Search Results (119)

Under prolonged loading and various environmental factors, the performance of stay cables gradually deteriorates, which impacts the safety of the bridge structure. To investigate the influence of cable damage on the static performance of cable-stayed bridges, a finite element model of a cable-stayed bridge with damaged cables was established. The element death method is used to simulate cable damage, examining the impact of various damage scenarios on the static performance of the cable-stayed bridge. The objective is to identify cable locations that have a greater impact on the structure, providing a basis for assessing the bridge’s safety and developing cable replacement strategies. The research indicates that damage to long cables has a more significant impact on the static performance of the cable-stayed bridge compared to damage to short cables. Additionally, damage to the side span cables has a more pronounced effect on the structure than damage to the mid-span cables. The influence of cable damage on cable forces is primarily reflected on the same side of the cable plane within the same bridge tower as the damaged cable. Changes in cable forces result in variations in the deflection of the main girder and the displacement of the main tower. When multiple cables are damaged, the impact on the static performance of the structure is similar to that of single-cable damage. In instances of longitudinal symmetric damage and adjacent cable impairment, the cables transition into a critical state, resulting in more pronounced alterations in the deflection of the main girder and the displacement of the main tower. Original symmetric damage has a relatively small impact on the static performance of the entire bridge, so it is recommended to adopt a symmetric approach for cable replacement projects. Considering the impact of damage to a single cable and multiple cables on the static structure, it is possible to initially determine the location and extent of the cable damage. Based on the damage patterns, a cable replacement plan can be designed. It is recommended to use a symmetry-based approach for the cable replacement, as this method results in minimal impact on the overall static performance of the bridge, thereby ensuring the safety of the bridge structure. Full article

In the paper analytical and numerical investigations on stable prestressed configurations of prismatic tensegrities with a non-minimal number of members are studied. Up to date, non-minimal prisms were rarely analyzed. Analytical equations are written based on the elastic energy approach and are further solved numerically. The prestressing procedure has a physical meaning due to changing the lengths of selected groups of members and is explained by a simple mathematical model. Also, an example of the physical model is presented. The results show that additional cables commonly used in non-minimal prismatic tensegrities can be replaced by bars, as well as that the total number of bars in non-minimal prismatic tensegrities can be doubled, in regard to minimal prismatic systems. Full article

Aging underground cables pose a threatening issue in distribution systems. Replacing all cables at once is economically unfeasible, making it crucial to prioritize replacements. Traditionally, age-based strategies have been used, but they are likely to fail to depict the real condition of cables. Insulation faults are influenced by electrical, mechanical, thermal, and chemical stresses, and partial discharges (PDs) often serve as early indicators and accelerators of insulation aging. The trends in PD activity provide valuable information about insulation condition, although they do not directly reveal the cable’s real age. Due to the absence of an established ranking methodology for such condition-based data, this paper proposes a fuzzy logic and fuzzy analytic hierarchy process (FAHP)-based cable vulnerability ranking framework that effectively manages uncertainty and expert-based conditions. The proposed framework requires only basic and readily accessible data inputs, specifically cable age, which utilities commonly maintain, and PD measurements, such as peak values and event counts, which can be acquired through cost-effective, noninvasive sensing methods. To systematically evaluate the method’s performance and robustness, particularly given the inherent uncertainties in cable age and PD characteristics, this study employs Monte Carlo simulations coupled with a Spearman correlation analysis. The effectiveness of the developed framework is demonstrated using real operational cable data from a Danish distribution network, meteorological information from the Danish Meteorological Institute (DMI), and synthetically generated PD data. The results confirm that the FAHP-based ranking approach delivers robust and consistent outcomes under uncertainty, thereby supporting utilities in making more informed and economical maintenance decisions. Full article

Research on pediatric hand exoskeletons remains limited compared to that on devices for adults. This paper presents the design and experimental validation of a customizable pediatric finger module, part of a hand exoskeleton tailored to individual anatomical features. The module aims to assist finger flexion in children with mild spasticity during activities of daily living. A patient-specific design methodology was applied to the case of a 12-year-old child. The finger module integrates compliant dorsal structures and cable-driven transmission with rigid anchoring elements to balance flexibility and structural stability. Different geometries and thickness values were tested to optimize comfort and quantify mechanical performance. Additive manufacturing was adopted to enable rapid prototyping and easy replacement of parts. Tensile and bending tests were conducted to determine stiffness and cable travel. Results support the feasibility of the proposed finger module, offering empirical data for selection and sizing of the actuation system and paving the way for the advancement of new modular pediatric devices. Full article

Digital twin is a virtual replica of a physical system that updates in real time using sensor data to enable simulations and predictions. For bridges constructed using rotation construction methods, the rotation phase demands continuous monitoring of structural behavior and coordination with surrounding traffic infrastructure. Therefore, a digital twin system for monitoring rotation construction is vital to ensure safety and schedule compliance. This paper explores the application of model-based systems engineering (MBSE), a modern approach that replaces text-based documentation with visual system models, to design a digital twin system for monitoring the rotation construction of a 90 m + 90 m single-tower cable-stayed bridge. A V-model architecture for the digital twin system, based on requirements analysis, functional analysis, logical design, and physical design analysis (RFLP), is proposed. Based on SysML language, the system’s requirements, functions, behaviors, and other aspects are modeled and analyzed using the MBSE approach, converting all textual specifications into the unified visual models. Compared to the traditional document-driven method, MBSE improves design efficiency by reducing ambiguities in system specifications and enabling early detection of design flaws through simulations. The digital twin system allows engineers to predict potential risks during bridge rotation and optimize construction plans before implementation. These advancements demonstrate how MBSE supports proactive problem-solving (forward design) and provides a robust foundation for future model validation and engineering applications. Full article

To meet the demand of not interrupting traffic during the replacement of suspenders in long-span railway suspension bridges, this research proposes for the first time the application of the unsupported replacement method to the suspender replacement of self-anchored railway suspension bridges. Based on the basic principle of suspension bridge, the safety control index in the process of boom replacement is proposed. Midas Civil 2024 software is used to analyze the structural response of the boom after removal under static force and train load, including the change of cable force of adjacent boom, the displacement of main cable and stiffening beam. The real bridge test was carried out based on the special bridge of Chongqing Egongyan Track. The results show that after the removal of the boom, the cable force of the adjacent boom increases by 42–55%, the main cable is partially twisted but the adjacent joints change little, and the displacement of the stiffened beam meets the specification requirements. When the train is fully loaded, the maximum increase of the cable force of the adjacent boom is 150 kN, the stress increment of the operating boom is far less than the design strength, the increase of the downtorsion of the main cable is only 2.22%, and the displacement of the stiffening beam is within the allowable range. The safety control index and real bridge test results show that the unsupported replacement method is feasible and safe in the replacement of the suspenders of long-span rail suspension bridges, which provides an important reference for related projects. Full article

Shape sensing with optical fiber sensors is an emerging technology with broad applications across various fields. This study evaluates the metrological performance of shape sensing cables in the presence of fiber core failures, a critical issue in scenarios where cable replacement is impractical due to technological and economic constraints. The impact of core failure is quantified by comparing the uncertainty in key parameters, such as curvature and bending angle, between pristine and damaged cables through Monte Carlo simulations. Results indicate that while core failure degrades performance, shape reconstruction remains achievable. However, the reconstruction becomes sensitive to bending direction due to the loss of core symmetry. Additionally, simulations of how measurement noise propagates into uncertainty in the 3D shape reconstruction are carried out. Analysis of specific shapes, including a circle and a right-handed helix, shows that increasing the number of sensing cores significantly mitigates the adverse effects of core failure. The most notable improvement occurs when the number of cores is increased from four to five. These findings show how shape reconstruction is still possible even in the presence of core damage, and how this changes the behavior of the sensing process. Full article

The present study investigates the relationship between the near-infrared (NIR) spectral characteristics of cross-linked polyethylene (XLPE) insulation materials and their macroscopic properties, with the aim of establishing a reference framework for non-destructive material aging analysis. Accelerated thermal aging tests were conducted on samples of XLPE cables. These samples underwent Fourier-transform infrared spectroscopy (FTIR), elongation at break (EAB), and tensile strength (TS) tests. The temporal variation curves of the carbonyl index (CI), EAB, and TS were obtained at aging temperatures of 105 °C, 135 °C, 155 °C, and 180 °C. Additionally, NIR spectroscopy was performed on the aged XLPE samples, producing absorbance curves corresponding to different aging times at these temperatures. The absorption peaks of ‘C-H (-CH₂-)’ (1730 nm/1764 nm) were analyzed to determine their temporal variation patterns. Finally, a correlation analysis was conducted between the NIR results and those of the FTIR, EAB, and TS tests, revealing numerical relationships between NIR characteristic peaks and FTIR, EAB, and TS data. These quantified correlations demonstrate that NIR can effectively represent macroscopic mechanical properties, thereby simplifying the procedures for monitoring material aging and providing valuable results without requiring destructive testing. Results indicate that there is a certain feasibility in replacing traditional cable aging tests with NIR. Full article

The rapid growth of electrical energy demands raises the need for the modernization of distribution grids. Medium-voltage (MV) aged cables are infrastructures facing significant challenges that can compromise the security of supply and reduce the reliability of power grids. To address the challenges, there is a growing interest in optimizing cable replacement and management strategies. This comprehensive review focuses on the technical challenges and innovations associated with MV cable replacement, highlighting defect detection, lifetime estimation, reliability assessment, and management strategies. Various methods for detecting and monitoring cable defects and discussing their advantages and limitations are surveyed. Moreover, different models and techniques for estimating the remaining useful life of MV cables are explored, emphasizing the importance of accurate predictions for assessing cable reliability and optimizing replacement schedules. Furthermore, emerging technologies that enhance cable management strategies are also highlighted. This review provides insights and recommendations for future research and development, paving the way for the sustainable evolution of power grids. Full article

If electric power is distributed by an overhead network of cables, the ignition of wildland fires is unavoidable, although prudent management efforts can reduce the losses. The economic aspects of these fires are driven by tort litigation, which tends to create serious problems of social fairness. The present system does not contain adequate incentives towards minimizing these costs, nor appropriate measures to ensure that costs are allocated in a fair manner. The problems are universal, but a specific focus on the wildfire situation in California is assumed. The electric utilities there are regulated by the California Public Utilities Commission, and the regulations are almost wholly prescriptive. Striking is the absence of any benefit/cost considerations in the regulation of utilities. Regulations have also created distortions in the insurance market, notably subsidizing fire-unsafe behaviors. The legal and regulatory system should be changed to promote fire-safe behaviors. It should also be changed to more fairly apportion the cost burdens. A strategy which should be adopted more widely is that of Public Safety Power Shutoffs. The optimal solution is to enact legislation to create a no-fault system, similar to Workers’ Compensation. In such a system, tort-based liability litigation is replaced by a system which provides basic compensation to wildfire victims, irrespective of the cause and associated fault. However, reform of insurance regulation and zoning are also required. Full article

Towards the decarbonisation of the power system, digital substations have gradually increased in smart grids, where Ethernet cables have replaced large quantities of copper wires. With this transition, the standardised communication protocols through the LAN network play a central role in exchanging information and data between the physical power system and the control centres. One of the well-known protocols in the digital substations is IEC 61850 GOOSE (Generic Object-Oriented Substation Event), which is used to share time-critical information related to protection, automation, and control. The transmission time of this protocol affects power system operation and raises various issues, such as communication latencies and incorrect information. Therefore, it is necessary to consider the protocol transmission time for further protection and control mechanisms to ensure the stability and efficiency of the power system. For this purpose, this paper contributes the implementation of a cyber–physical power system (CPPS) testbed to measure the transfer time of IEC 61850 GOOSE under the real-time domain using the real-time simulator, Typhoon HIL, and its toolchains. This paper can benefit scholars and researchers in the relevant domains in implementing a CPPS testbed and an approach for transfer time measurement of communication protocols within the laboratory, eliminating the need for real-world substation devices. Full article

The automotive industry is one of the most demanding sectors of all manufacturing industries due to its competitiveness. It is necessary to innovate through the implementation of automated and robotic equipment, leading to cycle time and labor cost reduction. This work aims to design semi-automatic equipment to assemble cabling connectors used in the automotive sector, replacing a manual process currently taking place in an automotive components company. In the proposed equipment, the operator places a connector in the equipment, and the components (pins and seals) are automatically inserted. A vision sensor with artificial intelligence then confirms the correct application. The equipment operation defined as Finite Element Method (FEM) was applied for structural verification; the materials and fabrication processes were detailed; the associated costs were calculated, and the equipment subsets were validated. The design was successfully accomplished, and the imposed requirements were fulfilled, with significant advantages over the current process, providing new knowledge on how semi-automatic systems can be deployed to enhance the productivity and quality of manufacturing processes. The design principles and insights gained from this work can be applied to other automation challenges, particularly where manual processes need to be replaced by more efficient semi-automatic or automatic systems. The modularity of the overall solution and the design concepts of the component inserter, component feeder, and assembly process allow for its use in different assembly scenarios beyond the automotive sector, such as electronics or aerospace, providing a contribution to increased competitiveness and survival in the global market. Full article

The marine controlled source electromagnetic (MCSEM) transmitter can transmit high currents near the seabed to detect the electrical structure of the seafloor. The use of three-phase alternating current (AC) transmission can lead to three-phase imbalance, which results in an excessive current in one phase’s power line and affects the safety of the tow cable. This paper proposes an MCSEM underwater constant high-voltage direct-current (DC) switching scheme that replaces AC transmission with DC transmission. This scheme can fundamentally avoid three-phase imbalance and the AC loss caused by inductance. After establishing a simulation model to analyze the effect of the scheme, the relevant hardware units were designed. The hardware unit mainly consists of three parts: a DC switching inverter unit, a filter unit, and a step-down rectification unit. The DC inverter unit controls six insulated gate bipolar transistor (IGBT) modules with sinusoidal pulse width modulation (SPWM) signals to convert DC to three-phase AC power; the filter unit filters out extra harmonic components; and the step-down rectification unit converts high-voltage three-phase AC to low-voltage DC. The scheme ultimately achieved an adjustable DC output of 48.3–73.4 V under a constant DC input voltage of 3000 V and effectively reduced the current on the cable. This scheme has the potential to replace the previous AC transmission, reducing the risk of tow cable burnout and enhancing the safety of MCSEM operations. Full article

In the future, the power of a commercial ocean current energy convertor will be able to reach the MW class, and its corresponding mooring rope tension will be very good. However, the power of convertors currently being researched is still at the KW class, which can bear less rope tension. The main mooring rope usually has a single cable and a single foundation. To investigate the dynamic response and rope tension of an MW-class ocean current generator mooring system, here, a similarity rule is proposed for (1) coefficients without any fluid–structure interaction (FSI) using the Buckingham theorem and (2) ones with FSI. The overall hydrodynamic drag and moment including the hydrodynamic coefficients in these two situations are represented in a Taylor series. Assuming similarity between the commercial MW-class and KW-class ocean current convertors, all hydrodynamic parameters of the MW-class system are estimated based on the known KW-class parameters and based on the similarity formula. In order to overcome the extreme tension of the MW-class system and to provide good stability, in this paper, we propose a pulley–rope design to replace the traditional single-traction-rope design. The static and dynamic mathematical models of this mooring system subjected to the impact of typhoon waves and currents are proposed, and analytical solutions are obtained. We find that the pulley–rope design can significantly reduce the dynamic rope tensions of the mooring system. The effect of the length ratio of the main traction rope, rope A, to the seabed depth on the dynamic tension of stabilizing converter rope D is significant. The length ratio is within a safe range, and the maximum rope dynamic tension is less than the fracture strength. In addition, if the rope length ratio is over the critical value, the larger the ratio, the higher the safety factor of the rope. In summary, the pulley–rope design can be safely used in an MW-level ocean current generator system. Full article

Bioimpedance imaging aims to generate a 3D map of the resistivity and permittivity of biological tissue from multiple impedance channels measured with electrodes applied to the skin. When the electrodes are distributed around the body (for example, by delineating a cross section of the chest or a limb), bioimpedance imaging is called electrical impedance tomography (EIT) and results in functional 2D images. Conventional EIT systems rely on individually cabling each electrode to master electronics in a star configuration. This approach works well for rack-mounted equipment; however, the bulkiness of the cabling is unsuitable for a wearable system. Previously presented cooperative sensors solve this cabling problem using active (dry) electrodes connected via a two-wire parallel bus. The bus can be implemented with two unshielded wires or even two conductive textile layers, thus replacing the cumbersome wiring of the conventional star arrangement. Prior research demonstrated cooperative sensors for measuring bioimpedances, successfully realizing a measurement reference signal, sensor synchronization, and data transfer though still relying on individual batteries to power the sensors. Subsequent research using cooperative sensors for biopotential measurements proposed a method to remove batteries from the sensors and have the central unit supply power over the two-wire bus. Building from our previous research, this paper presents the application of this method to the measurement of bioimpedances. Two different approaches are discussed, one using discrete, commercially available components, and the other with an application-specific integrated circuit (ASIC). The initial experimental results reveal that both approaches are feasible, but the ASIC approach offers advantages for medical safety, as well as lower power consumption and a smaller size. Full article