2,336 research outputs found
Conceal an entrance by means of superscatterer
By using the novel property of the rectangular superscatterer, we propose a
design which can conceal an entrance from electromagnetic wave detection. Such
a superscatterer is realized by coating a negative index material shell on a
perfect electrical conductor rectangle cylinder. The results are numerically
confirmed by full-wave simulations both in the far-field and near-field.Comment: 10 pages, 4 figure
Existence results for non-local elliptic systems with Hardy-Littlewood-Sobolev critical nonlinearities
In this article, we study the following nonlinear doubly nonlocal problem
involving the fractional Laplacian in the sense of Hardy-Littlewood-Sobolev
inequality \begin{equation*} \left\{\begin{aligned} (-\Delta)^s u & =
au+bv+\frac{2p}{p+q}\int_{\Omega}\frac{|v(y)|^q}{|x-y|^\mu}dy|u|^{p-2}u+2\xi_1\int_{\Omega}\frac{|u(y)|^{2^*_\mu}}{|x-y|^\mu}dy|u|^{2^*_\mu-2}u,&&
\text{in } \Omega;\\ (-\Delta)^s v & =
bu+cv+\frac{2q}{p+q}\int_{\Omega}\frac{|u(y)|^p}{|x-y|^\mu}dy|v|^{q-2}v+2\xi_2\int_{\Omega}\frac{|v(y)|^{2^*_\mu}}{|x-y|^\mu}dy|v|^{2^*_\mu-2}v,&&
\text{in } \Omega;\\ u &=v=0,\text{ in } \R^N\setminus\Omega,
\end{aligned}\right. \end{equation*} where is a smooth bounded domain
in , , , , is the well
known fractional Laplacian, , where
is the upper critical exponent in the
Hardy-Littlewood-Sobolev inequality. Under suitable assumptions on different
parameters and , we are able to prove some existence and
multiplicity results for the above equation by variational methods.Comment: arXiv admin note: text overlap with arXiv:1508.05206 by other author
Application of large underground seasonal thermal energy storage in district heating system: A model-based energy performance assessment of a pilot system in Chifeng, China
Seasonal thermal energy storage (STES) technology is a proven solution to resolve the seasonal discrepancy between heating energy generation from renewables and building heating demands. This research focuses on the performance assessment of district heating (DH) systems powered by low-grade energy sources with large-scale, high temperature underground STES technology. A pilot DH system, located in Chifeng, China that integrates a 0.5 million m3 borehole thermal energy storage system, an on-site solar thermal plant and excess heat from a copper plant is presented. The research in this paper adopts a model-based approach using Modelica to analyze the energy performance of the STES for two district heating system configurations. Several performance indicators such as the extraction heat, the injection heat and the storage coefficient are selected to assess the STES system performance. Results show that a lower STES discharge temperature leads to a better energy performance. A sensitivity analysis of the site properties illustrates that the thermal conductivity of soil is the most influential parameter on the STES system performance. The long-term performance of the STES is also discussed and a shorter stabilization time between one and two years could be achieved by discharging the STES at a lower temperature.This research is part of the seasonal storage for solar and industrial waste heat utilization for urban district heating project funded by the Joint Scientific Thematic Research Programme (JSTP)–Smart Energy in Smart Cities. We gratefully acknowledge the financial support from the Netherlands Organisation for Scientific Research (NWO). We would also like to thank our research partners from Tsinghua University working on the project of the International S&T Cooperation Programof China (ISTCP) (project No. 2015DFG62410). Without their efforts, we would not have been able to obtain the technical data to conduct the case study
Performance study of a novel solar solid dehumidification/regeneration bed for use in buildings air conditioning systems
In this paper, a novel solar solid dehumidification/regeneration bed has been proposed, and its three regeneration methods, i.e., simulated solar radiation regeneration, microwave regeneration, and combined regeneration of the microwave and simulated solar radiation, were experimentally investigated and compared, as well as the dehumidification performance. The degree of regeneration of the proposed system under the regeneration method combining both microwave irradiation and simulated solar radiation could reach 77.7%, which was 3.77 times higher than that of the system under the simulated solar regeneration method and 1.05 times higher than that of the system under the microwave regeneration. The maximum energy efficiency of the proposed system under the combined regeneration method was 21.7%, while it was only 19.4% for the system under microwave regeneration. All these proved that the combined regeneration method of the simulated solar and microwave radiation not only improved the regeneration efficiency of the system, but also enhanced the energy efficiency. For the dehumidification performance, the maximum transient moisture removal was 14.1 g/kg, the maximum dehumidification efficiency was 68.0% and the maximum speed of dehumidification was 0.294 g/(kgμs) when the inlet air temperature was at 26.09 °C and the air relative humidity was at 89.23%. By comparing the testing results with the semi-empirical results from the Page model, it was indicated that the Page model can predict the regeneration characteristics of the novel solar solid dehumidification/regeneration bed under the combined method of microwave and simulated solar regeneration. The results of this research should prove useful to researchers and engineers to exploit the potential of solar technologies in buildings worldwide
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