This study presents a preliminary investigation report on an aging-level-based (ALB) charging strategy that is possible to extend the battery lifespan by varying the charge current according to the state of health of a cell as opposed to the standard constant-current constant-voltage (CC-CV) and a four-stage constant current (4SCC) methods. Tests of Sanyo UR14500P lithium-ion batteries in the cylindrical shape with a nominal voltage of 3.7 V and a rated capacity of 840 mAh have been carried out. The results demonstrate that the ALB charging with a CC charge profile is able to slow down the cell capacity fade by 3.84% compared with the standard CC charging after 120 cycles, which increases the lifetime of 40 cycles to 50 cycles. Besides, the ALB charging with a 4SCC charge profile is able to slow down the cell capacity fade by 2.55% compared with the standard 4SCC charging after 100 cycles, which prolongs the lifetime of 30 cycles to 40 cycles. Nevertheless, the ALB charging strategy with both the CC and 4SCC charge profiles has much longer charging time than those with the standard charging method, and the charging time increases by 22.5% and 10.71%, respectively.

This article proposes an experimental test to examine the effect of weighting strategies on Taguchi-based optimization of the four-stage constant current (4SCC) charging method. The performance objectives used in the test include charging time, normalized discharge capacity, charging efficiency, average cell temperature rises, and energy losses. To simplify the optimization problem, a scalarization approach incorporating multiobjective functions into a single solution is utilized in this article. There are two types of weights in the scalarization: equal and unequal weights. In the equal weighting strategy, each performance objective is equally important. In the unequal weighting strategy, by contrast, unequal weights represent the performance priority of an objective function. To investigate the effect of the equal weighting strategy, an equal weight of 1/5 is given to each performance objective. For the unequal weighting strategy, this article adopts a random integer ranging from 1 to 5, and a floating-point value from 0 to 1, so the sum of all weights will be equal to 1. The test utilizes Sanyo UR14500P batteries in the cylindrical shape with a nominal voltage of 3.7 V and a rated capacity of 840 mAh. The experimental results show that the charging efficiency remains approximately the same regardless of which weighting strategy is adopted. The equal-weighted 4SCC charging yields the largest nominal charged capacity (96.7%), the longest charging time (102 min), and the smallest average cell temperature rise (1.714 °C). Considering charging time reduction, however, the performance of the unequal-weighted 4SCC charging is significantly better than that of the equal-weighted 4SCC charging. In addition, the energy losses brought by applying the equal- and unequal-weighted 4SCC charging are roughly the same.

Induction motors (IMs) have been commonly applied to industrial fields since the past decades; thus, developing advanced fault diagnosis methods becomes vital for IM applications. This study proposed an online fault diagnosis system for IMs based on the Random Forest (RF) and eXtreme Gradient Boosting (XGBoost) algorithms to reduce the additional repair costs and prevent unexpected downtime. It focused on detecting healthy three-phase IMs and five common fault conditions of the IMs, involving broken rotor bars, rotor unbalance, and composite faults with short-circuited stator windings that combined two or three types of the faults, for practical purposes. The experimental results show that the model performance improved by 15% over the default model when train-test split ratios, feature selection, and hyperparameter optimization, notably in XGBoost, are considered. The proposed XGBoost model enables a high accuracy of 96.06% for RF to perform a motor fault diagnosis under six different motor conditions. Furthermore, the execution time required by the proposed fault diagnosis system is 57% less than the time required by existing motor fault diagnosis methods. These results successfully demonstrate the effectiveness of the methods proposed in this study for online motor diagnosis.

This paper addresses the growing concern over air pollutant emissions (NOx, SOx, PM, CO₂) from ocean-going vessels in harbor areas and the role of Onshore Power Supply (OPS) systems in mitigating these emissions during vessel berthing. However, the slow progress in global shore power facilities is attributed to safety- and specification-related concerns. Our study conducts a comprehensive analysis, comparing international shore power regulations, with a specific focus on the IEC/IEEE 80005-1 standard and guidelines from various ship classification societies. We introduce checklists, scoring tables, and spider diagrams to evaluate the regulatory content, highlighting the strengths and weaknesses of each approach. Furthermore, this paper emphasizes the significance of a well-defined operational process for high-voltage shore connection (HVSC) to ensure the safety of OPS operations. We present process diagrams for key operational stages, based on IEC/IEEE 80005-1 specifications and evaluation criteria. The ultimate goal of this research is to drive the global adoption of shore power and foster the establishment of shore power facilities worldwide. This aligns with the broader environmental protection objectives of achieving cleaner ports and reducing emissions for a sustainable future.

In this study, a Taguchi-based optimization method is proposed to search the coil parameters used for low-power wireless charging that will maximize the transmission efficiency. The coils were then implemented to charge a battery with a nominal voltage of 3.7 V and a rated capacity of 760 mAh, and it was found that the coil transmission efficiency increased by 3.7% compared to adopting the coil parameters obtained by using a genetic algorithm. Moreover, a 5-watt wireless charging system integrated with the Taguchi-based coils was built to charge a battery with a nominal voltage of 3.7 V and a rated capacity of 2200 mAh. The results showed that the coil transmission efficiency was higher than that of a commercial charger, but the dimension of the coil was larger than that of the commercial charger. Nevertheless, the air gap between transmitter and receiver coils was larger than that in the charger, and the charge time required for a 2200 mAh battery to reach a full charge was shorter than that required for the commercial charger. Although outcomes are still far from being satisfactory in the transmission efficiency, the proposed approach can greatly reduce computation cost in designing coils used for wireless charging.

There is growing concern regarding air pollutants (NOx, SOx, and PM) and carbon emissions from ocean-going vessels in harbor areas and the role of high-voltage shore connection (HVSC) systems in mitigating these emissions during vessel berthing. The HVSC operates as a TN grounding system in humid environments, and it needs a proper grounding design to ensure safety when faults occur. This article intends to examine the overvoltage resulting from fault currents and its implications for the safety of operators when a single line-to-ground fault takes place within the design of HVSC grounding systems. The assessment is carried out by employing actual scenarios and parameters from a container berth at Kaohsiung Harbor in Taiwan. Considering site conditions, such as the wet ground surface, human body resistance, and electric shock duration, the tolerable safe voltage level is derived using IEEE Std. 80 and IEC 60479-1. Based on the shore power system grounding architecture specified in IEEE/IEC 80005-1, an equivalent circuit model is constructed to calculate the fault currents using symmetrical component analysis. The actual touch voltages generated in various locations are analyzed under scenarios of connecting or disconnecting the equipotential bonding between the ship and the shore using neutral grounding resistor (NGR) designs. This article delves into the scenarios of electric shock that may occur during the operation of an actual container ship’s shore power system. It evaluates whether various contact voltage values exceed current international standards and verifies the grounding design and safety voltage specifications of IEEE/IEC 80005-1. According to the results of this study, the use of NGR and protective earthed neutral (PEN) conductors in HVSC is crucial. This can limit fault currents, reduce touch voltage, and ensure the safety of personnel and equipment. Therefore, ensuring and monitoring equipment conductors and adopting NGRs of appropriate sizes are crucial elements in maintaining electrical safety in HVSC systems.