Search Results (37)

This paper presents a novel switchable branch-line coupler (BLC) designed to achieve variable phase shifts while maintaining a constant output power. The proposed design incorporates low stepwise phase shifters with incremental phase shifts of 10° to 20°, covering phase ranges from −3° to 150°. The initial structure is based on a 3 dB branch-line coupler with arm electrical lengths of 3λ_g/2. A novel delay line structure is integrated within the BLC arms, consisting of a λ_g/4 section bridged by a tapered stripline to accommodate a PIN diode switch, thereby altering the current path direction. Additionally, two interdigital capacitors (IDCs), uniquely mounted on a crescent-shaped extension, are implemented alongside the tapered line to elongate the current path when the PIN diode is in the OFF state. By controlling the PIN diode states, the delay time is differentially adjusted, resulting in variable differential phase shifts at the output ports. To validate the functionality, the proposed BLC was integrated with a two-element antenna array to demonstrate differential beam steering. The measurement results confirm that the phased array antenna can switch its main beam between −27° and 25° in the elevation plane, achieving an average realized gain of approximately 7 dBi. The BLC was designed and simulated using CST Microwave Studio and was fabricated on an RO4003C Roger substrate (ε_r = 3.55, 0.406 mm). The proposed design is well-suited for future Butler matrix-based beamforming networks in antenna array systems, particularly for 5G wireless applications. Full article

With the increasing popularity of low-cost, clean, and environmentally friendly new energy sources, the proportion of grid-connected new energy units has increased significantly. However, since these units are frequency decoupled from the grid through a power electronic interface, they are unable to provide inertia support during active power perturbations, which leads to a decrease in system inertia and reduced frequency stability. In this study, the urgent need to accurately assess inertia is addressed by developing an energy-function-based inertia identification technique that eliminates the effect of damping terms. By integrating vibration mechanics, the proposed method calculates the inertia value after a perturbation using port measurements (active power, voltage phase, and frequency). Simulation results of the Western System Coordinating Council (WSCC) 9-bus system show that the inertia estimation error of the method is less than 1%, which is superior to conventional methods such as rate-of-change-of-frequency (RoCoF) and least squares methods. Notably, the technique accurately evaluates the inertia of synchronous generators and doubly fed induction generators (DFIGs) under virtual inertia control, providing a robust inertia evaluation framework for low-inertia power systems with high renewable energy penetration. This research deepens the understanding of inertial dynamics and contributes to practical applications in grid stability analysis and control strategy optimalization. Full article

This study presents a structured multi-agent system (MAS) architecture aimed at optimizing operational efficiency in roll-on/roll-off (Ro-Ro) terminal management through intelligent coordination and decentralized decision-making. The proposed framework enhances space allocation, route planning, traffic control, and boarding coordination, enabling real-time decision-making and adaptive operational strategies. Through structured MAS architecture, agents interact dynamically to optimize vehicle flow, reducing congestion and improving overall efficiency. The study evaluates the system’s potential benefits compared to traditional port management models, highlighting improvements in transit time reduction, resource utilization, and operational resilience. The findings suggest that MAS-based automation can enhance decision-making, sustainability, and integration with Industry 4.0 paradigms, driving the transition toward intelligent, efficient, and scalable port logistics. Full article

This study examines the integration of the Internet of Vehicles (IoV) and blockchain as tools to optimize traffic management in Roll-on/Roll-off (Ro-Ro) terminals within the Spanish port system. Faced with increasing operational complexity, these technologies present innovative solutions to enhance efficiency, reduce waiting times, and ensure transparency in data management. The methodology follows five main phases: analysis of the current scenario, establishment of a baseline, calculations to evaluate key outcomes, analysis of blockchain implementation, and discussion of results. Key variables include waiting times, vehicular flow, CO₂ emissions, and operational costs, comparing manual and automated scenarios. The findings reveal that the combined use of IoV and blockchain can increase vehicular flow by up to 70%, reduce waiting times by 2.56 min, and decrease CO₂ emissions by 57.74 kg per hour. Additionally, automation significantly reduces operational costs, yielding average savings of over EUR 500 per hour. This study concludes that adopting these technologies transforms port operations by fostering sustainability, efficiency, and safety. However, challenges remain, including high initial implementation costs and system interoperability issues. This work underscores the need for strategic approaches to overcome these barriers and positions Spanish ports as potential leaders in logistics innovation, aligning with global demands for sustainable, efficient, and transparent port operations. Full article

Introduction: Single-port video-assisted techniques, such as one-trocar-assisted pyeloplasty (OTAP) or Round-Traction-Assisted Pyeloplasty (RoTAP), have proven helpful for correcting congenital ureteropelvic junction obstruction (UPJO), especially in infants. Surgical Technique: This manuscript presents a technical variation based on the gloveport system that allows bimanual endocavitary dissection and protects the surgical wound during the procedure without increasing the cost or technical difficulty. Comment: This new technique, called gloveport-assisted retroperitoneal pyeloplasty (GARP), could be a valuable alternative for this pathology. Full article

Roll-on/roll-off vessels (RO/RO vessels) are playing an increasingly critical role in international automobile transport, facilitating the efficient movement of vehicles and heavy machinery across continents. Despite this growing significance, there is still limited research specifically focused on the RO/RO shipping network and its impact on global trade. This paper studies the global RO/RO shipping network using AIS data on RO/RO vessels collected from 2020 to 2023. We construct a method based on the complex network theory and the graph feature extraction method to quantitatively assess the features of the RO/RO shipping network. This method assesses the complexity, sparsity, homogeneity, modularity, and hierarchy of the RO/RO shipping network across various ports and countries and employs the graph convolutional neural network (GCN) model to extract network features for community detection. This process enables the identification of port clusters that are frequently linked to RO/RO vessels, as well as regional transport modes. The paper’s findings support these conclusions: (1) From 2020 to 2023, the number of nodes in the RO/RO shipping network increased by 22%, primarily concentrated in African countries. The RO/RO shipping network underwent restructuring after the pandemic, with major complex network parameters showing an upward trend. (2) The RO/RO shipping network is complex, with a stable graph density of 0.106 from 2020 to 2023. The average degree increased by 7% to 4.224. Modularity decreased by 6.5% from 0.431 in 2022 to 0.403, while the hierarchy coefficient rose to 0.575, suggesting that post-pandemic, community routes have become more diverse, reflecting the reconstruction and maturation of the overall network. (3) The model yielded a silhouette coefficient of 0.548 and a Davies–Bouldin index of 0.559 using an improved automatic feature extraction method. In comparison between 2020 and 2023, the changes in the two indicators are small. This shows that GINs can effectively extract network features and give us results that we can understand for community detection. (4) In 2023, key communities divide the RO/RO shipping network, with one community handling 39% of global routes (primarily Europe–Asia), another community handling 23% (serving Asia–Pacific, Africa, and the Middle East), and a third community managing 38% (linking Asia, Europe, and South America). Full article

Increasingly restrictive environmental regulations for the maritime sector have led shipping companies to look for technological alternatives to reduce emissions. This article introduces a methodology to analyse emission reductions of ships in port by incorporating batteries into the ships or using an onshore power supply system. These have not yet been considered together for comparison or with a focus on ship operation. The aim is to avoid the use of auxiliary engines in ports. First, the cost calculation method to be used is specified; then, the engine’s behaviour and the established basic navigation criteria are analysed; and finally, different alternatives are considered. A methodology is afterwards defined for selecting alternatives, comparing their costs with those of using auxiliary engines in port. As an example, it is applied to a Ro-Ro route between the ports of Montoir (France) and Vigo (Spain). The results indicate that incorporating batteries into the ship produces greater savings in annual costs than onshore power supply. The cost savings from onshore power supply depend on the range of prices in each port. However, the greatest emission savings are obtained by using the onshore power supply. This methodology can be extrapolated to other routes and vessels by incorporating real operating data. Full article

Port state control (PSC) inspections, considered a crucial means of maritime safety supervision, are viewed by the industry as a critical line of defense ensuring the stability of the international supply chain. Due to the high level of globalization and strong regional characteristics of PSC inspections, improving the accuracy of these inspections and efficiently utilizing inspection resources have become urgent issues. The construction of a PSC inspection ontology model from top to bottom, coupled with the integration of multisource data from bottom to top, is proposed in this paper. The RoBERTa-wwm-ext model is adopted as the entity recognition model, while the XGBoost₄ model serves as the knowledge fusion model to establish the PSC inspection knowledge graph. Building upon an evolutionary game model of the PSC inspection knowledge graph, this study introduces an evolutionary game method to analyze the internal evolutionary dynamics of ship populations from a microscopic perspective. Through numerical simulations and standardization diffusion evolution simulations for ship support, the evolutionary impact of each parameter on the subgraph is examined. Subsequently, based on the results of the evolutionary game analysis, recommendations for PSC inspection auxiliary decision-making and related strategic suggestions are presented. The experimental results show that the RoBERTa-wwm-ext model and the XGBoost₄ model used in the PSC inspection knowledge graph achieve superior performance in both entity recognition and knowledge fusion tasks, with the model accuracies surpassing those of other compared models. In the knowledge graph-based PSC inspection evolutionary game, the reward and punishment conditions ($n,f$) can reduce the burden of the standardization cost for safeguarding the ship. A ship is more sensitive to changes in the detention rate $\beta$ than to changes in the inspection rate $\alpha$. To a certain extent, the detention cost $C_{DC}$ plays a role similar to that of the detention rate $\beta$. In small-scale networks, relevant parameters in the ship’s standardization game have a more pronounced effect, with detention cost $C_{DC}$ having a greater impact than standardization cost $C_S$ on ship strategy choice and scale-free network evolution. Based on the experimental results, PSC inspection strategies are suggested. These strategies provide port state authorities with auxiliary decision-making tools for PSC inspections, promote the informatization of maritime regulation, and offer new insights for the study of maritime traffic safety management and PSC inspections. Full article

In the present study, a new structure (0.5–18 GHz) with excellent phase noise characteristics and a fast switching speed is proposed. Ultra-wideband synthesizers with low phase noises and less spurious signals have been developed to be used as local oscillators and for built-in test (BIT) functions in the field of electronic warfare systems (EW), in which synthesizers are installed at the front-end of devices; this is accomplished by applying an SMT process using a packaged-type device. This paper compares the advantages and disadvantages of PLVCO (old) and DDS reference sources (new) based on two types of frequency synthesizers. At this time, different frequencies can be output from the two ports by different FPGA coding of the internal frequency plan according to the operating frequency. The main RF line will be made a dielectric substrate, RO4350, with a relative dielectric constant of 3.38 and a dielectric thickness of 0.508 mm. In the ultra-broadband synthesizer module, the phase noise of the DDS output (1.25 GHz) was −131 dBc/Hz at 10 KHz offset. The phase noise in the 18 GHz output is expected to be −105.9 dBc/Hz at 1 KHz offset. In particular, by proposing a structure for obtaining a wideband frequency using a single source (DDS), the structure secures reliability from the point of view of a system operating for a long time by implementing a similar circuit within a predictable range. Full article

This paper presents a novel approach to addressing the issue of temperature-induced instability in an optical, single-sideband transmitter based on a micro-ring resonator (MRR) suitable for millimeter-wave (mmW) radio-over-fiber (RoF) communications. We propose utilizing the drop port of the MRR to provide a feedback signal to the closed-loop control (CLC) system. The latter serves to maintain the optimal alignment between the laser’s carrier and the MRR’s resonant wavelength, thus mitigating the adverse effects of chromatic-dispersion-induced power fading at the receiving end. Since the feedback information is extracted from the otherwise-wasted resonant energy at the drop port, the control system does not compromise the delicate optical signal at the through port. A CLC was synthesized, designed, and prototyped to provide real-time wavelength tuning of the heat-pump-controlled laser based on the feedback signal. Experimental evaluations demonstrate that the wavelength of the laser could be successfully locked to the MRR’s resonance with a wavelength dither of less than 0.004 nm (~491 MHz). This allowed us to limit the power-penalty deterioration to less than 2 dB for a RoF link with a 2.5-km standard telecommunication single-mode fiber (SMF), a modulation frequency of 37.8 GHz, and a carrier wavelength of 1563.97 nm (~191.820 THz). The proposed solution offers an alternative approach for the carrier and the MRR’s resonant wavelength interlocking without the need for complex photonics like thermo-optic or electro-optic structures to control the temperature or phase velocity, respectively. Full article

Germany has a wide-meshed waterway network. Although inland navigation is one of the most efficient transportation methods, its share of transport is steadily decreasing. The research project Smart-Port-Shuttle Hildesheim aims to strengthen the waterway system both from the aspect of inland navigation and from the aspect of ports. For this purpose, a holistic approach is chosen, which includes technological innovations on the one hand and integration into a logistical concept on the other. This paper focuses on the first point: a technological approach for a (partially) automated inland vessel. It will present the hardware setup and an evaluation of the sensors at a selection of critical points, such as in a lock, at a bridge passage, or during the passing of an obstacle. Different methods, such as Galileo E5a measurements for positioning or Simultaneous Localization and Mapping (SLAM) for constructing and updating the map of the branch canal, are analyzed. The data structure of the Robot Operating System (ROS) is presented, as the raw data are available to the audience. Full article

This paper introduces a novel two-port ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna system with enhanced isolation characteristics. The antenna, designed on a thin 0.787 mm RO5880 substrate, achieves a compact form factor of 52 × 26 mm${}^2$ and offers a wide bandwidth of 9.2 GHz (2.3 GHz to 11.5 GHz) while meeting the VSWR 2:1 criterion. Notably, the proposed antenna demonstrates an impressive increase in isolation, up to 16 dB, through the integration of a shared radiator with small rectangular slots, effectively reducing interference and improving overall performance. Furthermore, a comprehensive analysis of additional MIMO performance parameters, including the envelope correlation coefficient (ECC) and diversity gain, confirms their satisfactory limits, validating the potential of the proposed UWB-MIMO antenna for various UWB applications. The time domain analysis of the UWB antenna is also analyzed, and results are found to be within satisfactory limits. Simulation and measurement results further support the practicality and effectiveness of the antenna design, highlighting its compact size, wide bandwidth, and enhanced isolation characteristics, positioning it as a promising solution for advanced UWB microwave imaging systems. Full article

The gradual commercialization of entirely autonomous vehicles is expected to bring numerous benefits, such as structural transformation in the industry. Specifically, in maritime transportation, automobile terminals that import and export finished autos are seen to transform their current loading system into a CAV (connected automated vehicle)-loading system to accommodate autonomous vehicles. In this study, the impact of introducing a CAV-loading system to a roll-on, roll-off (RORO) ports was investigated. Simulation models were developed to test the performance of the terminal with the CAV-loading system. Then, a cost model was developed to determine the economic benefits of the CAV-loading system. The results in this study revealed that operating costs were reduced by 90%, while terminal operations were significantly improved. In addition, the study revealed that using the CAV-loading system resulted in a 12% reduction in CO₂ emissions compared to that using the current loading system. The originality of this study lies in its transformative potential for an industry that heavily relies on human labor and has limited mechanization and automation. This study provides significant implications for incorporating autonomous vehicles in planned automobile terminal operations. Full article

As the largest modern passenger Roll-on Roll-off (RoRo) terminal around the world, the berthing operation of Xuwen terminal is occasionally suspended due to bad weather, such as strong wind or thick fog. During the suspension, the number of stranded passengers and vehicles increasingly accumulates. As soon as the weather permits, the growth exerts great pressure, especially on large-scale vessels leaving the port, whose inefficiency may cause a loss of access to the terminal for inbound ships and chaos for port management. The focus of this study is to improve the efficiency of departure scheduling by optimizing traffic rules in the harbor basin. A mathematical optimization model is formulated for minimizing the total scheduling time, and then an adaptive simulated annealing (ASA) algorithm is proposed to solve the model. A specific decoding rule is introduced, referring to the characteristics of the mentioned model. After employing the operation data of the Xuwen terminal, a numerical experiment showed that the proposed scheduling method outperformed the first-come, first-served (FCFS) strategy and an improved ant colony algorithm (ACA). Moreover, the constructed simulation model of the terminal manifested the validity of the optimal solution. Full article

In logistics and freight distribution, scheduling and cost efficiency are two crucial issues for transportation companies that look with favour at the innovation introduced by Intelligent Transportation Systems (ITS). Moreover, an infrastructure level of service, safety and environmental defence are important for planners and public administrations. In this sense, terminal capacity and landside operations at the maritime infrastructure represent an interesting task for the community. Thus, this paper contributes to the research by: (i) proposing a generic framework for the integration of autonomous and connected vehicles with physical infrastructures; (ii) evaluating the opportunity to manage traffic arrivals according to vehicles’ priority and testing the effects of the introduction of a buffer zone outside the maritime port; (iii) improving efficiency and security within the terminal area by reducing waiting time and avoiding interference between flows. Moreover, the proposal for a discrete-event simulation model to assess terminal capacity in a ro-ro terminal is presented. Therefore, the paper contributes to some critical aspects towards sustainable development. First, regarding policy measures and actions, it proposes a valuable tool to assess what-if scenarios. Secondly, it represents a step forward in the process of smart corridor design for freight vehicles; in fact, it proposes a tool for managing landside operations at maritime ports and focuses on intervention in solving specific barriers and bottlenecks for freight who cross a ro-ro terminal daily. Furthermore, it offers a viable solution for managing connected vehicles in a context where full automation still needs to be achieved. The results evidenced the framework’s capability to deal with the traffic demand, thus improving the efficiency of the terminal landside operations. Full article