With developments in materials, thin‐film processing, fine‐tuning of morphology, and optimization of device fabrication, the performance of organic solar cells (OSCs) has improved markedly in recent ...years. Designing low‐bandgap materials has been a focus in order to maximize solar energy conversion. However, there are only a few successful low‐bandgap donor materials developed with near‐infrared (NIR) absorption that are well matched to the existing efficient acceptors. Porphyrin has shown great potential as a useful building block for constructing low‐bandgap donor materials due to its large conjugated plane and strong absorption. Porphyrin‐based donor materials have been shown to contribute to many record‐high device efficiencies in small molecule, tandem, ternary, flexible, and OSC/perovskite hybrid solar cells. Specifically, non‐fullerene small‐molecule solar cells have recently shown a high power conversion efficiency of 12% using low‐bandgap porphyrin. All these have validated the great potential of porphyrin derivatives as effective donor materials and made DPPEZnP‐TRs a family of best low‐bandgap donor materials in the OSC field so far. Here, recent progress in the rational design, morphology, dynamics, and multi‐functional applications starting from 2015 will be highlighted to deepen understanding of the structure–property relationship. Finally, some future directions of porphyrin‐based OSCs are presented.
Porphyrin is a very promising unit to construct low‐bandgap materials to harness solar photons in the near‐infrared region. This can help organic solar cells (OSCs) maximize solar energy utilization. Recent progress of porphyrin‐based materials, design and synthesis routes, morphology, and applications in OSCs is summarized, and future perspective and endeavors are discussed to facilitate higher performance for OSCs.
With the flourishing development of the Internet of Things (IoT), federated learning has garnered significant attention as a distributed learning method aimed at preserving the privacy of participant ...data. However, certain IoT devices, such as sensors, face challenges in effectively employing conventional federated learning approaches due to limited computational and storage resources, which hinder their ability to train complex local models. Additionally, in IoT environments, devices often face problems of data heterogeneity and uneven benefit distribution between them. To address these challenges, a personalized and fair split learning framework is proposed for resource-constrained clients. This framework first adopts a U-shaped structure, dividing the model to enable resource-constrained clients to offload subsets of the foundational model to a central server while retaining personalized model subsets locally to meet the specific personalized requirements of different clients. Furthermore, to ensure fair benefit distribution, a model-aggregation method with optimized aggregation weights is used. This method reasonably allocates model-aggregation weights based on the contributions of clients, thereby achieving collaborative fairness. Experimental results demonstrate that, in three distinct data heterogeneity scenarios, employing personalized training through this framework exhibits higher accuracy compared to existing baseline methods. Simultaneously, the framework ensures collaborative fairness, fostering a more balanced and sustainable cooperation among IoT devices.
This paper presents a numerical model for analyzing the nonlinear interaction between the moored Submerged Floating Tunnel (SFT) and surface waves. The mechanics model of the moored floating body ...driven by wave forces is built, and an efficient mesh update method is employed to dynamically configure the computational meshes solving the Navier-Stokes equations for viscous and incompressible free surface flows with the volume of fluid (VOF) method. Two laboratory experiments are used for validating the numerical model in terms of surface elevations, motion responses and mooring forces of the SFT, indicating the proposed model is capable of simulating the dynamics of the moored floating body under the wave action. This hydrodynamic model is then utilized to simulate the wave-structure interaction of the prototype SFT designed for Funka Bay, Hokkaido located in Japan. A total of 49 cases are designed for the numerical simulation to investigate the characteristics of the wave-tunnel interaction for different hydrodynamic parameters, including wave height, wave period, immersion depth and buoyancy-weight ratio (BWR). The numerical experiments not only shed light on the mooring forces, as well as pitch, sway and heave responses of the SFT in different wave conditions, but also provide guidance for the choice of BWR in engineering design. A medium value of BWR is suggested to be suitable, which is useful for avoiding the happening of snap forces in mooring chains and preventing SFT from experiencing large movement under external forces in severe wave conditions. As the correlation between the motion responses and BWR is not merely linear or quadratic but parabolic with a peak value, the design of BWR should avoid the case where peak motion responses of SFT happen.
•A numerical model for analyzing the interaction between the moored SFT and surface waves is proposed.•A prototype SFT in Funka Bay is simulated using the verified model, mooring forces and motion responses are gained.•The effects of relevant parameters on motion responses are studied, and the guidance for the choice of BWR is provided.
Vegetated platforms have been constructed in recent years for the purpose of shore protection. This paper addresses some fundamental questions concerning the vegetated platform: (1) What is the ...difference in wave attenuation between a vegetated platform and a simple platform, and how much can vegetation increase the efficiency of reducing wave transmission? (2) Are there any differences between the effects of stems and roots on wave attenuation? (3) Does vegetation always reduce wave transmission? (4) Is it possible to develop an empirical formula for estimating the wave transmission of a vegetated platform? To answer the above questions, a numerical model solving the Navier–Stokes equations for wave propagation over a vegetated platform is established and validated by several existing laboratory experiments. A total of 244 numerical experiments based on this model have been carried out. The simulated results suggest that the platform plays a major role and the vegetation plays a supporting role in reducing wave transmission except for some special cases. Stems tend to have a larger influence than roots in reducing wave transmission with the same height. The roots always help reduce wave transmission, while the stems may increase wave transmission when the platform width is in the range of 37.5–62.5% of the incident wavelength. Based on our numerical experiments and existing laboratory data, the paper proposes a simple formula for predicting the wave transmission coefficient of a vegetated platform for engineering applications.
•Quantify the contributions of platform and vegetation to wave height reduction by a vegetated platform using a CFD model.•Vegetation stems on a vegetated surface breakwater tend to reduce more wave energy than do the roots with the same height.•Vegetation may increase wave transmission when the platform width is in the range of 37.5–62.5% of the incident wavelength.•An empirical formula has been developed for predicting the wave transmission over a vegetated free-surface breakwater.
This study investigated the effects of microwave sintering on the microstructures and properties of copper-rGO composites. Graphene oxide was coated onto copper particles by wet ball milling, and ...copper-rGO composites were formed upon microwave sintering in an argon atmosphere. Scanning electron microscopy was then used to observe the mixing in the ball-milled composite powder, and the morphology of the bulk composite after microwave sintering. Raman spectra revealed how graphene oxide changed with ball milling and with microwave sintering. The microhardness, electrical conductivity, and thermal conductivity of the composite were also measured. The results showed that graphene oxide and copper particles were well combined and uniformly distributed after wet ball milling. The overall microhardness of microwave-sintered samples was 81.1 HV, which was 14.2% greater than that of pure copper (71 HV). After microwave sintering, the microhardness of the samples in areas showing copper oxide precipitates with eutectic structures was 89.5 HV, whereas the microhardness of the precipitate-free areas was 70.6 HV. The electrical conductivity of the samples was 87.10 IACS%, and their thermal conductivity was 391.62 W·m−1·K−1.
The implementation of rainwater harvesting (RWH) has emerged as a key strategy to cope with the water crisis in urban areas. However, the required design parameters of the RWH system in different ...buildings vary widely because of the differences in architectural characteristics. In this paper, the relationships between the building characteristics parameters and the optimal tank (Tc) capacity are investigated by simulating the RWH system for more than 120 buildings at different locations in Guangzhou. Explicit expressions relating the optimal storage volume of RWH systems to building characteristics are derived based on nonlinear regression analysis. A set of bivariate exponential equations for estimating the optimal tank size under different building conditions was obtained. The model has a MER of less than 10% for buildings with a C/D ratio between 17.5 and 85. In Guangzhou, the unit cost of an RWH system can be reduced to CNY 2.62/m2 with optimally designed tanks.
Highlight
A generalization equation is proposed to assist in the design of cisterns for RWH systems.
The validity range of the equation is verified.
The derived analytical equation is adequate to determine the cistern volume for medium‐sized buildings.
Coverage is one of the important performance indexes in wireless sensor networks. When the target is covered by <inline-formula> <tex-math notation="LaTeX">k </tex-math></inline-formula> degrees by ...the sensor, more redundant data are generated, which may lead to network congestion, thus reducing the communication and coverage of the network and leading to a rapid depletion of energy. Therefore, this paper presents an energy balance and coverage control algorithm for the overlay network model based on node position relations. Areas are given by the analysis of the overlay network model. In terms of energy consumption, nodes with low energy consumption are scheduled by a given proportion of expected functions between the working nodes and the neighboring nodes, which balances the energy consumption of the entire network and optimizes network resources. Finally, the simulation results show that the proposed <inline-formula> <tex-math notation="LaTeX">k </tex-math></inline-formula>-degree coverage algorithm not only improves the coverage quality of the network but also reduces the rapid energy consumption and prolongs the service life of the network.
With the development of the Internet of Things, a huge number of devices are connected to the network, network traffic is exhibiting massive and low latency characteristics. At the same time, it is ...becoming cheaper and cheaper to launch DDoS attacks, and the attack traffic is becoming larger and larger. Software-defined networking SDN is proposed as a new network architecture. However, the controller as the core of SDN is vulnerable to DDoS attacks and causes a single point of failure in the network. This paper combines the ideas of distributed and edge computing, firstly, a DDoS attack detection algorithm using heterogeneous integrated feature selection and random forest algorithm is proposed. Then, this DDoS attack detection algorithm is distributed and deployed on the edge equipment switches of SDN to perform distributed edge parallel computing using the residual computing power of the switches for fast and accurate detection of DDoS attacks. Finally, simulation experiments are conducted in the SDN environment using the CIC-DDoS2019 dataset to evaluate the effectiveness and feasibility of the proposed scheme. The experimental results show that the performance evaluation metrics of this solution: accuracy, precision, recall and F-value all reach 99.99%, while the prediction time is only 0.4 s, all metrics are better than other DDoS attack detection methods in the same category. Therefore, this solution is able to detect DDoS attacks in a timely and accurate manner.
Stepped-frequency waveform may be used to synthesize a wideband signal with several narrow-band pulses and achieve a high-resolution range profile without increasing the instantaneous bandwidth. ...Nevertheless, the conventional stepped-frequency waveform is Doppler sensitive, which greatly limits its application to moving targets. For this reason, this paper proposes a waveform design method using a staggered pulse repetition frequency to improve the Doppler tolerance effectively. First, a generalized echo model of the stepped-frequency waveform is constructed in order to analyze the Doppler sensitivity. Then, waveform design is carried out in the stepped-frequency waveform by using a staggered pulse repetition frequency so as to eliminate the high-order phase component that is caused by the target's velocity. Further, the waveform design method is extended to the sparse stepped-frequency waveform, and we also propose corresponding methods for high-resolution range profile synthesis and motion compensation. Finally, experiments with electromagnetic data verify the high Doppler tolerance of the proposed waveform.
Abstract The expression of miR-203 has been reported to be significantly down-regulated in esophageal cancer. We showed here that overexpression of miR-203 in esophageal cancer cells dramatically ...increased cell apoptosis and inhibited cell proliferation, migration and invasion as well as tumor growth and down-regulated miR-21 expression. We subsequently identified that small GTPase Ran was a target gene of miR-203. Furthermore, Ran restoration partially counteracted the tumor suppressive effects of miR-203 and increased miR-21 expression. Taken together, our findings suggest that miR-203 may act as novel tumor suppressor in esophageal cancer through down-regulating the expression of Ran and miR-21.
PDF
