System Load Research Articles

Influence of Potting Radius on the Structural Performance and Failure Mechanism of Inserts in Sandwich Structures

In this study, the mechanical performance and failure modes of cold-potted inserts within sandwich structures were examined, focusing on the influence of the potting radius, while maintaining constant insert radius and specimen characteristics. In this research, destructive testing was used to evaluate the pull out, load-carrying capacity, and failure mechanisms of the inserts. The methods of stiffness degradation and acoustic emissions (AE) were employed for structural health monitoring to capture real-time data on failure progression, including core buckling, core rupture, and skin delamination. The results indicated that increasing the potting radius significantly altered the failure modes and critical failure load of the insert system. A critical potting radius was identified where maximum stiffness was achieved. Beyond this point, insert fracture became the dominant failure mode, with minimal damage to the surrounding core and CFRP skins. Larger potting radii also led to reduced displacement at failure, increased ultimate loads, and elevated stiffness, which were maintained until sudden structural failure. Through detailed isolation and observation of each failure event and with the use of AE data, precise identification of system damage in real time was allowed, offering insights into the progression and causes of failure.

Effectiveness of Friction Damper Configurations on the Behaviour of Bundled Tube High-Rise Building System for Lateral Loads

Effectiveness of Friction Damper Configurations on the Behaviour of Bundled Tube High-Rise Building System for Lateral Loads

Novel robust control with disturbance rejection for permanent magnet synchronous motors and experimental validation.

A novel robust control strategy is proposed in this work to address the dynamic control problem of permanent magnet synchronous motors (PMSM) position tracking and lessen the effect of system parameter and load fluctuations on the dynamic performance of PMSM. The tracking performance is improved by a robust control element built with the Lyapunov method to reduce the impact of uncertain factors such as parameter uncertainty, nonlinear friction, and external interference; the nominal control element is stabilized by the dynamics model. The uniformly bounded and uniformly final bounded systems are proven, and the associated conclusions are provided using the Lyapunov minimax approach. In this work, modeling and experimental investigation are conducted using the cSPACE fast controller, based on the permanent magnet synchronous motor test platform. The results of the testing and simulation show that the developed controller can effectively regulate the permanent magnet synchronous motor and achieve more accurate position tracking even in the face of ambiguity.

Ordered mesoporous silica and carbon as controlled release systems for cephalexin: Influence of surface modification and porosity

This study compares two in vitro loading and release systems for the antibiotic cephalexin (CFX), based on ordered mesoporous silica (SBA-15) and carbon (CMK-5) materials, both pure and modified with 3-aminopropyltriethoxysilane. Drug loading was performed using the adsorption method under constant conditions (pH: 6, T: 30°C, and t: 8 h), and the release mechanisms were investigated at gastric and intestinal pH to understand the phenomena involved in the oral delivery of CFX studied. The results revealed a higher adsorption capacity of CMK-5 due to its microporosity and π-π stacking interactions compared to SBA-15. Furthermore, the presence of functional groups prevented the formation of crystalline phases by adsorption on the external surface. A reduction in the release rate of CFX was observed with both carriers, governed by a Fickian diffusion mechanism. Notably, CMK-5 exhibited a higher release rate at gastric pH compared to SBA-15, while the opposite was true at intestinal pH. These findings provide deeper insights into the behavior of carriers with different chemical compositions in antibiotic release, suggesting their potential as an alternative to address issues associated with the dosing frequency of these drugs.

An integrated geospatial modelling framework of hybrid microgrid sizing for rural electrification planning.

Pursuing rural electrification in developing countries through hybrid generation systems is constrained by a lack of suitable energy modelling tools. Few tools include geographical parameters relevant to capturing specific spatial and socio-economic circumstances. Even less are openly available and find applications for rural areas of developing countries. This work presents an integrated geospatial energy modelling framework based on an extended tool, the GISEle (GIS for rural electrification) model, which aims for a least-cost energy solution. GISEle is an open-source tool supporting rural electrification planning strategies and challenges through optimal hybrid microgrid integration. The developed framework is universally applicable and explains how the extended GISEle tool can be used to become suitable for analysing decentralised hybrid generation systems within the context of rural areas of developing countries. This presented framework includes:•Advancing the approach to proper data collection to better capture local specificities and (future) demand and reporting results in rural areas of developing countries;•Adding the Remote-Areas Multi-energy systems load Profiles (RAMP) to improve load demand assessments, while considering the impact of electrification on growing demand scenarios;•Linking the Soil and Water Assessment Tool (SWAT) model to allow for hydropower sizing in GISEle.

Modeling method for simulating electrical load system of civil aircraft based on CPU-FPGA

Modeling method for simulating electrical load system of civil aircraft based on CPU-FPGA

Research and application of cargo hold management control technology in civil aviation cargo loading system

Research and application of cargo hold management control technology in civil aviation cargo loading system

Analyzing market plans for enhanced energy hub efficiency: strategies for integrating multiple energy sources and collaboration

ABSTRACT In this study, we introduce the Archimedes optimization algorithm as a key component of our methodology. The Archimedes algorithm, renowned for its robustness and efficiency, is specifically tailored to handle complex optimization problems encountered in energy management systems. By leveraging its unique capabilities, we ensure precise solutions and rapid convergence even under challenging solution conditions characterized by uncertain energy demand forecasts. The proposed algorithm operates by iteratively refining solutions based on probabilistic load predictions and system constraints. It employs sophisticated optimization techniques to navigate the multi-dimensional solution space efficiently, thereby identifying optimal strategies for energy resource allocation within EHs. By incorporating the Archimedes algorithm into our framework, we can effectively capture the dynamic interactions between various energy carriers and adapt to changing market conditions in real-time. Furthermore, the Archimedes algorithm’s ability to provide near-optimal solutions without the need for exhaustive computational resources makes it particularly well-suited for practical implementation in energy management systems. Its efficiency ensures that decision-makers can obtain actionable insights and make informed decisions quickly, thereby enhancing the operational efficiency and economic viability of EHs. The proposed optimization algorithm outperforms alternatives like Archimedes optimization algorithm (APO) and genetic algorithm (GA). On average, it requires 25% fewer iterations for convergence. Moreover, it achieves a 90% convergence rate within just 50 iterations, compared to 70 iterations for APO and 60 iterations for GA, based on 30 distinct runs.

Fatigue Experiment and Failure Mechanism Analysis of Aircraft Titanium Alloy Wing-Body Connection Joint.

Taking the titanium alloy wing-body connection joint at the rear beam of a certain type of aircraft as the research object, this study analyzed the failure mechanism and verified the structural safety of the wing-body connection joint under actual flight loads. Firstly, this study verified the validity of the loading system and the measuring system in the test system through the pre-test, and the repeatability of the test was analyzed for error to ensure the accuracy of the experimental data. Then, the test piece was subjected to 400,000 random load tests of flight takeoffs and landings, 100,000 Class A load tests, and ground-air-ground load tests, and the test piece fractured under the ground-air-ground load tests. Lastly, the mechanism analysis and structural safety verification of the fatigue fracture of the joints were carried out by using a stereo microscope and scanning electron microscope. The results show that fretting fatigue is the main driving force for crack initiation, and the crack shows significant fatigue damage characteristics in the stable growth stage and follows Paris' law. Entering the final fracture region, the joint mainly experienced ductile fracture, with typical plastic deformation features such as dimples and tear ridges before fracture. The fatigue crack growth behavior of the joint was quantitatively analyzed using Paris' law, and the calculated crack growth period life was 207,374 loadings. This result proves that the crack initiation life accounts for 95.19% of the full life cycle, which is much higher than the design requirement of 400,000 landings and takeoffs, indicating that the structural design of this test piece is on the conservative side and meets the requirements of aircraft operational safety. This research is of great significance in improving the safety and reliability of aircraft structures.

Phyto-phospholipid Complex Vesicles:A Revolutionary Approach for Enhancing Bioavailability and Optimizing Therapeutic Potential in Herbal Medicine

The medicinal potential of phytoconstituents obtained from plants is widely recognized. Whole-plant extracts or isolated phytoconstituents have been shown through experiments to exhibit a variety of medicinal potentials, including antibacterial, neurologically protective, liver-protective properties, an antioxidant and skin-protective properties. Although these phytoconstituents offer potential therapeutic effects, their usage is restricted due to inadequate bioavailability, persistence in physiological fluids, and authenticity problems. These remain unresolved issues that impact the use of these priceless traditional herbal remedies in the efficient management and treatment of a range of medical ailments. Phytoconstituents’ loading in phospholipid-based vesicular systems may be a way to tackle these challenging issues. The goal of this review is to summarize phyto-phospholipid vesicles and some of their relevant uses in drug delivery systems, as well as to emphasize the relationship between properties and applications, as well as the effect of phospholipid species on drug delivery efficiency. Based on the findings of various research investigations, this literature review attempts to investigate why Phyto-phospholipid vesicles are considered as the best nanotechnology in delivery systems for drugs. Optimal absorption and utilization of nutraceuticals and herbal medications can be enhanced by the process of Phyto phospholipid complexation.

Advanced Harmonic Mitigation in Photovoltaic Grid-Connected Systems: Jellyfish Search Optimization Approach

Increasing prevalence of nonlinear loads (NLL) in modern power systems poses significant challenges, particularly in terms of harmonic distortion. This distortion degrades the performance and efficiency of photovoltaic (PV) grid-connected systems (PV-GCS), demanding advanced control strategies. This study presents a unique optimization-based method that employs the Jellyfish Search Optimization (JSO) algorithm to enhance the Shunt Active Power Filter (SAPF) for effective harmonic reduction in PV-GCS with a high penetration of NLL in the distribution network. The study aims to reduce total harmonic distortion (THD) and regulate the DC-bus voltage (Vdc) in SAPF. A comprehensive comparison examination is performed between JSO and three frequently utilized optimization algorithms: genetic algorithm (GA), particle swarm optimization (PSO), and golden eagle algorithm (GE), to investigate the efficiency of JSO algorithm. The reduced THD by the JSO is only 1.32 percent, smoothly regulated the Vdc with a short settling time, without overshooting. These findings indicate that JSO outperforms others, emphasizing that it has the potential to improve power quality (PQ) in PV-GCS with NLL. This study presents a strong foundation for minimizing harmonics in PV integrating to the grids, which contributes to improved system reliability and efficiency.

Mathematical Modelling of Wind Power Plant Electric Power Scoping Process State Being Developed for Each Consumer

The relevance of wind power plant process state mathematical modeling, defining the volume of the developed electric power for each consumer on the basis of dynamic patterns of electricitydemanded for each consumer in northern areas, is proved. It is defined, that factors influencing on the dynamic patternselectricity demandby each consumer are electric power production variabilitydue to power unit idle time because of a weak or strong wind, or in case of planned or emergency maintenance. Technological process operating modes of capacity load (wind turbine, electric power storage system) to solve the problem electric power production variability due to power plant idle times because of a weak or strong wind, or to perform planned or emergency maintenance, are established. The description of the process state equation of wind power plant, defining the volume of the developed electric power for each consumer accounting for dynamic patterns of demanded electric power by a consumer as a result of developed electric power volume fixing to a certain time step, and also bytechnological processoperating mode factorthat takes into account the capacity load as a result of factors affecting electric power production variability, due topower plant idle times because of a weak or strong wind, or to perform planned or emergency maintenance, is executed. The description of the equation of equipment idle time calculation(wind turbine, electric power storage system) due to redistribution, maintenance or weak/strong windis made. The given equation is a component of the wind power plant process stateequation, defining volume of the developed electric power for each consumer on the account of the demanded electric power dynamic patterndemanded for each consumer. The description of the equation of index variation Si, defining power plant capacity load and electric power storage system, describing a technological process, as a part of wind power plant process state mathematical model for scoping the produced electric power for each consumer, is executed.

METHODS OF ANALYSIS OF DYNAMIC PROCESSES IN DISCRETE-CONTINUUM SYSTEMS UNDER PULSE EXCITATIONS

This paper addresses the enhancement of methods for calculating vibration-impact machines, particularly concerning adjustments to prevent potential shock resonances. This design criterion for substantiating the parameters of vibration-impact machines had not been previously considered. However, the likelihood of shock resonance increases significantly with the mass of the process load, operating frequencies of vibration excitation, and overall dimensions of the thin-walled bodies of vibrating machines. Hence, prioritizing the criterion of tuning out resonant modes through the appropriate choice of housing parameters becomes crucial for modern, heavily loaded machines. This novel approach is proposed in this paper for calculating vibration-impact machines and armored vehicles. To analyze the conditions for the onset of resonant modes under periodic shock loading, single-mass, multi-mass, and continuum dynamic systems were sequentially considered. It was shown that, in the absence of friction, shock resonance occurs when any natural frequency of the machine body oscillations matches a multiple of the excitation frequency from the drive. Additionally, numerical integration of the system of differential equations of motion was used to confirm shock resonance conditions. The numerical results were consistent with the analytical ones. It was also determined that tuning away from the resonant frequency by 5% to 10% significantly alters the steady-state mode of the vibration machine, notably reducing oscillation amplitudes. Therefore, to substantiate the parameters of vibrating machines, it is essential to maximize the adjustment of the natural frequency spectrum of their bodies, considered as elastically deformable structures, away from frequencies that are multiples of the drive frequency. To implement this algorithm, we propose adopting a generalized parametric description. Variable parameters include the thickness of housing elements, their cross-sections, reinforcement schemes, and the number of stiffeners. It was found that varying these parameters diversely affects the migration of natural frequencies in the spectrum. Specific parameters with the greatest impact on detuning from shock resonance frequencies were identified. This set of parameters is used to determine the optimal set that satisfies the criterion of maximum detuning from shock resonance. Similar developments and studies have been conducted for the armor hulls of lightly armored vehicles.

Resilient gas dependency-based planning of electricity distribution systems considering energy storage systems.

This article presents a planning framework to improve the weather-related resilience of natural gas-dependent electricity distribution systems. The problem is formulated as a two-stage stochastic mixed integer linear programing model. In the first stage, the measures for distribution line hardening, gas-fired distributed generation (DG) placement, electrical energy storage resource allocation, and tie-switch placement are determined. The second stage minimizes the electricity distribution system load shedding in realized hurricanes to achieve a compromise between operational benefits and investment costs when the dependence of electricity distribution system on the natural gas exists. The proposed stochastic model considers random failures of electricity distribution system lines and random errors in forecasting the load demand. The Monte Carlo simulation is employed to generate multiple scenarios for defining the uncertainties of electricity distribution system. For the sake of simplicity, weather-related outages of natural gas pipelines are considered deterministic. The nonlinear natural gas constraints are linearized and incorporated into the stochastic optimization model. The proposed framework was successfully implemented on an interconnected energy system composed of a 33-bus electricity distribution system and a 14-node natural gas distribution network. Numerical results of the defined case studies and a devised comparative study validate the effectiveness of the proposed framework as well.

Novel Power System Load Forecasting Method Based on Multi-indicator Clustering Optimization and Sensors

Novel Power System Load Forecasting Method Based on Multi-indicator Clustering Optimization and Sensors

MATHEMATICAL MODELING OF OPERATIONAL RELIABILITY OF GROUND-BASED NAVIGATION SYSTEMS

The theoretical justification for improving the effectiveness of vibration isolation for navigation equipment by reducing the natural frequency of the elastic suspension through the use of an additional electromagnetic loading system on the moving part is presented. An overview of the main elements of primary sensors and vibration protection systems for reproducing vibrations is provided. It is emphasized that vibration isolation of navigation equipment in the low-frequency disturbance range, typical for terrestrial carriers, is a crucial component in preventing emergency situations on airborne and marine vessels. A detailed calculation scheme for a vibration test stand using vertically installed flat springs is presented. Relationships between the natural frequency of the suspension and the system parameters are determined. One method for reducing the natural frequency of an elastic suspension on flat springs is analyzed. The calculation scheme for the suspension with vertically installed elastic springs is outlined. The stability conditions of the linear system, which depend on the amplitude of oscillations, are analytically investigated. It is emphasized that there is no translational movement of the suspension other than the chosen one. It is proposed to consider the calculation scheme of the suspension in the absence of dry friction. The structural component of the magnetic system is analyzed. The system of dispersive fluxes and their concentration in the air gap is outlined. An analysis of the compensatory nonlinearity of the stiffness characteristic of elastic elements is carried out. The reduction of distortions in the shape of the moving oscillations of the moving platform in the horizontal plane is analyzed. Stiffness characteristics of the suspension with a magnet for several actual values of kkk and δ\deltaδ are provided. Experimental calculations demonstrate that this vibration isolation system for navigation equipment leads to a significant reduction in the natural frequency of the suspension, ensuring its operational reliability and maximum prevention of low-frequency horizontal vibrations.

Enhancing line loadability in urban rail systems: evaluating the impact of distributed generation on voltage stability, power losses and generation costs

Alternative source of electrical energy for urban railway electrification system is Direct Current (DC). Traction Power Substations (TPS) were essentially connected to the electrical grid network managed by the electrical utility company for operating and powering purposes. Power unbalance frequently occurs in the high voltage railway network due to the load of the traction system. The aim of this project is to find the impact of distribution generation (DG) for line loadability in urban rail systems. The output that needs to be considered are the voltage profile, power losses and generation cost. The simulation was considered to prove the positive impact of distributed generation for line loadability in urban rail system. Electrical energy was crucial for Direct Current (DC) railway electrification systems, as it provided the traction power necessary for train operations via Traction Power Substations (TPS) that connected to the electrical grid network. However, power imbalances frequently arose due to the varying loads imposed by traction systems, resulting in inefficiencies, suboptimal voltage profiles, increased power losses and higher operational costs. With the expansion of urban rail networks and the growing need for efficient power management, it became vital to explore solutions that could enhance loadability and system performance. This project examined the impact of integrating Distributed Generation (DG) on the line loadability of urban rail systems, concentrating on improvements in voltage profiles, reductions in power losses and the evaluation of generation costs. The methodology involved developing a detailed simulation model of the urban rail system, incorporating DG scenarios, analyzing their effects on voltage stability, power losses and costs. The simulation results were anticipated to demonstrate that DG could improve voltage stability, reduce power losses, lower generation costs and increase line loadability. The implications of these findings encompassed enhanced operational efficiency, potential economic benefits despite high initial investments, increased sustainability through renewable energy and valuable guidance for future infrastructure development and investment decisions.

Variability of Suspended Sediment Runoff as an Expression of the Long-Term Dynamics of Loess Gully Development—An Example from the Lublin Upland (Eastern Poland)

In the 20-year period from 2003 to 2022, water runoff and suspended sediment load in a forested gully system with a total length of 7.5 km was recorded. The branching gully system cuts through an agricultural catchment of 1.24 km2 located within the loess plateau of the Nałęczów Plateau (E Poland). A rain gauge was installed close to the watershed and in the gully mouth water runoff was monitored using a limnigraph, installed with a water gauge on a Thomson triangular weir. To determine suspended sediment concentrations during erosion episodes, water was sampled at a frequency dependent on the rate and duration of the runoff. The aim of the monitoring studies was to specify the relationship between flow rate and suspended concentration for different water runoff conditions, which were used to calculate sediment load. The contribution of propluvial and pronivial runoff to gully development was assessed, particularly in the transport of sediment out of the catchment, and unit denudation rates were calculated as less than 1000 Mg km−2 year−1, average 173 Mg km−2 year−1, and during a single event as a maximal 900 Mg km−2.

Unknown input observer-Model predictive control scheme for state and disturbance estimation of shunt active filter

The distribution system's nonlinear loads cause low total harmonic distortion (THD), low distortion power factor, and localized communication interference, among other poor power quality metrics. Shunt active power filter (SAPF) capacity to function depends on the controller's ability to follow the reference signal. To manage larger systems with several inputs and outputs, it would be challenging task to design PID controllers, because excessive controller gains would need to be tuned. Also, every control loop would operate independently of one another, as if there were no interactions between the two loops. This paper proffers Model prediction control for Shunt active power filter (SAPF), which can manage systems with several inputs and outputs that may interact with one another. Luenberger observer (LO) and Proportional Integral observer (PIO) fail to estimates the actual states of SAPF to SAPF, as shown even in the presence of three unknown disturbances, i.e step, triangular and noise type. The proposed unknown input observer (UIO) in the presence of three unknown disturbances perfectly tracks the reference signal. Apart from state estimation, the proposed observer also estimates all the unknown disturbances, when compared to PIO. The results have been simulated in MATLAB environment.

IMPROVING THE EFFICIENCY OF ENERGY COMPANIES BY OPTIMISING THE DISTRIBUTION OF COSTS FOR MAINTENANCE AND REPAIR OF ELECTRICAL EQUIPMENT

At present, there is a high emergencies probability in the electric power system as an electrical equipment failures result caused primarily by the objectively existing ageing and its service life significant exhaustion. Emergencies arising from electrical equipment failures lead to the dynamic stability violation of power systems and power system load nodes by voltage, cascading accidents and, as a result, technological processes disruption of consumer enterprises, which is accompanied by significant losses. One of the ways to prevent sudden failures or minimise the risk of their occurrence is to ensure rational and efficient operation management and reduce the operating equipment cost without risking a decrease in the power system reliability. To solve the optimal distribution problems of power company operating costs, taking into account the objectively existing limiting factors, a generalised balance sheet model of cost allocation by electrical equipment groups and units is proposed, which is a total costs function of an operating factors number. Mathematical models for calculating the electrical equipment share participation coefficients in the costs formation for its repair and maintenance for each of the identified factors have been obtained. A linguistic mathematical model for determining generalised estimates of the electrical equipment units and groups significance degree in the repair and maintenance costs distribution formation, taking into account the main operational factors, has been proposed. An algorithm and software for modelling the modes of the electric power system with an electrical connections scheme of electric networks with a 35-330 kV voltage have been developed to assess the operation risk index and power company repair and maintenance costs distribution. The estimated power company repair and maintenance costs distribution according to the current technical equipment characteristics and power system subsystem modes was performed.