A Precoding Scheme to Reduce the Effect of Channel Correlation for MIMO-PLC System

MIMO technique can provide higher information throughput and transmission reliability for the PLC system.However,the MIMO-PLC system based on three-conductor cable has a high correlation among its sub-channels.Spatial multiplexing technology will be affected by the spatial correlation between MIMO-PLC sub-channels.To reduce the system bit error rate caused by MIMO-PLC correlation among sub-channels,this paper proposed a phase rotation precoding scheme for the 2×2 closed-loop MIMO-PLC system.According to the channel transfer function of high correlation MIMO-PLC system,the phase rotation precoding matrix F is calculated,and the transmission signal matrix S is modulated with the F,the code distance at the receiving point with smallest code distance is increased by phase rotation.Simulation results show that the scheme can effectively reduce the bit error rate of the 2×2 MIMO-PLC system based on ML detection,and significantly improve the system performance.

Evaluation and Analysis of Battery Technologies Applied to Grid-Level Energy Storage Systems Based on Rough Set Theory

Interest in the development of grid-level energy storage systems has increased over the years.As one of the most popular energy storage technologies currently available,batteries offer a number of high-value opportunities due to their rapid responses,flexible installation,and excellent performances.However,because of the complexity,multifunctionality,and wide deployment of power grids,trade-offs in battery performance exist,especially when considering economics,environmental effects,and safety.Therefore,establishing a comprehensive assessment of battery technologies is an urgent undertaking.In this work,we present an analysis of rough sets to evaluate the integration of battery systems(e.g.,lead-acid batteries,lithium-ion batteries,nickel/metal-hydrogen batteries,zinc-air batteries,and Na-S batteries)into a power grid.Specifically,technological properties,economic significance,environmental effects,and safety of these battery systems are evaluated on the basis of rough set theory.In addition,some perspectives are provided to promote the development of battery technologies for grid-level energy storage.

Internet of Things (IoT)–blockchain-enabled pharmaceutical supply chain resilience in the post-pandemic era

During the COVID-19 pandemic, the current operating environment of pharmaceutical supply chain (PSC) has rapidly changed and faced increasing risks of disruption. The Internet of Things (IoT) and blockchain not only help enhance the efficiency of PSC operations in the information technology domain but also address complex related issues and improve the visibility, flexibility, and transparency of these operations. Although IoT and blockchain have been widely examined in the areas of supply chain and logistics management, further work on PSC is expected by the public to enhance its resilience. To respond to this call, this paper combines a literature review with semi-structured interviews to investigate the characteristics of PSC, the key aspects affecting PSC, and the challenges faced by PSC in the post-pandemic era. An IoT–blockchain-integrated hospital-side oriented PSC management model is also developed. This paper highlights how IoT and blockchain technology can enhance supply chain resilience and provides a reference on how PSC members can cope with the associated risks.

Constructing vertical phase separation of polymer blends via mixed solvents to enhance their photovoltaic performance

A polymer blend comprising poly(3-hexylthiophene)(P3HT)donor and poly[2,7-(9,9′-octyl-fluorene)-alt-5,5-(4′,7′-di-2-thienyl-5′,6′-bis(hexyloxy)-2′,1′,3′-benzothiadiazole)](PFDTBT-OC6)acceptor is used as the active layer to fabricate all-polymer solar cells.The blend morphology variance processed with pure and mixed solvents,and the related photovoltaic performance,are investigated in detail.It is found that,due to its low surface energy,a thin P3HT enrichment layer on the top surface of the active layer greatly increases bimolecular recombination and results in S-kinks of the illuminated current density-voltage curves.With the incorporation of p-xylene(a marginal solvent of P3HT)in the blend solution,the P3HT enrichment atop the active layer surface is effectively decreased because the high boiling-point p-xylene suppresses the diffusion of P3HT chains toward the top surface during the film-drying process.The bimolecular recombination was thus improved and the S-kinks of the photovoltaic curves were completely removed.The overall power conversion efficiencies of the devices are strongly boosted(from 0.88%to 1.41%)when chlorobenzene:p-xylene mixed solvent is used to replace pure chlorobenzene.

Dithienocarbazole- and benzothiadiazole-based donor-acceptor conjugated polymers for bulk heterojunction polymer solar cells

Donor-acceptor(D-A)-conjugated polymers P(BT-C1)and P(BT-C2),with dithieno[2,3-b;7,6-b]carbazole(C1)or dithieno[3,2-b;6,7-b]carbazole(C2)as D-unit and benzothiadiazole(BT)as A-unit,were synthesized.The optical bandgaps of the polymers are similar(1.84 and 1.88 e V,respectively).The structures of donor units noticeably influence the energy levels and backbone curvature of the polymers.P(BT-C1)shows a large backbone curvature;its highest occupied molecular orbital(HOMO)energy level is 5.18 e V,whereas P(BT-C2)displays a pseudo-straight backbone and has a HOMO energy level of 5.37 e V.The hole mobilities of the polymers without thermal annealing are 1.9×10 3 and 2.7×10 3 cm2 V 1 s 1 for P(BT-C1)and P(BT-C2),respectively,as measured by organic thin-film transistors(OTFTs).Polymer solar cells using P(BT-C1)and P(BT-C2)as the donor and phenyl-C71-butyric acid methyl ester(PC71BM)as the acceptor were fabricated.Power conversion efficiencies(PCEs)of 4.9%and 5.0%were achieved for P(BT-C1)and P(BT-C2),respectively.The devices based on P(BT-C2)exhibited a higher Voc due to the deeper HOMO level of the polymer,which led to a slightly higher PCE.

Carbazole ring: A delicate rack for constructing thermally activated delayed fluorescent compounds with through-space charge transfer

Three carbazole derivatives, Ac PTC, Px PTC and Pt PTC, consisting of two 9,9-dimethyl-9,10-dihydroacridine,phenoxazine or phenothiazine donor groups and one diphenyltriazine acceptor group fixed at 1,8,9-positions of a single carbazole ring via phenylene, are designed and synthesized. X-ray diffraction analysis of Ac PTC reveals that there exist multiple π-π interactions between the donor and acceptor groups to form a sandwich-like structural unit with edge-to-face interaction model. The compounds thus show obvious thermally activated delayed fluorescence with through-space charge transfer character and possess considerable photoluminescence quantum yields of up to 73% in doped films with sky-blue to yellow emissions. The solution-processed electroluminescent devices achieve the highest maximum external quantum efficiencies of 10.0%, 11% and 5.6% for Ac PTC, Px PTC and Pt PTC, respectively, with small efficiency roll-offs.