrication, and fuel pin welding. All data have been taken from publicly available documents, journals, and books. This work was sponsored by the Finishing Processes-Mixed Oxide (MOX) Fuel Fabrication Studies program at HEDL

  19. The Influence of Space Environment on Substructure of Light-Absorbing Thermoregulating Al Coatings

    Leonid Skatkov; Petr Cheremskoy; Valeriy Gomozov; Boris Bayrachny; Gennadiy Tulskiy; Svetana Deribo

    2011-01-01

    Porous light-absorbing and thermoregulating low-vacuum aluminum coatings (AC) precipitated by thermal evaporation were the object of this study. The small-angle X-ray scattering (SAXS), electron microscopy, precision hydrostatic weighing, and the dynamical technique for argon low-temperature desorption were used for our investigations. It was shown that AC pore formation in open space (OS) is conditioned by the reduction of molecular flow orienting impact and the increase of the diffusing-vac...

  20. Literature search on Light Water Reactor (LWR) fuel and absorber rod fabrication, 1960--1976

    Sample, C R [comp.

    1977-02-01

    A literature search was conducted to provide information supporting the design of a conceptual Light Water Reactor (LWR) Fuel Fabrication plant. Emphasis was placed on fuel processing and pin bundle fabrication, effects of fuel impurities and microstructure on performance and densification, quality assurance, absorber and poison rod fabrication, and fuel pin welding. All data have been taken from publicly available documents, journals, and books. This work was sponsored by the Finishing Processes-Mixed Oxide (MOX) Fuel Fabrication Studies program at HEDL.

  1. Principles of light energy management

    Davis, N.

    1994-01-01

    Six methods used to minimize excess energy effects associated with lighting systems for plant growth chambers are reviewed in this report. The energy associated with wall transmission and chamber operating equipment and the experimental requirements, such as fresh air and internal equipment, are not considered here. Only the energy associated with providing and removing the energy for lighting is considered.

  2. Synthesis of dumbbell-like Au nanostructure and its light-absorbance study

    Background: By changing the size or the morphology of Au nanostructure, they can absorb different wavelength light due to the localized surface plasmon resonance (LSPR). Because Au nanorods show good ability to transform light into heat (photothermal effect), they have been wildly used to deliver the drugs and release them controllably. However, when applying such nanostructure for in vivo treatments, Au nanorods must have long aspect ratio which often make it hard to prepare heterogeneous nanostructure. Purpose: A new method to synthesize Au nanostructure with uniform size and to achieve long wavelength light absorbance is needed. This work attempts to synthesize such Au nanostructure by using bio-nano techniques. Methods: New nanostructures are prepared by growing Au nanoparticles on the surface of Au nanorods modified with DNA molecules. Results: Dumbbell-Ikea Au nanostructures were prepared firstly. Its maximum absorbance locates at near ultraviolet region, which means that it can be used as a potential tool for the deep-skin photothermal treatment. Moreover, other two kinds of nanostructures, i.e. Au nanorods with Au splinter at two ends and sea urchin-like nanostructures, are also studied. Conclusions: We successfully fabricated novel Au nanostructures which can be used for drug delivery, surface-enhanced Raman spectroscopy and catalysis. (authors)

  3. Material Model Evaluation of a Composite Honeycomb Energy Absorber

    Jackson, Karen E.; Annett, Martin S.; Fasanella, Edwin L.; Polanco, Michael A.

    2012-01-01

    A study was conducted to evaluate four different material models in predicting the dynamic crushing response of solid-element-based models of a composite honeycomb energy absorber, designated the Deployable Energy Absorber (DEA). Dynamic crush tests of three DEA components were simulated using the nonlinear, explicit transient dynamic code, LS-DYNA . In addition, a full-scale crash test of an MD-500 helicopter, retrofitted with DEA blocks, was simulated. The four material models used to represent the DEA included: *MAT_CRUSHABLE_FOAM (Mat 63), *MAT_HONEYCOMB (Mat 26), *MAT_SIMPLIFIED_RUBBER/FOAM (Mat 181), and *MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM (Mat 142). Test-analysis calibration metrics included simple percentage error comparisons of initial peak acceleration, sustained crush stress, and peak compaction acceleration of the DEA components. In addition, the Roadside Safety Verification and Validation Program (RSVVP) was used to assess similarities and differences between the experimental and analytical curves for the full-scale crash test.

  4. Surface-active and Light-absorbing Secondary Organic Aerosol (SOA) Material

    McNeill, V. F.; Sareen, N.; Schwier, A. N.; Shapiro, E. L.

    2009-12-01

    We have observed the formation of light-absorbing, high-molecular-weight, and surface-active organics from methylgyloxal interacting with ammonium salts in aqueous aerosol mimics. Mixtures of methylglyoxal and glyoxal also form light-absorbing products and exhibit surface tension depression with a Langmuir-like dependence on initial methylglyoxal concentration. We used chemical ionization mass spectrometry with a volatilization flow tube inlet (Aerosol-CIMS) to characterize the product species. The results are consistent with aldol condensation products, carbon-nitrogen species, sulfur-containing compounds, and oligomeric species up to 759 amu. These observations have potentially significant implications for our understanding of the effects of SOA on climate, since a) SOA are typically treated as non-absorbing in climate models, and b) surface tension depression in aqueous aerosols by SOA material may result in increased cloud condensation nucleus (CCN) activity. Furthermore, surface film formation could affect aerosol heterogeneous chemistry. We will also discuss aerosol flow tube O3 oxidation experiments designed to determine the atmospheric lifetimes of the observed product compounds.

  5. Energy-donor phosphorescence quenching study of triplet–triplet energy transfer between UV absorbers

    The intermolecular triplet–triplet energy transfer from a photounstable UV-A absorber, 4-tert-butyl-4′-methoxydibenzoylmethane (BMDBM), to UV-B absorbers, 2-ethylhexyl 4-methoxycinnamate (octyl methoxycinnamate, OMC), octocrylene (OCR) and dioctyl 4-methoxybenzylidenemalonate (DOMBM) has been observed using a 355 nm laser excitation in rigid solutions at 77 K. The decay curves of the energy-donor phosphorescence in the presence of the UV-B absorbers deviate from the exponential decay at the initial stage of the decay. The Stern–Volmer formulation is not valid in rigid solutions because molecular diffusion is impossible. The experimental results indicate that the rate constant of triplet–triplet energy transfer from BMDBM to the UV-B absorbers, kT–T, decreases in the following order: kT–T (BMDBM–DOMBM)>kT–T (BMDBM–OMC)≥kT–T (BMDBM–OCR). The presence of DOMBM enhances the photostability of the widely used combination of UV-A and UV-B absorbers, BMDBM and OCR. The effects of the triplet–triplet energy transfer on the photostability of BMDBM are discussed. - Highlights: • The intermolecular triplet–triplet energy transfer between UV absorbers was observed. • The phosphorescence decay deviates from exponential at the initial stage of decay. • The effects of triplet–triplet energy transfer on the photostability are discussed

  6. Energy-donor phosphorescence quenching study of triplet–triplet energy transfer between UV absorbers

    Kikuchi, Azusa; Nakabai, Yuya [Department of Chemistry, Graduate School of Engineering, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan); Oguchi-Fujiyama, Nozomi; Miyazawa, Kazuyuki [Shiseido Research Center, Hayabuchi, Tsuzuki-ku, Yokohama 224-8558 (Japan); Yagi, Mikio, E-mail: yagimiki@ynu.ac.jp [Department of Chemistry, Graduate School of Engineering, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan)

    2015-10-15

    The intermolecular triplet–triplet energy transfer from a photounstable UV-A absorber, 4-tert-butyl-4′-methoxydibenzoylmethane (BMDBM), to UV-B absorbers, 2-ethylhexyl 4-methoxycinnamate (octyl methoxycinnamate, OMC), octocrylene (OCR) and dioctyl 4-methoxybenzylidenemalonate (DOMBM) has been observed using a 355 nm laser excitation in rigid solutions at 77 K. The decay curves of the energy-donor phosphorescence in the presence of the UV-B absorbers deviate from the exponential decay at the initial stage of the decay. The Stern–Volmer formulation is not valid in rigid solutions because molecular diffusion is impossible. The experimental results indicate that the rate constant of triplet–triplet energy transfer from BMDBM to the UV-B absorbers, k{sub T–T}, decreases in the following order: k{sub T–T} (BMDBM–DOMBM)>k{sub T–T} (BMDBM–OMC)≥k{sub T–T} (BMDBM–OCR). The presence of DOMBM enhances the photostability of the widely used combination of UV-A and UV-B absorbers, BMDBM and OCR. The effects of the triplet–triplet energy transfer on the photostability of BMDBM are discussed. - Highlights: • The intermolecular triplet–triplet energy transfer between UV absorbers was observed. • The phosphorescence decay deviates from exponential at the initial stage of decay. • The effects of triplet–triplet energy transfer on the photostability are discussed.

  7. Photosynthesis-Light Response Curve Derived from Light Absorbed in a Leaf : II. Soybean and Corn Plants

    Hirota, Osamu

    1987-01-01

    Using the model proposed in this paper, the linear relationship of incident light with photosynthetic rates of soybean and corn leaves was obtained in low light intensity. In this range, efficiencies of light energy conversion for PhAR were 3.5-9.1 %in soybean and 7.4-16.4 %in corn leaves. The linear relationship between light and Photosynthesis started to deviate at light intensity 0.036-0.078 cal (PhAR)/cm^2 min for soybean and at 0.073-0.116 cal (PhAR)/cm^2 min for corn. Using both these v...

  8. Source attribution of insoluble light-absorbing particles in seasonal snow across northern China

    R. Zhang

    2013-06-01

    Full Text Available Seasonal snow samples obtained at 46 sites in 6 provinces of China in January and February 2010 were analyzed for a suite of chemical species and these data are combined with previously determined concentrations of insoluble light-absorbing particles (ILAP, including all particles that absorb light in the 650–700 nm wavelength interval. The ILAP, together with 14 other analytes, are used as input to a positive matrix factorization (PMF receptor model to explore the sources of ILAP in the snow. The PMF analysis for ILAP sources is augmented with backward trajectory cluster analysis and the geographic locations of major source areas for the three source types. The two analyses are consistent and indicate that three factors/sources were responsible for the measured light absorption of snow: a soil dust source, an industrial pollution source, and a biomass and / or biofuel burning source. Soil dust was the main source of the ILAP, accounting for ~53% of ILAP on average.

  9. Source attribution of light-absorbing impurities in seasonal snow across northern China

    R. Zhang

    2013-01-01

    Full Text Available Seasonal snow samples obtained at 46 sites in 6 provinces of China in January and February 2010 were analyzed for a suite of chemical species and these data are combined with previously determined concentrations of light-absorbing impurities (LAI, including all particles that absorb light in the 650–700 nm wavelength interval. The LAI, together with 14 other analytes, are used as input to a positive matrix factorization (PMF receptor model to explore the sources of the LAI in the snow. The PMF analysis for the LAI sources is augmented with backward trajectory cluster analysis and the geographic locations of major source areas for the three source types. The two analyses are consistent and indicate that three factors/sources were responsible for the measured snow light absorption: a soil dust source, an industrial pollution source, and a biomass and biofuels burning source. Soil dust was the main source of the LAI, accounting for ~ 53% of the LAI on average.

  10. Energy Efficient Task Light

    Logadottir, Asta; Ardkapan, Siamak Rahimi; Johnsen, Kjeld;

    2014-01-01

    only standard components in the prototype, the optimal light distribution for the purpose of meeting the requirements could not be obtained . The light distribution was approximated to the requirements by using combinations of different beam shaping lenses. A final product would benefit from custom...... made lenses, capable of providing the desired light distribution. The user test shows that when working with general lighti ng of 100 lx in the room the developed task lig ht with its wide light distribution provides flexibility in choosing a reading task area on the desk and provides more visibility...

  11. Organic-inorganic hybrid perovskites as light absorbing/hole conducting material in solar cells

    Ghanavi, Saman

    2013-01-01

    Solar cells involving two different perovskites were manufactured and analyzed. The perovskites were (CH3NH3)PbI3 and (CH3NH3)SnI3. Both perovskites have a shared methyl ammonium group (MA) and are used as both light absorbing material and hole conducting material (HTM) in this project. The preparation procedures for the complete device were according to previous attempts to make stable organic-inorganic hybrid perovskites and involved different layers and procedures. Both perovskites were ma...

  12. The Influence of Space Environment on Substructure of Light-Absorbing Thermoregulating Al Coatings

    Leonid Skatkov

    2011-12-01

    Full Text Available Porous light-absorbing and thermoregulating low-vacuum aluminum coatings (AC precipitated by thermal evaporation were the object of this study. The small-angle X-ray scattering (SAXS, electron microscopy, precision hydrostatic weighing, and the dynamical technique for argon low-temperature desorption were used for our investigations. It was shown that AC pore formation in open space (OS is conditioned by the reduction of molecular flow orienting impact and the increase of the diffusing-vacancy mechanism on coatings formation in zero-gravity conditions, which causes the formation of coarse and equiaxed pores with lowered polydispersity levels.

  13. Laser Writing Block Copolymer Self-Assembly on Graphene Light-Absorbing Layer.

    Jin, Hyeong Min; Lee, Seung Hyun; Kim, Ju Young; Son, Seung-Woo; Kim, Bong Hoon; Lee, Hwan Keon; Mun, Jeong Ho; Cha, Seung Keun; Kim, Jun Soo; Nealey, Paul F; Lee, Keon Jae; Kim, Sang Ouk

    2016-03-22

    Recent advance of high-power laser processing allows for rapid, continuous, area-selective material fabrication, typically represented by laser crystallization of silicon or oxides for display applications. Two-dimensional materials such as graphene exhibit remarkable physical properties and are under intensive development for the manufacture of flexible devices. Here we demonstrate an area-selective ultrafast nanofabrication method using low intensity infrared or visible laser irradiation to direct the self-assembly of block copolymer films into highly ordered manufacturing-relevant architectures at the scale below 12 nm. The fundamental principles underlying this light-induced nanofabrication mechanism include the self-assembly of block copolymers to proceed across the disorder-order transition under large thermal gradients, and the use of chemically modified graphene films as a flexible and conformal light-absorbing layers for transparent, nonplanar, and mechanically flexible surfaces. PMID:26871736

  14. Light-absorbing secondary organic material formed by glyoxal in aqueous aerosol mimics

    Shapiro, E. L.; Szprengiel, J.; Sareen, N.; Jen, C. N.; Giordano, M. R.; McNeill, V. F.

    2009-01-01

    Light-absorbing and high-molecular-weight secondary organic products were observed to result from the reaction of glyoxal in mildly acidic (pH=4) aqueous inorganic salt solutions mimicking aqueous tropospheric aerosol particles. High-molecular-weight (500-600 amu) products were observed when ammonium sulfate ((NH4)2SO4) or sodium chloride (NaCl) was present in the aqueous phase. The products formed in the (NH4)2SO4 solutions absorb light at UV and visible wavelengths. Substantial absorption at 300-400 nm develops within two hours, and absorption between 400-600 nm develops within days. Pendant drop tensiometry measurements show that the products are not surface-active. The experimental results along with ab initio predictions of the UV/Vis absorption of potential products suggest that an aldol condensation mechanism is active in the glyoxal-(NH4)2SO4system, resulting in the formation of pi-conjugated products. If similar products are formed in atmospheric aerosol particles, they could change the optical properties of the seed aerosol over its lifetime.

  15. Light-absorbing secondary organic material formed by glyoxal in aqueous aerosol mimics

    E. L. Shapiro

    2009-01-01

    Full Text Available Light-absorbing and high-molecular-weight secondary organic products were observed to result from the reaction of glyoxal in mildly acidic (pH=4 aqueous inorganic salt solutions mimicking aqueous tropospheric aerosol particles. High-molecular-weight (500–600 amu products were observed when ammonium sulfate ((NH42SO4 or sodium chloride (NaCl was present in the aqueous phase. The products formed in the (NH42SO4 solutions absorb light at UV and visible wavelengths. Substantial absorption at 300–400 nm develops within two hours, and absorption between 400–600 nm develops within days. Pendant drop tensiometry measurements show that the products are not surface-active. The experimental results along with ab initio predictions of the UV/Vis absorption of potential products suggest that an aldol condensation mechanism is active in the glyoxal-(NH42SO4system, resulting in the formation of pi-conjugated products. If similar products are formed in atmospheric aerosol particles, they could change the optical properties of the seed aerosol over its lifetime.

  16. Light-absorbing secondary organic material formed by glyoxal in aqueous aerosol mimics

    E. L. Shapiro

    2009-04-01

    Full Text Available Light-absorbing and high-molecular-weight secondary organic products were observed to result from the reaction of glyoxal in mildly acidic (pH=4 aqueous inorganic salt solutions mimicking aqueous tropospheric aerosol particles. High-molecular-weight (500–600 amu products were observed when ammonium sulfate ((NH42SO4 or sodium chloride (NaCl was present in the aqueous phase. The products formed in (NH42SO4 or ammonium nitrate (NH4NO3 solutions absorb light at UV and visible wavelengths. Substantial absorption at 300–400 nm develops within two hours, and absorption between 400–600 nm develops within days. Pendant drop tensiometry measurements show that the products are not surface-active. The experimental results along with ab initio predictions of the UV/Vis absorption of potential products suggest a mechanism involving the participation of the ammonium ion. If similar products are formed in atmospheric aerosol particles, they could change the optical properties of the seed aerosol over its lifetime.

  17. Sources of light-absorbing aerosol in arctic snow and their seasonal variation

    D. A. Hegg

    2010-06-01

    Full Text Available Two data sets consisting of measurements of light absorbing aerosols (LAA in arctic snow together with suites of other corresponding chemical constituents are presented; the first from Siberia, Greenland and near the North Pole obtained in 2008, and the second from the Canadian arctic obtained in 2009. A preliminary differentiation of the LAA into black carbon (BC and non-BC LAA is done. Source attribution of the light absorbing aerosols was done using a positive matrix factorization (PMF model. Four sources were found for each data set (crop and grass burning, boreal biomass burning, pollution and marine. For both data sets, the crops and grass biomass burning was the main source of both LAA species, suggesting the non-BC LAA was brown carbon. Depth profiles at most of the sites allowed assessment of the seasonal variation in the source strengths. The biomass burning sources dominated in the spring but pollution played a more significant (though rarely dominant role in the fall, winter and, for Greenland, summer. The PMF analysis is consistent with trajectory analysis and satellite fire maps.

  18. Sources of light-absorbing aerosol in arctic snow and their seasonal variation

    Dean A. Hegg

    2010-11-01

    Full Text Available Two data sets consisting of measurements of light absorbing aerosols (LAA in arctic snow together with suites of other corresponding chemical constituents are presented; the first from Siberia, Greenland and near the North Pole obtained in 2008, and the second from the Canadian arctic obtained in 2009. A preliminary differentiation of the LAA into black carbon (BC and non-BC LAA is done. Source attribution of the light absorbing aerosols was done using a positive matrix factorization (PMF model. Four sources were found for each data set (crop and grass burning, boreal biomass burning, pollution and marine. For both data sets, the crops and grass biomass burning was the main source of both LAA species, suggesting the non-BC LAA was brown carbon. Depth profiles at most of the sites allowed assessment of the seasonal variation in the source strengths. The biomass burning sources dominated in the spring but pollution played a more significant (though rarely dominant role in the fall, winter and, for Greenland, summer. The PMF analysis is consistent with trajectory analysis and satellite fire maps.

  19. Nanostructured semiconductor solar absorbers with near 100% absorption and related light management picture

    Li, Yali; Gao, Pingqi; Chen, Qiang; Yang, Jiaming; Li, Junshuai; He, Deyan

    2016-06-01

    Optical behaviors of both polycrystalline silicon (Si) and gallium arsenide (GaAs) nanocone (NC)-capped nanowire (NW) arrays are systematically investigated and a full light management picture is presented. The study demonstrates that compared to shape- and environment-sensitive optical resonance modes, including leaky modes and guided longitudinal resonances, optimization of light harvesting based on light scattering is more operable to guide related device fabrication. Under this consideration, near 100% absorption above the bandgap energy is realized for GaAs NC-capped NW arrays with an effective thickness of only ~1000 nm through balancing antireflection and light scattering in the optical systems. Further study under oblique incidence shows that light absorption for the optimized NC-capped NW arrays is almost insensitive to the incident angle, indicating excellent omnidirectional light management in the NC-capped NW configuration.

  20. Nonlinear modeling of magnetorheological energy absorbers under impact conditions

    Mao, Min; Hu, Wei; Choi, Young-Tai; Wereley, Norman M.; Browne, Alan L.; Ulicny, John; Johnson, Nancy

    2013-11-01

    Magnetorheological energy absorbers (MREAs) provide adaptive vibration and shock mitigation capabilities to accommodate varying payloads, vibration spectra, and shock pulses, as well as other environmental factors. A key performance metric is the dynamic range, which is defined as the ratio of the force at maximum field to the force in the absence of field. The off-state force is typically assumed to increase linearly with speed, but at the higher shaft speeds occurring in impact events, the off-state damping exhibits nonlinear velocity squared damping effects. To improve understanding of MREA behavior under high-speed impact conditions, this study focuses on nonlinear MREA models that can more accurately predict MREA dynamic behavior for nominal impact speeds of up to 6 m s-1. Three models were examined in this study. First, a nonlinear Bingham-plastic (BP) model incorporating Darcy friction and fluid inertia (Unsteady-BP) was formulated where the force is proportional to the velocity. Second, a Bingham-plastic model incorporating minor loss factors and fluid inertia (Unsteady-BPM) to better account for high-speed behavior was formulated. Third, a hydromechanical (HM) analysis was developed to account for fluid compressibility and inertia as well as minor loss factors. These models were validated using drop test data obtained using the drop tower facility at GM R&D Center for nominal drop speeds of up to 6 m s-1.

  1. Nonlinear modeling of magnetorheological energy absorbers under impact conditions

    Magnetorheological energy absorbers (MREAs) provide adaptive vibration and shock mitigation capabilities to accommodate varying payloads, vibration spectra, and shock pulses, as well as other environmental factors. A key performance metric is the dynamic range, which is defined as the ratio of the force at maximum field to the force in the absence of field. The off-state force is typically assumed to increase linearly with speed, but at the higher shaft speeds occurring in impact events, the off-state damping exhibits nonlinear velocity squared damping effects. To improve understanding of MREA behavior under high-speed impact conditions, this study focuses on nonlinear MREA models that can more accurately predict MREA dynamic behavior for nominal impact speeds of up to 6 m s−1. Three models were examined in this study. First, a nonlinear Bingham-plastic (BP) model incorporating Darcy friction and fluid inertia (Unsteady-BP) was formulated where the force is proportional to the velocity. Second, a Bingham-plastic model incorporating minor loss factors and fluid inertia (Unsteady-BPM) to better account for high-speed behavior was formulated. Third, a hydromechanical (HM) analysis was developed to account for fluid compressibility and inertia as well as minor loss factors. These models were validated using drop test data obtained using the drop tower facility at GM R and D Center for nominal drop speeds of up to 6 m s−1. (paper)

  2. Light-absorbing particulates in seasonal snow in western North America

    Dang, Cheng

    Commonly found light-absorbing particulates (LAPs) in snow are black carbon (BC), organic carbon (OC), and mineral dust (MD). These LAPs can reduce the very high albedo of snowpack and trigger positive feedback processes, eventually accelerate the snowmelt and hence influence the climate and hydrology. From the January to March of 2013, a field campaign was conducted to study the LAPs in seasonal snow across 13 American states and 3 Canadian Provinces in western North America. We collected and filtered more than 600 snow samples from 67 sites to extract the water-insoluble LAPs in snow, and saved melted snow samples. More than 500 LAP nuclepore samples were analyzed in a spectrophotometer to estimate the light absorption due to LAP samples. This optical analysis also allow us to calculate the absorption Angstrom exponent (A) of LAPs, estimate the BC mixing ratio, and partition the light absorption by BC and non-BC LAPs. About 100 LAP GHP samples were extracted by a serial of chemical solvents to remove OC; then measured in the spectrophotometer to estimate the light absorption changes. The iron concentration was derived from ICP-MS (Inductively Coupled Plasma - Mass Spectroscopy), and was used to estimate the light absorption due to MD. The BC mixing ratio varies from 4--510 ng/g (ng of BC/g of snow), with regional medians vary from 14 ng/g in the Pacific Northwest to 65 ng/g in the Northern Plains. This amount of BC is lower than that found in China, and the LAP in the cleanest sites is as low as that found in the Arctic snow. The regional medians of A vary from 1.6 to 2.6, indicating that BC is not the only LAP in snow. Chemical extractions suggest that methanol-soluble OC (polar OC) and base-soluble HULIS are responsible for 3% and 8% of light absorption by all LAP respectively. They are likely generated from biomass burning or soil. The fractional light absorption produced by OC and HULIS in the Northern Plains is a factor of two higher than that of the other

  3. Self-action of continuous laser radiation and Pearcey diffraction in a water suspension with light-absorbing particles

    Angelsky, O. V.; Bekshaev, A. Ya.; Maksimyak, P. P.; Maksimyak, A. P.; Hanson, Steen Grüner; Zenkova, C. Yu.

    2014-01-01

    Water suspension of light-absorbing nano-sized particles is an example of a medium in which non-linear effects are present at moderate light intensities favorable for optical treatment of organic and biological objects. We study experimentally the phenomena emerging in a thin layer of such a medium...

  4. Sound-absorbing slabs and structures based on granular materials (bound and unbound). [energy absorbing efficiency of porous material

    Petre-Lazar, S.; Popeea, G.

    1974-01-01

    Sound absorbing slabs and structures made up of bound or unbound granular materials are considered and how to manufacture these elements at the building site. The raw material is a single grain powder (sand, expanded blast furnace slag, etc.) that imparts to the end products an apparent porosity of 25-45% and an energy dissipation within the structure leading to absorption coefficients that can be compared with those of mineral wool and urethane.

  5. Research On Solar Energy Collector With Cell Polycarbonate Absorber

    Putāns, Henriks; Zagorska, Viktorija; Ziemelis, Imants; Jesko, Zanis

    2015-01-01

    A flat plate solar collector with cell polycarbonate absorber and transparent cover has been made and its experimental investigation carried out. The collector consists of a wooden box, into which, a layer of heat insulation with a mirror film and 4 mm thick cell polycarbonate sheet, as the absorber, are placed. The coherence between collector’s efficiency, heat carrier and ambient air temperature, as well as intensity of the solar radiation and heat power in the experimental investigation ha...

  6. Potential climatic effects of light absorbing particles over the Third Pole regions

    Ji, Zhenming; Kang, Shichang

    2016-04-01

    Light absorbing particles (LAPs) have important impact on regional climate over the Third Pole regions. Carbonaceous and mineral aerosols, which are considered as the anthropogenic and natural sources respectively, can absorb and scatter incident solar radiation in the atmosphere. Meanwhile, LAPs deposition in snow/ice can also change the surface albedo, resulting in perturbations in the surface radiation balance. However, most studies that have made quantitative assessments of the climatic effect of LAPs over the Third Pole regions did not consider the impact of dust on snow/ice at the surface. In this study, a regional climate model RegCM4.3.4 (Regional Climate Model version 4.3.4) coupled with an aerosol-snow/ice feedback module was used to investigate the emission, distribution, and deposition of carbonaceous and dust aerosols. The study was focused on the two issues: 1) the evaluation of model performance; 2) the assessment of climatic effects induced by carbonaceous and mineral dust aerosols, respectively.

  7. Light Pipe Energy Savings Calculator

    Owens, Erin; Behringer, Ernest R.

    2009-04-01

    Dependence on fossil fuels is unsustainable and therefore a shift to renewable energy sources such as sunlight is required. Light pipes provide a way to utilize sunlight for interior lighting, and can reduce the need for fossil fuel-generated electrical energy. Because consumers considering light pipe installation may be more strongly motivated by cost considerations than by sustainability arguments, an easy means to examine the corresponding costs and benefits is needed to facilitate informed decision-making. The purpose of this American Physical Society Physics and Society Fellowship project is to create a Web-based calculator to allow users to quantify the possible cost savings for their specific light pipe application. Initial calculations show that the illumination provided by light pipes can replace electric light use during the day, and in many cases can supply greater illumination levels than those typically given by electric lighting. While the installation cost of a light pipe is significantly greater than the avoided cost of electricity over the lifetime of the light pipe at current prices, savings may be realized if electricity prices increase.

  8. Disturbance of light-absorbing aerosols on the albedo in a winter snowpack of Central Tibet

    Jing Ming; Pengling Wang; Shuyu Zhao; Pengfei Chen

    2013-01-01

    A field observation on the albedo of the snowpack in Central Tibet was conducted in the Nam Co region in the winter of 2011.Snow properties,including grain size and density,were measured in the field,and surface-layer snow samples (down to 5 cm) were collected.The average concentrations of black carbon and dust were 72 ppbm (close to that in the glaciers of Mt.Nyainqentanglha) and 120 ppmm,respectively.Inverse trends were found to exist between the albedo of the snowpack and light-absorbing aerosols (LAAs) as well as grain size growth.Modeling showed that black carbon,dust,and grain growth in the winter snowpack can reduce the broadband albedo by 11%,28%,and 61%,respectively.

  9. Light absorbing organic aerosols (brown carbon) over the tropical Indian Ocean: impact of biomass burning emissions

    The first field measurements of light absorbing water-soluble organic carbon (WSOC), referred as brown carbon (BrC), have been made in the marine atmospheric boundary layer (MABL) during the continental outflow to the Bay of Bengal (BoB) and the Arabian Sea (ARS). The absorption signal measured at 365 nm in aqueous extracts of aerosols shows a systematic linear increase with WSOC concentration, suggesting a significant contribution from BrC to the absorption properties of organic aerosols. The mass absorption coefficient (babs) of BrC shows an inverse hyperbolic relation with wavelength (from ∼300 to 700 nm), providing an estimate of the Angstrom exponent (αP, range: 3–19; Av: 9 ± 3). The mass absorption efficiency of brown carbon (σabs−BrC) in the MABL varies from 0.17 to 0.72 m2 g−1 (Av: 0.45 ± 0.14 m2 g−1). The αP and σabs−BrC over the BoB are quite similar to that studied from a sampling site in the Indo-Gangetic Plain (IGP), suggesting the dominant impact of organic aerosols associated with the continental outflow. A comparison of the mass absorption efficiency of BrC and elemental carbon (EC) brings to focus the significant role of light absorbing organic aerosols (from biomass burning emissions) in atmospheric radiative forcing over oceanic regions located downwind of the pollution sources. (letter)

  10. Imaging spectroscopy of albedo and radiative forcing by light-absorbing impurities in mountain snow

    Painter, Thomas H.; Seidel, Felix C.; Bryant, Ann C.; McKenzie Skiles, S.; Rittger, Karl

    2013-09-01

    Recent studies show that deposition of dust and black carbon to snow and ice accelerates snowmelt and perturbs regional climate and hydrologic cycles. Radiative forcing by aerosols is often neglected in climate and hydrological models in part due to scarcity of observations. Here we describe and validate an algorithm suite (Imaging Spectrometer-Snow Albedo and Radiative Forcing (IS-SnARF)) that provides quantitative retrievals of snow grain size, snow albedo, and radiative forcing by light-absorbing impurities in snow and ice (LAISI) from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data collected on 15 June 2011 in the Senator Beck Basin Study Area (SBBSA), SW Colorado, USA. Radiative forcing by LAISI is retrieved by the integral of the convolution of spectral irradiance with spectral differences between the spectral albedo (scaled from the observed hemispherical-directional reflectance factor (HDRF)) and modeled clean snow spectral albedo. The modeled surface irradiance at time of acquisition at test sites was 1052 W m-2 compared to 1048 W m-2 measured with the field spectroradiometer measurements, a relative difference of 0.4%. HDRF retrievals at snow and bare soil sites had mean errors relative to in situ measurements of -0.4 ± 0.1% reflectance averaged across the spectrum and root-mean-square errors of 1.5 ± 0.1%. Comparisons of snow albedo and radiative forcing retrievals from AVIRIS with in situ measurements in SBBSA showed errors of 0.001-0.004 and 2.1 ± 5.1 W m-2, respectively. A counterintuitive result was that, in the presence of light absorbing impurities, near-surface snow grain size increased with elevation, whereas we generally expect that at lower elevation the grain size would be larger.

  11. Solution structure of a cyanobacterial phytochrome GAF domain in the red-light-absorbing ground state.

    Cornilescu, Gabriel; Ulijasz, Andrew T; Cornilescu, Claudia C; Markley, John L; Vierstra, Richard D

    2008-11-01

    The unique photochromic absorption behavior of phytochromes (Phys) depends on numerous reversible interactions between the bilin chromophore and the associated polypeptide. To help define these dynamic interactions, we determined by NMR spectroscopy the first solution structure of the chromophore-binding cGMP phosphodiesterase/adenylcyclase/FhlA (GAF) domain from a cyanobacterial Phy assembled with phycocyanobilin (PCB). The three-dimensional NMR structure of Synechococcus OS-B' cyanobacterial Phy 1 in the red-light-absorbing state of Phy (Pr) revealed that PCB is bound to Cys138 of the GAF domain via the A-ring ethylidene side chain and is buried within the GAF domain in a ZZZsyn,syn,anti configuration. The D ring of the chromophore sits within a hydrophobic pocket and is tilted by approximately 80 degrees relative to the B/C rings by contacts with Lys52 and His169. The solution structure revealed remarkable flexibility for PCB and several adjacent amino acids, indicating that the Pr chromophore has more freedom in the binding pocket than anticipated. The propionic acid side chains of rings B and C and Arg101 and Arg133 nearby are especially mobile and can assume several distinct and energetically favorable conformations. Mutagenic studies on these arginines, which are conserved within the Phy superfamily, revealed that they have opposing roles, with Arg101 and Arg133 helping stabilize and destabilize the far-red-light-absorbing state of Phy (Pfr), respectively. Given the fact that the Synechococcus OS-B' GAF domain can, by itself, complete the Pr --> Pfr photocycle, it should now be possible to determine the solution structure of the Pfr chromophore and surrounding pocket using this Pr structure as a framework. PMID:18762196

  12. Thermoelectricity without absorbing energy from the heat sources

    Whitney, Robert S.; Sánchez, Rafael; Haupt, Federica; Splettstoesser, Janine

    2016-01-01

    We analyze the power output of a quantum dot machine coupled to two electronic reservoirs via thermoelectric contacts, and to two thermal reservoirs - one hot and one cold. This machine is a nanoscale analogue of a conventional thermocouple heat-engine, in which the active region being heated is unavoidably also exchanging heat with its cold environment. Heat exchange between the dot and the thermal reservoirs is treated as a capacitive coupling to electronic fluctuations in localized levels, modeled as two additional quantum dots. The resulting multiple-dot setup is described using a master equation approach. We observe an "exotic" power generation, which remains finite even when the heat absorbed from the thermal reservoirs is zero (in other words the heat coming from the hot reservoir all escapes into the cold environment). This effect can be understood in terms of a non-local effect in which the heat flow from heat source to the cold environment generates power via a mechanism which we refer to as Coulomb heat drag. It relies on the fact that there is no relaxation in the quantum dot system, so electrons within it have a non-thermal energy distribution. More poetically, one can say that we find a spatial separation of the first-law of thermodynamics (heat to work conversion) from the second-law of thermodynamics (generation of entropy). We present circumstances in which this non-thermal system can generate more power than any conventional macroscopic thermocouple (with local thermalization), even when the latter works with Carnot efficiency.

  13. Reprint of : Thermoelectricity without absorbing energy from the heat sources

    Whitney, Robert S.; Sánchez, Rafael; Haupt, Federica; Splettstoesser, Janine

    2016-08-01

    We analyze the power output of a quantum dot machine coupled to two electronic reservoirs via thermoelectric contacts, and to two thermal reservoirs - one hot and one cold. This machine is a nanoscale analogue of a conventional thermocouple heat-engine, in which the active region being heated is unavoidably also exchanging heat with its cold environment. Heat exchange between the dot and the thermal reservoirs is treated as a capacitive coupling to electronic fluctuations in localized levels, modeled as two additional quantum dots. The resulting multiple-dot setup is described using a master equation approach. We observe an "exotic" power generation, which remains finite even when the heat absorbed from the thermal reservoirs is zero (in other words the heat coming from the hot reservoir all escapes into the cold environment). This effect can be understood in terms of a non-local effect in which the heat flow from heat source to the cold environment generates power via a mechanism which we refer to as Coulomb heat drag. It relies on the fact that there is no relaxation in the quantum dot system, so electrons within it have a non-thermal energy distribution. More poetically, one can say that we find a spatial separation of the first-law of thermodynamics (heat to work conversion) from the second-law of thermodynamics (generation of entropy). We present circumstances in which this non-thermal system can generate more power than any conventional macroscopic thermocouple (with local thermalization), even when the latter works with Carnot efficiency.

  14. A review on the performance of conventional and energy-absorbing rockbolts

    Charlie C.Li; Gisle Stjern; Arne Myrvang

    2014-01-01

    This is a review paper on the performances of both conventional and energy-absorbing rockbolts manifested in laboratory tests. Characteristic parameters such as ultimate load, displacement and energy absorption are reported, in addition to loadedisplacement graphs for every type of rockbolt. Conven-tional rockbolts refer to mechanical rockbolts, fully-grouted rebars and frictional rockbolts. According to the test results, under static pull loading a mechanical rockbolt usually fails at the plate;a fully-grouted rebar bolt fails in the bolt shank at an ultimate load equal to the strength of the steel after a small amount of displacement;and a frictional rockbolt is subjected to large displacement at a low yield load. Under shear loading, all types of bolts fail in the shank. Energy-absorbing rockbolts are developed aiming to combat instability problems in burst-prone and squeezing rock conditions. They absorb deformation energy either through ploughing/slippage at predefined load levels or through stretching of the steel bolt. An energy-absorbing rockbolt can carry a high load and also accommodate significant rock displacement, and thus its energy-absorbing capacity is high. The test results show that the energy absorption of the energy-absorbing bolts is much larger than that of all conventional bolts. The dynamic load capacity is smaller than the static load capacity for the energy-absorbing bolts displacing based on ploughing/slippage while they are approximately the same for the D-Bolt that displaces based on steel stretching.

  15. From fast to slow light in a resonantly driven absorbing medium

    We theoretically study the propagation through a resonant absorbing medium of a time-dependent perturbation modulating the amplitude of a continuous wave (cw). Modeling the medium as a two-level system and linearizing the Maxwell-Bloch equations for the perturbation, we establish an exact analytical expression of the transfer function relating the Fourier transforms of the incident and transmitted perturbations. It directly gives the gain and the phase shift undergone in the medium by a harmonic modulation. For the case of a pulse modulation, it enables us to determine the transmission time of the pulse center of mass (group delay), evidencing the relative contributions of the coherent and incoherent (population) relaxations. We show that the group delay has a negative value (fast light) fixed by the coherent effects when the cw intensity is small compared to the saturation intensity and becomes positive (slow light) when this intensity increases, before attaining a maximum that cannot exceed the population relaxation time. The analytical results are completed by numerical determinations of the shape of the transmitted pulses in the different regimes.

  16. Secondary organic material formed by methylglyoxal in aqueous aerosol mimics - Part 1: Surface tension depression and light-absorbing products

    Schwier, A. N.; Shapiro, E. L.; Sareen, N.; McNeill, V. F.

    2009-07-01

    We show that methylglyoxal forms light-absorbing secondary organic material in aqueous ammonium sulfate and ammonium nitrate solutions mimicking tropospheric aerosol particles. The light-absorbing products form on the order of minutes, and solution composition continues to change over several days. The results suggest an aldol condensation pathway involving the participation of the ammonium ion. Aqueous solutions of methylglyoxal, with and without inorganic salts, exhibit surface tension depression. Methylglyoxal uptake could potentially change the optical properties, climate effects, and heterogeneous chemistry of the seed aerosol over its lifetime.

  17. Impact resistance of fiber composites - Energy-absorbing mechanisms and environmental effects

    Chamis, C. C.; Sinclair, J. H.

    1985-01-01

    Energy absorbing mechanisms were identified by several approaches. The energy absorbing mechanisms considered are those in unidirectional composite beams subjected to impact. The approaches used include: mechanic models, statistical models, transient finite element analysis, and simple beam theory. Predicted results are correlated with experimental data from Charpy impact tests. The environmental effects on impact resistance are evaluated. Working definitions for energy absorbing and energy releasing mechanisms are proposed and a dynamic fracture progression is outlined. Possible generalizations to angle-plied laminates are described.

  18. Bottom Slamming on Heaving Point Absorber Wave Energy Devices

    De Backer, Griet; Vantorre, Marc; Frigaard, Peter;

    2010-01-01

    Oscillating point absorber buoys may rise out of the water and be subjected to bottom slamming upon re-entering the water. Numerical simulations are performed to estimate the power absorption, the impact velocities and the corresponding slamming forces for various slamming constraints. Three buoy...

  19. Development of methodology for assessment of absorbed dose and stopping power for low energy conversion electrons

    The evaluation of absorbed dose in the case of external and internal contamination due to radionuclides is sometimes hard, because of the difficulties in the assessment of the absorbed dose caused by electrons with energy less than 100 KeV in mucous membrane. In this work, a methodology for assessment of absorbed dose and stopping power in VYNS (co-polymer of polivinyl chloride - acetate) absorbers, for the 62.5 KeV and 84-88 KeV energy 109 Cd conversion electrons, working with a 4 π proportional pressurized detector, is presented. In order to assure the reproducibility of measurement conditions, one of the detector halves has been used to obtain a spectrum of a thin 109 Cd source, without absorber. The other half of the detector was used in concomitance to obtain spectra with different thicknesses if absorber. The absorbed energy was obtained subtracting each spectrum with absorber from the spectrum without absorber, which were stored in a microcomputer connected to signal processing systems by ACE type interface. The VYNS weight and thickness were evaluated using common radionuclide metrology procedures. As VYNS has characteristics similar to a tissue equivalent material, the results obtained are consistent with dosimetric concepts and have a good agreement with those of the literature. (author)

  20. Specific Energy Absorbed Study Of Aluminum (2024-351T Tubes Alloy Under Lateral Crush

    Ayad Arab Ghaidan

    2013-04-01

    Full Text Available This paper aims to find SEA (Specific Energy Absorber for lateral crushing (statically behavior for Aluminum (2024-T351 alloy with difference lengths (10, 20, and 30 mm. An experimental, finite element simulation, and theoretical models present to find force-deformation curves and then find SEA for difference lengths. Experimental results more agreements with finite elements simulation and theoretical when length of tubes is increase for load deformation curve, because when the length increases the plastic region increase with initial plastic collapse load (Pc. The experimental, ANSYS simulation and theoretical results have plotted and it has seen that the theory also underestimates the ANSYS results because in theoretical model, is customary to assume that the material is perfectly plastic, therefore, the finite element simulation might predict the experimental results better than the theoretical one. The results show that light density Aluminum alloy is suitable for SEA.

  1. 2004: Finite-Difference Time Domain Solution of Light Scattering by an Infinite Dielectric Column Immersed in an Absorbing Medium

    Sun, W.; Loeb, N. G.; Tanev, S.; Videen, G.

    2004-01-01

    The two-dimensional (2-D) finite-difference time domain (FDTD) method is applied to calculate light scattering and absorption by an arbitrarily shaped infinite column embedded in an absorbing dielectric medium. A uniaxial perfectly matched layer (UPML) absorbing boundary condition (ABC) is used to truncate the computational domain. The single-scattering properties of the infinite column embedded in the absorbing medium, including scattering phase functions, extinction and absorption efficiencies, are derived using an area integration of the internal field. An exact solution for light scattering and absorption by a circular cylinder in an absorbing medium is used to examine the accuracy of the 2-D UPML FDTD code. With use of a cell size of 1/120 incident wavelength in the FDTD calculations, the errors in the extinction and absorption efficiencies and asymmetry factors from the 2-D UPML FDTD are generally smaller than approx .1%. The errors in the scattering phase functions are typically smaller than approx .4%. Using the 2-D UPML FDTD technique, light scattering and absorption by long noncircular columns embedded in absorbing media can be accurately solved.

  2. Chromophore absorbance change quantification in tissue during low-level light therapy

    Huynh, Daniel; Chung, Christine; Qian, Li; Lilge, Lothar

    2012-03-01

    Low Level Light Therapy (LLLT) has been implicated to stimulate tissue, promoting healing and reducing pain. One of the potential pathways stimulated by LLLT relates to the electron transport chain, where photon quantum energy can induce a change in the biochemical reactions within the cell. The aim of this study is to assess the feasibility to exploit light additionally as a diagnostic tool to determine tissue physiological states, particularly in quantifying the changes in redox states of Cytochrome C as a result of induced LLLT biochemical reactions.

  3. Energy Efficiency Through Lighting Upgrades

    Berst, Kara [Chickasaw Nation, Ada, OK (United States); Howeth, Maria [Chickasaw Nation, Ada, OK (United States)

    2013-02-26

    Lighting upgrades including neon to LED, incandescent to CFL's and T-12 to T-8 and T-5's were completed through this grant. A total of 16 Chickasaw nation facilities decreased their carbon footprint because of these grant funds. Calculations used were based on comparing the energy usage from the previous year's average and the current energy usage. For facilities without a full year's set of energy bills, the month after installation was compared to the same month from the previous year. Overall, the effect the lighting change-outs had for the gaming centers and casinos far exceeded expectations. For the Madill Gaming Center; both an interior and exterior upgrade was performed which resulted in a 31% decrease in energy consumption. This same reduction was seen in every facility that participated in the grant. Just by simply changing out light bulbs to newer energy efficient equivalents, a decrease in energy usage can be achieved and this was validated by the return on investment seen at Chickasaw Nation facilities. Along with the technical project tasks were awareness sessions presented at Chickasaw Head Starts. The positive message of environmental stewardship was passed down to head start students and passed along to Chickasaw employees. Excitement was created in those that learned what they could do to help reduce their energy bills and many followed through and took the idea home. For a fairy low cost, the general public can also use this technique to lower their energy consumption both at home and at work. Although the idea behind the project was somewhat simple, true benefits have been gained through environmental awareness and reductions of energy costs.

  4. Energy Star Lighting Verification Program

    Conan O' Rourke; Yutao Zhou

    2006-09-30

    The Program for the Evaluation and Analysis of Residential Lighting (PEARL) is a watchdog program. It was created in response to complaints received by utility program managers about the performance of certain Energy Star lighting products being promoted within their service territories and the lack of a self-policing mechanism within the lighting industry that would ensure the reliability of these products and their compliance with ENERGY STAR specifications. To remedy these problems, PEARL purchases and tests products that are available to the consumers in the marketplace. The Lighting Research Center (LRC) tests the selected products against the corresponding Energy Star specifications. This report includes the experimental procedure and results of Cycle Seven of PEARL program during the period of April 2006 to September 2006, along with the description of apparatus used, equipment calibration process, experimental methodology, and research findings from the testing. LRC continued receiving the CFL samples purchased by sponsors and finished performing the sphere testing for all CFL models at 100 hours of life. After that LRC aged the CFL samples to 1000 hours of life, and then performed sphere testing for all CFL models at 1000 hours of life. Then the CFLs were placed on the test rack to be aged to 40% of their rated life. Rapid Cycle Stress Test was also performed for all models using different sets of CFL samples.

  5. Energy Star Lighting Verification Program

    Conan O' Rourke; Yutao Zhou

    2007-03-31

    The Program for the Evaluation and Analysis of Residential Lighting (PEARL) is a watchdog program. It was created in response to complaints received by utility program managers about the performance of certain Energy Star lighting products being promoted within their service territories and the lack of a self-policing mechanism within the lighting industry that would ensure the reliability of these products and their compliance with ENERGY STAR specifications. To remedy these problems, PEARL purchases and tests products that are available to the consumers in the marketplace. The Lighting Research Center (LRC) tests the selected products against the corresponding Energy Star specifications. This report includes the experimental procedure and results of Cycle Seven and Cycle Eight of PEARL program during the period of October 2006 to March 2007, along with the description of apparatus used, equipment calibration process, experimental methodology, and research findings from the testing. LRC finished performing the sphere testing for all CFL models in Cycle Seven at 40% of their rated life. LRC also performed re-test of Rapid Cycle Stress Test, under the request of DOE, for five CFL models that failed the Rapid Cycle Stress Test in Cycle Seven. From January 2007 to March 2007, LRC coordinated the procuring efforts for the CFL models that were selected for Cycle Eight.

  6. Finite-Difference Time Domain Solution of Light Scattering and Absorption by Particles in an Absorbing Medium

    Sun, W.; Loeb, N. G.; Fu, Q.

    2002-01-01

    The three-dimensional (3-D) finite-difference time-domain (FDTD) technique has been extended to simulate light scattering and absorption by nonspherical particles embedded in an absorbing dielectric medium. A uniaxial perfectly matched layer (UPML) absorbing boundary condition is used to truncate the computational domain. When computing the single-scattering properties of a particle in an absorbing dielectric medium, we derive the single-scattering properties including scattering phase functions, extinction, and absorption efficiencies using a volume integration of the internal field. A Mie solution for light scattering and absorption by spherical particles in an absorbing medium is used to examine the accuracy of the 3-D UPML FDTD code. It is found that the errors in the extinction and absorption efficiencies from the 3-D UPML FDTD are less than similar to 2%. The errors in the scattering phase functions are typically less than similar to 5%. The errors in the asymmetry factors are less than similar to 0.l%. For light scattering by particles in free space, the accuracy of the 3-D UPML FDTD scheme is similar to a previous model.

  7. Submicron-resolution photoacoustic microscopy of endogenous light-absorbing biomolecules

    Zhang, Chi

    Photoacoustic imaging in biomedicine has the unique advantage of probing endogenous light absorbers at various length scales with a 100% relative sensitivity. Among the several modalities of photoacoustic imaging, optical-resolution photoacoustic microscopy (OR-PAM) can achieve high spatial resolution, on the order of optical wavelength, at high spatial resolution in 3D. The lateral resolution was improved by using optical objectives with high numerical apertures for optical focusing. The axial resolution was improved by using broadband ultrasonic transducers for ultrasound detection. We achieved 220 nm lateral resolution in transmission mode, 0.43 microm lateral resolution in reflection mode, 7.6 microm axial resolution in normal tissue, and 5.8 microm axial resolution with silicone oil immersion/injection. The achieved lateral resolution and axial resolution were the finest reported at the time. With high-resolution in 3D, PAM was demonstrated to resolve cellular and subcellular structures in vivo, such as red blood cells and melanosomes in melanoma cells. Compared with previous PAM systems, our high-resolution PAM could resolve capillaries in mouse ears more clearly. As an example application, we demonstrated intracellular temperature imaging, assisted by fluorescence signal detection, with sub-degree temperature resolution and sub-micron lateral resolution. The second part of this dissertation describes the exploration of endogenous light-absorbing biomolecules for PAM. We demonstrated cytochromes and myoglobin as new absorption contrasts for PAM and identified the corresponding optimal wavelengths for imaging. Fixed fibroblasts on slides and mouse ear sections were imaged by PAM at 422 nm and 250 nm wavelengths to reveal cytoplasms and nuclei, respectively, as confirmed by standard hematoxylin and eosin (H&E) histology. By imaging a blood-perfused mouse heart at 532 nm down to 150 microm in depth, we derived the myocardial sheet thickness and the cleavage

  8. A review on the performance of conventional and energy-absorbing rockbolts

    Charlie C. Li

    2014-08-01

    Full Text Available This is a review paper on the performances of both conventional and energy-absorbing rockbolts manifested in laboratory tests. Characteristic parameters such as ultimate load, displacement and energy absorption are reported, in addition to load–displacement graphs for every type of rockbolt. Conventional rockbolts refer to mechanical rockbolts, fully-grouted rebars and frictional rockbolts. According to the test results, under static pull loading a mechanical rockbolt usually fails at the plate; a fully-grouted rebar bolt fails in the bolt shank at an ultimate load equal to the strength of the steel after a small amount of displacement; and a frictional rockbolt is subjected to large displacement at a low yield load. Under shear loading, all types of bolts fail in the shank. Energy-absorbing rockbolts are developed aiming to combat instability problems in burst-prone and squeezing rock conditions. They absorb deformation energy either through ploughing/slippage at predefined load levels or through stretching of the steel bolt. An energy-absorbing rockbolt can carry a high load and also accommodate significant rock displacement, and thus its energy-absorbing capacity is high. The test results show that the energy absorption of the energy-absorbing bolts is much larger than that of all conventional bolts. The dynamic load capacity is smaller than the static load capacity for the energy-absorbing bolts displacing based on ploughing/slippage while they are approximately the same for the D-Bolt that displaces based on steel stretching.

  9. A new thermal radiation detector using optical heterodyne detection of absorbed energy

    Davis, C. C.; Petuchowski, S. J.

    1983-01-01

    The operating principles of a new kind of room-temperature thermal radiation detector are described. In this device modulated light heats a gas, either directly or by conduction from a thin absorbing membrane, and the resultant change in density of the gas is detected by optical heterodyning. The performance of a membrane device of this kind agrees well with the predictions of theory.

  10. Synthesis and properties of polyamide–Ag2S composite based solar energy absorber surfaces

    Krylovaa, Valentina; Baltrusaitis, Jonas

    2013-01-01

    Silver sulfide (Ag2S), an efficient solar light absorber, was synthesized using a modified chemical bath deposition (CBD) method and polyamide 6 (PA) as a host material via solution phase reaction between AgNO3 and Na2S2O3. X-ray diffraction (XRD) data showed a single, α-Ag2S (acanthite), crystallin

  11. Effectiveness of the light absorber on different parts of beta-spectrum

    This work describes the researches of absorbent characteristics of integument tissues. This question is dominant on the stage of elaboration of algorithm of determination of physical characteristics of heterogeneous system - humans skull. (authors)

  12. Stowable Energy-Absorbing Rocker-Bogie Suspensions

    Harrington, Brian; Voorhees, Christopher

    2007-01-01

    A report discusses the design of the rocker-bogie suspensions of the Mars Exploration Rover vehicles, which were landed on Mars in January 2004. Going beyond the basic requirements regarding mobility on uneven terrain, the design had to satisfy requirements (1) to enable each suspension to contort so that the rover could be stowed within limited space in a tetrahedral lander prior to deployment and (2) that the suspension be able to absorb appreciable impact loads, with limited deflection, during egress from the lander and traversal of terrain. For stowability, six joints (three on the right, three on the left) were added to the basic rocker-bogie mechanism. One of the joints on each side was a yoke-and-clevis joint at the suspension/differential interface, one was a motorized twist joint in the forward portion of the rocker, and one was a linear joint created by modifying a fixed-length bogie member into a telescoping member. For absorption of impact, the structural members were in the form of box beams made by electron-beam welding of machined, thin-walled, C-channel, titanium components. The box beams were very lightweight and could withstand high bending and torsional loads.

  13. Linearity evaluation in absorbance detection: the use of light-emitting diodes for on-capillary detection in capillary electrophoresis.

    Macka, M; Andersson, P; Haddad, P R

    1996-12-01

    A model which takes into account both stray light and polychromatic light was used to predict and evaluate linearity in on-capillary detection in capillary electrophoresis (CE). According to the model the stray light is the major factor which determines linearity under typical CE operating conditions. By calculating theoretical absorbance versus concentration plots, the influence of different levels of stray light and polychromatic light on linearity is demonstrated. Experimentally, six light-emitting diodes (LEDs) in the range from 563 to 654 nm were examined as light sources for on-capillary detection in CE. Fitting theoretical curves to measured linearity plots enabled determination of the values of both effective path length and stray light for a particular detection system. The detector linearity for the four LEDs was compared to mercury and tungsten lamps used with interference filters. For potassium permanganate as the test compound, the linear range for a 563 nm LED was two times greater than that for a mercury lamp operated at 546 nm. The relatively poor linearity of the mercury lamp detector is explained by its high level of stray light. The noise of the LED563-based detector was the same as for the mercury lamp, whereas the other LEDs of higher light intensity gave approximately half the noise of the mercury lamp. The lowest noise level of 3 x 10(-5) AU was obtained for the LED at 554 nm (determined at a detector time constant of 0.1 s). PMID:9034772

  14. Absorber materials for low-energy neutrons - Theoretical and experimental studies

    Absorber materials for low-energy neutrons are studied in the theoretical framework of quantum mechanics with a complex potential. Analytical expressions and numerical calculations of the neutron reflectivity for perpendicular and isotropic motion towards a surface for four different material classes are presented. Comparative experimental studies of four absorber materials have been carried out: Polyethylene, titanium, boron-10 and lithium stearate. In a quasi-storage experiment with ultracold neutrons the latter material features the highest absorption property.

  15. Synthesis of Numerical Methods for Modeling Wave Energy Converter-Point Absorbers: Preprint

    Li, Y.; Yu, Y. H.

    2012-05-01

    During the past few decades, wave energy has received significant attention among all ocean energy formats. Industry has proposed hundreds of prototypes such as an oscillating water column, a point absorber, an overtopping system, and a bottom-hinged system. In particular, many researchers have focused on modeling the floating-point absorber as the technology to extract wave energy. Several modeling methods have been used such as the analytical method, the boundary-integral equation method, the Navier-Stokes equations method, and the empirical method. However, no standardized method has been decided. To assist the development of wave energy conversion technologies, this report reviews the methods for modeling the floating-point absorber.

  16. Energy loss by resonance line photons in an absorbing medium

    Hummer, D. G.; Kunasz, P. B.

    1980-01-01

    The mean path length of photons undergoing repeated scatterings in media of large optical thickness is calculated from accurate numerical solutions of the transfer equation including the effect of frequency redistribution characteristic of combined Doppler and natural broadening. Energy loss by continuous absorption processes, such as ionization or dust absorption, is discussed, and asymptotic scaling laws for the energy loss, the mean path length, and the mean number of scatterings are inferred from the numerical data.

  17. Measurement of absorbed energy during radiation solidification of polyester coatings on wood

    Calculated and experimental data are given of the absorbed energy dose distribution in the polyester film and wood during the irradiation of polyester coatings on the wood by an accelerated election beam with the aid of accelerator with a sinusoidal modulated beam. The measurement of the absorbed energy allows to solve the problem on the energy distribution of the electron beam between the coating and the base, on the choice of coating thickness. The results of the investigation have been utilized in the development of radiation technology of polyester hardening on the wood

  18. Simultaneous measurements of absorbed dose and linear energy transfer in therapeutic proton beams

    Granville, Dal A.; Sahoo, Narayan; Sawakuchi, Gabriel O.

    2016-02-01

    The biological response resulting from proton therapy depends on both the absorbed dose in the irradiated tissue and the linear energy transfer (LET) of the beam. Currently, optimization of proton therapy treatment plans is based only on absorbed dose. However, recent advances in proton therapy delivery have made it possible to vary the LET distribution for potential therapeutic gain, leading to investigations of using LET as an additional parameter in plan optimization. Having a method to measure and verify both absorbed dose and LET as part of a quality assurance program would be ideal for the safe delivery of such plans. Here we demonstrated the potential of an optically stimulated luminescence (OSL) technique to simultaneously measure absorbed dose and LET. We calibrated the ratio of ultraviolet (UV) to blue emission intensities from Al2O3:C OSL detectors as a function of LET to facilitate LET measurements. We also calibrated the intensity of the blue OSL emission for absorbed dose measurements and introduced a technique to correct for the LET-dependent dose response of OSL detectors exposed to therapeutic proton beams. We demonstrated the potential of our OSL technique by using it to measure LET and absorbed dose under new irradiation conditions, including patient-specific proton therapy treatment plans. In the beams investigated, we found the OSL technique to measure dose-weighted LET within 7.9% of Monte Carlo-simulated values and absorbed dose within 2.5% of ionization chamber measurements.

  19. The Development of a Conical Composite Energy Absorber for Use in the Attenuation of Crash/Impact Loads

    Littell, Justin D.

    2014-01-01

    A design for a novel light-weight conical shaped energy absorbing (EA) composite subfloor structure is proposed. This composite EA is fabricated using repeated alternating patterns of a conical geometry to form long beam structures which can be implemented as aircraft subfloor keel beams or frame sections. The geometrical features of this conical design, along with the hybrid composite materials used in the manufacturing process give a strength tailored to achieve a constant 25-40 g sustained crush load, small peak crush loads and long stroke limits. This report will discuss the geometrical design and fabrication methods, along with results from static and dynamic crush testing of 12-in. long subcomponents.

  20. An implementation of ionisation energy loss in very thin absorbers for the GEANT4 simulation package

    Apostolakis, John; Urbàn, L; Maire, M; Bagulya, A V; Grichine, V M

    2000-01-01

    We discuss an implementation of Photo Absorption Ionisation model describing ionisation energy loss produced by a relativistic charged particle in very thin absorbers. The implementation allows us to calculate ionisation energy losses in any material consisting of elements with atomic numbers in the range 1-100. Comparisons of simulation with the experimental data from gaseous and solid state detectors are presented. (24 refs).

  1. Secondary absorbed doses from light ion irradiation in anthropomorphic phantoms representing an adult male and a 10 year old child

    Secondary organ absorbed doses were calculated by Monte Carlo simulations with the SHIELD-HIT07 code coupled with the mathematical anthropomorphic phantoms CHILD-HIT and ADAM-HIT. The simulated irradiations were performed with primary 1H, 4He, 7Li, 12C and 16O ion beams in the energy range 100-400 MeV/u which were directly impinging on the phantoms, i.e. approximating scanned beams, and with a simplified beamline for 12C irradiation. The evaluated absorbed doses to the out-of-field organs were in the range 10-6 to 10-1 mGy per target Gy and with standard deviations 0.5-20%. While the contribution to the organ absorbed doses from secondary neutrons dominated in the ion beams of low atomic number Z, the produced charged fragments and their subsequent charged secondaries of higher generations became increasingly important for the secondary dose delivery as Z of the primary ions increased. As compared to the simulated scanned 12C ion beam, the implementation of a simplified beamline for prostate irradiation with 12C ions resulted in an increase of 2-50 times in the organ absorbed doses depending on the distance from the target volume. Comparison of secondary organ absorbed doses delivered by 1H and 12C beams showed smaller differences when the RBE for local tumor control of the ions was considered and normalization to the RBE-weighted dose to the target was performed.

  2. Energy Transfer in Light-Adapted Photosynthetic Membranes: From Active to Saturated Photosynthesis

    Fassioli, Francesca; Olaya-Castro, Alexandra; Scheuring, Simon; Sturgis, James N.; Neil F. Johnson

    2009-01-01

    In bacterial photosynthesis light-harvesting complexes, LH2 and LH1 absorb sunlight energy and deliver it to reaction centers (RCs) with extraordinarily high efficiency. Submolecular resolution images have revealed that both the LH2:LH1 ratio, and the architecture of the photosynthetic membrane itself, adapt to light intensity. We investigate the functional implications of structural adaptations in the energy transfer performance in natural in vivo low- and high-light-adapted membrane archite...

  3. Pipes as energy absorbers for dynamic loads in nuclear power plants

    Pipes can also be utilized in nuclear power plants as energy absorbers to limit dynamic loads on the structures to an admissible value by means of plastic deformation. Two cases will be presented in this paper: 1. A deforming device consisting of a pipe element in which six plastic hinges appear when the load is applied at certain points of it. The load-deflection curve of this energy absorber is approximately ideal elastic-plastic and consequently the reaction load has the smallest value for a given amount of energy to be absorbed by that device. Static and dynamic tests were performed on the device. Theoretical formulae will be presented in this paper for the load-deflection curve. 2. A calculation method for determining the local deformation and of the deformation load of a protective pipe supported at its ends and loaded by a force caused by an impacting object. (orig.)

  4. Thermoluminescent dosemeters for determining the energy absorbed during X-ray radiography of the vertebral column

    The dose and absorbed energy during normal diagnostic X-ray of various sections of the vertebral column were determined with LiF-dosemeters in a phantom. The paper describes a method to be used to determine integral doses from the dose measurements. The energy absorbed for one X-ray picture of the vertebral column is between 5 and 30 mJ. Compared to other diagnostical X-rays the quantity of the energy absorbed during X-ray of the vertebral column is rather high and is only reached by X-rays in the pelvic region. The speculations on the rate of incidence of malignent neoplasms on the basis of diagnostical X-ray of the vertebral column reveal a value of 50 per 60 x 106 persons. This value is likely to overestimate the risk, seems, however, to be low in comparison to other risks of every day life (traffic accident, mountainering, etc). (orig./HP)

  5. Multi-Level Experimental and Analytical Evaluation of Two Composite Energy Absorbers

    Jackson, Karen E.; Littell, Justin D.; Fasanella, Edwin L.; Annett, Martin S.; Seal, Michael D., II

    2015-01-01

    Two composite energy absorbers were developed and evaluated at NASA Langley Research Center through multi-level testing and simulation performed under the Transport Rotorcraft Airframe Crash Testbed (TRACT) research program. A conical-shaped energy absorber, designated the conusoid, was evaluated that consisted of four layers of hybrid carbon-Kevlar plain weave fabric oriented at [+45 deg/-45 deg/-45 deg/+45 deg] with respect to the vertical, or crush, direction. A sinusoidal-shaped energy absorber, designated the sinusoid, was developed that consisted of hybrid carbon-Kevlar plain weave fabric face sheets, two layers for each face sheet oriented at +/-45deg with respect to the vertical direction and a closed-cell ELFOAM P200 polyisocyanurate (2.0-lb/cu ft) foam core. The design goal for the energy absorbers was to achieve average floor-level accelerations of between 25- and 40-g during the full-scale crash test of a retrofitted CH-46E helicopter airframe, designated TRACT 2. Variations in both designs were assessed through dynamic crush testing of component specimens. Once the designs were finalized, subfloor beams of each configuration were fabricated and retrofitted into a barrel section of a CH-46E helicopter. A vertical drop test of the barrel section was conducted onto concrete to evaluate the performance of the energy absorbers prior to retrofit into TRACT 2. The retrofitted airframe was crash tested under combined forward and vertical velocity conditions onto soil, which is characterized as a sand/clay mixture. Finite element models were developed of all test articles and simulations were performed using LS-DYNA, a commercial nonlinear explicit transient dynamic finite element code. Test-analysis results are presented for each energy absorber as comparisons of time-history responses, as well as predicted and experimental structural deformations and progressive damage under impact loading for each evaluation level.

  6. Secondary brown carbon - Formation of light-absorbing compounds in atmospheric particulates from selected dicarbonyls and amines

    Kampf, Christopher; Filippi, Alexander; Hoffmann, Thorsten

    2015-04-01

    One of the main open questions regarding organic compounds in atmospheric chemistry today is related to the formation of optically-active compounds and the occurrence of so called brown carbon (Andreae and Gelencsér, 2006). While organic compounds in ambient fine particles for decades have been assumed to not absorb solar radiation, thus resulting in a net cooling effect on climate (IPCC, 2007), it is now generally accepted that a continuum of light-absorbing carbonaceous species is present in fine aerosols (Pöschl, 2003). In this study, light-absorbing compounds from reactions between dicarbonyl compounds, i.e., glyoxal, methylglyoxal, acetylacetone, 2,3-butanedione, 2,5-hexanedione, and glutaraldehyde, and amine species, i.e., ammonia and glycine, were investigated at atmospherically relevant concentrations in bulk solution experiments mimicking atmospheric particulates. Product analyses were performed using UV/Vis spectrophotometry and (ultra) high performance liquid chromatography coupled to diode array detection and ion trap mass spectrometry (HPLC-DAD-ESI-MS/MS), as well as ultra-high resolution (Orbitrap) mass spectrometry (UHPLC-ESI-HRMS/MS). We demonstrate that light-absorbing compounds are formed from a variety of atmospherically relevant dicarbonyls via particle phase reactions with amine nucleophiles. Single dicarbonyl and mixed dicarbonyl experiments were performed and products were analyzed. The reaction products are suggested to be cyclic nitrogen containing compounds such as imidazoles or dihydropyridines as well as open chain compounds resulting from aldol condensation reactions. Further, the reactive turnover was found to be higher at increasing pH values. The aforementioned processes may be of higher relevance in regions with high aerosol pH, e.g., resulting from high ammonia emissions as for example in northern India (Clarisse et al., 2009). References Andreae, M.O., and Gelencsér, A. (2006): Black carbon or brown carbon? The nature of light-absorbing

  7. Optimisation of energy absorbing liner for equestrian helmets. Part II: Functionally graded foam liner

    The energy absorbing liner of safety helmets was optimised using finite element modelling. In this present paper, a functionally graded foam (FGF) liner was modelled, while keeping the average liner density the same as in a corresponding reference single uniform density liner model. Use of a functionally graded foam liner would eliminate issues regarding delamination and crack propagation between interfaces of different density layers which could arise in liners with discrete density variations. As in our companion Part I paper [Forero Rueda MA, Cui L, Gilchrist MD. Optimisation of energy absorbing liner for equestrian helmets. Part I: Layered foam liner. Mater Des [submitted for publication

  8. Synthesis and properties of polyamide-Ag2S composite based solar energy absorber surfaces

    Krylova, Valentina; Baltrusaitis, Jonas

    2013-10-01

    Silver sulfide (Ag2S), an efficient solar light absorber, was synthesized using a modified chemical bath deposition (CBD) method and polyamide 6 (PA) as a host material via solution phase reaction between AgNO3 and Na2S2O3. X-ray diffraction (XRD) data showed a single, α-Ag2S (acanthite), crystalline phase present while surface and bulk chemical analyses, performed using X-ray photoelectron (XPS) and energy dispersive (EDS) spectroscopies, showed 2:1 Ag:S ratio. Direct and indirect bandgaps obtained from Tauc plots were 1.3 and 2.3 eV, respectively. Detailed surface chemical analysis showed the presence of three distinct sulfur species with majority component due to the Ag2S chemical bonds and minority components due to two types of oxygen-sulfur bonds. Conductivity of the resulting composite material was shown to change with the reaction time thus enabling to obtain controlled conductivity composite material. The synthesis method presented is based on the low solubility of Ag2S and is potentially green, no by-product producing, as all Ag2S nucleated outside the host material can be recycled into the process via dissolving it in HNO3.

  9. Synthesis and properties of polyamide–Ag{sub 2}S composite based solar energy absorber surfaces

    Krylova, Valentina, E-mail: valentina.krylova@ktu.lt [Department of Inorganic Chemistry, Kaunas University of Technology, Radvilenu st. 19, LT-50254 Kaunas (Lithuania); Baltrusaitis, Jonas, E-mail: j.baltrusaitis@utwente.nl [PhotoCatalytic Synthesis Group, MESA Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Meander 229, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2013-10-01

    Silver sulfide (Ag{sub 2}S), an efficient solar light absorber, was synthesized using a modified chemical bath deposition (CBD) method and polyamide 6 (PA) as a host material via solution phase reaction between AgNO{sub 3} and Na{sub 2}S{sub 2}O{sub 3}. X-ray diffraction (XRD) data showed a single, α-Ag{sub 2}S (acanthite), crystalline phase present while surface and bulk chemical analyses, performed using X-ray photoelectron (XPS) and energy dispersive (EDS) spectroscopies, showed 2:1 Ag:S ratio. Direct and indirect bandgaps obtained from Tauc plots were 1.3 and 2.3 eV, respectively. Detailed surface chemical analysis showed the presence of three distinct sulfur species with majority component due to the Ag{sub 2}S chemical bonds and minority components due to two types of oxygen–sulfur bonds. Conductivity of the resulting composite material was shown to change with the reaction time thus enabling to obtain controlled conductivity composite material. The synthesis method presented is based on the low solubility of Ag{sub 2}S and is potentially green, no by-product producing, as all Ag{sub 2}S nucleated outside the host material can be recycled into the process via dissolving it in HNO{sub 3}.

  10. Highly efficient energy absorbers made of aluminium foam; Hocheffiziente Energieabsorber aus Aluminiumschaum

    Baumeister, J. [Fraunhofer-Institut fuer Angewandte Materialforschung, Bremen (Germany). Abt. Pulvertechnologie; Banhart, J.; Weber, M.

    1995-12-31

    Due to their specific deformation behaviour aluminium foams are an ideal material for designing energy absorbers of high efficiency. After a short description of the manufacturing process for metallic foams three different methods for characterisation and selection of foamed aluminium for energy absortion tasks are discussed. In particular these are the efficiency of energy absorption as well as the energy absorption capacity and the application of energy absorption diagrams as a selection criterion for the conception of energy absorbing devices. (orig.) [Deutsch] Aluminiumschaeume eignen sich aufgrund ihres speziellen Verformungsverhaltens sehr gut fuer die Herstellung von hocheffizienten Bauteilen fuer Energieabsorptionsaufgaben. Nach einer kurzen Darstellung des Herstellungsverfahrens fuer Metallschaeume werden drei verschiedene Methoden zur Beurteilung und Auswahl von Aluminiumschaum als Energieabsorber beschrieben. Dabei handelt es sich insbesondere um die Effizienz der Energieabsorption, die Energieabsorptionskapazitaet und die Verwendung von Energieabsorptionsdiagrammen als Selektionskriterium bei der Konzeption von energieabsorbierenden Bauteilen. (orig.)

  11. Wave Energy Conversion: Direct Coupled Point Absorber in Heave with Induction Machine as Power Take Off

    Skjervheim, Ottar

    2007-01-01

    In the area of offshore renewable, wave energy can give great contribution. There has been research for developing wave energy converters since the late eighteenth century when the first patent was applied for in 1799 [1], without any remarkable breakthrough. This master thesis will discuss the topic of wave energy conversion by a point absorber in heave with a directly coupled induction machine power take off. A wave to wire approach has been attempted in this thesis. The tool needed is a h...

  12. A study on energy gain on evacuated collector tube with cylindric absorber on building southern facade

    Min Zijian [Information Engineering Coll., Capital Normal Univ., BJ (China); Ge Hongchuan [Beijing Eurocon Solar Energy Tech. Co., Ltd., BJ (China); Ma Yiqing [Special Education Coll. of Beijing Union Univ., BJ (China)

    2008-07-01

    According to the Clear-Day Model, daily energy gain and its annual variation of single evacuated collector tube with cylindric absorber in three different installation on building southern facade are studied. The solar energy gain of vertical installed tube and east-west horizontal installed tube comparing with local latitude tilted installed tube are presented. During the summer season the east-west horizontal installed tube has more solar energy gain than the vertical installed tube. (orig.)

  13. Chemistry and light - part 2: light and energy

    Franco Scandola; Carlo Alberto Bignozzi; Vincenzo Balzani

    1997-01-01

    The conversion of solar energy into more useful forms of energy, such as chemical fuels or electricity, is one of the central problems facing modern science. Progress in photochemistry and chemical synthesis has led to a point where light energy conversion by means of artificial molecular devices can be rationally attempted. In this article, a general approach towards this challenging goal is presented.

  14. Highly predictable photosynthetic production in natural macroalgal communities from incoming and absorbed light

    Middelboe, Anne Lise; Sand-Jensen, Kaj; Binzer, Thomas

    2006-01-01

    was unrelated to incident irradiance, temperature and mean thallus photosynthesis, while community absorptance was a highly significant predictor. Actual rates of community photosynthesis were closely related to incident and absorbed irradiance alone. Community absorptance in turn was correlated to...... communities metabolically active, and (3) maximum possible absorptance at 100% constrains the total photosynthesis of all species. Our results imply that the photosynthetic production of macroalgal communities is more predictable than their complex and dynamic nature suggest and that predictions are possible...

  15. Reducing uncertainties associated with filter-based optical measurements of light absorbing carbon particles with chemical information

    J. E. Engström

    2011-08-01

    Full Text Available The presented filter-based optical method for determination of soot (light absorbing carbon or Black Carbon, BC can be implemented in the field under primitive conditions and at low cost. This enables researchers with small economical means to perform monitoring at remote locations, especially in the Asia where it is much needed.

    One concern when applying filter-based optical measurements of BC is that they suffer from systematic errors due to the light scattering of non-absorbing particles co-deposited on the filter, such as inorganic salts and mineral dust. In addition to an optical correction of the non-absorbing material this study provides a protocol for correction of light scattering based on the chemical quantification of the material, which is a novelty. A newly designed photometer was implemented to measure light transmission on particle accumulating filters, which includes an additional sensor recording backscattered light. The choice of polycarbonate membrane filters avoided high chemical blank values and reduced errors associated with length of the light path through the filter.

    Two protocols for corrections were applied to aerosol samples collected at the Maldives Climate Observatory Hanimaadhoo during episodes with either continentally influenced air from the Indian/Arabian subcontinents (winter season or pristine air from the Southern Indian Ocean (summer monsoon. The two ways of correction (optical and chemical lowered the particle light absorption of BC by 63 to 61 %, respectively, for data from the Arabian Sea sourced group, resulting in median BC absorption coefficients of 4.2 and 3.5 Mm−1. Corresponding values for the South Indian Ocean data were 69 and 97 % (0.38 and 0.02 Mm−1. A comparison with other studies in the area indicated an overestimation of their BC levels, by up to two orders of magnitude. This raises the necessity for chemical correction protocols on optical filter

  16. Förster energy transfer theory as reflected in the structures of photosynthetic light harvesting systems

    Şener, Melih; Strümpfer, Johan; Hsin, Jen; Chandler, Danielle; Scheuring, Simon; Hunter, C. Neil; Schulten, Klaus

    2011-01-01

    Förster’s theory of resonant energy transfer underlies a fundamental process in nature, namely the harvesting of sunlight by photosynthetic life forms. The theoretical framework developed by Förster and others describes how electronic excitation migrates in the photosynthetic apparatus of plants, algae, and bacteria from light absorbing pigments to so-called reaction centers where light energy is utilized for the eventual conversion into chemical energy. The demand for highest possible effici...

  17. National absorbed dose to water references for radiotherapy medium energy X-rays by water calorimetry

    LNE-LNHB current references for medium energy X-rays are established in terms of air kerma. Absorbed dose to water, which is the quantity of interest for radiotherapy, is obtained by transfer dosimetric techniques following a methodology described in international protocols. The aim of the thesis is to establish standards in terms of absorbed dose to water in the reference protocol conditions by water calorimetry. The basic principle of water calorimetry is to measure the absorbed dose from the rise in temperature of water under irradiation. A calorimeter was developed to perform measurements at a 2 cm depth in water according to IAEA TRS-398 protocol for medium energy x-rays. Absorbed dose rates to water measured by calorimetry were compared to the values established using protocols based on references in terms of air kerma. A difference lower than 2.1% was reported. Standard uncertainty of water calorimetry being 0.8%, the one associated to the values from protocols being around 3.0%, results are consistent considering the uncertainties. Thanks to these new standards, it will be possible to use IAEA TRS-398 protocol to determine absorbed dose to water: a significant reduction of uncertainties is obtained (divided by 3 by comparison with the application of the IAEA TRS-277 protocol). Currently, none of the counterparts' laboratories own such an instrument allowing direct determination of standards in the reference conditions recommended by the international radiotherapy protocols. (author)

  18. Arctic climate response to forcing from light-absorbing particles in snow and sea ice in CESM

    N. Goldenson

    2012-09-01

    Full Text Available The presence of light-absorbing aerosol particles deposited on arctic snow and sea ice influences the surface albedo, causing greater shortwave absorption, warming, and loss of snow and sea ice, lowering the albedo further. The Community Earth System Model version 1 (CESM1 now includes the radiative effects of light-absorbing particles in snow on land and sea ice and in sea ice itself. We investigate the model response to the deposition of black carbon and dust to both snow and sea ice. For these purposes we employ a slab ocean version of CESM1, using the Community Atmosphere Model version 4 (CAM4, run to equilibrium for year 2000 levels of CO2 and fixed aerosol deposition. We construct experiments with and without aerosol deposition, with dust or black carbon deposition alone, and with varying quantities of black carbon and dust to approximate year 1850 and 2000 deposition fluxes. The year 2000 deposition fluxes of both dust and black carbon cause 1–2 °C of surface warming over large areas of the Arctic Ocean and sub-Arctic seas in autumn and winter and in patches of Northern land in every season. Atmospheric circulation changes are a key component of the surface-warming pattern. Arctic sea ice thins by on average about 30 cm. Simulations with year 1850 aerosol deposition are not substantially different from those with year 2000 deposition, given constant levels of CO2. The climatic impact of particulate impurities deposited over land exceeds that of particles deposited over sea ice. Even the surface warming over the sea ice and sea ice thinning depends more upon light-absorbing particles deposited over land. For CO2 doubled relative to year 2000 levels, the climate impact of particulate impurities in snow and sea ice is substantially lower than for the year 2000 equilibrium simulation.

  19. Comparison of proton energy loss in thick absorbers in terms of a reduced calibration curve

    Yevseyeva, O.; de Assis, J. T.; Evseev, I. G.; Schelin, H. R.; Ahmann, F.; Paschuk, S. A.; Milhoretto, E.; Setti, J. A. P.; Diaz, K. S.; Hormaza, J. M.; Lopes, R. T.

    2011-10-01

    Monte Carlo simulations are essential for the support of particle experiments and developments of novel particle registration systems ranging from detectors developed for high-energy physics experiments at CERN to those for medical tomography. For proton beams, popular Monte Carlo codes like TRIM/SRIM, MCNPX and GEANT4 generate very similar final energy spectra for relatively thin absorbers, with differences unlikely to be detected in experiments. For thick absorbers, however, the disagreement is much larger, even for a moderate energy resolution. The reason for this is unclear because the actual overall accuracy of the proton stopping power in the Bethe-Bloch domain is known to be about 1%. One approach to investigate these differences is to compare, for example, the data from the NIST PSTAR and the SRIM reference data tables with the output of the Monte Carlo codes. When the various codes are validated against these tables, the differences in the simulated spectra mainly reflect the differences in the reference tables. Of more practical interest is the validation of the codes against experimental data for thick absorbers. However, only few experimental data sets are available here, and the existing data have been acquired at different initial proton energies and for different absorber materials. In order to compare the results of Monte Carlo simulations with existing experimental data, we applied the so-called reduced calibration method. This reduced calibration curve represents the range-energy dependence normalizing the range scale to the full projected range (for a given initial proton energy in a given material), and the proton energy scale to the given initial proton energy. The advantage of this approach is that the reduced calibration curve is nearly energy and material independent, and, thus, experimental, simulated and published reference data obtained at different energies and for different materials can be compared in one graph.

  20. Comparison of proton energy loss in thick absorbers in terms of a reduced calibration curve

    Monte Carlo simulations are essential for the support of particle experiments and developments of novel particle registration systems ranging from detectors developed for high-energy physics experiments at CERN to those for medical tomography. For proton beams, popular Monte Carlo codes like TRIM/SRIM, MCNPX and GEANT4 generate very similar final energy spectra for relatively thin absorbers, with differences unlikely to be detected in experiments. For thick absorbers, however, the disagreement is much larger, even for a moderate energy resolution. The reason for this is unclear because the actual overall accuracy of the proton stopping power in the Bethe-Bloch domain is known to be about 1%. One approach to investigate these differences is to compare, for example, the data from the NIST PSTAR and the SRIM reference data tables with the output of the Monte Carlo codes. When the various codes are validated against these tables, the differences in the simulated spectra mainly reflect the differences in the reference tables. Of more practical interest is the validation of the codes against experimental data for thick absorbers. However, only few experimental data sets are available here, and the existing data have been acquired at different initial proton energies and for different absorber materials. In order to compare the results of Monte Carlo simulations with existing experimental data, we applied the so-called reduced calibration method. This reduced calibration curve represents the range-energy dependence normalizing the range scale to the full projected range (for a given initial proton energy in a given material), and the proton energy scale to the given initial proton energy. The advantage of this approach is that the reduced calibration curve is nearly energy and material independent, and, thus, experimental, simulated and published reference data obtained at different energies and for different materials can be compared in one graph.

  1. The METAS absorbed dose to water calibration service for high energy photon and electron beam radiotherapy

    Full text: The Swiss Federal Office of Metrology and Accreditation (METAS) provides an absorbed dose to water calibration service for reference dosimeters using 60Co γ radiation, ten X-ray beam qualities between TPR20,10=0.639 and 0.802 and ten electron beam qualities between R50=1.75 gcm-2 and 8.54 gcm-2. A 22 MeV microtron accelerator with a conventional treatment head is used as radiation source for the high energy photon and electron beams. The treatment head produces clinical beams. The METAS absorbed dose calibration service for high energy photons is based on a primary standard sealed water calorimeter of the Domen type, that is used to calibrate several METAS transfer standards of type NE2611A and NE2571A in terms of absorbed dose to water in the energy range from 60Co to TPR20,10 = 0.802. User reference dosimeters are compared with the transfer standards to give calibration factors in absorbed dose to water with an uncertainty of 1.0% for 60Co γ radiation and 1.4% for higher energies (coverage factor k=2). The calibration service was launched in 1997. The calibration factors measured by METAS have been compared with those derived from the Code of Practice of the International Atomic Energy Agency using the calculated kQ factors listed in table 14. The comparison showed a maximum difference of 0.8% for the NE25611A and NE 2571A chambers. At 60Co γ radiation the METAS primary standard of absorbed dose to water was bilaterally compared with the primary standards of the Bureau International des Poids et Mesures BIPM (Sevres) as well as of the National Research Council NRC (Canada). In either case the standards were in agreement within the comparison uncertainties. The METAS absorbed dose calibration service for high energy electron beams is based on a primary standard chemical dosimeter. A monoenergetic electron beam of precisely known particle energy and beam charge is totally absorbed in Fricke solution (ferrous ammonium sulphate) of a given mass. This

  2. Effects of Consecutive Wideband Tympanometry Trials on Energy Absorbance Measures of the Middle Ear

    Burdiek, Laina M.; Sun, Xiao-Ming

    2014-01-01

    Purpose: Wideband acoustic immittance (WAI) is a new technique for assessing middle ear transfer function. It includes energy absorbance (EA) measures and can be acquired with the ear canal pressure varied, known as "wideband tympanometry" (WBTymp). The authors of this study aimed to investigate effects of consecutive WBTymp testing on…

  3. Non-Linear Numerical Modeling and Experimental Testing of a Point Absorber Wave Energy Converter

    Zurkinden, Andrew Stephen; Ferri, Francesco; Beatty, S.;

    2014-01-01

    A time domain model is applied to a three-dimensional point absorber wave energy converter. The dynamical properties of a semi-submerged hemisphere oscillating around a pivot point where the vertical height of this point is above the mean water level are investigated. The numerical model includes...

  4. The METAS absorbed dose to water calibration service for high energy photon and electron beam radiotherapy

    The Swiss Federal Office of Metrology and Accreditation (METAS) provides an absorbed dose to water calibration service for reference dosimeters. The calibration service uses 60Co gamma radiation, ten high energy photon beam qualities between TPR20,10 = 0.639 and 0.802 and ten electron beam qualities between R50 = 1.75 g/cm2 and 8.54 g/cm2. The METAS absorbed dose calibration service for high energy photons is based on a primary standard sealed water calorimeter used to calibrate several METAS NE 2611A and NE 2571A type ionization chamber working standards in terms of absorbed dose to water in the energy range of 60Co to TPR20,10 = 0.802. The users' reference dosimeters are compared with the working standards to give calibration factors in absorbed dose to water with an uncertainty of 1.0% for 60Co radiation and 1.4% for higher energies (coverage factor k = 2). The calibration service was launched in 1997. The calibration factors measured by METAS have been compared with those derived from the IAEA Technical Reports Series No. 398 (TRS 398) code of practice and from Recommendations No. 4 of the Swiss Society of Radiobiology and Medical Physics (SSRMP). The comparisons showed a maximum difference of 1.2% for the NE 2561A and NE 2571A chambers. At 60Co gamma radiation the METAS primary standard of absorbed dose to water was bilaterally compared with the primary standards of the Bureau international des poids et mesures.The standards were in agreement within the comparison uncertainties. The METAS absorbed dose calibration service for high energy electron beams is based on a primary standard chemical dosimeter. A monoenergetic electron beam of known particle energy and beam charge is totally absorbed in Fricke solution. The experiment was carried out in the energy range of 5.3 MeV to 22.4 MeV, which allows the determination of the response of the Fricke dosimeter. Finally, the users' dosimeters are compared with the METAS working standards. The overall uncertainty in

  5. Impact Testing and Simulation of a Sinusoid Foam Sandwich Energy Absorber

    Jackson, Karen E.; Fasanella, Edwin L; Littell, Justin D.

    2015-01-01

    A sinusoidal-shaped foam sandwich energy absorber was developed and evaluated at NASA Langley Research Center through multi-level testing and simulation performed under the Transport Rotorcraft Airframe Crash Testbed (TRACT) research project. The energy absorber, designated the "sinusoid," consisted of hybrid carbon- Kevlar® plain weave fabric face sheets, two layers for each face sheet oriented at +/-45deg with respect to the vertical or crush direction, and a closed-cell ELFOAM(TradeMark) P200 polyisocyanurate (2.0-lb/ft3) foam core. The design goal for the energy absorber was to achieve an average floor-level acceleration of between 25- and 40-g during the full-scale crash test of a retrofitted CH-46E helicopter airframe, designated TRACT 2. Variations in the design were assessed through quasi-static and dynamic crush testing of component specimens. Once the design was finalized, a 5-ft-long subfloor beam was fabricated and retrofitted into a barrel section of a CH-46E helicopter. A vertical drop test of the barrel section was conducted onto concrete to evaluate the performance of the energy absorber prior to retrofit into TRACT 2. Finite element models were developed of all test articles and simulations were performed using LSDYNA ®, a commercial nonlinear explicit transient dynamic finite element code. Test analysis results are presented for the sinusoid foam sandwich energy absorber as comparisons of load-displacement and acceleration-time-history responses, as well as predicted and experimental structural deformations and progressive damage for each evaluation level (component testing through barrel section drop testing).

  6. A Preliminary Study of Energy Recovery in Vehicles by Using Regenerative Magnetic Shock Absorbers

    Road vehicles can expend a significant amount of energy in undesirable vertical motions that are induced by road bumps, and much of that is dissipated in conventional shock absorbers as they dampen the vertical motions. Presented in this paper are some of the results of a study aimed at determining the effectiveness of efficiently transforming that energy into electrical power by using optimally designed regenerative electromagnetic shock absorbers. In turn, the electrical power can be used to recharge batteries or other efficient energy storage devices (e.g., flywheels) rather than be dissipated. The results of the study are encouraging - they suggest that a significant amount of the vertical motion energy can be recovered and stored

  7. Multireference excitation energies for bacteriochlorophylls A within light harvesting system 2

    Anda, Andre; Hansen, Thorsten; De Vico, Luca

    2016-01-01

    Light-harvesting system 2 (LH2) of purple bacteria is one of the most popular antenna complexes used to study Nature's way of collecting and channeling solar energy. The dynamics of the absorbed energy is probed by ultrafast spectroscopy. Simulation of these experiments relies on fitting a range of...

  8. Exposure distribution, absorbed doses, and energy imparted for panoramic radiography using Orthopantomograph model OP 5

    The absorbed doses and energy imparted for the Orthopantomograph model OP 5 using two different collimators (0.9-1.3 X 33 mm2 and 0.6-0.9 X 39.5 mm2, respectively) were examined at 70 and 75 kV. The absorbed doses were estimated by thermoluminescence dosimetry in a sectioned phantom and by the energy imparted from measurements of areal exposure using a plane parallel transmission ionization chamber. The exposure distribution was surveyed on radiographic film. The anterior part of the parotid glands received the highest absorbed doses (2.4-3.2 mGy) when the wider collimator was used, with a decrease of two to three times when the narrower collimator was used. Other areas received absorbed doses of about 1.0 to 1.5 mGy or below. An increase of the kV from 70 to 75 had a minor influence. The energy imparted for the wider collimator was 0.6-0.8 and for the narrower collimator, 0.4-0.6 mJ

  9. On the absorbed dose determination method in high energy electrons beams

    The absorbed dose determination method in water for electron beams with energies in the range from 1 MeV to 50 MeV is presented herein. The dosimetry equipment for measurements is composed of an UNIDOS.PTW electrometer and different ionization chambers calibrated in air kerma in a Co60 beam. Starting from the code of practice for high energy electron beams, this paper describes the method adopted by the secondary standard dosimetry laboratory (SSDL) in NILPRP - Bucharest

  10. Phenolic carbonyls undergo rapid aqueous photodegradation to form low-volatility, light-absorbing products

    Smith, Jeremy D.; Kinney, Haley; Anastasio, Cort

    2016-02-01

    We investigated the aqueous photochemistry of six phenolic carbonyls - vanillin, acetovanillone, guaiacyl acetone, syringaldehyde, acetosyringone, and coniferyl aldehyde - that are emitted from wood combustion. The phenolic carbonyls absorb significant amounts of solar radiation and decay rapidly via direct photodegradation, with lifetimes (τ) of 13-140 min under Davis, CA winter solstice sunlight at midday (solar zenith angle = 62°). The one exception is guaiacyl acetone, where the carbonyl group is not directly connected to the aromatic ring: This species absorbs very little sunlight and undergoes direct photodegradation very slowly (τ > 103 min). We also found that the triplet excited states (3C*) of the phenolic carbonyls rapidly oxidize syringol (a methoxyphenol without a carbonyl group), on timescales of 1-5 h for solutions containing 5 μM phenolic carbonyl. The direct photodegradation of the phenolic carbonyls, and the oxidation of syringol by 3C*, both efficiently produce low volatility products, with SOA mass yields ranging from 80 to 140%. Contrary to most aliphatic carbonyls, under typical fog conditions we find that the primary sink for the aromatic phenolic carbonyls is direct photodegradation in the aqueous phase. In areas of significant wood combustion, phenolic carbonyls appear to be small but significant sources of aqueous SOA: over the course of a few hours, nearly all of the phenolic carbonyls will be converted to SOA via direct photodegradation, enhancing the POA mass from wood combustion by approximately 3-5%.

  11. Anomalous diffraction approximation for light scattering cross section: Case of random clusters of non-absorbent spheres

    Jacquier, Sandra [Ecole Nationale Superieure des Mines de Saint-Etienne, 158 Cours Fauriel, 42023 F-St. Etienne (France); Gruy, Frederic [Ecole Nationale Superieure des Mines de Saint-Etienne, 158 Cours Fauriel, 42023 F-St. Etienne (France)], E-mail: fgruy@emse.fr

    2008-11-15

    We previously [Jacquier S, Gruy F. Approximation of the light scattering cross-section for aggregated spherical non-absorbent particles. JQSRT 2008;109:789-810] reformulated the anomalous diffraction (AD) approximation to calculate the light scattering cross section of aggregates by introducing their chord length distribution (CLD). It was applied to several ordered aggregates. This new method is entitled ADr, with the r for rapid because this one is at least 100 times faster than the standard AD method. In this article, we are searching for an approximated expression for CLD suitable all at once for ordered and disordered aggregates. The corresponding scattering cross-section values are compared to the ones coming from the standard AD approximation.

  12. Determination of water-insoluble light absorbing matter in rainwater using polycarbonate membrane filters and photometric detection

    J. E. Engström

    2009-02-01

    Full Text Available A method for determination of water-insoluble light absorbing matter in rainwater has been developed. After collection the rainwater samples were filtered using polycarbonate membrane filter in the laboratory. After drying the filter in filtered air, the amount of water-insoluble light absorbing matter (soot on the filters was determined with photometry at a wavelength of 555 nm. The precision for the method was better than 10% calculated as relative standard deviation. The overall loss of soot due to adsorption during collection and filtration was 22±2%. The detection limit was estimated to 0.025 in optical density, or 2 ng/ml expressed as a concentration assuming a filtration volume of 30 ml. Analysis of environmental samples have been successfully performed with the described method at the Maldives Climate Observatory Hanimaadhoo and Nepal Climate Observatory. At Maldives the average soot concentration in rain was 0.048 μg/ml and at the Nepal obseravtory 0.086 μg/ml.

  13. Effect of elevated manganese on the ultraviolet- and blue light-absorbing compounds of cucumber cotyledons and leaf tissues

    The effect of manganese [Mn(II)] on the pigments of cucumber (Cucumis sativus L., cv Poinsett 76) leaf and cotyledon tissues was investigated. Tissue disks (7 mm) were exposed to increasing Mn(II) concentrations from 100 micromolar to 2.5 mM. Acetone (carotenoid-rich fraction) and acidified methanol (flavonoid-rich fraction) extracts were analyzed by high performance liquid chromatography. Although none of the Mn(II)-treated tissues showed visible damage, Mn(II) at concentrations of 250 micromolar and above significantly reduced (60%) the beta-carotene levels of light-incubated leaf tissues. A major Mn(II)-induced, UV-absorbing compound was observed in methanol extracts of cotyledonary tissues exposed to Mn(II) in the dark. In leaf tissues, Mn(II) reduced the levels of certain UV-absorbing compounds under both light conditions. These results demonstrate that excess leaf Mn(II) can rapidly impair isoprenoid metabolism, altering tissue carotenoid composition. Furthermore, Mn(II) may also modify phenylpropanoid metabolism, changing the tissue flavonoid composition. Both situations could sensitize plant tissues to oxidative stresses, particularly enhanced solar UV-B radiation, and may reduce the nutritional quality of leafy vegetables

  14. ENERGY STAR Certified Decorative Light Strings

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 1.5 ENERGY STAR Program Requirements for Decorative Light Strings that are effective as...

  15. ENERGY STAR Certified Light Commercial HVAC

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 2.0 ENERGY STAR Program Requirements for Light Commercial HVAC that are effective as of...

  16. The influence of mammographic X-ray spectra on absorbed energy distribution in breast: Monte Carlo simulation studies

    A mathematical model, based on Monte Carlo simulation, is proposed for deriving absorbed energy and dose distribution in mammography utilizing a mathematical water-like phantom. The model was validated for its accuracy against experimental and published data. The main factor discriminating absorbed energy distribution characteristics among different mammographic techniques was considered the X-ray spectrum. The absorbed energy distribution inside the phantom was investigated via percentage depth dose and isodose curves. The influence of the factors affecting X-ray spectrum (tube voltage, anode material, filter material and thickness) on absorbed energy distribution was examined. The hardness of the beam, due to increase of tube voltage or filtration, was found to be the major factor affecting absorbed energy distribution inside the phantom. In general, Mo and W anode systems demonstrated superior dosimetric characteristics against those of W-Mo or Rh. The model presented can be used for estimating absolute and relative breast dose values and their spatial distributions

  17. Scattered-field FDTD and PSTD algorithms with CPML absorbing boundary conditions for light scattering by aerosols

    As fundamental parameters for polarized-radiative-transfer calculations, the single-scattering phase matrix of irregularly shaped aerosol particles must be accurately modeled. In this study, a scattered-field finite-difference time-domain (FDTD) model and a scattered-field pseudo-spectral time-domain (PSTD) model are developed for light scattering by arbitrarily shaped dielectric aerosols. The convolutional perfectly matched layer (CPML) absorbing boundary condition (ABC) is used to truncate the computational domain. It is found that the PSTD method is generally more accurate than the FDTD in calculation of the single-scattering properties given similar spatial cell sizes. Since the PSTD can use a coarser grid for large particles, it can lower the memory requirement in the calculation. However, the Fourier transformations in the PSTD need significantly more CPU time than simple subtractions in the FDTD, and the fast Fourier transform requires a power of 2 elements in calculations, thus using the PSTD could not significantly reduce the CPU time required in the numerical modeling. Furthermore, because the scattered-field FDTD/PSTD equations include incident-wave source terms, the FDTD/PSTD model allows for the inclusion of an arbitrarily incident wave source, including a plane parallel wave or a Gaussian beam like those emitted by lasers usually used in laboratory particle characterizations, etc. The scattered-field FDTD and PSTD light-scattering models can be used to calculate single-scattering properties of arbitrarily shaped aerosol particles over broad size and wavelength ranges. -- Highlights: • Scattered-field FDTD and PSTD models are developed for light scattering by aerosols. • Convolutional perfectly matched layer absorbing boundary condition is used. • PSTD is generally more accurate than FDTD in calculating single-scattering properties. • Using same spatial resolution, PSTD requires much larger CPU time than FDTD

  18. Green Lighting. Energy-efficient integrated lighting systems - Final report

    Linhart, F.; Scartezzini, J.-L.

    2009-10-15

    The objective of the Green Lighting project was to develop a High Performance Integrated Lighting System, based on advanced technologies for day- and electric lighting, achieving a Lighting Power Density (LPD) that does not exceed 3 W/m{sup 2}. The project has revealed that Anidolic Daylighting Systems (ADS) are an ideal basis for High Performance Integrated Lighting Systems. Not only are they able to provide adequate illumination (i.e. sufficiently high illuminance) in office rooms during large fractions of normal office hours, under various sky conditions and over the entire year, but they are also highly appreciated by office occupants at the condition that glare control mechanisms are available. Complementary electric lighting is, however, still necessary to back up the ADS at times when there is insufficient daylight flux available. It was shown during this project, that the most interesting trade-offs between energy-efficiency and visual comfort are obtained by using a combination of ceiling-mounted directly emitting luminaires with very high optical efficiencies for ambient lighting and portable desk lamps for temporary task lighting. The most appropriate lamps for the ceiling-mounted luminaires are currently highly efficient fluorescent tubes, but white LED tubes can be considered a realistic option for the future. The most suitable light sources for desk lamps for temporary task lighting are Compact Fluorescent Lamps (CFLs) and white LED light bulbs. Based on the above-mentioned technologies, a High Performance Integrated Lighting System with a very low LPD has been developed over the last three years. The system has been set up in an office room of the LESO solar experimental building located on the EPFL campus; it has been tested intensively during a Post-Occupancy Evaluation (POE) study involving twenty human subjects. This study has revealed that the subjects' performance and subjective visual comfort was improved by the new system, compared to

  19. Optimisation of energy absorbing liner for equestrian helmets. Part I: Layered foam liner

    The energy absorbing foam liner used in safety helmets was optimised using finite element modelling. Computational simulations of certification standard tests were carried out to obtain the best performing configurations of helmet liner. For each test condition, the best configuration of helmet liner was identified. Two alternative designs were considered: the first was composed of three layers of different foam density, the second was a conventional liner of one single uniform density. The observed reduction in peak acceleration for the best performing helmet liners in various test conditions are directly related to the contact area, the distribution of material stresses and the dissipated plastic energy density (DPED). Peak linear accelerations are shown to be lowered by increasing the contact areas of the inner and outer surfaces of the energy absorbing liner, or by varying the foam density through the thickness of the liner to ensure that the foam absorbs energy plastically when the stress reaches the late plateau stage of the foam stress-strain curve.

  20. Energy backscattering of electron beams and absorbed dose in thin layer

    Recent research development in this laboratory concerning radiation effects on the thin layer specimens of organic polymers and p-n junction of semiconductors requires the accurate evaluation of backscattered energy which is especially important for low energy electrons below 1.0 MeV and gives rise to errors of up to some 60 % depending on the materials of backing substrates. The present report describes the past studies on backscattering phenomena on backing substances of various elements and summarizes the experimental results of the measurements of the dose rate absorbed by the thin layer substance on backing substances of various elements as numerical tables which allow convenient determination of dose absorbed by the thin layer specimens on the backing substances. (author)

  1. Modelling the energy absorbed during a laser beam metal melting process

    The interaction between a high-density laser beam and a metallic surface produces a deep narrow melted area that has a characteristic keyhole geometric pattern. The amount of energy absorbed by the meal will depend on the parameters of the laser being applied, and the nature and geometry of the piece. In this paper, a formulation is presented which makes it possible to quantitatively determine the amount of energy absorbed by the metal as a function of a series of experimental parameters. The formulation that has been developed is especially applicable in bead-on-plate tests commonly used to analyze laser-metal interactions in laser technology research. The formulation applies specifically to two types of aluminium alloys. Al-Mg-Si and Al-Zn-Mg. (Author) 15 refs

  2. The application of energy absorbing structures on side impact protection systems

    Njuguna, James A. K.

    2011-01-01

    This paper presents a system to improve the protection to the occupants of a World Rally Championship Car in case of a side impact involving a tree collision using energy-absorbing structures. An outline of the immediate events after the car crash into a tree is provided followed by an analysis of a typical standard rollcage, then the design criteria and features of a carefully selected design concept. The design model is produced using solid modelling/I-DEAS 11 softwares an...

  3. Optimisation of energy absorbing liner for equestrian helmets. Part I: Layered foam liner

    Forero Rueda, Manuel A.; Cui, Liang; Gilchrist, M. D.

    2009-01-01

    The energy absorbing foam liner used in safety helmets was optimised using finite element modelling. Computational simulations of certification standard tests were carried out to obtain the best performing configurations of helmet liner. For each test condition, the best configuration of helmet liner was identified. Two alternative designs were considered: the first was composed of three layers of different foam density, the second was a conventional liner of one single uniform density. The o...

  4. Optimisation of energy absorbing liner for equestrian helmets. Part II: Functionally graded foam liner

    Cui, Liang; Forero Rueda, Manuel A.; Gilchrist, M. D.

    2009-01-01

    The energy absorbing liner of safety helmets was optimised using finite element modelling. In this present paper, a functionally graded foam (FGF) liner was modelled, while keeping the average liner density the same as in a corresponding reference single uniform density liner model. Use of a functionally graded foam liner would eliminate issues regarding delamination and crack propagation between interfaces of different density layers which could arise in liners with discrete density variatio...

  5. Renewable Energy Laboratory for Lighting Systems

    Cristian, Dumitru; Adrian, Gligor

    2010-01-01

    Nowadays, the electric lighting is an important part of our lives and also represents a significant part of the electric power consumption. Alternative solutions such as renewable energy applied in this domain are thus welcomed. This paper presents a workstation conceived for the study of photovoltaic solar energy for lighting systems by students of power engineering and civil engineering faculty. The proposed system is realized to study the generated photovoltaic solar energy parameters for ...

  6. Embodied Energy and Off-Grid Lighting

    Alstone, Peter; Mills, Evan; Jacobson, Arne

    2011-01-25

    The greenhouse gas (GHG) emissions from fuel-based lighting are substantial given the paltry levels of lighting service provided to users, leading to a great opportunity for GHG mitigation byencouraging the switch from fuel-based to rechargeable LED lighting. However, as with most new energy technology, switching to efficient lighting requires an up-front investment of energy(and GHGs) embedded in the manufacture of replacement components. We studied a population of off-grid lighting users in 2008-2009 in Kenya who were given the opportunity to adopt LEDlighting. Based on their use patterns with the LED lights and the levels of kerosene offset we observed, we found that the embodied energy of the LED lamp was"paid for" in only one month for grid charged products and two months for solar charged products. Furthermore, the energyreturn-on investment-ratio (energy produced or offset over the product's service life divided by energy embedded) for off-grid LED lighting ranges from 12 to 24, which is on par with on-gridsolar and large-scale wind energy. We also found that the energy embodied in the manufacture of a typical hurricane lantern is about one-half to one-sixth of that embodied in the particular LEDlights that we evaluated, indicating that the energy payback time would be moderately faster if LEDs ultimately displace the production of kerosene lanterns. As LED products improve, weanticipate longer service lives and more successful displacement of kerosene lighting, both of which will speed the already rapid recovery of embodied energy in these products. Our studyprovides a detailed appendix with embodied energy values for a variety of components used to construct off-grid LED lighting, which can be used to analyze other products.

  7. New Light on Dark Energy

    2008-01-01

    observations show that the temperature changes with radius are much steeper than predicted by the currently favoured models, indicating that most of the near-infrared emission emerges from hot material located very close to the star, that is, within one or two times the Earth-Sun distance (1-2 AU). This also implies that dust cannot exist so close to the star, since the strong energy radiated by the star heats and ultimately destroys the dust grains. ESO PR Photo 03/08 ESO PR Photo 03b/08 The Region Around MWC 147 "We have performed detailed numerical simulations to understand these observations and reached the conclusion that we observe not only the outer dust disc, but also measure strong emission from a hot inner gaseous disc. This suggests that the disc is not a passive one, simply reprocessing the light from the star," explained Kraus. "Instead, the disc is active, and we see the material, which is just transported from the outer disc parts towards the forming star." ESO PR Photo 03/08 ESO PR Photo 03c/08 Close-up on MWC 147 The best-fit model is that of a disc extending out to 100 AU, with the star increasing in mass at a rate of seven millionths of a solar mass per year. "Our study demonstrates the power of ESO's VLTI to probe the inner structure of discs around young stars and to reveal how stars reach their final mass," said Stefan Kraus. More Information The authors report their results in a paper in the Astrophysical Journal ("Detection of an inner gaseous component in a Herbig Be star accretion disk: Near- and mid-infrared spectro-interferometry and radiative transfer modeling of MWC 147", by Stefan Kraus, Thomas Preibisch, Keichii Ohnaka").

  8. Instrumentation and method for measuring NIR light absorbed in tissue during MR imaging in medical NIRS measurements

    Myllylä, Teemu S.; Sorvoja, Hannu S. S.; Nikkinen, Juha; Tervonen, Osmo; Kiviniemi, Vesa; Myllylä, Risto A.

    2011-07-01

    Our goal is to provide a cost-effective method for examining human tissue, particularly the brain, by the simultaneous use of functional magnetic resonance imaging (fMRI) and near-infrared spectroscopy (NIRS). Due to its compatibility requirements, MRI poses a demanding challenge for NIRS measurements. This paper focuses particularly on presenting the instrumentation and a method for the non-invasive measurement of NIR light absorbed in human tissue during MR imaging. One practical method to avoid disturbances in MR imaging involves using long fibre bundles to enable conducting the measurements at some distance from the MRI scanner. This setup serves in fact a dual purpose, since also the NIRS device will be less disturbed by the MRI scanner. However, measurements based on long fibre bundles suffer from light attenuation. Furthermore, because one of our primary goals was to make the measuring method as cost-effective as possible, we used high-power light emitting diodes instead of more expensive lasers. The use of LEDs, however, limits the maximum output power which can be extracted to illuminate the tissue. To meet these requirements, we improved methods of emitting light sufficiently deep into tissue. We also show how to measure NIR light of a very small power level that scatters from the tissue in the MRI environment, which is characterized by strong electromagnetic interference. In this paper, we present the implemented instrumentation and measuring method and report on test measurements conducted during MRI scanning. These measurements were performed in MRI operating rooms housing 1.5 Tesla-strength closed MRI scanners (manufactured by GE) in the Dept. of Diagnostic Radiology at the Oulu University Hospital.

  9. Slow light in ruby: delaying energy beyond the input pulse

    Wisniewski-Barker, Emma; Gibson, Graham; Franke-Arnold, Sonja; Shi, Zhimin; Narum, Paul; Boyd, Robert W.; Padgett, Miles J.

    2015-03-01

    The mechanism by which light is slowed through ruby has been the subject of great debate. To distinguish between the two main proposed mechanisms, we investigate the problem in the time domain by modulating a laser beam with a chopper to create a clean square wave. By exploring the trailing edge of the pulsed laser beam propagating through ruby, we can determine whether energy is delayed beyond the input pulse. The effects of a time-varying absorber alone cannot delay energy into the trailing edge of the pulse, as a time-varying absorber can only attenuate a coherent pulse. Therefore, our observation of an increase in intensity at the trailing edge of the pulse provides evidence for a complicated model of slow light in ruby that requires more than just pulse reshaping. In addition, investigating the Fourier components of the modulated square wave shows that harmonic components with different frequencies are delayed by different amounts, regardless of the intensity of the component itself. Understanding the difference in delays of the individual Fourier components of the modulated beam reveals the cause of the distortion the pulse undergoes as it propagates through the ruby.

  10. Light thoughts on dark energy

    Linder, Eric V.

    2004-04-01

    The physical process leading to the acceleration of the expansion of the universe is unknown. It may involve new high energy physics or extensions to gravitation. Calling this generically dark energy, we examine the consistencies and relations between these two approaches, showing that an effective equation of state function w(z) is broadly useful in describing the properties of the dark energy. A variety of cosmological observations can provide important information on the dynamics of dark energy and the future looks bright for constraining dark energy, though both the measurements and the interpretation will be challenging. We also discuss a more direct relation between the spacetime geometry and acceleration, via ''geometric dark energy'' from the Ricci scalar, and superacceleration or phantom energy where the fate of the universe may be more gentle than the Big Rip.

  11. A Systematic Approach to the Design Optimization of Light-Absorbing Indenofluorene Polymers for Organic Photovoltaics

    Kirkpatrick, James

    2012-01-09

    The synthesis and optimization of new photovoltaic donor polymers is a time-consuming process. Computer-based molecular simulations can narrow the scope of materials choice to the most promising ones, by identifying materials with desirable energy levels and absorption energies. In this paper, such a retrospective analysis is presented of a series of fused aromatic push-pull copolymers. It is demonstrated that molecular calculations do indeed provide good estimates of the absorption energies measured by UV-vis spectroscopy and of the ionization potentials measured by photoelectron spectroscopy in air. Comparing measured photovoltaic performance of the polymer series to the trend in efficiencies predicted by computation confirms the validity of this approach. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Functional Arrays for Light Energy Capture and Charge Separation.

    Flamigni, Lucia

    2016-06-01

    This article draws, with a simplified but rigorous approach, the typical procedure for the design and optimization of functional multicomponent structures for light to chemical energy conversion for two series of multipartite structures based on prototypical chromophores: polypyridyl metal complexes and porphyrinoids. Starting from a photophysical study performed by steady-state and time-resolved spectroscopic methods, the full deactivation dynamics of the light-absorbing chromophore(s) are disclosed. The preferred deactivation step (electron transfer in this case) is then optimized. This can be done by simply operating on the solvent, but also by changing structure/components that can alter electronic and nuclear factors, via continuous feedback with the research groups in charge of the synthesis. With a presentation suitable for a wide audience, it is here discussed how the effective design of functional multicomponent structures for charge separation can be achieved. PMID:27027981

  13. New Insight into the Angle Insensitivity of Ultrathin Planar Optical Absorbers for Broadband Solar Energy Harvesting.

    Liu, Dong; Yu, Haitong; Duan, Yuanyuan; Li, Qiang; Xuan, Yimin

    2016-01-01

    Two challenging problems still remain for optical absorbers consisting of an ultrathin planar semiconductor film on top of an opaque metallic substrate. One is the angle-insensitive mechanism and the other is the system design needed for broadband solar energy harvesting. Here, first we theoretically demonstrates that the high refractive index, instead of the ultrathin feature as reported in previous studies, is the physical origin of the angle insensitivity for ultrathin planar optical absorbers. They exhibit omnidirectional resonance for TE polarization due to the high complex refractive index difference between the semiconductor and the air, while for TM polarization the angle insensitivity persists up to an incident angle related to the semiconductor refractive index. These findings were validated by fabricating and characterizing an 18 nm Ge/Ag absorber sample (representative of small band gap semiconductors for photovoltaic applications) and a 22 nm hematite/Ag sample (representative of large band gap semiconductors for photoelectrochemical applications). Then, we took advantage of angle insensitivity and designed a spectrum splitting configuration for broadband solar energy harvesting. The cascaded solar cell and unassisted solar water splitting systems have photovoltaic and photoelectrochemical cells that are also spectrum splitters, so an external spectrum splitting element is not needed. PMID:27582317

  14. Calculation of fluence and absorbed dose in head tissues due to different photon energies

    Calculations of fluence and absorbed dose in head tissues due to different photon energies were carried out using the MCNPX code, to simulate two models of a patient's head: one spherical and another more realistic ellipsoidal. Both head models had concentric shells to describe the scalp skin, the cranium and the brain. The tumor was located at the center of the head and it was a 1 cm-radius sphere. The MCNPX code was run for different energies. Results showed that the fluence decreases as the photons pass through the different head tissues. It can be observed that, although the fluence into the tumor is different for both head models, absorbed dose is the same. - Highlights: • A Monte Carlo algorithm to simulate the passage of photons through a homogeneous material was developed. • Two models of a patient's head, one spherical and another more realistic ellipsoidal model, were simulated using the Monte Carlo code. • The fluence into the tumor is different for both head models, but absorbed dose in the tumor is the same

  15. Point-by-point near-field optical energy deposition around plasmonic nanospheres in absorbing media.

    Harrison, R K; Ben-Yakar, Adela

    2015-08-01

    Here we investigate the effects of absorbing media on plasmon-enhanced near-field optical energy deposition. We find that increasing absorption by the medium results in increased particle scattering at the expense of particle absorption, and that much of this increased particle scattering is absorbed by the medium close to the particle surface. We present an analytical method for evaluating the spatial distribution of near-field enhanced absorption surrounding plasmonic metal nanospheres in absorbing media using a new point-by-point method. We propose criteria to define relevant near-field boundaries and calculate the properties of the local absorption enhancement, which redistributes absorption to the near-field and decays asymptotically as a function of the distance from the particle to background levels. Using this method, we performed a large-scale parametric study to understand the effect of particle size and wavelength on the near-field absorption for gold nanoparticles in aqueous media and silicon, and identified conditions that are relevant to enhanced local infrared absorption in silicon. The presented approach provides insight into the local energy transfer around plasmonic nanoparticles for predicting near-field effects for advanced concepts in optical sensing, thin-film solar cells, nonlinear imaging, and photochemical applications. PMID:26367296

  16. New Insight into the Angle Insensitivity of Ultrathin Planar Optical Absorbers for Broadband Solar Energy Harvesting

    Liu, Dong; Yu, Haitong; Duan, Yuanyuan; Li, Qiang; Xuan, Yimin

    2016-01-01

    Two challenging problems still remain for optical absorbers consisting of an ultrathin planar semiconductor film on top of an opaque metallic substrate. One is the angle-insensitive mechanism and the other is the system design needed for broadband solar energy harvesting. Here, first we theoretically demonstrates that the high refractive index, instead of the ultrathin feature as reported in previous studies, is the physical origin of the angle insensitivity for ultrathin planar optical absorbers. They exhibit omnidirectional resonance for TE polarization due to the high complex refractive index difference between the semiconductor and the air, while for TM polarization the angle insensitivity persists up to an incident angle related to the semiconductor refractive index. These findings were validated by fabricating and characterizing an 18 nm Ge/Ag absorber sample (representative of small band gap semiconductors for photovoltaic applications) and a 22 nm hematite/Ag sample (representative of large band gap semiconductors for photoelectrochemical applications). Then, we took advantage of angle insensitivity and designed a spectrum splitting configuration for broadband solar energy harvesting. The cascaded solar cell and unassisted solar water splitting systems have photovoltaic and photoelectrochemical cells that are also spectrum splitters, so an external spectrum splitting element is not needed. PMID:27582317

  17. Note: Three wavelengths near-infrared spectroscopy system for compensating the light absorbance by water

    Bhutta, M. Raheel; Hong, Keum-Shik; Kim, Beop-Min; Hong, Melissa Jiyoun; Kim, Yun-Hee; Lee, Se-Ho

    2014-02-01

    Given that approximately 80% of blood is water, we develop a wireless functional near-infrared spectroscopy system that detects not only the concentration changes of oxy- and deoxy-hemoglobin (HbO and HbR) during mental activity but also that of water (H2O). Additionally, it implements a water-absorption correction algorithm that improves the HbO and HbR signal strengths during an arithmetic task. The system comprises a microcontroller, an optical probe, tri-wavelength light emitting diodes, photodiodes, a WiFi communication module, and a battery. System functionality was tested by means of arithmetic-task experiments performed by healthy male subjects.

  18. Modelling a point absorbing wave energy converter by the equivalent electric circuit theory: A feasibility study

    Hai, Ling; Svensson, Olle; Isberg, Jan; Leijon, Mats

    2015-04-01

    There is a need to have a reliable tool to quickly assess wave energy converters (WECs). This paper explores whether it is possible to apply the equivalent electric circuit theory as an evaluation tool for point absorbing WEC system modelling. The circuits were developed starting from the force analysis, in which the hydrodynamic, mechanical, and electrical parameters were expressed by electrical components. A methodology on how to determine the parameters for electrical components has been explained. It is found that by using a multimeter, forces in the connection line and the absorbed electric power can be simulated and read directly from the electric circuit model. Finally, the circuit model has been validated against the full scale offshore experiment. The results indicated that the captured power could be predicted rather accurately and the line force could be estimated accurately near the designed working condition of the WEC.

  19. Optimal Discrete PTO Force Point Absorber Wave Energy Converters in Regular Waves

    Hansen, Anders Hedegaard; Pedersen, Henrik C.

    2013-01-01

    For ocean wave energy converters (WECs) to become a cost-effective alternative in the energy production system a large increase in the conversion efficiency is needed. Fluid power technology is the leading technology for the Power Take- Off (PTO) system of wave energy converters. However the...... of discrete force systems for PTO, by focusing on how to choose the optimal PTO force levels and force profile when seeking to increase energy harvesting. The work concerns point absorber WECs and utilises a simple float model based on linear wave theory. Utilising the principle of superposition and...... the Laplace transform a solution of the float movement is found when subjected an incoming wave and a discrete PTO force. Finally an optimisation leads to the force profile implying the highest harvested energy....

  20. Light Thoughts on Dark Energy

    Linder, Eric V.

    2004-01-01

    The physical process leading to the acceleration of the expansion of the universe is unknown. It may involve new high energy physics or extensions to gravitation. Calling this generically dark energy, we examine the consistencies and relations between these two approaches, showing that an effective equation of state function w(z) is broadly useful in describing the properties of the dark energy. A variety of cosmological observations can provide important information on the dynamics of dark e...

  1. Procedure to Measure Indoor Lighting Energy Performance

    Deru, M.; Blair, N.; Torcellini, P.

    2005-10-01

    This document provides standard definitions of performance metrics and methods to determine them for the energy performance of building interior lighting systems. It can be used for existing buildings and for proposed buildings. The primary users for whom these documents are intended are building energy analysts and technicians who design, install, and operate data acquisition systems, and who analyze and report building energy performance data. Typical results from the use of this procedure are the monthly and annual energy used for lighting, energy savings from occupancy or daylighting controls, and the percent of the total building energy use that is used by the lighting system. The document is not specifically intended for retrofit applications. However, it does complement Measurement and Verification protocols that do not provide detailed performance metrics or measurement procedures.

  2. Light and energy - daylight measurements

    Christoffersen, Jens; Logadottir, A.; Traberg-Borup, S.; Barrie-Nielsen, K.

    2009-07-01

    All measurements where conducted in the spring of 2007, except the Interpane panel. The solar cell panels have been evaluated by three performance indicators to assess the daylight quantity within the room and the systems ability to maintain view to the outside. In the study, we used two performance indicators to assess the daylight quantity within the room: 1. the daylight factor (overcast sky) 2. the relative work plane illuminance (clear sky condition) Overcast sky: In general, all panels provided less daylight than the recommended requirement in the Danish Building Regulation of 2% on the work plane. This will most likely result in additional need for electric lighting. However, larger window areas and more parts of the facade with clear unobstructed glass may be one solution. Clear sky: In general, all panels provided less interior light levels than the two reference systems in the back of the room. Almost all systems aloud more or less direct sunlight in the window perimeter through the clear openings and additional needs for some kind of shading device is to be expected. Some systems blocked a large portion of the light in the majority of the room, and additional electric light in this part of the room may be needed. Only one performance indicator where used to describe the quality of the panels. View: In general, all panels, except two, obstruct the view significantly and cause figure/background confusion for a view position close to the window and the discrepancies of colour judgements. Only two systems provided a fairly clear view to the outside without to much distortion of the view. (au)

  3. Measurement of absorbed dose to water for low and medium energy x-rays

    Full text: Over the last decade, the treatment of superficial or intercavitary malignancies with medium-energy x-rays has regained popularity. This development puts renewed and increased emphasis on the importance of accurate dosimetry in this energy range. An appreciable number of publications dealing with various aspects of dosimetry in medium-energy x-ray beams has appeared and several protocols for the dosimetry of medium-energy x-ray appeared which led to the publication of a comparison between the various protocols. Attempts were made to model x-ray radiotherapy units by Monte Carlo methods, a method originally developed for high-energy treatment systems. In-phantom dosimetry for medium-energy x-rays suffers from the lack of a primary standard which would allow direct determination of the water absorbed dose. Attempts at a direct measurement of the water absorbed dose were made employing water calorimetry. These attempts suffered from the unknown energy dependence of the chemical yield for ferrous sulfate dosimetry, or from insufficient knowledge of the calorimetric heat defect. In the absence of a direct method, two different approaches have mainly been made. In one of these an ionisation chamber calibrated in free air in terms of air kerma is positioned at reference depth inside the water phantom. The absorbed dose to water is obtained by conversion of the air kerma measured in the water phantom to water kerma or, which is essentially equivalent in this energy range, to absorbed dose to water. When this method is used, correction factors have to be applied, which have to take into account i) the differences in the properties of the radiation field used for calibration in free air and of that inside the phantom and ii) the modification of the in-phantom radiation field caused by the presence of the ionisation chamber with its air cavity and with non water-equivalent walls and chamber stem. The other approach is to start with the measurement of absorbed dose

  4. Effects of progressive drought on photosynthesis and partitioning of absorbed light in apple trees

    MA Ping; BAI Tuan-hui; MA Feng-wang

    2015-01-01

    To understand how drought stress affects CO2 assimilation and energy partitioning in apple (Malus domestica Borkh.), we investigated photosynthesis and photo-protective mechanisms when irrigation was withheld from potted Fuji trees. As the drought progressing, soil relative water content (SRWC) decreased from 87 to 24%in 15 d;this combined the decreasing in leaf relative water content (LRWC), net photosynthesis rate (Pn) and stomatal conductance (Gs). However, the concen-trations of chlorophyl s (Chl) remained unchanged while Pn values were declining. Photochemistry reactions were slightly down-regulated only under severe drought. Rubisco activity was signiifcantly decreased as drought conditions became more severe. The actual efifciency of photosystem II (ΦPSI ) was diminished as drought became more intense. Consequently, xanthophyl-regulated dissipation of thermal energy was greatly enhanced. Simultaneously, the ratio ofΦPSI to the quantum yield of carbon metabolism, which is measured under non-photorespiratory conditions, increased in paral el with drought severity. Our results indicate that, under progressive drought stress, the reduction in photosynthesis in apple leaves can be attributed primarily to stomatal limitations and the inhibited capacity for CO2 ifxation. Xanthophyl cycle-dependent ther-mal dissipation and the Mehler reaction are the most important pathways for dispersing excess energy from apple leaves during periods of drought stress.

  5. Flow of light energy in benthic photosynthetic microbial mats

    Al-Najjar, Mohammad Ahmad A.

    2010-12-15

    The work in this thesis demonstrates the assessment of the energy budget inside microbial mat ecosystems, and the factors affecting light utilization efficiency. It presents the first balanced light energy budget for benthic microbial mat ecosystems, and shows how the budget and the spatial distribution of the local photosynthetic efficiencies within the euphotic zone depend on the absorbed irradiance (Jabs). The energy budget was dominated by heat dissipation on the expense of photosynthesis. The maximum efficiency of photosynthesis was at light limiting conditions When comparing three different marine benthic photosynthetic ecosystems (originated from Abu-Dhabi, Arctic, and Exmouth Gulf in Western Australia), differences in the efficiencies were calculated. The results demonstrated that the maximum efficiency depended on mat characteristics affecting light absorption and scattering; such as, photopigments ratio and distribution, and the structural organization of the photosynthetic organisms relative to other absorbing components of the ecosystem (i.e., EPS, mineral particles, detritus, etc.). The maximum efficiency decreased with increasing light penetration depth, and increased with increasing the accessory pigments (phycocyanin and fucoxanthin)/chlorophyll ratio. Spatial heterogeneity in photosynthetic efficiency, pigment distribution, as well as light acclimation in microbial mats originating from different geographical locations was investigated. We used a combined pigment imaging approach (variable chlorophyll fluorescence and hyperspectral imaging), and fingerprinting approach. For each mat, the photosynthetic activity was proportional to the local pigment concentration in the photic zone, but not for the deeper layers and between different mats. In each mat, yield of PSII and E1/2 (light acclimation) generally decreased in parallel with depth, but the gradients in both parameters varied greatly between samples. This mismatch between pigments concentration

  6. Electrochemically synthesized visible light absorbing vertically aligned N-doped TiO2 nanotube array films

    Graphical abstract: Display Omitted Highlights: ► Single step electrochemical synthesis of N-doped TiO2 nanotube array films. ► Effective substitutional N-doping achieved. ► Different N-concentrations were achieved by varying the N-precursor concentration in the electrolyte. ► Visible light absorption observed at high N-doping. -- Abstract: Visible light absorbing vertically aligned N-doped anatase nanotube array thin films were synthesized by anodizing Ti foils in ethylene glycol + NH4F + water mixture containing urea as nitrogen source. Different nitrogen concentrations were achieved by varying the urea content in the electrolyte. The structure, morphology, composition and optical band gap of the nanotube arrays were determined by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy, respectively. The substitution of O2− ions by N3− ions in the anion sublattice as well as the formulae of the doped samples was confirmed from the results of XPS. The optical band gap of the nanotube arrays was found to decrease with N-concentration. The sample with the highest concentration corresponding to the formula TiO1.83N0.14 showed two regions in the Tauc's plot indicating the presence of interband states.

  7. Identification of light absorbing oligomers from glyoxal and methylglyoxal aqueous processing: a comparative study at the molecular level

    Finessi, Emanuela; Hamilton, Jacqueline; Rickard, Andrew; Baeza-Romero, Maria; Healy, Robert; Peppe, Salvatore; Adams, Tom; Daniels, Mark; Ball, Stephen; Goodall, Iain; Monks, Paul; Borras, Esther; Munoz, Amalia

    2014-05-01

    Numerous studies point to the reactive uptake of gaseous low molecular weight carbonyls onto atmospheric waters (clouds/fog droplets and wet aerosols) as an important SOA formation route not yet included in current models. However, the evaluation of these processes is challenging because water provides a medium for a complex array of reactions to take place such as self-oligomerization, aldol condensation and Maillard-type browning reactions in the presence of ammonium salts. In addition to adding to SOA mass, aqueous chemistry products have been shown to include light absorbing, surface-active and high molecular weight oligomeric species, and can therefore affect climatically relevant aerosol properties such as light absorption and hygroscopicity. Glyoxal (GLY) and methylglyoxal (MGLY) are the gaseous carbonyls that have perhaps received the most attention to date owing to their ubiquity, abundance and reactivity in water, with the majority of studies focussing on bulk physical properties. However, very little is known at the molecular level, in particular for MGLY, and the relative potential of these species as aqueous SOA precursors in ambient air is still unclear. We have conducted experiments with both laboratory solutions and chamber-generated particles to simulate the aqueous processing of GLY and MGLY with ammonium sulphate (AS) under typical atmospheric conditions and investigated their respective aging products. Both high performance liquid chromatography coupled with UV-Vis detection and ion trap mass spectrometry (HPLC-DAD-MSn) and high resolution mass spectrometry (FTICRMS) have been used for molecular identification purposes. Comprehensive gas chromatography with nitrogen chemiluminescence detection (GCxGC-NCD) has been applied for the first time to these systems, revealing a surprisingly high number of nitrogen-containing organics (ONs), with a large extent of polarities. GCxGC-NCD proved to be a valuable tool to determine overall amount and rates of

  8. Measurements of absorbed energy distributions in water from pulsed electron beams

    An evaluation of the use of a holographic interferometer to measure the energy deposition as a function of depth in water from pulsed electron beams, together with a brief description of the interferometer and the technique of generating a hologram are presented. The holographic interferometer is used to measure the energy deposition as a function of depth in water from various pulsed beams of monoenergetic electrons in the energy range from 1.0 to 2.5 MeV. These results are compared to those computed by using a Monte Carlo radiation transport code, ETRAN-15, for the same electron energies. After the discrepancies between the measured and computed results are evaluated, reasonable agreement is found between the measured and computed absorbed energy distributions as a function of depth in water. An evalutation of the response of the interferometer as a function of electron intensities is performed. A comparison among four energy deposition curves that result from the irradiation of water with pulsed electron beams from a Febetron accelerator, model 705, is presented. These pulsed beams were produced by the same vacuum diode with the same charging voltage. The results indicate that the energy distribution of the electrons in the pulsed beam is not always constant. A comparison of the energy deposition curves that result from the irradiation of water with electron pulses from different vacuum diodes but the same charging voltage is presented. These results indicate again that the energy distribution of the electrons in the pulsed beam may vary between vacuum diodes. These differences would not be realized by using a totally absorbing metal calorimeter and Faraday Cup

  9. Secondary organic material formed by methylglyoxal in aqueous aerosol mimics – Part 1: Surface tension depression and light-absorbing products

    V. F. McNeill

    2009-07-01

    Full Text Available We show that methylglyoxal forms light-absorbing secondary organic material in aqueous ammonium sulfate and ammonium nitrate solutions mimicking tropospheric aerosol particles. The light-absorbing products form on the order of minutes, and solution composition continues to change over several days. The results suggest an aldol condensation pathway involving the participation of the ammonium ion. Aqueous solutions of methylglyoxal, with and without inorganic salts, exhibit surface tension depression. Methylglyoxal uptake could potentially change the optical properties, climate effects, and heterogeneous chemistry of the seed aerosol over its lifetime.

  10. Mechanical Design of a High Energy Beam Absorber for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab

    Baffes, C; Leibfritz, J; Oplt, S; Rakhno, I

    2013-01-01

    A high energy beam absorber has been built for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab. In the facility's initial configuration, an electron beam will be accelerated through 3 TTF-type or ILC-type RF cryomodules to an energy of 750MeV. The electron beam will be directed to one of multiple downstream experimental and diagnostic beam lines and then deposited in one of two beam absorbers. The facility is designed to accommodate up to 6 cryomodules, which would produce a 75kW beam at 1.5GeV; this is the driving design condition for the beam absorbers. The beam absorbers consist of water-cooled graphite, aluminum and copper layers contained in a Helium-filled enclosure. This paper describes the mechanical implementation of the beam absorbers, with a focus on thermal design and analysis. In addition, the potential for radiation-induced degradation of the graphite is discussed.

  11. Mechanical Design of a High Energy Beam Absorber for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab

    Baffes, C.; Church, M.; Leibfritz, J.; Oplt, S.; Rakhno, I.; /Fermilab

    2012-05-10

    A high energy beam absorber has been built for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab. In the facility's initial configuration, an electron beam will be accelerated through 3 TTF-type or ILC-type SRF cryomodules to an energy of 750MeV. The electron beam will be directed to one of multiple downstream experimental and diagnostic beam lines and then deposited in one of two beam absorbers. The facility is designed to accommodate up to 6 cryomodules, which would produce a 75kW beam at 1.5GeV; this is the driving design condition for the beam absorbers. The beam absorbers consist of water-cooled graphite, aluminum and copper layers contained in a helium-filled enclosure. This paper describes the mechanical implementation of the beam absorbers, with a focus on thermal design and analysis. The potential for radiation-induced degradation of the graphite is discussed.

  12. Household transitions to energy efficient lighting

    New energy efficient lighting technologies can significantly reduce household electricity consumption, but adoption has been slow. A unique dataset of German households is used in this paper to examine the factors associated with the replacement of old incandescent lamps (ILs) with new energy efficient compact fluorescent lamps (CFLs) and light emitting diodes (LEDs). The ‘rebound’ effect of increased lamp luminosity in the transition to energy efficient bulbs is analyzed jointly with the replacement decision to account for household self-selection in bulb-type choice. Results indicate that the EU ban on ILs accelerated the pace of transition to CFLs and LEDs, while storage of bulbs significantly dampened the speed of the transition. Higher lighting needs and bulb attributes like energy efficiency, environmental friendliness, and durability spur IL replacement with CFLs or LEDs. Electricity gains from new energy efficient lighting are mitigated by 23% and 47% increases in luminosity for CFL and LED replacements, respectively. Model results suggest that taking the replacement bulb from storage and higher levels of education dampen the magnitude of these luminosity rebounds in IL to CFL transitions. - Highlights: • EU ban on ILs has fostered transitions to energy efficient lightingEnergy efficient, environmentally friendly, and durable lighting preferences make CFL and LED transitions more likely • Indicators of greater lighting needs are associated with higher propensities to replace ILs with CFLs and LEDs • For residential lighting, the rebound effect manifests itself through increases in luminosity • In IL to CLF transitions luminosity increases are lower with higher levels of education

  13. An APL program for the distribution of energy deposition by charged particles passing through thin absorbers

    Howell, L. W.

    1985-01-01

    An APL program which numerically evaluates the probability density function (PDF) for the energy deposited in a thin absorber by a charged particle is proposed, with application to the construction, pointing, and control of spacecraft. With this program, the PDF of the restricted energy loss distribution of Watts (1973) is derived, and Vavilov's (1957) distribution is obtained by proper parameter selection. The method is demonstrated with the example of the effect of charged particle induced radiation on the Hubble Space Telescope (HST) pointing accuracy. A Monte Carlo study simulates the photon noise caused by charged particles passing through the photomultiplier tube window, and the stochastic variation of energy loss is introduced into the simulation by generating random energy losses from a power law distribution. The program eliminates annoying loop procedures, and model parameter sensitivity can be studied using the graphical output.

  14. Diamond detector in absorbed dose measurements in high-energy linear accelerator photon and electron beams.

    Ravichandran, Ramamoorthy; Binukumar, John Pichy; Al Amri, Iqbal; Davis, Cheriyathmanjiyil Antony

    2016-01-01

    Diamond detectors (DD) are preferred in small field dosimetry of radiation beams because of small dose profile penumbras, better spatial resolution, and tissue-equivalent properties. We investigated a commercially available 'microdiamond' detector in realizing absorbed dose from first principles. A microdiamond detector, type TM 60019 with tandem electrometer is used to measure absorbed doses in water, nylon, and PMMA phantoms. With sensitive volume 0.004 mm3, radius 1.1mm, thickness 1 x10(-3) mm, the nominal response is 1 nC/Gy. It is assumed that the diamond detector could collect total electric charge (nC) developed during irradiation at 0 V bias. We found that dose rate effect is less than 0.7% for changing dose rate by 500 MU/min. The reproducibility in obtaining readings with diamond detector is found to be ± 0.17% (1 SD) (n = 11). The measured absorbed doses for 6 MV and 15 MV photons arrived at using mass energy absorption coefficients and stop-ping power ratios compared well with Nd, water calibrated ion chamber measured absorbed doses within 3% in water, PMMA, and nylon media. The calibration factor obtained for diamond detector confirmed response variation is due to sensitivity due to difference in manufacturing process. For electron beams, we had to apply ratio of electron densities of water to carbon. Our results qualify diamond dosimeter as a transfer standard, based on long-term stability and reproducibility. Based on micro-dimensions, we recommend these detectors for pretreatment dose verifications in small field irradiations like stereotactic treatments with image guidance. PMID:27074452

  15. The use of energy absorbers to protect structures against impact loading

    When a flying missile impacts a fixed structure, the interface loading is dependent on the deformation characteristics of both impacting and impacted bodies. If both are too rigid to accommodate the amount of gross deformation required to neutralize the incoming kinetic energy, or if such energy absorption has a chance to proceed in uncontrolled and unreliable ways, then there is a need to interpose a specifically designed 'energy absorber' between missile and structure, from which a well-defined load time history can be derived during the course of impact. The required characteristics of such an energy absorption material are: the capability to accommodate large permanent deformation without structural failure; and the reliable and controlled 'load-deformation' (or 'stress-stain') behaviour under dynamic conditions, with an aim at an optimal square shape curve. Consideration must also be given to environmental or other disturbing effects, like temperature, humidity, and 'out of plane' loading. A short survey is presented of the wide range of energy absorbers already described in technical papers or used in a number of practical safety applications within varied engineering fields (from vehicle crash barriers to high energy pipe whipping restraints). However, with such open a literature, information is usually lacking in the specific data required for design analysis. The following 'energy absorption' materials and processes have thus been further experimentally investigated, with an aim at pipe whipping restraint application for nuclear power plants: (1) plastic extension of austenitic stainless steel rods; (2) plastic compression of copper bumpers; and (3) punching of lightweight concrete structures. (Auth.)

  16. Energy scaling of a carbon nanotube saturable absorber mode-locked femtosecond bulk laser

    Baylam, Işınsu; Çankaya, Hüseyin; Sennaroğlu, Alphan; Ozharar, S.; Choi, S. Y.; Kim, K.; Rotermund, F.; Griebner, U.; Petrov, V.

    2012-01-01

    We report successful energy scaling of a room-temperature femtosecond Cr4+: forsterite laser by using a single-walled carbon nanotube saturable absorber (SWCNT-SA). By incorporating a q-preserving multipass cavity, a repetition rate of 4.51 MHz was realized, and the oscillator produced 121 fs, 10 nJ pulses at 1247 nm, with an average output power of 46 mW. To the best of our knowledge, the peak power of 84 kW is the highest generated to date from a SWCNT-SA mode-locked oscillator. Furthermore...

  17. FracTherm - fractal hydraulic structures for energy efficient solar absorbers and other heat exchangers

    Hermann, M. [Fraunhofer Inst. for Solar Energy Systems, Freiburg (Germany)

    2004-07-01

    The energy efficiency of heat exchangers such as solar absorbers is determined both by their thermal efficiency - evaluated by the collector efficiency factor F' - and the primary energy which is needed to drive the pump transporting the fluid. The former is strongly influenced by the uniformity of the volume flow whereas the latter also depends on the pressure drop in the fluid channels. Thus, in order to obtain a high energy efficiency, it is necessary to ensure a uniform flow distribution with low pressure drop. However, conventional hydraulic structures often show a high pressure drop (serial flow) or a non-uniform flow distribution (parallel flow). In contrast to these channel designs, many natural structures are built of multiple branched channels (''fractals''). The aim of a current research work, which is funded by the German Federal Environmental Foundation (DBU), is to transfer those principles of fluid channel design to technical applications (bionic approach) and compare the structures with conventional ones. This paper describes how fractal hydraulic structures are generated and assessed using hydraulic and thermal simulations. Flow experiments as well as thermography with an absorber model are shown. Furthermore, investigations of flow phenomena using Computational Fluid Dynamics (CFD) are presented. (orig.)

  18. A new optical method coupling light polarization and Vis-NIR spectroscopy to improve the measured absorbance signal's quality of soil samples.

    Gobrecht, Alexia; Bendoula, Ryad; Roger, Jean-Michel; Bellon-Maurel, Véronique

    2014-05-01

    Visible - Near-infrared spectroscopy (Vis-NIRS) is now commonly used to measure different physical and chemical parameters of soils, including carbon content. However, prediction model accuracy is insufficient for Vis-NIRS to replace routine laboratory analysis. One of the biggest issues this technique is facing up to is light scattering due to soil particles. It causes departure in the assumed linear relationship between the Absorbance spectrum and the concentration of the chemicals of interest as stated by Beer-Lambert's Law, which underpins the calibration models. Therefore it becomes essential to improve the metrological quality of the measured signal in order to optimize calibration as light/matter interactions are at the basis of the resulting linear modeling. Optics can help to mitigate scattering effect on the signal. We put forward a new optical setup coupling linearly polarized light with a Vis-NIR spectrometer to free the measured spectra from multi-scattering effect. The corrected measured spectrum was then used to compute an Absorbance spectrum of the sample, using Dahm's Equation in the frame of the Representative Layer Theory. This method has been previously tested and validated on liquid (milk+ dye) and powdered (sand + dye) samples showing scattering (and absorbing) properties. The obtained Absorbance was a very good approximation of the Beer-Lambert's law absorbance. Here, we tested the method on a set of 54 soil samples to predict Soil Organic Carbon content. In order to assess the signal quality improvement by this method, we built and compared calibration models using Partial Least Square (PLS) algorithm. The prediction model built from new Absorbance spectrum outperformed the model built with the classical Absorbance traditionally obtained with Vis-NIR diffuse reflectance. This study is a good illustration of the high influence of signal quality on prediction model's performances.

  19. Impact characteristics of energy absorbing materials for radioactive material transport packages

    A series of high-velocity impact tests using grout as the package energy-absorbing material was successfully carried out. The purpose of these tests was to characterize the dynamic behavior of grout material when used as an energy-absorbing material for packages. These package-impact tests were simulated accurately with the dynamic finite element code DYNA, using appropriate grout material properties. The need to invoke the grout damage curve illustrates the fact that the grout mix under study undergoes a transition where the grout retains its full strength at relatively low impact velocity to a diminished strength where progressive debonding and pulverization takes place as the impact velocity increases. The transitional velocity range is a function of a particular grout mix as well as impact conditions. Laboratory tests of the grout mix that include the failure region and different failure modes should be an integral part of the investigation process to accurately correlate package benchmark tests with analytical models. (J.P.N.)

  20. Full-Scale Crash Test of a MD-500 Helicopter with Deployable Energy Absorbers

    Kellas, Sotiris; Jackson, Karen E.; Littell, Justin D.

    2010-01-01

    A new externally deployable energy absorbing system was demonstrated during a full-scale crash test of an MD-500 helicopter. The deployable system is a honeycomb structure and utilizes composite materials in its construction. A set of two Deployable Energy Absorbers (DEAs) were fitted on the MD-500 helicopter for the full-scale crash demonstration. Four anthropomorphic dummy occupants were also used to assess human survivability. A demonstration test was performed at NASA Langley's Landing and Impact Research Facility (LandIR). The test involved impacting the helicopter on a concrete surface with combined forward and vertical velocity components of 40-ft/s and 26-ft/s, respectively. The objectives of the test were to evaluate the performance of the DEA concept under realistic crash conditions and to generate test data for validation of dynamic finite element simulations. Descriptions of this test as well as other component and full-scale tests leading to the helicopter test are discussed. Acceleration data from the anthropomorphic dummies showed that dynamic loads were successfully attenuated to within non-injurious levels. Moreover, the airframe itself survived the relatively severe impact and was retested to provide baseline data for comparison for cases with and without DEAs.

  1. Formation of nitrogen- and sulfur-containing light-absorbing compounds accelerated by evaporation of water from secondary organic aerosols

    Nguyen, Tran B.; Lee, Paula B.; Updyke, Katelyn M.; Bones, David L.; Laskin, Julia; Laskin, Alexander; Nizkorodov, Sergey A.

    2012-01-01

    Aqueous extracts of secondary organic aerosols (SOA) generated from the ozonolysis of d-limonene were subjected to dissolution, evaporation, and re-dissolution in the presence and absence of ammonium sulfate (AS). Evaporation with AS at pH 4-9 produced chromophores that were stable with respect to hydrolysis and had a distinctive absorption band at 500 nm. Evaporation accelerated the rate of chromophore formation by at least three orders of magnitude compared to the reaction in aqueous solution, which produced similar compounds. Absorption spectroscopy and high-resolution nanospray desorption electrospray ionization (nano-DESI) mass spectrometry experiments suggested that the molar fraction of the chromophores was small (105 L mol-1 cm-1 at 500 nm) increased the effective mass absorption coefficient of the residual organics in excess of 103 cm2 g-1 - a dramatic effect on the optical properties from minor constituents. Evaporation of SOA extracts in the absence of AS resulted in the production of colored compounds only when the SOA extract was acidified to pH ˜ 2 with sulfuric acid. These chromophores were produced by acid-catalyzed aldol condensation, followed by a conversion into organosulfates. The presence of organosulfates was confirmed by high resolution mass spectrometry experiments. Results of this study suggest that evaporation of cloud or fog droplets containing dissolved organics leads to significant modification of the molecular composition and serves as a potentially important source of light-absorbing compounds.

  2. Short-time dynamics of 2-thiouracil in the light absorbing S2(ππ∗) state

    Ultrahigh quantum yields of intersystem crossing to the lowest triplet state T1 are observed for 2-thiouracils (2TU), which is in contrast to the natural uracils that predominantly exhibit ultrafast internal conversion to the ground state upon excitation to the singlet excited state. The intersystem crossing mechanism of 2TU has recently been investigated using second-order perturbation methods with a high-level complete-active space self-consistent field. Three competitive nonadiabatic pathways to the lowest triplet state T1 from the initially populated singlet excited state S2 were proposed. We investigate the initial decay dynamics of 2TU from the light absorbing excited states using resonance Raman spectroscopy, time-dependent wave-packet theory in the simple model, and complete-active space self-consistent field (CASSCF) and time dependent-Becke’s three-parameter exchange and correlation functional with the Lee-Yang-Parr correlation functional (TD-B3LYP) calculations. The obtained short-time structural dynamics in easy-to-visualize internal coordinates were compared with the CASSCF(16,11) predicted key nonadiabatic decay routes. Our results indicate that the predominant decay pathway initiated at the Franck-Condon region is toward the S2/S1 conical intersection point and S2T3 intersystem crossing point, but not toward the S2T2 intersystem crossing point

  3. Light energy dissipation under water stress conditions

    Using 14CO2 gas exchange and metabolite analyses, stomatal as well as total internal CO2 uptake and evolution were estimated. Pulse modulated fluorescence was measured during induction and steady state of photosynthesis. Leaf water potential of Digitalis lanata EHRH. plants decreased to -2.5 megapascals after withholding irrigation. By osmotic adjustment, leaves remained turgid and fully exposed to irradiance even at severe water stress. Due to the stress-induced reduction of stomatal conductance, the stomatal CO2 exchange was drastically reduced, whereas the total CO2 uptake and evolution were less affected. Stomatal closure induced an increase in the reassimilation of internally evolved CO2. This CO2-recycling consumes a significant amount of light energy in the form of ATP and reducing equivalents. As a consequence, the metabolic demand for light energy is only reduced by about 40%, whereas net photosynthesis is diminished by about 70% under severe stress conditions. By CO2 recycling, carbon flux, enzymatic substrate turnover and consumption of light energy were maintained at high levels, which enabled the plant to recover rapidly after rewatering. In stressed D. lanata plants a variable fluorescence quenching mechanism, termed coefficient of actinic light quenching, was observed. Besides water conservation, light energy dissipation is essential and involves regulated metabolic variations

  4. Lumbar load attenuation for rotorcraft occupants using a design methodology for the seat impact energy-absorbing system

    Moradi, Rasoul; Beheshti, Hamid; Lankarani, Hamid

    2012-12-01

    Aircraft occupant crash-safety considerations require a minimum cushion thickness to limit the relative vertical motion of the seat-pelvis during high vertical impact loadings in crash landings or accidents. In military aircraft and helicopter seat design, due to the potential for high vertical accelerations in crash scenarios, the seat system must be provided with an energy absorber to attenuate the acceleration level sustained by the occupants. Because of the limited stroke available for the seat structure, the design of the energy absorber becomes a trade-off problem between minimizing the stroke and maximizing the energy absorption. The available stroke must be used to prevent bottoming out of the seat as well as to absorb maximum impact energy to protect the occupant. In this study, the energy-absorbing system in a rotorcraft seat design is investigated using a mathematical model of the occupant/seat system. Impact theories between interconnected bodies in multibody mechanical systems are utilized to study the impact between the seat pan and the occupant. Experimental responses of the seat system and the occupant are utilized to validate the results from this study for civil and military helicopters according to FAR 23 and 25 and MIL-S-58095 requirements. A model for the load limiter is proposed to minimize the lumbar load for the occupant by minimizing the relative velocity between the seat pan and the occupant's pelvis. The modified energy absorber/load limiter is then implemented for the seat structure so that it absorbs the energy of impact in an effective manner and below the tolerable limit for the occupant in a minimum stroke. Results show that for a designed stroke, the level of occupant lumbar spine injury would be significantly attenuated using this modified energy-absorber system.

  5. Application of Charpy Impact Absorbed Energy to the Safety Assessment Based on SINTAP

    2006-01-01

    The European Structural Integrity Assessment Procedure(SINTAP) was applied to the assessment of welded joints of the APl 5L X65 pipeline steel with an assumed embedded flaw and surface flaw at the weld toe. At default level( level 0), the assessment point was established by estimating fracture toughness value KIc conservatively from Charpy energy test data. At the same time, the analysis level 1 (basic level)was applied based on the fracture toughness CTOD. Then the two assessment levels were compared. The assessment results show that all assessment points are located within the failure lines of analysis levels 0 and 1. So the welded joint of the pipeline is safe. It can be concluded that the assessment based on Charpy absorbed energy is practicable when other fracture toughness data are not available, or cannot be easily obtained. The results are conservative.

  6. Analysis of cellular metals as energy-absorbing elements in car seats

    Nesic, Srecko; Michels, Wilhelm; Krupp, Ulrich [Laboratory for Material Design and Structural Integrity, Faculty of Engineering and Computer Science, University of Applied Sciences Osnabrueck (Germany); Schaeffler, Peter [Alulight International GmbH, Ranshofen (Austria); Unruh, Klaus [Faurecia Autositze GmbH, Stadthagen (Germany)

    2011-11-15

    Due to the high energy-absorption potential of metal foams and their excellent weight-to-stiffness ratio, metal foams in car seats may contribute to both increasing passenger safety and also weight reduction. An overview and the first results of a research project to apply cellular metals as energy-absorbing components in car seats in case of a crash are discussed. The project aims are material optimization and the generation of standards and design criteria for a novel technical application of metal foams. The first results reveal the microstructure and mechanical behavior of different metal foams and metal-foam/metal-sheet sandwich structures. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Experimental Investigation of the Power Generation Performance of Floating-Point Absorber Wave Energy Systems: Preprint

    Li, Y.; Yu, Y.; Epler, J.; Previsic, M.

    2012-04-01

    The extraction of energy from ocean waves has gained interest in recent years. The floating-point absorber (FPA) is one of the most promising devices among a wide variety of wave energy conversion technologies. Early theoretical studies mainly focused on understanding the hydrodynamics of the system and on predicting the maximum power that could be extracted by a heaving body. These studies evolve from the investigation of floating-body interactions in offshore engineering and naval architecture disciplines. To our best knowledge, no systematic study has been reported about the investigation of the power generation performance of an FPA with a close-to-commercial design. A series of experimental tests was conducted to investigate the power extraction performance of an FPA system.

  8. An energy absorbing far-field boundary condition for the elastic wave equation

    Petersson, N A; Sjogreen, B

    2008-07-15

    The authors present an energy absorbing non-reflecting boundary condition of Clayton-Engquist type for the elastic wave equation together with a discretization which is stable for any ratio of compressional to shear wave speed. They prove stability for a second order accurate finite-difference discretization of the elastic wave equation in three space dimensions together with a discretization of the proposed non-reflecting boundary condition. The stability proof is based on a discrete energy estimate and is valid for heterogeneous materials. The proof includes all six boundaries of the computational domain where special discretizations are needed at the edges and corners. The stability proof holds also when a free surface boundary condition is imposed on some sides of the computational domain.

  9. In situ aerosol optics in Reno, NV, USA during and after the summer 2008 California wildfires and the influence of absorbing and non-absorbing organic coatings on spectral light absorption

    M. Gyawali

    2009-10-01

    Full Text Available Hundreds of wildfires in Northern California were sparked by lightning during the summer of 2008, resulting in downwind smoke for the months of June and July. Comparisons are reported for aerosol optics measurements in Reno, Nevada made during the very smoky month of July and the relatively clean month of August. Photoacoustic instruments equipped with integrating nephelometers were used to measure aerosol light scattering and absorption coefficients at wavelengths of 405 nm and 870 nm, revealing a strong variation of aerosol light absorption with wavelength. Insight on fuels burned is gleaned from comparison of Ångström exponents of absorption (AEA versus single scattering albedo (SSA of the ambient measurements with laboratory biomass smoke measurements for many fuels. Measurements during the month of August, which were largely unaffected by fire smoke, exhibit surprisingly low AEA for aerosol light absorption when the SSA is highest, again likely as a consequence of the underappreciated wavelength dependence of aerosol light absorption by particles coated with non-absorbing organic and inorganic matter. Coated sphere calculations were used to show that AEA as large as 1.6 are possible for wood smoke even with non-absorbing organic coatings on black carbon cores, suggesting care be exercised when diagnosing AEA.

  10. Study on preparation of the core-nanoshell composite absorbers by high-energy ball milling at room temperature.

    Che, Ruxin; Gao, Hong; Yu, Bing; Wang, Shuo; Wang, Chunxia

    2012-02-01

    Electromagnetic (EM) wave pollution has become the chief physical pollution for environment. In recent years, some researches have been focused on the preparation of nano-composite absorbers at low temperatures or even at room temperature. In this letter, preparation of nanocomposite by using high-energy ball milling at room temperature is reported. The core-nanoshell composite absorbers with magnetic fly-ash hollow cenosphere (MFHC) as nuclear and nanocrystalline magnetic material as shell were prepared by high-energy ball milling and vacuum-sintering in this paper. The pre-treatment of MFHC, the sintering process and the mol ratio of starting chemicals had a significant impact for property of composite absorbers. The results of X-ray diffraction analysis (XRD), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA) analysis indicated that perfect-crystalline nanomagnetic material coating was gotten with a particle size of 12 nm after ball milling. The results show the MFHC is dielectric loss and magnetic loss too; the exchange-coupling interaction happened between ferrite of the MFHC and nanocrystalline magnetic material coating. The exchange-coupling interaction enhances magnetic loss of composite absorbers. They have a perfect EM parameters at low microwave frequency. The core-nanoshell composite absorbers have a higher magnetic loss at low frequencies, and it is consistent with requirements of the microwave absorbing material at the low-frequency absorption. The microwave absorptivity of the core-nanoshell composite absorbers is better than single material. PMID:22630008

  11. Energy balance on light nuclear reactions

    A new model has been developed for calculating all kinds of reaction cross sections and double differential cross sections for neutron induced reactions on light nuclei. In the model the recoil effect is taken into account exactly to keep the energy balance both in C.M.S. and L.S.. The formulation of the new model gives the energy conservation exactly both in C.M.S. and L.S., and the ENDF-B6 outputting is reliable

  12. Experimental and Analytical Evaluation of a Composite Honeycomb Deployable Energy Absorber

    Jackson, Karen E.; Kellas, Sotiris; Horta, Lucas G.; Annett, Martin S.; Polanco, Michael A.; Littell, Justin D.; Fasanella, Edwin L.

    2011-01-01

    In 2006, the NASA Subsonic Rotary Wing Aeronautics Program sponsored the experimental and analytical evaluation of an externally deployable composite honeycomb structure that is designed to attenuate impact energy during helicopter crashes. The concept, which is designated the Deployable Energy Absorber (DEA), utilizes an expandable Kevlar honeycomb structure to dissipate kinetic energy through crushing. The DEA incorporates a unique flexible hinge design that allows the honeycomb to be packaged and stowed flat until needed for deployment. A variety of deployment options such as linear, radial, and/or hybrid methods can be used. Experimental evaluation of the DEA utilized a building block approach that included material characterization testing of its constituent, Kevlar -129 fabric/epoxy, and flexural testing of single hexagonal cells. In addition, the energy attenuation capabilities of the DEA were demonstrated through multi-cell component dynamic crush tests, and vertical drop tests of a composite fuselage section, retrofitted with DEA blocks, onto concrete, water, and soft soil. During each stage of the DEA evaluation process, finite element models of the test articles were developed and simulations were performed using the explicit, nonlinear transient dynamic finite element code, LS-DYNA. This report documents the results of the experimental evaluation that was conducted to assess the energy absorption capabilities of the DEA.

  13. Vibration suppression of electronic box by a dual function piezoelectric energy harvester-tuned vibration absorber

    Over the past few years, remarkable developments in piezoelectric materials have motivated many researchers to work in the field of vibration energy harvesting by using piezoelectric beam like smart structures. This paper aimed to present the most recent application of a dual function piezoelectric device which can suppress vibration and harvest vibration energy simultaneously and a brief illustration of conventional mechanical and electrical TVAs (Tuned Vibration Absorber). It is shown that the proposed dual function device combines the benefits of conventional mechanical and electrical TVAs and reduces their relative disadvantages. Conversion of mechanical energy into electrical energy introduces damping and, hence, the optimal damping required by this TVA is generated by the energy harvesting effects. This paper presents the methodology of implementing the theory of electromechanical TVAs to suppress the response of any real world structure. The work also illustrates the prospect of extensive applications of such novel electromechanical TVAs in defence and industry. The results show that the optimum degree of vibration suppression of an electronic box is achieved by this dual function TVA through suitable tuning of the attached electrical circuitry. (author)

  14. Magnetic Energy Fluctuations: Observations by Light Scattering

    Lyons, K. B.; Fleury, P. A.

    1982-01-01

    The first observations of magnetic energy fluctuations by light scattering are reported. The spectra observed in antiferromagnetic KNiF3 are strongly polarized, mildly q dependent, but strongly temperature dependent near TN=248.5 K. The observed line shapes exhibit two characteristic frequencies, one less than 0.6 GHz and the other between 5 and 15 GHz, depending on temperature.

  15. Lighting

    Federal Laboratory Consortium — Lighting Systems Test Facilities aid research that improves the energy efficiency of lighting systems. • Gonio-Photometer: Measures illuminance from each portion of...

  16. Formation of Nitrogen- and Sulfur-Containing Light-Absorbing Compounds Accelerated by Evaporation of Water from Secondary Organic Aerosols

    Nguyen, Tran B.; Lee, Paula B.; Updyke, Katelyn M.; Bones, David L.; Laskin, Julia; Laskin, Alexander; Nizkorodov, Sergey

    2012-01-14

    Aqueous extracts of secondary organic aerosols (SOA) generated from the ozonolysis of dlimonene were subjected to dissolution, evaporation, and re-dissolution in the presence and absence of ammonium sulfate (AS). Evaporation with AS at pH 4-9 produced chromophores that were stable with respect to hydrolysis and had a distinctive absorption band at 500 nm. Evaporation accelerated the rate of chromophore formation by at least three orders of magnitude compared to the reaction in aqueous solution, which produced similar compounds. Absorption spectroscopy and high-resolution nanospray desorption electrospray ionization (nano-DESI) mass spectrometry experiments suggested that the molar fraction of the chromophores was small (< 2%), and that they contained nitrogen atoms. Although the colored products represented only a small fraction of SOA, their large extinction coefficients (>10{sup 5} L mol{sup -1} cm{sup -1} at 500 nm) increased the effective mass absorption coefficient of the residual organics in excess of 10{sup 3} cm{sup 2} g{sup -1} - a dramatic effect on the optical properties from minor constituents. Evaporation of SOA extracts in the absence of AS resulted in the production of colored compounds only when the SOA extract was acidified to pH {approx} 2 with sulfuric acid. These chromophores were produced by acid-catalyzed aldol condensation, followed by a conversion into organosulfates. The presence of organosulfates was confirmed by high resolution mass spectrometry experiments. Results of this study suggest that evaporation of cloud or fog droplets containing dissolved organics leads to significant modification of the molecular composition and serves as a potentially important source of light-absorbing compounds.

  17. Capturing the Energy Absorbing Mechanisms of Composite Structures under Crash Loading

    Wade, Bonnie

    As fiber reinforced composite material systems become increasingly utilized in primary aircraft and automotive structures, the need to understand their contribution to the crashworthiness of the structure is of great interest to meet safety certification requirements. The energy absorbing behavior of a composite structure, however, is not easily predicted due to the great complexity of the failure mechanisms that occur within the material. Challenges arise both in the experimental characterization and in the numerical modeling of the material/structure combination. At present, there is no standardized test method to characterize the energy absorbing capability of composite materials to aide crashworthy structural design. In addition, although many commercial finite element analysis codes exist and offer a means to simulate composite failure initiation and propagation, these models are still under development and refinement. As more metallic structures are replaced by composite structures, the need for both experimental guidelines to characterize the energy absorbing capability of a composite structure, as well as guidelines for using numerical tools to simulate composite materials in crash conditions has become a critical matter. This body of research addresses both the experimental characterization of the energy absorption mechanisms occurring in composite materials during crushing, as well as the numerical simulation of composite materials undergoing crushing. In the experimental investigation, the specific energy absorption (SEA) of a composite material system is measured using a variety of test element geometries, such as corrugated plates and tubes. Results from several crush experiments reveal that SEA is not a constant material property for laminated composites, and varies significantly with the geometry of the test specimen used. The variation of SEA measured for a single material system requires that crush test data must be generated for a range of

  18. Acoustic coherent perfect absorbers

    In this paper, we explore the possibility of achieving acoustic coherent perfect absorbers. Through numerical simulations in two dimensions, we demonstrate that the energy of coherent acoustic waves can be totally absorbed by a fluid absorber with specific complex mass density or bulk modulus. The robustness of such absorbing systems is investigated under small perturbations of the absorber parameters. We find that when the resonance order is the lowest and the size of the absorber is comparable to the wavelength in the background, the phenomenon of perfect absorption is most stable. When the wavelength inside both the background and the absorber is much larger than the size of the absorber, perfect absorption is possible when the mass density of the absorber approaches the negative value of the background mass density. Finally, we show that by using suitable dispersive acoustic metamaterials, broadband acoustic perfect absorption may be achieved. (papers)

  19. Local Collision Simulation of an SC Wall Using Energy Absorbing Steel

    This study evaluates the local damage of a turbine in an auxiliary building of a nuclear power plant due to an external impact by using the LS-DYNA finite element program. The wall of the auxiliary building is SC structure and the material of the SC wall plate is high manganese steel, which has superior ductility and energy absorbance compared to the ordinary steel used for other SC wall plates. The effects of the material of the wall, collision speed, and angle on the magnitude of the local damage were evaluated by local collision analysis. The analysis revealed that the SC wall made of manganese steel had significantly less damage than the SC wall made of ordinary steel. In conclusion, an SC wall made of manganese steel can have higher effective resistance than an SC wall made of ordinary steel against the local collision of an airplane engine or against a turbine impact

  20. A fail-safe magnetorheological energy absorber for shock and vibration isolation

    Magnetorheological (MR) energy absorbers (EAs) are an effective adaptive EA technology with which to maximize shock and vibration isolation. However, to realize maximum performance of the semi-active control system, the off-state (i.e., field off) stroking load of the MREA must be minimized at all speeds, and the dynamic range of the MREA must be maximized at high speed. This study presents a fail-safe MREA (MREA-FS) concept that, can produce a greater dynamic range at all piston speeds. A bias damping force is generated in the MREA-FS using permanent magnetic fields, which enables fail-safe behavior in the case of power failure. To investigate the feasibility and capability of the MREA-FS in the context of the semi-active control systems, a single-degree-of-freedom base excited rigid payload is mathematically constructed and simulated with skyhook control

  1. Vibration Mitigation in Partially Liquid-Filled Vessel using Passive Energy Absorbers

    Farid, Maor; Gendelman, O V

    2016-01-01

    This paper treats possible solutions for vibration mitigation in reduced-order model of partially-filled liquid tank under impulsive forcing. Such excitation may lead to hydraulic impacts applied on the tank inner walls. Finite stiffness of the tank walls is taken into account. We explore both linear (Tuned Mass Damper) and nonlinear (Nonlinear Energy Sink) passive vibration absorbers; mitigation performances are examined numerically. The liquid sloshing mass is modeled by equivalent massspring-dashpot system, which can both perform small-amplitude linear oscillations and impact the vessel walls. We use parameters of the equivalent mass-spring-dashpot system for well-explored case of cylindrical tanks. The hydraulic impacts are modeled by high-power potential and dissipation functions. Critical location in the tank structure is determined and expression of the corresponding local mechanical stress is derived. We use finite-elemet approach to assess the natural frequencies for specific system parameters and to...

  2. Stability analysis of the Gyroscopic Power Take-Off wave energy point absorber

    Nielsen, Søren R. K.; Zhang, Zili; Kramer, Morten Mejlhede; Olsen, Jan

    The Gyroscopic Power Take-Off (GyroPTO) wave energy point absorber consists of a float rigidly connected to a lever. The operational principle is somewhat similar to that of the so-called gyroscopic hand wrist exercisers, where the rotation of the float is brought forward by the rotational particle...... motion of the waves. At first, the equations of motion of the system are derived based on analytical rigid body dynamics. Next, assuming monochromatic waves simplified equations are derived, valid under synchronisation of the ring of the gyro to the angular frequency of the excitation. Especially, it is...... demonstrated that the dynamics of the ring can be described as an autonomous nonlinear single-degree-of-freedom system, affected by three different types of point attractors. One where the ring vibrations are attracted to a static equilibrium point indicating unstable synchronisation and two types of...

  3. Development of Lead Free Energy Absorber for Space Shuttle Blast Container

    Balles, Donald; Ingram, Thomas; Novak, Howard; Schricker, Albert

    1999-01-01

    The Space Shuttle is connected to the mobile launch platform (MLP) by four aft skirt hold down studs on each solid rocket booster (SRB). Prior to lift-off, the frangible nuts inside the aft skirt blast containers are severed into two nut halves by two pyrotechnic booster cartridges. This action releases the Space Shuttle and allows the hold down studs to eject through the aft skirt bore and then down into the MLP. USBI has been tasked to upgrade the blast container for two specific reasons: (1) To eliminate lead for environmental concerns, and (2) To reduce the chance of nut recontact with the holddown stud. Nut recontact with the stud has been identified as a likely contributor to stud hang-ups. This upgrade will replace the lead liner with a unique open cell aluminum foam material, that has commercial and military uses. The aluminum foam used as an energy absorber is a proven design in many other aerospace/defense applications. Additional benefits of using the open cell, energy absorbent aluminum foam in place of the solid lead liner are: (1) Lead handling / exposure and possible contamination, along with hazardous waste disposal, will be eliminated; (2) Approximately 200 lbs. weight savings will be contributed to each Space Shuttle flight by using aluminum foam instead of lead; (3) The new aluminum liner is designed to catch all shrapnel from frangible nuts, thus virtually eliminating chance of debris exiting the HDP and causing potential damage to the vehicle; (4) Using the lighter aluminum liner instead of lead, allows for easier assembly and disassembly of blast container elements, which also improves safety, operator handling, and the efficiency of operations.

  4. Considering linear generator copper losses on model predictive control for a point absorber wave energy converter

    Highlights: • We considered the linear generator copper losses in the proposed MPC strategy. • We maximized the power transferred to the generator side power converter. • The proposed MPC increases the useful average power injected into the grid. • The stress level of the PTO system can be reduced by the proposed MPC. - Abstract: The amount of energy that a wave energy converter can extract depends strongly on the control strategy applied to the power take-off system. It is well known that, ideally, the reactive control allows for maximum energy extraction from waves. However, the reactive control is intrinsically noncausal in practice and requires some kind of causal approach to be applied. Moreover, this strategy does not consider physical constraints and this could be a problem because the system could achieve unacceptable dynamic values. These, and other control techniques have focused on the wave energy extraction problem in order to maximize the energy absorbed by the power take-off device without considering the possible losses in intermediate devices. In this sense, a reactive control that considers the linear generator copper losses has been recently proposed to increase the useful power injected into the grid. Among the control techniques that have emerged recently, the model predictive control represents a promising strategy. This approach performs an optimization process on a time prediction horizon incorporating dynamic constraints associated with the physical features of the power take-off system. This paper proposes a model predictive control technique that considers the copper losses in the control optimization process of point absorbers with direct drive linear generators. This proposal makes the most of reactive control as it considers the copper losses, and it makes the most of the model predictive control, as it considers the system constraints. This means that the useful power transferred from the linear generator to the power

  5. High-strength steel sheets offering high impact energy-absorbing capability; Kochoryoku gohan no shogeki kyushu tokusei

    Uenishi, A.; Kuriyama, Y.; Takahashi, M.

    1998-05-31

    Demand for increased impact safety as well as weight reduction of automobiles has increased the use of high-strength steel sheets. The impact energy absorbing capability of high-strength steel sheets up to 590 MPa was investigated by finite element method (FEM) analyses in combination with tension tests at speeds comparable to those of automobile collisions. The FEM analyses show that high dynamic strength and high work hardenability that improves the stability of the buckling process are advantageous in enhancing the impact energy absorbing capability of automobile parts. TRIP (transformation-induced plasticity) and DP (dual-phase) steels are superior in these properties and suitable for impact energy absorbing components. (author)

  6. Effect of hot rolling on the microstructure and impact absorbed energy of the strip steel by CSP

    Yang, Jing-jing; Wu, Run; Liang, Wen; Xiang, Zhi-dong; Tang, Meng-xia

    2014-07-01

    The microstructures and impact absorbed energies at various temperatures were investigated for steel strips hot rolled to thickness reductions of 95.5%, 96.0%, 96.5%, 97.0%, and 97.5%. Results indicate that grain refinement can be realized with an increase in hot rolling reduction. Besides, finer precipitates can be achieved with an increase in hot rolling reduction from 95.5% to 97.0%. The impact absorbed energy decreases with a decrease in testing temperature for steel strips hot rolled to 95.5%, 96.0%, and 96.5% reductions in thickness. However, in the case of steel strips hot rolled to 97.0% and 97.5% reductions in thickness, the impact absorbed energy remained almost constant with a decrease in testing temperature.

  7. Einstein 1905: From “Energy quanta” to “Light quanta”

    Beléndez Vázquez, Augusto

    2015-01-01

    “The energy of a light ray spreading out from a point source is not continuously distributed over an increasing space [wave theory of light] but consists of a finite number of energy quanta which are localized at points in space, which move without dividing, and which can only be produced and absorbed as complete units.” With these words Albert Einstein (1879-1955) introduced his “heuristic point of view toward the emission and transformation of light” which was presented in his first Annus M...

  8. Buck-boost converter for simultaneous semi-active vibration control and energy harvesting for electromagnetic regenerative shock absorber

    Li, Peng; Zhang, Chongxiao; Kim, Junyoung; Yu, Liangyao; Zuo, Lei

    2014-04-01

    Regenerative semi-active suspensions can capture the previously dissipated vibration energy and convert it to usable electrical energy for powering on-board electronic devices, while achieve both the better ride comfort and improved road handling performance at the same time when certain control is applied. To achieve this objective, the power electronics interface circuit connecting the energy harvester and the electrical loads, which can perform simultaneous vibration control and energy harvesting function is in need. This paper utilized a buck-boost converter for simultaneous semi-active vibration control and energy harvesting with electromagnetic regenerative shock absorber, which utilizes a rotational generator to converter the vibration energy to electricity. It has been found that when the circuit works in discontinuous current mode (DCM), the ratio between the input voltage and current is only related to the duty cycle of the switch pulse width modulation signal. Using this property, the buck-boost converter can be used to perform semi-active vibration control by controlling the load connected between the terminals of the generator in the electromagnetic shock absorber. While performing the vibration control, the circuit always draw current from the shock absorber and the suspension remain dissipative, and the shock absorber takes no additional energy to perform the vibration control. The working principle and dynamics of the circuit has been analyzed and simulations were performed to validate the concept.

  9. Performance of a Tethered Point Wave-Energy Absorber in Regular and Irregular Waves

    Bachynski, Erin E.

    2010-01-01

    The importance of the mooring system on the dynamic response of a point-absorber type ocean-wave energy converter (WEC) is investigated using a frequency-domain approach. In order to ensure the safety of WECs, careful consideration of the response and resonance frequencies in all motions must be evaluated, including the effects of the mooring system. In this study, a WEC floater with a closed, flat bottom is modeled as a rigid vertical cylinder tethered by elastic mooring lines. The WEC hydrodynamic added mass and damping are obtained using established potential-flow methods, with additional damping provided by the energy-extraction system. The results show that the response of the WEC, and the corresponding power takeoff, varies with the diameter-to-draft (D=T) ratio, mooring system stiffness, and mass distribution. For a given wave climate in Northern California, near San Francisco, the heave energy extraction is found to be best for a shallow WEC with a soft mooring system, compared to other systems that were examined. This result assumes a physical limit (cap) on the motion which is related to the significant wave height to draft ratio. Shallow draft designs, however, may experience excessive pitch motions and relatively larger viscous damping. In order to mitigate the pitch response, the pitch radius of gyration should be small and the center of mass should be low. Copyright © 2010 by ASME.

  10. Hybrid sunlight/LED illumination and renewable solar energy saving concepts for indoor lighting.

    Tsuei, Chih-Hsuan; Sun, Wen-Shing; Kuo, Chien-Cheng

    2010-11-01

    A hybrid method for using sunlight and light-emitting diode (LED) illumination powered by renewable solar energy for indoor lighting is simulated and presented in this study. We can illuminate an indoor space and collect the solar energy using an optical switching system. When the system is turned off, the full spectrum of the sunlight is concentrated by a concentrator, to be absorbed by solar photovoltaic devices that provide the electricity to power the LEDs. When the system is turned on, the sunlight collected by the concentrator is split into visible and non-visible rays by a beam splitter. The visible rays pass through the light guide into a light box where it is mixed with LED light to ultimately provide uniform illumination by a diffuser. The non-visible rays are absorbed by the solar photovoltaic devices to provide electrical power for the LEDs. Simulation results show that the efficiency of the hybrid sunlight/LED illumination with the renewable solar energy saving design is better than that of LED and traditional lighting systems. PMID:21165097

  11. Design and performance simulation of a segmented-absorber based muon detection system for high energy heavy ion collision experiments

    Ahmad, S. [University of Kashmir, Srinagar (India); Bhaduri, P.P. [Variable Energy Cyclotron Centre, Kolkata (India); Jahan, H. [Aligarh Muslim University, Aligarh (India); Senger, A. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Adak, R.; Samanta, S. [Bose Institute, Kolkata (India); Prakash, A. [Banaras Hindu University, Varanasi (India); Dey, K. [Gauhati University, Guwahati (India); Lebedev, A. [Institute für Kernphysik, Goethe Universität Frankfurt, Frankfurt (Germany); Kryshen, E. [Petersburg Nuclear Physics Institute (PNPI) NRC Kurchatov Institute, Gatchina (Russian Federation); Chattopadhyay, S., E-mail: sub@vecc.gov.in [Variable Energy Cyclotron Centre, Kolkata (India); Senger, P. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Bhattacharjee, B. [Gauhati University, Guwahati (India); Ghosh, S.K.; Raha, S. [Bose Institute, Kolkata (India); Irfan, M.; Ahmad, N. [Aligarh Muslim University, Aligarh (India); Farooq, M. [University of Kashmir, Srinagar (India); Singh, B. [Banaras Hindu University, Varanasi (India)

    2015-03-01

    A muon detection system (MUCH) based on a novel concept using a segmented and instrumented absorber has been designed for high-energy heavy-ion collision experiments. The system consists of 6 hadron absorber blocks and 6 tracking detector triplets. Behind each absorber block a detector triplet is located which measures the tracks of charged particles traversing the absorber. The performance of such a system has been simulated for the CBM experiment at FAIR (Germany) that is scheduled to start taking data in heavy ion collisions in the beam energy range of 6–45 A GeV from 2019. The muon detection system is mounted downstream to a Silicon Tracking System (STS) that is located in a large aperture dipole magnet which provides momentum information of the charged particle tracks. The reconstructed tracks from the STS are to be matched to the hits measured by the muon detector triplets behind the absorber segments. This method allows the identification of muon tracks over a broad range of momenta including tracks of soft muons which do not pass through all the absorber layers. Pairs of oppositely charged muons identified by MUCH could therefore be combined to measure the invariant masses in a wide range starting from low mass vector mesons (LMVM) up to charmonia. The properties of the absorber (material, thickness, position) and of the tracking chambers (granularity, geometry) have been varied in simulations of heavy-ion collision events generated with the UrQMD generator and propagated through the setup using the GEANT3, the particle transport code. The tracks are reconstructed by a Cellular Automaton algorithm followed by a Kalman Filter. The simulations demonstrate that low mass vector mesons and charmonia can be clearly identified in central Au+Au collisions at beam energies provided by the international Facility for Antiproton and Ion Research (FAIR)

  12. Design and performance simulation of a segmented-absorber based muon detection system for high energy heavy ion collision experiments

    A muon detection system (MUCH) based on a novel concept using a segmented and instrumented absorber has been designed for high-energy heavy-ion collision experiments. The system consists of 6 hadron absorber blocks and 6 tracking detector triplets. Behind each absorber block a detector triplet is located which measures the tracks of charged particles traversing the absorber. The performance of such a system has been simulated for the CBM experiment at FAIR (Germany) that is scheduled to start taking data in heavy ion collisions in the beam energy range of 6–45 A GeV from 2019. The muon detection system is mounted downstream to a Silicon Tracking System (STS) that is located in a large aperture dipole magnet which provides momentum information of the charged particle tracks. The reconstructed tracks from the STS are to be matched to the hits measured by the muon detector triplets behind the absorber segments. This method allows the identification of muon tracks over a broad range of momenta including tracks of soft muons which do not pass through all the absorber layers. Pairs of oppositely charged muons identified by MUCH could therefore be combined to measure the invariant masses in a wide range starting from low mass vector mesons (LMVM) up to charmonia. The properties of the absorber (material, thickness, position) and of the tracking chambers (granularity, geometry) have been varied in simulations of heavy-ion collision events generated with the UrQMD generator and propagated through the setup using the GEANT3, the particle transport code. The tracks are reconstructed by a Cellular Automaton algorithm followed by a Kalman Filter. The simulations demonstrate that low mass vector mesons and charmonia can be clearly identified in central Au+Au collisions at beam energies provided by the international Facility for Antiproton and Ion Research (FAIR)

  13. Nearshore Tests of the Tidal Compensation System for Point-Absorbing Wave Energy Converters

    Valeria Castellucci

    2015-04-01

    Full Text Available The power production of the linear generator wave energy converter developed at Uppsala University is affected by variations of mean sea level. The reason is that these variations change the distance between the point absorber located on the surface and the linear generator located on the seabed. This shifts the average position of the translator with respect to the center of the stator, thereby reducing the generator output power. A device mounted on the point absorber that compensates for tides of small range by regulating the length of the connection line between the buoy at the surface and the linear generator has been constructed and tested. This paper describes the electro-mechanical, measurement, communication and control systems installed on the buoy and shows the results obtained before its connection to the generator. The adjustment of the line was achieved through a linear actuator, which shortens the line during low tides and vice versa. The motor that drives the mechanical device was activated remotely via SMS. The measurement system that was mounted on the buoy consisted of current and voltage sensors, accelerometers, strain gauges and inductive and laser sensors. The data collected were transferred via Internet to a Dropbox server. As described within the paper, after the calibration of the sensors, the buoy was assembled and tested in the waters of Lysekil harbor, a few kilometers from the Uppsala University research site. Moreover, the performance of the sensors, the motion of the mechanical device, the power consumption, the current control strategy and the communication system are discussed.

  14. Absorbed dose calibration factors for parallel-plate chambers in high energy photon beams

    An investigation was carried out into the performance of parallel-plate chambers in 60Co and MV photon beams. The aim was to derive calibration factors, investigate chamber-to-chamber variability and provide much-needed information on the use of parallel-plate chambers in high-energy X-ray beams. A set of NE2561/NE2611 reference chambers, calibrated against the primary standard graphite calorimeter is used for the dissemination of absorbed dose to water. The parallel-plate chambers were calibrated by comparison with the NPL reference chambers in a water phantom. Two types of parallel-plate chamber were investigated - the NACP -02 and Roos and measurements were made at 60C0 and 6 linac photon energies (6-19 MV). Calibration factors were derived together with polarity corrections. The standard uncertainty in the calibration of a chamber in terms of absorbed dose to water is estimated to be ±0.75%. The results of the polarity measurements were somewhat confusing. One would expect the correction to be small and previous measurements in electron beams have indicated that there is little variation between chambers of these types. However, some chambers gave unexpectedly large polarity corrections, up to 0.8%. By contrast the measured polarity correction for a NE2611 chamber was less than 0.13% at all energies. The reason for these large polarity corrections is not clear, but experimental error and linac variations have been ruled out. By combining the calibration data for the different chambers it was possible to obtain experimental kQ factors for the two chamber types. It would appear from the data that the variations between chambers of the same type are random and one can therefore define a generic curve for each chamber type. These are presented in Figure 1, together with equivalent data for two cylindrical chamber types - NE2561/NE2611 and NE2571. As can be seen, there is a clear difference between the curves for the cylindrical chambers and those for the parallel

  15. Reuse of the Reflective Light and the Recycle Heat Energy in Concentrated Photovoltaic System

    Hsin-Chien Chen; Liann-Be Chang; Ho-Thea Lin; Ming-Jer Jeng; Lee Chow

    2013-01-01

    A complex solar unit with microcrystalline silicon solar cells placed around the centered GaAs triple junction solar cell has been proposed and carried out. With the same illumination area and intensity, the total resultant power shows that the excess microcrystalline silicon solar cells increase the total output power by 13.2% by absorbing the reflective light from the surface of optical collimators. Furthermore, reusing the residual heat energy generated from the above-mentioned mechanism h...

  16. Radiation-absorbed doses and energy imparted from panoramic tomography, cephalometric radiography, and occlusal film radiography in children

    The absorbed doses and energy imparted from radiographic examinations of children, using panoramic tomography (PTG), cephalometric radiography (CPR), and maxillary frontal occlusal overview (FOO), were examined. The absorbed dose at various sites of the head were measured with TL dosimeters in a phantom and in patients. The energy imparted was calculated from measurements of areal exposure using a planparallel ionization chamber. The maximum absorbed doses for panoramic tomography were located around the lateral rotation center, for cephalometric radiography in the left (tube side) parotid region, and for frontal occlusal radiography in the nose. The absorbed doses in the eyes, thyroid gland, and skin are discussed and compared with previous reports and, for the most part, are found to be in agreement. The mean energy imparted from all three examination methods is 5 mJ with about 57 percent from panoramic, 33 percent from cephalometric, and 10 percent from frontal occlusal examinations. The energy imparted from cephalometric radiography can be reduced to about 10 percent with the use of an improved examination technique, leaving panoramic tomography responsible for contributing about 80 percent of the total energy imparted

  17. Energy loss and associated higher order moments for swift heavy ions in different absorbers: a systematic study

    It is a well known fact that swift heavy ion beams are widely being used in experimental research in various disciplines. In many experiments related to nuclear physics, the data interpretation requires the proper analysis of the recorded energy spectra. In thin absorbers, such spectra are analyzed assuming the shape to be Gaussian in nature. However the situation is different in case of thick absorbers. In this situation the shape of such a spectrum deviates from the Gaussian nature and becomes skewed with tailing towards lower energies. The required parameters to analyze the data are energy loss caused by the ion within the absorber and the associated higher moments like straggling, skewness etc. Although a good quantum of information related to the energy loss process for different projectile - target combinations are available in the literature but only very limited information is available for straggling, skewness etc. In this direction we have carried out some systematic studies for energy loss, associated straggling and skewness for swift heavy ions in different absorbers

  18. Light incoherence theory revisited by Heisenberg time-energy uncertainty challenges solar cell optimization

    Herman, Aline; Deparis, Olivier

    2014-01-01

    Optimization of the efficiency of solar cells is a major challenge for renewable energies. Using a rigorous theoretical approach, we show that the photocurrent generated in a solar cell depends strongly on the degree of coherence of the incident light. In accordance with Heisenberg uncertainty time-energy, incoherent light at photons of carrier energy lower than the active material bandgap can be absorbed whereas coherent light at the same carrier energy cannot. We identify cases where incoherence does enhance efficiency. This result has a dramatical impact on the way solar cells must be optimized regarding sunlight. As an illustration, surface-corrugated GaAs and c-Si thin-film solar cells are considered.

  19. Experimental Study of Heat Energy Absorber with Porous Medium for Thermoelectric Conversion System

    Tzer-Ming Jeng

    2013-12-01

    Full Text Available The thermoelectric conversion system usually consists of the heat absorber, the thermoelectric generator (TEG and the heat sink, while the heat absorber collects the heat to increase the temperature on the hot surface of TEG and enhances the generating electricity. This study experimentally investigated the performance of the brass-beads packed-bed heat absorber for the thermoelectric conversion system. The packed-bed heat absorber is installed in a square channel with the various flow orientation systems and the small ratio of channel width to bead diameter. The flow orientation systems included the straight flow and jet flow systems. This study showed the local and average heat transfer characteristics for various parameters. The experimental results can be the base of designs for the novel porous heat absorber of the thermoelectric conversion system.

  20. A COMPARISON OF ENERGY ABSORBING CAPABILITIES OF PAPER AND STEEL STRUCTURES SUBJECTED TO PROGRESSIVE FAILURE UNDER FREE FALLING OBJECTS

    QASIM H. SHAH

    2007-08-01

    Full Text Available An inverted paper cup of 0.26 mm thickness was subjected to deformation under a freely falling steel ball at a velocity of 2.77 m/sec. The deformed features of the paper cup were measured. The dynamic loading event was simulated using piecewise linear plasticity material model in LSDYNA. Deformed shape of the paper cup in finite element model matched closely with experimental results with ignorable small discrepancies. The paper cup was able to absorb all the kinetic energy of the falling steel ball for the above mentioned falling speed and the ball did not bounce out of the cavity generated by the impact. In LSDYNA a similar size steel cup was also subjected to a freely falling ball with same speed and the energy absorbed was compared to the energy absorbed by the paper cup. It was found that under similar conditions a paper cup would undergo a significant progressive failure and absorb all the energy of the falling object.

  1. Miniature photovoltaic energy system for lighting

    In this project a miniature photovoltaic energy system has been designed and developed, that may be used in remote areas and villages for lighting purposes. System sizing is the important part of the project because it affects the cost of the system. Therefore, first of all system sizing has been done. For conversion of dc voltage of the battery into ac voltage, an inverter has been designed. To charge the battery when the sun is not shining, a standby system has been developed using a bicycle and dynamo. To indicate the battery's state of charge and discharge, a battery monitoring circuit has also been developed. Similarly, to protect the battery from over discharging, a battery protection circuit has been designed. In order to measure how much energy is going from standby system to the battery, an efficient dc electronic energy meter has been designed and developed. The working of the overall system has been tested and found to give good performance. (author)

  2. Atomistic study of energy funneling in the light-harvesting complex of green sulfur bacteria

    Huh, Joonsuk; Brookes, Jennifer C; Valleau, Stéphanie; Fujita, Takatoshi; Aspuru-Guzik, Alán

    2013-01-01

    Phototrophic organisms such as plants, photosynthetic bacteria and algae use microscopic complexes of pigment molecules to absorb sunlight. Within the light-harvesting complexes, which frequently have multiple functional and structural subunits, the energy is transferred in the form of molecular excitations with very high efficiency. Green sulfur bacteria are considered to be amongst the most efficient light-harvesting organisms. Despite multiple experimental and theoretical studies of these bacteria the physical origin of the efficient and robust energy transfer in their light-harvesting complexes is not well understood. To study excitation dynamics at the systems level we introduce an atomistic model that mimic a complete light-harvesting apparatus of green sulfur bacteria. The model contains about 4000 pigment molecules and comprises a double wall roll for the chlorosome, a baseplate and six Fenna-Matthews-Olson trimer complexes. We show that the fast relaxation within functional subunits combined with the...

  3. Specific absorbed fractions of energy at various ages from internal photon sources: 7, Adult male

    Specific absorbed fractions (PHI's) in various organs of the body (target organs) from sources of monoenergetic photons in various other organs (source organs) are tabulated. In this volume PHI-values are tabulated for an adult male (70-kg Reference Man). These PHI-values can be used in calculating the photon component of the dose-equivalent rate in a given target organ from a given radionuclide that is present in a given source organ. The International Commission on Radiological Protection recognizes that the endosteal, or bone surface, cells are the tissue at risk for bone cancer. We have applied the dosimetry methods developed for beta-emitting radionuclides deposited in bone to follow the transport of secondary electrons that were freed by photon interactions through the microscopic structure of the skeleton. With these methods we can estimate PHI in the endosteal cells and can better estimate PHI in the active marrow; the latter is overestimated with other methods at photon energies below 200 keV. 12 refs., 2 tabs

  4. Specific absorbed fractions of energy at various ages from internal photon sources: 6, Newborn

    Specific absorbed fraction (PHI's) in various organs of the body (target organs) from sources of monoenergetic photons in various other organs (source organs) are tabulated. In this volume PHI-values are tabulated for a newborn or 3.4-kg person. These PHI-values can be used in calculating the photon component of the dose-equivalent rate in a given target from a given radionuclide that is present in a given source organ. The International Commission on Radiological Protection recognizes that the endosteal, or bone surface, cells are the tissue at risk for bone cancer. We have applied the dosimetry methods that Spiers and co-workers developed for beta-emitting radionuclides deposited in bone to follow the transport of secondary electrons that were freed by photon interactions through the microscopic structure of the skeleton. With these methods we can estimate PHI in the endosteal cells and can better estimate PHI in the active marrow; the latter is overestimated with other methods at photon energies below 200 keV. 12 refs., 2 tabs

  5. Stability analysis of the Gyroscopic Power Take-Off wave energy point absorber

    Nielsen, Søren R. K.; Zhang, Zili; Kramer, Morten M.; Olsen, Jan

    2015-10-01

    The Gyroscopic Power Take-Off (GyroPTO) wave energy point absorber consists of a float rigidly connected to a lever. The operational principle is somewhat similar to that of the so-called gyroscopic hand wrist exercisers, where the rotation of the float is brought forward by the rotational particle motion of the waves. At first, the equations of motion of the system are derived based on analytical rigid body dynamics. Next, assuming monochromatic waves simplified equations are derived, valid under synchronisation of the ring of the gyro to the angular frequency of the excitation. Especially, it is demonstrated that the dynamics of the ring can be described as an autonomous nonlinear single-degree-of-freedom system, affected by three different types of point attractors. One where the ring vibrations are attracted to a static equilibrium point indicating unstable synchronisation and two types of attractors where the ring is synchronised to the wave angular frequency, either rotating in one or the opposite direction. Finally, the stability conditions and the basins of attraction to the point attractors defining the synchronised motion are determined.

  6. Experimental validation of a magnetorheological energy absorber design optimized for shock and impact loads

    A linear stroke adaptive magnetorheological energy absorber (MREA) was designed, fabricated and tested for intense impact conditions with piston velocities up to 8 m s−1. The performance of the MREA was characterized using dynamic range, which is defined as the ratio of maximum on-state MREA force to the off-state MREA force. Design optimization techniques were employed in order to maximize the dynamic range at high impact velocities such that MREA maintained good control authority. Geometrical parameters of the MREA were optimized by evaluating MREA performance on the basis of a Bingham-plastic analysis incorporating minor losses (BPM analysis). Computational fluid dynamics and magnetic FE analysis were conducted to verify the performance of passive and controllable MREA force, respectively. Subsequently, high-speed drop testing (0–4.5 m s−1 at 0 A) was conducted for quantitative comparison with the numerical simulations. Refinements to the nonlinear BPM analysis were carried out to improve prediction of MREA performance. (paper)

  7. Simulating the Response of a Composite Honeycomb Energy Absorber. Part 2; Full-Scale Impact Testing

    Fasanella, Edwin L.; Annett, Martin S.; Jackson, Karen E.; Polanco, Michael A.

    2012-01-01

    NASA has sponsored research to evaluate an externally deployable composite honeycomb designed to attenuate loads in the event of a helicopter crash. The concept, designated the Deployable Energy Absorber (DEA), is an expandable Kevlar(Registered TradeMark) honeycomb. The DEA has a flexible hinge that allows the honeycomb to be stowed collapsed until needed during an emergency. Evaluation of the DEA began with material characterization of the Kevlar(Registered TradeMark)-129 fabric/epoxy, and ended with a full-scale crash test of a retrofitted MD-500 helicopter. During each evaluation phase, finite element models of the test articles were developed and simulations were performed using the dynamic finite element code, LS-DYNA(Registered TradeMark). The paper will focus on simulations of two full-scale impact tests involving the DEA, a mass-simulator and a full-scale crash of an instrumented MD-500 helicopter. Isotropic (MAT24) and composite (MAT58) material models, which were assigned to DEA shell elements, were compared. Based on simulations results, the MAT58 model showed better agreement with test.

  8. A Computational Approach for Model Update of an LS-DYNA Energy Absorbing Cell

    Horta, Lucas G.; Jackson, Karen E.; Kellas, Sotiris

    2008-01-01

    NASA and its contractors are working on structural concepts for absorbing impact energy of aerospace vehicles. Recently, concepts in the form of multi-cell honeycomb-like structures designed to crush under load have been investigated for both space and aeronautics applications. Efforts to understand these concepts are progressing from tests of individual cells to tests of systems with hundreds of cells. Because of fabrication irregularities, geometry irregularities, and material properties uncertainties, the problem of reconciling analytical models, in particular LS-DYNA models, with experimental data is a challenge. A first look at the correlation results between single cell load/deflection data with LS-DYNA predictions showed problems which prompted additional work in this area. This paper describes a computational approach that uses analysis of variance, deterministic sampling techniques, response surface modeling, and genetic optimization to reconcile test with analysis results. Analysis of variance provides a screening technique for selection of critical parameters used when reconciling test with analysis. In this study, complete ignorance of the parameter distribution is assumed and, therefore, the value of any parameter within the range that is computed using the optimization procedure is considered to be equally likely. Mean values from tests are matched against LS-DYNA solutions by minimizing the square error using a genetic optimization. The paper presents the computational methodology along with results obtained using this approach.

  9. Specific absorbed fractions of energy at various ages from internal photon sources: 1, Methods

    Specific absorbed fractions (PHI's) in various organs of the body (target organs) from sources of monoenergetic photons in various other organs (source organs) are tabulated. This volume outlines various methods used to compute the PHI-values and describes how the ''best'' estimates recommended by us are chosen. These PHI-values can be used in calculating the photon component of the dose-equivalent rate in a given target organ from a given radionuclide that is present in a given source organ. The International Commission on Radiological Protection recognizes that the endosteal, or bone surface, cells are the tissue at risk for bone cancer. We have applied the dosimetry methods that Spiers and co-workers developed for beta-emitting radionuclides deposited in bone to follow the transport of secondary electrons that were freed by photon interactions through the microscopic structure of the skeleton. With these methods we can estimate PHI in the endosteal cells and can better estimate PHI in the active marrow; the latter is overestimated with the methods at photon energies below 200 keV. 41 refs., 25 figs., 23 tabs

  10. The photoacoustic spectrometer based on the three-colour light-emitting diode for investigation of photosynthesis transformation of light energy

    The photoacoustic spectrometer based on the three-colour light-emitting diode with a wavelengths of 465 nm, 526 nm and 638 nm and two-chamber photoacoustic cell, allowing one to determine rates of photosynthesis in different layers of the plant leaves has been developed. Possibilities of quantitative evaluation of parameters of thermal dissipation and photochemical assimilation of the absorbed light energy, depending on both the depth of light penetration into the leaves and the physiological state of a plant are shown. (authors)