This article presents W-IQ-TREE, an intuitive and user-friendly web interface and server for IQ-TREE, an efficient phylogenetic software for maximum likelihood analysis. W-IQ-TREE supports multiple ...sequence types (DNA, protein, codon, binary and morphology) in common alignment formats and a wide range of evolutionary models including mixture and partition models. W-IQ-TREE performs fast model selection, partition scheme finding, efficient tree reconstruction, ultrafast bootstrapping, branch tests, and tree topology tests. All computations are conducted on a dedicated computer cluster and the users receive the results via URL or email. W-IQ-TREE is available at http://iqtree.cibiv.univie.ac.at It is free and open to all users and there is no login requirement.
Large phylogenomics data sets require fast tree inference methods, especially for maximum-likelihood (ML) phylogenies. Fast programs exist, but due to inherent heuristics to find optimal trees, it is ...not clear whether the best tree is found. Thus, there is need for additional approaches that employ different search strategies to find ML trees and that are at the same time as fast as currently available ML programs. We show that a combination of hill-climbing approaches and a stochastic perturbation method can be time-efficiently implemented. If we allow the same CPU time as RAxML and PhyML, then our software IQ-TREE found higher likelihoods between 62.2% and 87.1% of the studied alignments, thus efficiently exploring the tree-space. If we use the IQ-TREE stopping rule, RAxML and PhyML are faster in 75.7% and 47.1% of the DNA alignments and 42.2% and 100% of the protein alignments, respectively. However, the range of obtaining higher likelihoods with IQ-TREE improves to 73.3-97.1%. IQ-TREE is freely available at http://www.cibiv.at/software/iqtree.
The integration of microgrids (MGs) in distribution networks forms the networked microgrids (NMGs). The peer-to-peer (P2P) control architecture is able to fully exploit the flexibility and resilience ...of NMGs. This paper proposes a multi-layer and multi-agent architecture to achieve P2P control of NMGs. The control framework is fully distributed and contains three control layers operated in the agent of each MG. For primary control, a droop control is adopted by each MG-agent for localized power sharing. For secondary control, a distributed consensus algorithm is proposed for frequency/voltage restoration and arbitrary power sharing among MGs. For tertiary control, the power loss in the NMG system is minimized by using alternating direction method of multipliers (ADMM). The architecture of the MG agent are designed, which processes the three control layers via information exchange among neighbouring agents. The proposed framework is validated in a hardware-in-the-loop test-bed, where NMG system with six buses and three MGs is emulated in the OPAL-RT, while the control algorithms are realized by a multi-agent system. The experimental results verify the effectiveness and advantages of the proposed framework, which demonstrates a practical control framework design for NMG systems.
A multiple-input-multiple-output (MIMO) antenna system with low-profile and small element spacing characteristics is presented in this paper. This antenna contains multiple elements arranged in both ...E-plane and H-plane configurations. The original strong coupling between the MIMO elements can be suppressed by exciting orthogonal operating modes. To achieve this, a half-wavelength microstrip line and a quarter-wavelength grounded stub are utilized to decouple the H- and E-plane MIMO arrays. A 2 × 2 antenna prototype is fabricated and measured to demonstrate the decoupling concept's feasibility. The measured impedance bandwidth is from 4.78 to 4.81 GHz. Across this band, the isolation is better than 15 dB with extremely small edge-to-edge distances of 0.032λ and 0.026λ in the E- and H-plane, respectively. Featuring the simple decoupling structure, small element spacing, and the capability of extending to a large-scale 2 × N array, the proposed antenna can be used for 5G Internet of Things (IoT) applications operating at the N79 frequency band.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this article, a distributed hierarchical control framework with coordinated secondary and tertiary levels is proposed for islanded microgrids (MGs). The structure and functionality of each agent ...are formulated to process simultaneously the secondary control and TC in a peer-to-peer communication network. First, the distributed secondary control is proposed for restoring system frequency/voltage while providing power sharing considering droop coefficients and upper level power dispatch orders. Then the distributed TC minimizes the network power loss in the islanded MG by using alternating direction method of multipliers (ADMM) algorithm. The multiagent system is designed to cover both control levels for cyber-physical implementations. A laboratory cyber-physical MG platform has been built to validate the proposed control framework in real-time and hardware-in-the-loop conditions. A six-bus three-DG MG is implemented on the platform and the experimental results validate the effectiveness of the proposed method.
This paper shows an effective method to significantly enhance the isolation of a closely spaced two-port patch antenna, which can be deployed for full-duplex transceivers as well as ...multiple-input-multiple-output (MIMO) systems. Two rectangular microstrip patches are arranged in the E-plane configuration. To achieve high isolation, a grounded stub is positioned between the radiating patches. For validation of the proposed concept, an antenna prototype is fabricated for measurements. The measured data demonstrates that the port-to-port mutual coupling can be suppressed to -50 dB, which is useful in self-interference cancellation for full-duplex communication systems. Compared with the coupled design, the isolation is significantly enhanced by 43 dB with an inter-element spacing of 0.034lambda.sub.c, where lambda.sub.c is a free-space wavelength at the center operating frequency. Regarding MIMO metrics, the antenna also shows good MIMO diversity performance based on an envelope correlation coefficient and a diversity gain.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This article presents a novel Cyber-Hardware-in-the-Loop (Cyber-HIL) platform for assessing control operation in ship cyber-physical systems. The proposed platform employs cutting-edge technologies, ...including Docker containers, real-time simulator <inline-formula><tex-math notation="LaTeX">OPAL-RT</tex-math></inline-formula>, and network emulator <inline-formula><tex-math notation="LaTeX">ns3</tex-math></inline-formula>, to create a secure and controlled testing and deployment environment for investigating the potential impact of cyber attack threats on ship control systems. Real-time experiments were conducted using an advanced load-shedding controller as a control object in both synchronous and asynchronous manners, showcasing the platform's versatility and effectiveness in identifying vulnerabilities and improving overall Ship Cyber Physical System (SCPS) security. Furthermore, the performance of the load-shedding controller under cyber attacks was evaluated by conducting tests with man-in-the-middle (MITM) and denial-of-service (DoS) attacks. These attacks were implemented on the communication channels between the controller and the simulated ship system, emulating real-world scenarios. The proposed Cyber-HIL platform provides a comprehensive and effective approach to test and validate the security of ship control systems in the face of cyber threats.
A microgrid (MG) is a cyber-physical system with coupled power and communication networks. The centralized secondary control of MGs with periodical communications restricts system efficiency and ...resilience. This article proposes a distributed event-triggered secondary control scheme in islanded MGs with its cyber-physical implementation. The proposed control scheme operates with the reduced frequency of communications depending on the MG states change "events" (e.g., load variations and communication failures). Besides, the secondary control objectives, including frequency/voltage regulation and accurate real/reactive power sharing, are decoupled into two timescales. Instead of designing event-triggering conditions (ETCs) for each secondary control functions, only ETCs for power sharing control in slower timescale are designed. Thus, the communication burden is significantly reduced since communications among neighbor controllers are only needed at the event-triggered time. The proposed controller has been tested on a hardware-in-the-loop (HIL) platform, where the physical system is modeled in the OPAL-RT and the cyber system is realized in Raspberry Pis. The control effectiveness is validated by the HIL results.
•Study proposes an ensemble STLF method merging parallel and series approaches for high-renewable energy loads.•Parallel method captures load trends; series uses deep learning for short-term ...variations.•Final forecast combines parallel/series methods with coefficients for accurate, robust modeling.•The method was evaluated using real-world load data and compared with two other methods, demonstrating its superior performance.
The increasing integration of renewable energy sources into large buildings and structures has emphasized the importance of effective control systems to optimize resource use, grid stability, and reliability. In this context, load forecasting is critical for predicting future energy demand and managing the intermittency and variability of renewable energy resources to ensure a stable performance. This study proposes an ensemble-based short-term load forecasting (STLF) method tailored for buildings. It combines parallel and series approaches for a 24-hour forecasting horizon. The parallel approach uses similar historical days to capture the general load trend, holidays, and user behavior, while the series component employs a deep learning-based neural network to address short-term changes. The final ensemble-based forecast is the culmination of these two methods. Evaluated using real load profile data sets with 15-minute resolution, the proposed method demonstrates more than 23% and 24% improvements in MAE and RMSE, respectively, compared to other methods. These results demonstrated the superior performance of the proposed method in terms of both accuracy and robustness, making it an effective solution for short-term load forecasting in buildings heavily reliant on renewable energy.
We examine the impact of the media on firms’ leverage adjustments. Using a comprehensive sample of global news across 33 countries, we find that greater news coverage and more positive news sentiment ...are associated with greater leverage adjustment speeds. This finding is consistent with the argument that media coverage and content help lower the cost of firms’ adjustment toward target leverage. We further find evidence supporting two mechanisms through which the news media affects leverage adjustments: information dissemination and monitoring. Overall, our results are consistent with the dynamic trade-off theory of capital structure.
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