33,135 research outputs found
Hohenpeissenberg Photochemical Experiment (HOPE 2000) : measurements and photostationary state calculations of OH and peroxy radicals
No full textMeasurements of OH, total peroxy radicals, non-methane hydrocarbons (NMHCs) and various other trace gases were made at the Meteorological Observatory Hohenpeissenberg in June 2000. The data from an intensive measurement period characterised by high solar insolation (18-21 June) are analysed. The maximum midday OH concentration ranged between 4.5x106 molecules cm-3 and 7.4x106 molecules cm-3. The maximum total ROx (ROx =OH+RO+HO2+RO2) mixing ratio increased from about 55 pptv on 18 June to nearly 70 pptv on 20 and 21 June. A total of 64 NMHCs, including isoprene and monoterpenes, were measured every 1 to 6 hours. The oxidation rate of the NMHCs by OH was calculated and reached a total of over 14x106 molecules cm-3 s-1 on two days. A simple photostationary state balance model was used to simulate the ambient OH and peroxy radical concentrations with the measured data as input. This approach was able to reproduce the main features of the diurnal profiles of both OH and peroxy radicals. The balance equations were used to test the effect of the assumptions made in this model. The results proved to be most sensitive to assumptions about the impact of unmeasured volatile organic compounds (VOC), e.g. formaldehyde (HCHO), and about the partitioning between HO2 and RO2. The measured OH concentration and peroxy radical mixing ratios were reproduced well by assuming the presence of 3 ppbv HCHO as a proxy for oxygenated hydrocarbons, and a HO2/ RO2 ratio between 1:1 and 1:2. The most important source of OH, and conversely the greatest sink for peroxy radicals, was the recycling of HO2 radicals to OH. This reaction was responsible for the recycling of more than 45x106 molecules cm-3 s-1 on two days. The most important sink for OH, and the largest source of peroxy radicals, was the oxidation of NMHCs, in particular, of isoprene and the monoterpenes
A critical point analysis of Landau-Ginzburg potentials with bulk in Gelfand-Cetlin systems
No full text© 2021 by Kyoto University.Using the bulk deformation of Floer cohomology by Schubert classes and non-Archimedean analysis of Fukaya-Oh-Ohta-Ono's bulk-deformed potential function, we prove that every complete flag manifold Fl(n) (n ≥ 3) with a monotone Kirillov-Kostant-Souriau (KKS) symplectic form carries a continuum of nondisplaceable Lagrangian tori which degenerates to a nontorus fiber in the Hausdorff limit. In particular, the Lagrangian S3-fiber in Fl(3) is nondisplaceable, answering a question raised by Nohara and Ueda who computed its Floer cohomology to be vanishing.11Nsciescopu
Seasonal measurements of total OH reactivity emission rates from Norway spruce in 2011
No full textNumerous reactive volatile organic compounds (VOCs) are emitted into the atmosphere by vegetation. Most biogenic VOCs are highly reactive towards the atmosphere's most important oxidant, the hydroxyl (OH) radical. One way to investigate the chemical interplay between biosphere and atmosphere is through the measurement of total OH reactivity, the total loss rate of OH radicals. This study presents the first determination of total OH reactivity emission rates (measurements via the comparative reactivity method) based on a branch cuvette enclosure system mounted on a Norway spruce (Picea abies) throughout spring, summer and autumn 2011. In parallel VOC emission rates were monitored by a second proton-transfer-reaction mass spectrometer (PTR-MS), and total ozone (O3) loss rates were obtained inside the cuvette. Total OH reactivity emission rates were in general temperature and light dependent, showing strong diel cycles with highest values during daytime. Monoterpene emissions contributed most, accounting for 56–69% of the measured total OH reactivity flux in spring and early summer. However, during late summer and autumn the monoterpene contribution decreased to 11–16%. At this time, a large missing fraction of the total OH reactivity emission rate (70–84%) was found when compared to the VOC budget measured by PTR-MS. Total OH reactivity and missing total OH reactivity emission rates reached maximum values in late summer corresponding to the period of highest temperature. Total O3 loss rates within the closed cuvette showed similar diel profiles and comparable seasonality to the total OH reactivity fluxes.
Total OH reactivity fluxes were also compared to emissions from needle storage pools predicted by a temperature-only-dependent algorithm. Deviations of total OH reactivity fluxes from the temperature-only-dependent emission algorithm were observed for occasions of mechanical and heat stress. While for mechanical stress, induced by strong wind, measured VOCs could explain total OH reactivity emissions, during heat stress they could not. The temperature-driven algorithm matched the diel variation of total OH reactivity emission rates much better in spring than in summer, indicating a different production and emission scheme for summer and early autumn. During these times, unmeasured and possibly unknown primary biogenic emissions contributed significantly to the observed total OH reactivity flux
A context-based storytelling with a responsive multimedia system (RMS)
No full textIn this paper, we present a Context-based Storytelling with Responsive Multimedia System (RMS). Many researches related to virtual storytelling have been presented with the advancement of multimedia technology. However, people have different abilities to understand a story according to their experience, knowledge, age, gender, etc. In the proposed approach, virtual story is unfolded by interaction between users, Multi-modal Tangible User Interface (MTUI) and Virtual Environment Manager (VEManager) with vr-UCAM (a unified Context-aware Application Model for Virtual Environments). We adopt an interactive StoryMap and tangible interfaces into MTUI with vr-UCAM such that VEManager can control the responses of virtual objects according to the user's context. Accordingly, the users can experience a personalized story since action of virtual objects, interaction level and scene of VE are reorganized and adjusted according to a user's profile and preference. To demonstrate the effectiveness of the proposed approach, we applied it to a virtual storytelling with RMS. According to the experimental results, we observed that the combination of virtual reality technology and context-aware computing could be promising technologies that enables users to experience a personalized virtual story. Therefore, we expect that the proposed approach plays an important role in virtual storytelling applications such as education, entertainment, games, etc
What can 14 CO measurements tell us about OH?
No full textThe possible use of 14CO measurements to constrain hydroxyl radical (OH) concentrations in the atmosphere is investigated. 14CO is mainly produced in the upper atmosphere from cosmic radiation. Measurements of 14CO at the surface show lower concentrations compared to the upper atmospheric source region, which is the result of oxidation by OH. In this paper, the sensitivity of 14CO mixing ratio surface measurements to the 3-D OH distribution is assessed with the TM5 model. Simulated 14CO mixing ratios agree within a few molecules 14CO cm¿3 (STP) with existing measurements at five locations worldwide. The simulated cosmogenic 14CO distribution appears mainly sensitive to the assumed upper atmospheric 14C source function, and to a lesser extend to model resolution. As a next step, the sensitivity of 14CO measurements to OH is calculated with the adjoint TM5 model. The results indicate that 14CO measurements taken in the tropics are sensitive to OH in a spatially confined region that varies strongly over time due to meteorological variability. Given measurements with an accuracy of 0.5 molecules 14CO cm¿3 STP, a good characterization of the cosmogenic 14CO fraction, and assuming perfect transport modeling, a single 14CO measurement may constrain OH to 0.2¿0.3×106 molecules OH cm¿3 on time scales of 6 months and spatial scales of 70×70 degrees (latitude×longitude) between the surface and 500 hPa. The sensitivity of 14CO measurements to high latitude OH is about a factor of five higher. This is in contrast with methyl chloroform (MCF) measurements, which show the highest sensitivity to tropical OH, mainly due to the temperature dependent rate constant of the MCF¿OH reaction. A logical next step will be the analysis of existing 14CO measurements in an inverse modeling framework. This paper presents the required mathematical framework for such an analysis
Síntesis y caracterización de la heterounión de la interfaz In (O; OH) S / AgInS2
No full textIn this work,we presented some complementary studies for In(O,OH)S thin films deposited on AgInS2 thin films to fabricate a new system absorbent-layer/buffer-layer to be used in tandem and/or in one-junction solar cells. As showed in previous works carried out for us, AgInS2layers were grown by co-evaporation from metal precursors in a two-step process; and In(O,OH)S thin films were deposited by Chemical Bath deposition.X-ray diffraction measurements indicated that AgInS2 thin film grown with chalcopyrite structure; and In(O,OH)S films grown with polycrystalline structure.The AgInS2thin films presented p-type conductivity, andfrom tranductance measurements it was found a high absorption coefficient (greater than 104 cm−1) and an energy band gap of 1.95 eV; and In(O,OH),S thin films presented Egabout 3.01 eV;morphological analysis indicated that under this synthesis conditions,In(O,OH)S thin films coated completely the AgInS2absorber layer. Finally, in this work, the Avrami-Erofeev equation was used to study In(O,OH)S thin film growth rate on AgInS2 substrate. Results indicate that the developed system can be used in single-junction and multiple junction solar cells.En este trabajo, presentamos algunos estudios complementarios para las películas delgadas In (O, OH) S depositadas en películas delgadas AgInS2 para fabricar un nuevo sistema de capa absorbente / capa buffer que se utilizará en tándem y / o en células solares de una unión. Como se demostró en trabajos previos llevados a cabo para nosotros, las capas de AgInS2 se cultivaron por co-evaporación a partir de precursores de metal en un proceso de dos pasos; y en (O, OH) S las películas delgadas se depositaron mediante deposición de baño químico. Las mediciones de difracción de rayos X indicaron que la película delgada de AgInS2 crecía con estructura de calcopirita; e In (O, OH) películas S crecidas con estructura policristalina. Las películas delgadas AgInS2 presentaron conductividad de tipo p, y desde las mediciones de tranductancia se encontró un alto coeficiente de absorción (mayor de 104 cm-1) y un intervalo de banda de energía de 1.95 eV ; y en (O, OH), las películas delgadas S presentaron Egabout 3.01 eV, el análisis morfológico indicó que bajo estas condiciones de síntesis, las películas delgadas en (O, OH) S recubrieron completamente la capa absorbente AgInS2. Finalmente, en este trabajo, se utilizó la ecuación de Avrami-Erofeev para estudiar la velocidad de crecimiento de la película fina In (O, OH) S sobre el sustrato AgInS2. Los resultados indican que el sistema desarrollado se puede usar en células solares de unión única y unión múltiple
Laser-induced fluorescence study of OH in flat flames of 1–10 bar compared with resonance CARS experiments
No full textKohse-Höinghaus K, Meier U, Attal-Trétout B. Laser-induced fluorescence study of OH in flat flames of 1–10 bar compared with resonance CARS experiments. Applied Optics. 1990;29(10):1560-1569.Laser-induced fluorescence (LIF) measurements of OH were performed in flat stoichiometric CH4/air flames burning at 1, 3, 5, 7, and 9.6 bar, which had previously been investigated using OH resonance CARS. In the LIF study, line shape information and temperatures were extracted from excitation spectra; in addition, OH profiles as a function of height above the burner surface and an estimate of the OH concentration for the different flames were obtained. The perspectives and feasibility of quantitative fluorescence measurements in high pressure flames are discussed, particularly in comparison with the application of resonance CARS
A Lightweight and Cost-Effective 3D Omnidirectional Depth Sensor Based on Laser Triangulation
No full textIn this paper, we propose a new lightweight and cost-effective 3D omnidirectional depth sensor based on laser triangulation in order to ensure a wide field of view (FOV) while achieving portability and affordability. The proposed sensor is tiny palm-sized and hence easily installed even on small moving objects, which is largely composed of a structured light-based 2D sensor and a rotating motor for creating a full 360 degree horizontal FOV, thus providing a 3D omnidirectional sensing capability. The structured light-based 2D sensor is specially designed to maximize the vertical FOV by employing a fisheye camera and a laser beam passing through two cylindrical lenses for projecting a line onto a surface. From the rotational movement of the 2D sensor due to the mounted motor, its surroundings are scanned by extracting the corresponding 3D omnidirectional depth information from laser triangulation. The actual implementation is carried out to examine the technical feasibility of realizing the proposed 3D omnidirectioanl depth sensor. It turns out that the proposed depth sensor covers over 97% area of its surrounding sphere. It is also observed through experiments that the proposed 3D omnidirectional depth sensor has similar accuracy to that of a Velodyne HDL-32, 32-channel light detection and ranging (LIDAR) sensor, at a range of 5 m to 6 m while providing much wider vertical FOV and higher vertical resolution.11Ysciescopu
Síntesis y caracterización de interfase de heterojuntura In(O;OH)S/AgInS2
No full textEn este trabajo presentamos estudios complementarios de películas delgadas de In(O;OH)S depositadas sobre películas delgadas de AgInS2 para fabricar un sistema capa absorbente/capa buffer utilizado en celdas solares tipo tándem o celdas de juntura simple. Como se demostró en trabajos anteriores realizados por los autores, las capas de AgInS2 crecieron por coevaporación de los metales precursores en un proceso de dos etapas; y las películas delgadas de In(O:OH)S se depositaron por baño químico. Las medidas de rayos X indican que las películas de AgInS2 crecen con estructura tipo calcopirita y las de In(O:OH)S con estructura policristalina. Las películas de AgInS2 presentan conductividad tipo P, y de las medidas de transductancia se encontró un coeficiente de absorción alto (mayor a 104 cm-1), y un gap de 1.95 eV; las películas de In(O:OH)S presentaron un gap de 3.01 eV; el análisis morfológico indica que bajo estas condiciones de síntesis, las películas de In(O:OH)S recubren completamente la capa absorbente de AgInS2 . Finalmente, en este trabajo se aplicó la ecuación de Avrami-Erofeev para estudiar la tasa de crecimiento de las películas delgadas de In(O:OH)S sobre el substrato de AgInS2 . Los resultados indican que el sistema desarrollado puede utilizarse en celdas solares de juntura simple o multijuntura.In this work, we presented some complementary studies for In(O,OH)S thin films deposited on AgInS2 thin films to fabricate a new system absorbent-layer/ buffer-layer to be used in tandem and/or in one-junction solar cells. As showed in previous works carried out for us, AgInS2 layers were grown by co-evaporation from metal precursors in a two-step process; and In(O,OH)S thin films were deposited by Chemical Bath deposition. X-ray diffraction measurements indicated that AgInS2 thin film grown with chalcopyrite structure; and In(O,OH)S films grown with polycrystalline structure. The AgInS2 thin films presented p-type conductivity, and from transductance measurements it was found a high absorption coefficient (greater than 104 cm−1) and an energy band gap of 1.95 eV; and In(O,OH)S thin films presented Eg about 3.01 eV; morphological analysis indicated that under this synthesis conditions, In(O,OH) S thin films coated completely the AgInS2 absorber layer. Finally, the Avrami-Erofeev equation was used in this work to study In(O,OH)S thin film growth rate on AgInS2 substrate. Results indicate that the developed system can be used in single-junction and multiple junction solar cells
On the use of 2.5-Gb/s Mach-Zehnder modulators to generate 10-Gb/s optical duobinary signals
No full textWe demonstrate the generation of 10-Gb/s optical duobinary signals from 2.5-Gb/s Mach-Zehnder (MZ) modulators without using duobinary encoders. The absence of the duobinary encoder not only permits the monolithic integration of electrical components but also reduces the required bandwidth of MZ modulators as low as 3 GHz. However, it might induce pattern-length dependency to the signals. Our demonstration, performed with four 2.5-Gb/s MZ modulators obtained from two different vendors, shows that the receiver sensitivity of better than -33.8 dBm is achieved at a pseudorandom bit sequence length of 2(31) - 1 when dispersion of 1200 similar to 1700 ps/nm is applied to the signals. This is 1.6 dB poorer than using an 8.5-GHz bandwidth MZ modulator along with a 3.0-GHz Bessel filter. Therefore, this scheme can be used to implement cost-effective 10-Gb/s optical duobinary transmitters without significant performance degradation
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