| 1. |
- Yu, ChaoQing, et al.
(författare)
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Managing nitrogen to restore water quality in China
- 2019
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 567:7749, s. 516-520
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Tidskriftsartikel (refereegranskat)abstract
- The nitrogen cycle has been radically changed by human activities(1). China consumes nearly one third of the world's nitrogen fertilizers. The excessive application of fertilizers(2,3) and increased nitrogen discharge from livestock, domestic and industrial sources have resulted in pervasive water pollution. Quantifying a nitrogen 'boundary'(4) in heterogeneous environments is important for the effective management of local water quality. Here we use a combination of water-quality observations and simulated nitrogen discharge from agricultural and other sources to estimate spatial patterns of nitrogen discharge into water bodies across China from 1955 to 2014. We find that the critical surface-water quality standard (1.0 milligrams of nitrogen per litre) was being exceeded in most provinces by the mid-1980s, and that current rates of anthropogenic nitrogen discharge (14.5 +/- 3.1 megatonnes of nitrogen per year) to fresh water are about 2.7 times the estimated 'safe' nitrogen discharge threshold (5.2 +/- 0.7 megatonnes of nitrogen per year). Current efforts to reduce pollution through wastewater treatment and by improving cropland nitrogen management can partially remedy this situation. Domestic wastewater treatment has helped to reduce net discharge by 0.7 +/- 0.1 megatonnes in 2014, but at high monetary and energy costs. Improved cropland nitrogen management could remove another 2.3 +/- 0.3 megatonnes of nitrogen per year-about 25 per cent of the excess discharge to fresh water. Successfully restoring a clean water environment in China will further require transformational changes to boost the national nutrient recycling rate from its current average of 36 per cent to about 87 per cent, which is a level typical of traditional Chinese agriculture. Although ambitious, such a high level of nitrogen recycling is technologically achievable at an estimated capital cost of approximately 100 billion US dollars and operating costs of 18-29 billion US dollars per year, and could provide co-benefits such as recycled wastewater for crop irrigation and improved environmental quality and ecosystem services.
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| 2. |
- Le, Cuong, 1982, et al.
(författare)
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Analysis of Power Disturbances from Monitoring Multiple Levels and Locations in a Power System
- 2010
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Ingår i: The 14th IEEE Int'l Conf. on Harmonics and Quality of Power, 26-29 Sep. 2010, Bergamo, Italy. - : IEEE Communications Society. - 9781424472444 - 9781424472451
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a new methodology for diagnosing the original source and underlying causes of power system disturbances, where voltage and current recordings from different locations of a power system are collected. In the proposed method, disturbances are first pre-classified based on the number of transition segments. The spatial zone of the source of disturbances is coarsely determined from voltage recordings only. Disturbances are then further analyzed and characterized by extracting information from both voltages and currents. Finally more accurate information about the location of the source of disturbances is obtained by different techniques depending on the type of disturbances. Several underlying causes are analyzed and classified by using the proposed features extracted from both voltage and current waveforms. Finally, the location of the source of disturbances is refined once the underlying causes are found. Case studies were performed on a large grid-connected wind farm with disturbances from several underlying causes, including: fault, unit tripping, transformer, capacitor, and cable energizing generated by PSCAD/EMTDC.
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| 3. |
- Gu, Irene Yu-Hua, 1953, et al.
(författare)
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Signal Processing and Classification Tools for Intelligent Distributed Monitoring and Analysis of the Smart Grid
- 2011
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Ingår i: IEEE PES Innovative Smart Grid Technologies Conference Europe. 2011 2nd IEEE PES International Conference and Exhibition on Innovative Smart Grid Technologies, ISGT Europe 2011, Manchester, 5 - 7 December 2011. - Piscataway, N.J : IEEE Communications Society. - 9781457714214
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a novel framework for an intelligent monitoring system that supervises the performance of the future power system. The increased complexity of the power system could endanger the reliability, voltage quality, operational security or resilience of the power system. A distributed structure for such a monitoring system is described and some of the advanced signal processing techniques or tools that could be used in such a monitoring system are given. Several examples for seeking the spatial locations and finding the underlying causes of disturbances are included.
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| 4. |
- Le, Cuong, 1982, et al.
(författare)
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A method to evaluate harmonic model-based estimations under non-white measured noise
- 2011
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Ingår i: 2011 IEEE PES Trondheim PowerTech. - Piscataway, NJ : IEEE Communications Society. - 9781424484195 - 9781424484171
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Konferensbidrag (refereegranskat)abstract
- Automatic extracting information from power-system event recordings requires applications of signal-processing estimation techniques whose performance has been verified under white noise. This paper proposes a method to test these techniques under real power-system noise, which is very different from white noise, to evaluate their application feasibility. The first part of the paper describes the evaluation method used to evaluate the techniques in a statistical sense and a method to extract noise from measured power-system recordings. The second part of the paper focuses on the evaluation of a number of harmonic model-based techniques under non-white noise, including: Kalman filter, MUSIC, ESPRIT, and segmentation algorithms. The paper shows that for the Kalman filter, a very high order with high computational burden is necessary only if high frequency components are of interest. The application of MUSIC, ESPRIT, and the segmentation algorithms under natural power-system noise is shown to be feasible.
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| 5. |
- Le, Cuong, 1982, et al.
(författare)
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Joint Causal and Anti-Causal Segmentation and Location of Transitions in Power Disturbances
- 2010
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Ingår i: IEEE Power Engineering Society (PES) General Meeting, 25-29 Jul. 2010, Minneapolis, Minnesota, USA. - Piscataway, NJ : IEEE Communications Society. - 9781424483570 - 9781424465491
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Konferensbidrag (refereegranskat)abstract
- An important step in power disturbance data analysis is to first partition the disturbance sequence into transition and event segments. One main contribution of the paper is the propose of a new segmentation scheme that jointly uses the causal and anti-causal segmentation. We show that the actual location of a trigger point can be accurately estimated by combining the causal and anti-causal transition segments. Another main contribution is a new method for setting the threshold of detection parameter. From the residuals of Kalman filter, a detection parameter is defined and the threshold for this parameter is computed based on pdf estimates and hypothesis tests on measurement sequences with/without disturbances. Using the proposed segmentation and the statistically-based threshold, we show that transition segments, especially the trigger points, are allocated more accurately. Tests are performed on semi-synthetic disturbance sequences containing step, ramp and multi-stage transition. The proposed method is shown to be able to locate fast transitions with very high accuracy. The performance of segmentation against the point on wave, depth of transition, speed of transition, and polluted noise level are also evaluated.
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| 6. |
- Abata, E., et al.
(författare)
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Study of energy response and resolution of the ATLAS barrel calorimeter to hadrons of energies from 20 to 350 GeV
- 2010
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576 .- 0167-5087. ; 621:1-3, s. 134-150
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Tidskriftsartikel (refereegranskat)abstract
- A fully instrumented slice of the ATLAS detector was exposed to test beams from the SPS (Super Proton Synchrotron) at CERN in 2004. In this paper, the results of the measurements of the response of the barrel calorimeter to hadrons with energies in the range 20-350 GeV and beam impact points and angles corresponding to pseudo-rapidity values in the range 0.2-0.65 are reported. The results are compared to the predictions of a simulation program using the Geant 4 toolkit. (C) 2010 Published by Elsevier B.V.
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| 7. |
- Palmgren, Pål, et al.
(författare)
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Strong interactions in dye-sensitized interfaces
- 2008
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:15, s. 5972-5977
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Tidskriftsartikel (refereegranskat)abstract
- Phthalocyanines (Pcs) are capable of converting sunlight into electric energy when adsorbed on TiO2 in a dye-sensitized solar cell. Of special interest in this type of cell is the energy level alignment as well as how molecules adsorb on the surface as it determines the output of the cell. We investigated the FePc-TiO2(110) interface using scanning tunneling microscopy, synchrotron-based photoelectron spectroscopy, and X-ray absorption spectroscopy. We found a strong coupling of the first-layer FePc to the substrate resulting in an alteration of the electronic structure and charge transfer from the molecules. The FePc in the second layer is not severely affected by the bonding to the surface and has bulk-like electronic properties. The growth of FePc thin films proceeds in a layer plus island mode, and the molecular plane is parallel to the surface. The energy level alignment at the interface is determined, and the lowest unoccupied molecular orbital is found above the conduction band minimum of the oxide substrate.
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| 8. |
- Chang, Jian, 1990-, et al.
(författare)
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Tailor-Made White Photothermal Fabrics : A Bridge between Pragmatism and Aesthetic
- 2023
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 35:41
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Tidskriftsartikel (refereegranskat)abstract
- Maintaining human thermal comfort in the cold outdoors is crucial for diverse outdoor activities, e.g., sports and recreation, healthcare, and special occupations. To date, advanced clothes are employed to collect solar energy as a heat source to stand cold climates, while their dull dark photothermal coating may hinder pragmatism in outdoor environments and visual sense considering fashion. Herein, tailor-made white webs with strong photothermal effect are proposed. With the embedding of cesium–tungsten bronze (CsxWO3) nanoparticles (NPs) as additive inside nylon nanofibers, these webs are capable of drawing both near-infrared (NIR) and ultraviolet (UV) light in sunlight for heating. Their exceptional photothermal conversion capability enables 2.5–10.5 °C greater warmth than that of a commercial sweatshirt of six times greater thickness under different climates. Remarkably, this smart fabric can increase its photothermal conversion efficiency in a wet state. It is optimal for fast sweat or water evaporation at human comfort temperature (38.5 °C) under sunlight, and its role in thermoregulation is equally important to avoid excess heat loss in wilderness survival. Obviously, this smart web with considerable merits of shape retention, softness, safety, breathability, washability, and on-demand coloration provides a revolutionary solution to realize energy-saving outdoor thermoregulation and simultaneously satisfy the needs of fashion and aesthetics.
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| 9. |
- Ding, Shaozhen, et al.
(författare)
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novoPathFinder: a webserver of designing novel-pathway with integrating GEM-model
- 2020
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 48:W1, s. W477-W487
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Tidskriftsartikel (refereegranskat)abstract
- To increase the number of value-added chemicals that can be produced by metabolic engineering and synthetic biology, constructing metabolic space with novel reactions/pathways is crucial. However, with the large number of reactions that existed in the metabolic space and complicated metabolisms within hosts, identifying novel pathways linking two molecules or heterologous pathways when engineering a host to produce a target molecule is an arduous task. Hence, we built a user-friendly web server, novoPathFinder, which has several features: (i) enumerate novel pathways between two specified molecules without considering hosts; (ii) construct heterologous pathways with known or putative reactions for producing target molecule within Escherichia coli or yeast without giving precursor; (iii) estimate novel pathways with considering several categories, including enzyme promiscuity, Synthetic Complex Score (SCScore) and LD50 of intermediates, overall stoichiometric conversions, pathway length, theoretical yields and thermodynamic feasibility. According to the results, novoPathFinder is more capable to recover experimentally validated pathways when comparing other rule-based web server tools. Besides, more efficient pathways with novel reactions could also be retrieved for further experimental exploration. novoPathFinder is available at http://design.rxnfinder.org/novopathfinder/.
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| 10. |
- Fu, Le, et al.
(författare)
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Microstructure of rapidly-quenched ZrO2-SiO2 glass-ceramics fabricated by container-less aerodynamic levitation technology
- 2023
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Ingår i: Journal of The American Ceramic Society. - : John Wiley & Sons. - 0002-7820 .- 1551-2916. ; 106:4, s. 2635-2651
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Tidskriftsartikel (refereegranskat)abstract
- In this work, an aerodynamic levitation technology (ALT) was utilized to prepare ZrO2-SiO2 glass-ceramics with two different ZrO2 contents, that is, 35 mol% and 50 mol%. The glass-ceramics were partially melted at similar to 2000 degrees C or fully melted at similar to 3000 degrees C by ALT, followed by rapid quenching to obtain spherical glass-ceramic beads. The phase compositions and microstructures of the glass-ceramics were characterized. Crystallization of ZrO2 occurred during the solidification process and ZrO2 content, processing temperature, and the addition of yttrium (3 mol%) affected the crystalline phase of ZrO2. No ZrSiO4 or crystalline SiO2 were formed during the solidification process and the glass-ceramics were away from thermodynamic equilibrium due to rapid quenching. The glass-ceramics showed a microstructure of irregular-shaped ZrO2 micro-aggregates embedded in an amorphous SiO2 matrix, with lamellar twins and lattice defects formed within ZrO2 crystals. For samples prepared at similar to 3000 degrees C, a liquid-liquid phase separation occurred in the melt, which eventually resulted in the formation of large and irregular-shaped ZrO2 aggregates. In comparison, for samples prepared at similar to 2000 degrees C, pre-existed ZrO2 crystals formed during heating acted as nucleation sites during the cooling process, followed by grain growth to form large ZrO2 aggregates. Solidification and microstructure formation mechanisms were proposed to elucidate the solidification process during rapid cooling and the microstructure of the glass-ceramics obtained.
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