Search Results (106)

Maritime routes ensure connectivity between nations, carrying a vast flow of goods across borders, while ports serve as the critical junctions within this network, managing a wide spectrum of commodities from raw materials to finished goods. Ports also generate employment across numerous sectors and underpin a broad range of allied industries. A seaport is a maritime facility equipped with docks, cranes, and storage infrastructure for international trade, where ships load and unload cargo, containers, and passengers. Key functions of seaports include customs processing, warehousing, and vessel services, with major global hubs such as Shanghai, PSA Singapore, DP World, and Rotterdam handling immense volumes of cargo each year. In contrast, Bangladesh’s ports, Chittagong, Mongla, and Payra, play a vital role in sustaining regional commerce. Today, ports are widely recognized as essential capital infrastructure and prime movers of economic activity. Smart ports are automated facilities that leverage advanced digital technologies, including sensors, big data analytics, artificial intelligence (AI), machine learning (ML), deep learning (DL), augmented reality (AR), digital twins, the Internet of Things (IoT), and various automation systems, to optimize overall operational efficiency. These tools streamline cargo movement while embedding sustainable practices to protect the environment. Beyond operational gains, smart ports deliver faster, more advanced services to all stakeholders involved in port operations, including shipping companies, customs agencies, local communities, and other relevant parties. Renewable energy sources, electric vehicle charging stations, onshore power supply, and smart logistics infrastructure are among the defining sustainability features of smart ports in the present-day context. This study examines the current status and future development trajectory of Bangladesh’s sea ports in relation to the broader global imperative toward smart port transformation. Full article

The objective of the research presented in this paper was to develop methods for simulating the operating conditions of traction power supply systems (TPSSs) equipped with asynchronous generators (ASGs), which may be driven by wind or hydraulic turbines as prime movers, thereby significantly reducing train traction energy costs and lowering carbon monoxide emissions. Using phase-coordinate methods and the Fazonord AC-DC industrial software package, simulations were performed for a TPSS configuration comprising three traction substations (TSs) with ASGs connected to the 6 kV busbars. The results demonstrate that connecting the ASG reduces the maximum active power flow from the utility grid by 27%, decreases peak losses in the 220 kV primary supply line by 44%, and lowers voltage unbalance levels at the 220 kV busbars by 71–76%. Additionally, electromagnetic safety conditions along the 220 kV overhead lines feeding the substations are improved, and the temperature at the hottest points of the traction transformers is reduced. The developed ASG models, implemented using three controlled current sources, are universal and can be applied to TPSSs of various configurations and design layouts. Full article

This paper analyzes the operation of a spark-ignition reciprocating engine fueled by purified landfill gas (LFG). The engine serves as the prime mover for an electric generator and a heat source within a Combined Heat and Power (CHP) unit. Experimental data is retrieved from the Engine Control Unit (ECU). The findings encompass 3000 operating hours (September–December), a period characterized by evolving spark plug conditions, during which various adjustments and service tasks are performed. This study primarily addresses operational strategies for spark plug maintenance to guarantee CHP system reliability, with a specific focus on electrode degradation and its subsequent effect on engine performance. A significant portion of the research analyzes the wear of eight OEM spark plugs installed during the observation period. Utilizing data from a specific interval (4044 to 4797 h), the study calculates the wear rates for both center and ground electrodes based on volume loss measurements obtained via digital microscopy. The results indicate varied electrode wear across the set. Furthermore, the correlation between spark plug condition, misfire counts, emergency shutdowns, and service intervals is examined. The misfires counter is proposed as a parameter for predicting emergency shutdowns and as an indicator for spark plug adjustment or replacement. Lastly, the paper describes potential causes of accelerated ground electrode wear and suggests probable methods for enhancing component longevity. Full article

Among lower-body techniques in karate, the Mawashi Geri Jodan is regarded as the most frequently applied, technically sophisticated, and potentially hazardous skill. Yet, whether karate athletes of varying proficiency levels exhibit differential mastery of this technique remains empirically unexamined. This study aimed to reveal movement control strategies of elite athletes by comparing kinematic and surface electromyography (sEMG) characteristics of Mawashi Geri Jodan between elite and sub-elite female karate practitioners. A total of eight female karate athletes (4 elite, 4 sub-elite) were recruited. During the execution of the dominant-leg Mawashi Geri Jodan, they struck a karate punching bag positioned at head height, while kinematic and sEMG data were synchronously collected. Analyzed metrics included phase durations, center of mass (COM) displacement, joint angles/angular velocities, and integral electromyography (IEMG) with muscle work percentage of 8 lower limb muscles. Independent-sample t-tests were used for intergroup comparisons (α = 0.05). Compared with the sub-elite group, elite athletes completed the full Mawashi Geri Jodan in significantly less time (0.825 ± 0.07 s vs. 1.030 ± 0.05 s, p < 0.01) and exhibited a shorter core striking phase (p < 0.05). Kinematically, elite athletes showed smaller vertical COM displacement during the striking phase (p < 0.05) and greater hip joint range of motion (p < 0.05). sEMG data revealed significantly higher activation of lower limb prime movers (vastus lateralis, gastrocnemius) during the striking phase and greater rectus femoris contribution during the recovery phase in elite athletes. Elite female karate practitioners demonstrate superior movement efficiency, body stability, and neuromuscular coordination in Mawashi Geri Jodan. Technical training should prioritize hip joint flexibility and stability, synergistic explosive force generation of the lower limb kinetic chain during the striking phase, and active rectus femoris activation during the recovery phase to enhance execution precision and efficiency. Full article

Objectives: The present study compared the amplitude and spatial distribution of muscle excitation between a seated row performed with a fixed scapular position (fixed-SR) and a free scapular position (free-SR) in resistance-trained men, analyzing concentric and eccentric phases separately using high-density surface EMG (HD-sEMG). Methods: Fourteen resistance-trained males (age: 25 ± 4 years; stature: 1.74 ± 0.06 m; body mass: 76.22 ± 5.73 kg) performed fixed-SR and free-SR in a randomized cross-over design using 8-repetition maximum as the load for both variations. HD-sEMG grids recorded the activity from the upper/middle/lower trapezius, latissimus dorsi, lateral/posterior deltoid, biceps brachii, triceps brachii, and erector spinae. Normalized root mean squared (RMS) amplitude and excitation centroids in the mediolateral and craniocaudal planes were computed for the concentric and eccentric phases. Data were analyzed using repeated-measures statistical models, with significance set at p < 0.05. Results: During the concentric phase, nRMS amplitude was greater for the posterior deltoid in fixed-SR compared with free-SR (effect size [ES] = 0.66), whereas no between-condition difference was observed for the remaining muscles. During the eccentric phase, nRMS amplitude was greater in the fixed-SR for the middle trapezius (ES = 0.67) and the latissimus dorsi (ES = 0.85), with no between-condition differences detected for the remaining muscles. The centroid position analysis revealed that, during the eccentric phase, the middle trapezius centroid was located more laterally in the fixed-SR condition (ES = 0.54), while the posterior deltoid centroid was positioned more caudally in the fixed-SR compared with the free-SR condition (ES = 0.22). Conclusions: The fixed-SR and free-SR conditions produce comparable overall muscle excitation patterns, while showing some quantitative and spatial differences in selected upper-back muscles. These results suggest that scapular constraint influences the distribution of muscular excitation rather than overall excitation levels. Accordingly, both variations can be effectively used in resistance training, selecting to fix or free the scapulae depending on the emphasis on the scapular movements rather than a substantial difference in muscle excitation. Full article

The decoupling properties and low-inertia characteristics of large-scale wind power have heightened concerns regarding power grid frequency stability, particularly as modern power systems impose stringent frequency regulation requirements on wind integration, leading to an increased complexity of frequency response characteristics under fault conditions. To address this challenge in high-wind-penetration grids, this paper proposes a post-fault frequency dynamics analysis method capable of concurrently accommodating multi-wind-speed scenarios through three key innovations: the linearization of traditional AC system components (including network equations, composite load models, and generator prime mover-governor systems) to establish nodal power increment equations; the development of wind turbine frequency regulation models under diverse wind conditions using small-signal analysis, incorporating regional operational disparities and refined by information entropy-based reliability quantification for adaptive parameter adjustment; and the derivation of the system state equation for post-fault frequency response using wide-area measurement system (WAMS) data, yielding an analytical model that captures region-specific regulation characteristic disparities for physically faithful frequency analysis. Validation via tailored IEEE 39-node simulations convincingly demonstrates the method’s effectiveness and superiority in handling fault-induced transients and wind variability. Full article

The contribution of Higher Education Institutions (HEIs) in achieving UN-Sustainable Development Goals (SDGs) is critical. HEIs’ contribution to the SDGs is not only confined to education and research but also to their engagement with society, policy-ma-king, infrastructure establishment, and sustainability practice in the institution. By aligning their programs and projects to the SDGs, HEIs can share significantly, producing a more sustainable development for all. One of the notable investments of Davao Oriental State University (DOrSU) is the construction of the University Research Complex (UResCom). The structure contains the university’s research laboratories and working spaces for academic scholars to conduct cutting-edge research and scientific breakthroughs. The seed fund for the laboratory equipment and initial research participation was sponsored by project grants from the Department of Science and Technology—Philippine Council for Industry, Energy, and Emerging Technology Research and Development (DOST-PCIEERD). Partnering with established laboratories and institutions is also an effective tool to guide developing universities. This approach will strengthen more productive research engagements as one of the prime movers of the university’s development. It will enhance scientific research outputs and coverage, improve the faculty’s technological competence, enable partnerships with the industrial sector, and is a leverage for the submission of project proposals. This approach will significantly contribute to improving the country’s Global Innovation Index (GII) ranking and to the achievement of these goals. Full article

The potential for hydrogen to reshape energy systems has been recognized for over a century. Yet, as decarbonization priorities have sharpened in many regions, three distinct frontier areas are critical to consider: hydrogen produced from wind; hydrogen produced from nuclear power; and the development of natural hydrogen. These pathways reflect technology and policy changes, including a 54% increase in the globally installed wind capacity since 2020, plus new signs of potential emerging in nuclear energy and natural hydrogen. Broadly speaking, there is a considerable number of studies covering hydrogen production from electrolysis, yet none systematically examine wind- and nuclear-derived hydrogen, natural hydrogen, or the policies that enable their adoption in key countries. This article highlights international policy and technology developments, with a focus on prime movers: Germany, China, the US, and Russia. Full article

Based on the actual data of a 300 MW doubly-fed variable speed pumped storage units (DFVSPSUs) in China, the reactive power characteristics of both the stator side and the grid-side converter are analyzed, and the reactive power regulation capability of the unit is discussed. First, the power coupling relationship is analyzed, demonstrating that the reactive power-regulation capability is jointly composed of the stator side and the grid-side converter, without direct coupling between them. Next, we determine the doubly-fed induction generator (DFIG) capacity, explaining that the capacity of the DFIG exceeds the rated capacity of the unit. Then, we note that the stator-side reactive power regulation capability is limited by prime mover power, stator current, and rotor current, while the grid-side converter regulation capability is influenced by converter capacity and rotor-side real power. Furthermore, the stator-side, grid-side converter and total reactive power-regulation capabilities of the unit under different water heads and real power conditions are determined. The results demonstrate that fully considering the grid-side converter can increase the unit’s reactive power regulation capability by 12% to 26%. Finally, by comparing the reactive power operating ranges of fixed-speed and variable-speed units, the reactive power advantages of the variable-speed unit are quantified. Full article

Alzheimer’s dementia (AD) is a disease of the ageing brain. It begins in the hippocampal region with the epicentre in the entorhinal cortex, then gradually extends into adjacent brain areas involved in memory and cognition. The events which initiate the damage are unknown and under intense investigation. Localization to the hippocampus can now be explained by anatomical features of the blood vessels supplying this region. Blood supply and hence oxygen delivery to the area are jeopardized by poor flow through narrowed arteries. In genomic and metabolomic studies, the respiratory chain and mitochondrial pathways which generate ATP were leading pathways associated with AD. This review explores the notion that ATP depletion resulting from hippocampal hypoperfusion has a prime role in initiating damage. Sections cover sensing of ATP depletion and protective responses, vulnerable processes with very heavy ATP consumption (the malate shuttle, the glutamate/glutamine/GABA (γ-aminobutyric acid) cycle, and axonal transport), phospholipid disturbances and peroxidation by reactive oxygen species, hippocampal perfusion and the effects of hypertension, chronic hypoxia, and arterial vasospasm, and an overview of recent relevant genomic studies. The findings demonstrate strong scientific arguments for the proposal with increasing supportive evidence. These lines of enquiry should be pursued. Full article

Background/Objectives: This study aims to investigate the effects of caffeinated chewing gum on maximal strength, muscular power, and neural drive to the prime movers during bench press and back squat in resistance-trained men. Methods: Sixteen resistance-trained males participated in a double-blind, randomized trial, chewing either caffeinated gum (4 mg/kg) or placebo gum on two separate occasions, seven days apart. After chewing for 5 min, participants performed a maximal strength test followed by muscular power assessments at 25%, 50%, 75%, and 90% of their one-repetition maximum (1RM), completing with 3, 2, 1, and 1 repetition (s), respectively, for bench press and back squat. Surface electromyography data were recorded for each repetition. Results: Caffeinated gum did not significantly improve one-repetition maximum (1RM) for bench press (p > 0.05), but increased mean frequency (MF) and median frequency (MDF) in anterior deltoid, pectoralis major, and biceps brachii (all p < 0.05) compared to placebo. For back squat, 1RM increased with caffeinated gum, along with higher MF and MDF in vastus medialis (all p < 0.05). Caffeinated gum also improved mean and peak velocities, and mean and peak power outputs at 25–75% 1RM during the bench press (all p < 0.05), along with elevated MDF in pectoralis major and biceps brachii (all p < 0.05). Similar improvements were seen in mean and peak velocities during the back squat at 25–90% 1RM (all p < 0.05), along with higher MF and MDF in vastus medialis and increased normalized root mean square activity in gluteus maximus (all p < 0.05). Conclusions: Caffeinated chewing gum (4 mg/kg) enhanced muscular power (25–75% 1RM) in the bench press and improved maximal strength and muscular power (25–90% 1RM) in the back squat by increasing muscle recruitment in resistance-trained men. Full article

The removal of pineapple eyes is a crucial step in pineapple processing. However, their irregularly distributed spiral arrangement presents a dual challenge for positioning accuracy and automated removal by the end-effector. In order to solve this problem, a pineapple eye removal device based on machine vision was designed. The device comprises a clamping mechanism, an eye removal end-effector, an XZ two-axis sliding table, a depth camera, and a control system. Taking the eye removal time and rotational angular velocity as variables, the relationship between the rod length of the prime mover and the contact force and gear torque during the eye removal process was simulated and analyzed using ADAMS (2020) software. Based on these simulations, the optimal length of the prime mover for the end-effector was determined to be 23.00 mm. The performance of various YOLOv5 models was compared in terms of accuracy, recall rate, mean detection error, and detection time. The YOLOv5s model was chosen for real-time pineapple eye detection, and the eye’s position was determined through coordinate transformation. The control system then actuated the XZ two-axis sliding table to position the eye removal end-effector for effective removal. The results indicated an average complete removal rate of 88.5%, an incomplete removal rate of 6.6%, a missed detection rate of 4.9%, and an average removal time of 156.7 s per pineapple. Compared with existing solutions, this study optimized the end-effector design for pineapple eye removal. Depth information was captured with a depth camera, and machine vision was combined with three-dimensional localization. These steps improved removal accuracy and increased production efficiency. Full article

Objectives: This study aimed to compare the acute responses of the muscular activity of primary movers during bench press execution under asymmetric loads (25%, 50%, and 75%). Methods: The study included 30 resistance-trained males (n = 25, age = 22.73 ± 3.44 years, height= 1.77 ± 0.06 m, body mass= 76.77 ± 9.28 kg) and females (n = 5, age = 22.5 ± 1.19 years, height = 1.63 ± 0.04 m, body mass = 56.78 ± 2.90 kg). We assessed the two portions of the dominant pectoralis major, triceps brachii, anterior deltoid, and both external oblique peak activities (sEMG) during concentric and eccentric phases. We performed a repeated-measures design to establish the differences between muscle activity, barbell center of mass acceleration, and OMNI-Perceived Exertion Scale for Resistance Exercise (OMNI-RES) in a bench press under seven different conditions. Results: The linear mixed model showed a significant fixed effect for exercise condition for muscles (p < 0.001) in the concentric and eccentric phases. We found significantly higher clavicularis (d = 0.54; d = 1.15) and sternalis (d = 0.38; d = 0.86) pectoralis major activation of the dominant side under high (50% and 75%), non-dominant-side, de-loaded conditions in the eccentric phase (p < 0.001), with large effects. Contralateral core muscles (external oblique) of the dominant and non-dominant sides were significantly (p < 0.001) highly activated under all asymmetric conditions in the concentric phase (from d = 0.89 to d = 2.30). Conclusions: The asymmetric load bench press provoked a higher pectoralis major activation on the loaded side when de-loading the other side. The contralateral external oblique doubles the muscle activity in the most asymmetric conditions. Full article

Background/Objectives: When manipulating an object placed on the palm, the eyes and fingers move together. To perform this task precisely, coordination of the eyes and fingers is needed. Based on this view, the present study examined the three-way interaction among the central motor drives to the eyes, index finger, and little finger. Methods: Healthy male participants abducted the right index and/or little finger with or without concomitant saccadic eye movement to the right in response to a visual cue, while the forearm was in the pronated or supinated position. We measured the reaction time (RT), velocity, and amplitude of the eye movements, as well as the RT and amplitude of the electromyographic (EMG) responses in the prime movers for the independent and dependent finger movements. Results: The velocity, amplitude, and RT of the eye movement were not changed by the additional involvement of the finger movement, indicating that the central motor drive to the finger does not influence the eye motor excitability and central motor drive to the eyes. On the one hand, the RT of the finger was not changed by the eye movement, indicating that the central motor drive to the eyes does not influence the central motor drive to the finger muscle. On the other hand, the EMG amplitude in the first dorsal interosseous muscle at the movement onset decreased during the concomitant eye movement, indicating that the central motor drive to the eyes suppresses the motor excitability of the independent finger muscle. The RT increased and EMG amplitude decreased in one finger muscle when the other finger concurrently moved, indicating that the central motor drive to one finger muscle suppresses the motor excitability of and central motor drive to the other finger muscle. The change in the RT and EMG amplitude in one finger muscle caused by the concomitant execution of the other finger movement and/or eye movement varied with forearm position, indicating that forearm proprioception influences the interaction of the motor execution processes among the fingers and eyes. Conclusions: The central motor drive to the eyes or finger muscles suppresses the motor excitability of the other finger muscles and the central motor drive to that muscle, but the central motor drive to the finger muscles does not influence those for the eyes. Forearm proprioception influences the motor excitability of the finger muscle and central motor drive to that muscle. Full article

Load rating, using nominated rating vehicles by individual road authorities, is described in the Australian standard for bridge assessment, AS 5100.7, for all load effects, including shear. The load rating can be used to indicate the strength condition of bridges and to determine load posting for weak bridges. Thus, the information is useful for managing vehicle movements. However, for road authorities to accurately assess requested movements for a heavy vehicle with a prime mover and a platform trailer, additional information is required. This paper describes an approach employing a nonlinear search technique to determine the maximum allowable cartage loads of vehicles for various number of trailer axles up to that of a nominated load rating vehicle to ensure shear adequacy. A vehicle–bridge system has been analyzed considering a two-span bridge girder subject to a nominated rating vehicle. The calculated scaling factors for trailer loads corresponding to the total number of axles in the vehicle are presented. A platform table can then be created to assess the requested permits. The approach ensures full compliance with Modified Compression Field Theory (MCFT) as the section shear strength used for load rating is consistent with the load effects of the rating vehicle for the vehicle–bridge system under assessment. Full article