The emerging fifth generation (5G) and beyond radio access networks are expected to be extremely dense and heterogeneous as compared to the current networks, involving a large number of different classes of base stations (BSs), namely macro, micro, femto and pico BSs. Among several performance requirements 5G and beyond systems aim to achieve, energy efficiency is one of the crucial requirements. In order to achieve energy-efficient design in dense heterogeneous 5G networks, various approaches in terms of resource allocation, off-loading techniques, hardware solutions and energy harvesting are being considered. In this regard, this paper develops an energy usage optimization framework in a cellular heterogeneous network (HetNet) consisting of a central macro-BS and a number of micro-BSs, equipped with renewable energy sources (RESs) such as solar panels and wind turbines. The proposed framework incorporates an energy cooperation mechanism along with a sleep mechanism (BS ON/OFF switching), in which the BSs having lean traffic are put into a sleep mode and their traffic load gets shared by the central BS. The surplus harvested energy from RESs of the sleeping BSs can then be sold back to the grid. An optimization problem for maximizing the utilization of RES and minimizing the usage of the traditional sources, such as utility and generator, is formulated and this mixed integer non-linear programming problem is solved through an interior point method. The presented results for various HetNet sizes demonstrate the significant savings in the energy cost with the proposed RES-enabled HetNet sleep mechanism model over the conventional approaches.
Polyvinyl alcohol/chitosan/silver (PVA/CS/Ag) nanocomposite membranes were synthesized by γ-radiation with promising antimicrobial and biomedical applications. The nanocomposite membranes were prepared by mixing PVA and CS solutions with different copolymer compositions in the presence of silver nitrate (AgNO3) and glutaraldehyde as cross-linker, followed by in situ reduction with γ-radiation at different doses. The nanocomposite membranes were characterized by ultraviolet spectroscopy (UV), Fourier transform infrared, X-ray diffraction (XRD) and transmission electron microscopy (TEM). UV studies showed a strong peak around λmax at 430 nm due to surface plasmon resonance of silver nanoparticles formed during irradiation. As the irradiation dose increased from 25 to 75 kGy, the plasmon band is shifted from 430 to 418 nm with high intensity, indicating the formation of smaller particles. TEM investigation showed uniform distribution of silver nanoparticles (AgNPs) in the membranes with mean diameter of 32–19 nm. XRD results confirmed that the mean diameter of AgNPs estimated from the Debye–Scherrer formula was in the range of 27.5–12.8 nm which confirms the TEM results. The PVA/CS/Ag nanocomposite membranes exhibited good antibacterial activity and were found to cause significant reduction in microbial growth. The nanocomposite membranes showed non-thrombogenicity effect and slightly haemolytic potential, suggesting their promising use in biomedical applications. 相似文献
Ba0.7Sr0.3ZrxTi1?xO3 (BSZT; where x=0.02, 0.04, 0.06, 0.08, 0.1) ceramics were processed through a sol‐gel method at 1450°C for 6 h. All the samples showed a diffuse phase transition which might be due to the presence of polar nanoregions, those associated with the composition inhomogeneity in the BSZT ceramics. The sample with x=0.02 exhibited a dielectric constant (?=23714) which successively decreased with increasing x up to 8569 for the sample with x=0.1 around Tc measured at 10 kHz. Ceramic samples showed a ferroelectric hysteresis behavior similar to relaxor materials. 相似文献
The fixed oil (26%) of the seeds of Marigold (Calendula officinalis) locally known as “Gul-e-Ashrafi” growing around the laboratories, was studied for its physico-chemical properties. Fatty acid composition of the seed oil as determined by gaschromatography and UV-spectroscopy showed the presence of lauric (3.90%), myristic (3.58%), palmitic (14.96%), stearic (10.13%), palmito-oleic (4.55%), oleic (16.26%), linoleic (39.45%) and linolenic (7.15%) acids. In the seed oil, conjugated acid is present to the extent of 4.5% whereas the percentage of non-conjugated acid (linolenic acid) is only 2.65%. The residual meal after the extraction of oil was also studied for its proteins (18%) and amino acids composition. 相似文献
Research and development activities relating to the grid have generally focused on applications where data is stored in files. However, many scientific and commercial applications are highly dependent on Information Servers (ISs) for storage and organization of their data. A data-information system that supports operations on multiple information servers in a grid environment is referred to as an interoperable grid system. Different perceptions by end-users of interoperable systems in a grid environment may lead to different reasons for integrating data. Even the same user might want to integrate the same distributed data in various ways to suit different needs, roles or tasks. Therefore multiple mediator views are needed to support this diversity. This paper describes our approach to supporting semantic interoperability in a heterogeneous multi-information server grid environment. It is based on using Integration Operators for generating multiple semantically rich RDF/OWL-based user defined mediator views above the grid participating ISs. These views support different perceptions of the distributed and heterogeneous data available. A set of grid services are developed for the implementation of the mediator views. 相似文献
In this paper, we suggest a fractional functional for the variational iteration method to solve the linear and nonlinear fractional order partial differential equations with fractional order initial and boundary conditions by using the modified Riemann-Liouville fractional derivative proposed by G. Jumarie. Fractional order Lagrange multiplier has been considered. Solution has been plotted for different values of α. 相似文献
Vertically aligned Ni nanowires and nanotubes have been electrodeposited in alumina templates at room temperature. The detailed study of angular dependent coercivity and squareness demonstrates that the magnetic easy axis of Ni nanowires is perpendicular to that of Ni nanotubes axis. The mechanisms of magnetization reversal in Ni nanowires and Ni nanotubes are found to occur through the nucleation mode with the propagation of transverse domain wall and curling mode, respectively. Field dependant magnetization results at different temperatures have depicted that the magnetocrystalline anisotropy might cause a crossover of easy axis at room temperature to that of low temperature in both Ni nanowires and nanotubes. Furthermore, the variation in temperature dependent coercivity illustrates that the magnetoelastic anisotropy induced by the alumina matrix plays a dominant role in the magnetization reversal of the nanowires and nanotubes at low temperature. 相似文献