| 1. |
- Eliasson, Bengt, et al.
(författare)
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Laser radiation pressure acceleration of monoenergetic protons in an ultra-thin foil
- 2009
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Ingår i: New Developments in Nonlinear Plasma Physics. - : American Institute of Physics. - 9780735407541 ; , s. 35-49
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Konferensbidrag (refereegranskat)abstract
- Wepresent theoretical and numerical studies of the acceleration of monoenergeticprotons in a double layer formed by the laser irradiationof an ultra-thin film. The stability of the foil isinvestigated by direct Vlasov-Maxwell simulations for different sets of laser-plasmaparameters. It is found that the foil is stable, dueto the trapping of both electrons and ions in thethin laser-plasma interaction region, where the electrons are trapped ina potential well composed of the ponderomo-tive potential of thelaser light and the electrostatic potential due to the ions,and the ions are trapped in a potential well composedof the inertial potential in an accelerated frame and theelectrostatic potential due to the electrons. The result is astable double layer, where the trapped ions are accelerated tomonoenergetic energies up to 100 MeV and beyond, which makesthem suitable for medical applications cancer treatment. The underlying physicsof trapped and untapped ions in a double layer isalso investigated theoretically and numerically.
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| 2. |
- Liu, Chuan S., et al.
(författare)
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Laser acceleration of quasi-monoenergetic protons via radiation pressure driven thin foil
- 2010
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Ingår i: Modern challenges in nonlinear plasma physics. - : AIP. - 9780735408753 ; , s. 104-110
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Konferensbidrag (refereegranskat)abstract
- We present a theoretical and simulation study of laser acceleration of quasi-monoenergetic protons in a thin foil irradiated by high intensity laser light. The underlying physics of radiation pressure acceleration (RPA) is discussed, including the importance of optimal thickness and circularly polarized light for efficient acceleration of ions to quasimonoenergetic beams. Preliminary two-dimensional simulation studies show that certain parameter regimes allow for stabilization of the Rayleigh-Taylor instability and possibility of acceleration of monoenergetic ions to an excess of 200MeV, making them suitable for important applications such as medical cancer therapy and fast ignition. © 2010 American Institute of Physics.
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| 3. |
- Xi, Teng, et al.
(författare)
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Energy-efficient Collaborative Localization for Participatory Sensing System
- 2015
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Ingår i: 2015 IEEE Global Communications Conference (Globecom). - 9781479959525
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Konferensbidrag (refereegranskat)abstract
- Location based services are getting increasingly popular in participatory sensing systems. They make use of location information on the mobile devices to support applications that improve personal health, object search, and entertainment. However, GPS positioning consumes a lot of energy, which can drain a mobile device's battery. Although WiFi localization and cell tower localization have been suggested as alternatives, they have lower localization accuracy and limited coverage. In this paper, we suggest a novel solution for multiple mobile devices to perform collaborative localization to reduce energy consumption and provide accurate localization. We divide the mobile devices into two groups, the aggregator group and the collector group. The aggregator group turns on their GPS periodically, while the collector group uses the locations of the aggregators to estimate their own locations. We formulate the aggregator set selection problem and propose two novel algorithms to minimize the energy consumption in collaborative localization. Simulations with real traces showed that our proposed solution can save up to 88% of the energy of the entire network.
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| 4. |
- Xi, X., et al.
(författare)
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Air pollution related externality of district heating - A case study of Changping, Beijing
- 2019
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Ingår i: Energy Procedia. - : Elsevier Ltd. - 1876-6102. ; , s. 4323-4330
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Konferensbidrag (refereegranskat)abstract
- Air pollution, caused by the use of fossil fuel, has been an environmental plague in China. It has a strong negative impact on human health. Since the costs of damage to health are not born by the pollution producers, these costs translate to social externality. Policies have an important role in optimizing resource allocation, such as penalizing the pollutant producers and incentivizing clean energy development. Among others, replacing coal with natural gas for heating represents an important example of air quality improvement measures. This paper presents a study that evaluates the health impacts from air pollution and the external cost of the "Coal-To-Gas" policy in district heating using Changping District (Beijing, China) as an example. Four scenarios were considered based on the historical and standard PM2.5 concentration. Results show that PM2.5 is responsible for causing an increase of 40% premature deaths in 2015 and that the monetary value of damage to health is higher than 1.2 billion CNY. In 2016 and 2017, the reported air quality was better than that in 2015. As a result, 13.3% and 26% premature deaths caused by air pollution were avoided in 2016 and 2017 compared to 2015 respectively. If the PM2.5 concentration level were to be reduced to national standard, the number of premature deaths attributed to PM2.5 could further decrease to 47.7% compared to 2015. Overall, the Coal-To-Gas policy in district heating reduces 0.017%~0.45% of premature death caused by air pollution each year. Air pollution reduction policies, which are expected to improve air quality together in the future, and the specific policy of Coal-To-Gas in district heating, could make great contribution to reducing the premature death caused by environmental problem and need more attention from the government and the public.
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