Use of Renewable Energy in Buildings: Experiences With Solar Thermal Utilization

Solar energy is receiving much more attention in building energy systems in recent years. Solar thermal utilization should be based on the integration of solar collectors into buildings. The facades of buildings can be important solar collectors, and therefore become multifunctional. In addition, solar collectors can be used to enhance the appearance of the façade when considering aesthetic compatibility. Currently, the feasible approach for integration of solar collectors into buildings is to install collectors on the south tilted roofs, south walls, balconies or awnings. Experiences on solar thermal utilization are mainly introduced in this paper, which include solar hot water systems with different design methods in residential buildings and solar-powered integrated energy systems in public buildings. Then suggestions are given. In cities of China, an ideal opportunity to carry out solar renovation with roof-integrated collectors is in combination with the rebuilding of apartment roofs, from flat to inclined. With regard to multi-story residential buildings, a central hot water supply system and central-individual hot water supply system are more appropriate in view of aesthetic compatibility of solar collectors with building roof and convenience of management. As for public buildings, it is highly recommended to design solar-powered integrated energy systems for the purpose of high solar fraction

Use of Renewable Energy in Buildings: Experiences With Solar Thermal Utilization

Solar energy is receiving much more attention in building energy systems in recent years. Solar thermal utilization should be based on the integration of solar collectors into buildings. The facades of buildings can be important solar collectors, and therefore become multifunctional. In addition, solar collectors can be used to enhance the appearance of the façade when considering aesthetic compatibility. Currently, the feasible approach for integration of solar collectors into buildings is to install collectors on the south tilted roofs, south walls, balconies or awnings. Experiences on solar thermal utilization are mainly introduced in this paper, which include solar hot water systems with different design methods in residential buildings and solar-powered integrated energy systems in public buildings. Then suggestions are given. In cities of China, an ideal opportunity to carry out solar renovation with roof-integrated collectors is in combination with the rebuilding of apartment roofs, from flat to inclined. With regard to multi-story residential buildings, a central hot water supply system and central-individual hot water supply system are more appropriate in view of aesthetic compatibility of solar collectors with building roof and convenience of management. As for public buildings, it is highly recommended to design solar-powered integrated energy systems for the purpose of high solar fraction

An Anti-Interference Scheme for UAV Data Links in Air–Ground Integrated Vehicular Networks

As one of the main applications of the Internet of things (IoT), the vehicular ad-hoc network (VANET) is the core of the intelligent transportation system (ITS). Air–ground integrated vehicular networks (AGIVNs) assisted by unmanned aerial vehicles (UAVs) have the advantages of wide coverage and flexible configuration, which outperform the ground-based VANET in terms of communication quality. However, the complex electromagnetic interference (EMI) severely degrades the communication performance of UAV sensors. Therefore, it is meaningful and challenging to design an efficient anti-interference scheme for UAV data links in AGIVNs. In this paper, we propose an anti-interference scheme, named as Mary-MCM, for UAV data links in AGIVNs based on multi-ary (M-ary) spread spectrum and multi-carrier modulation (MCM). Specifically, the Mary-MCM disperses the interference power by expanding the signal spectrum, such that the anti-interference ability of AGIVNs is enhanced. Besides, by using MCM and multiple-input multiple-output (MIMO) technologies, the Mary-MCM improves the spectrum utilization effectively while ensuring system performance. The simulation results verify that the Mary-MCM achieves excellent anti-interference performance under different EMI combinationsFunding: This work was supported in part by the National Natural Science Foundation of China under Grants 61571370, 61601365, 61901381, 61801388, 61901378, and 61901379; in part by the Science and Technology Research Program of Shaanxi Province under Grants 2018ZDCXL-GY-03-04, 2019ZDLGY07-10, 2019JQ-253, 2019JQ-631, and 2019JM-345; in part by the Advance Research Program on Common Information System Technologies under Grant 315075702; in part by the Postdoctoral Science Foundation of China under Grants BX20180262, BX20190287, 2018M641020, and 2018M641019; and in part by the Fundamental Research Funds for the Central Universities under Grants G2019KY05302, 31020180QD095, and 3102017OQD091.Scopu

Resilient routing mechanism for wireless sensor networks with deep learning link reliability prediction

Wireless sensor networks play an important role in Internet of Things systems and services but are prone and vulnerable to poor communication channel quality and network attacks. In this paper we are motivated to propose resilient routing algorithms for wireless sensor networks. The main idea is to exploit the link reliability along with other traditional routing metrics for routing algorithm design. We proposed firstly a novel deep-learning based link prediction model, which jointly exploits Weisfeiler-Lehman kernel and Dual Convolutional Neural Network (WL-DCNN) for lightweight subgraph extraction and labelling. It is leveraged to enhance self-learning ability of mining topological features with strong generality. Experimental results demonstrate that WL-DCNN outperforms all the studied 9 baseline schemes over 6 open complex networks datasets. The performance of AUC (Area Under the receiver operating characteristic Curve) is improved by 16% on average. Furthermore, we apply the WL-DCNN model in the design of resilient routing for wireless sensor networks, which can adaptively capture topological features to determine the reliability of target links, especially under the situations of routing table suffering from attack with varying degrees of damage to local link community. It is observed that, compared with other classical routing baselines, the proposed routing algorithm with link reliability prediction module can effectively improve the resilience of sensor networks while reserving high-energy-efficiency

Nanoscale Suppression of Magnetization at Atomically Assembled Manganite Interfaces

Using polarized X-rays, we compare the electronic and magnetic properties of a La(2/3)Sr(1/3)MnO(3)(LSMO)/SrTiO(3)(STO) and a modified LSMO/LaMnO(3)(LMO)/STO interface. Using the technique of X-ray resonant magnetic scattering (XRMS), we can probe the interfaces of complicated layered structures and quantitatively model depth-dependent magnetic profiles as a function of distance from the interface. Comparisons of the average electronic and magnetic properties at the interface are made independently using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). The XAS and the XMCD demonstrate that the electronic and magnetic structure of the LMO layer at the modified interface is qualitatively equivalent to the underlying LSMO film. From the temperature dependence of the XMCD, it is found that the near surface magnetization for both interfaces falls off faster than the bulk. For all temperatures in the range of 50K - 300K, the magnetic profiles for both systems always show a ferromagnetic component at the interface with a significantly suppressed magnetization that evolves to the bulk value over a length scale of ~1.6 - 2.4 nm. The LSMO/LMO/STO interface shows a larger ferromagnetic (FM) moment than the LSMO/STO interface, however the difference is only substantial at low temperature.Comment: 4 pages, 4 figure

Magnetically asymmetric interfaces in a (LaMnO3_3)/(SrMnO3_3) superlattice due to structural asymmetries

Polarized neutron reflectivity measurements of a ferromagnetic [(LaMnO$_3$)$_{11.8}$/(SrMnO$_3$)$_{4.4}$]$_6$ superlattice reveal a modulated magnetic structure with an enhanced magnetization at the interfaces where LaMnO$_3$ was deposited on SrMnO$_3$ (LMO/SMO). However, the opposite interfaces (SMO/LMO) are found to have a reduced ferromagnetic moment. The magnetic asymmetry arises from the difference in lateral structural roughness of the two interfaces observed via electron microscopy, with strong ferromagnetism present at the interfaces that are atomically smooth over tens of nanometers. This result demonstrates that atomic-scale roughness can destabilize interfacial phases in complex oxide heterostructures.Comment: 5 pages, 4 figure