Introduction Of Load Research Articles

Multi-distributed resource coordination based on GAMS (general algebraic modeling system)

To achieve the economic operation of distributed energy resources in the grid, a GAMS-based multi-distributed resource optimization and control method is proposed. Firstly, considering the coexistence of electricity load and heat load in the grid system, a virtual power plant structure involving heat generation from distributed energy is established. Secondly, the General Algebraic Modeling System (GAMS) is utilized to create a detailed mathematical model for the distributed resources within the virtual grid. Subsequently, considering the influence of various uncertain factors, the CLPEX solver is employed for optimization and solution. Research results indicate that during the operation of the virtual power plant, the introduction of system heat load significantly enhances the expected profit and improves the economic efficiency of the operation.

Multi-scale flexibility assessment of electrical, thermal and gas multi-energy systems based on morphological decomposition

The rapid development of renewable energy has also had an impact on the flexibility of multi energy systems such as electricity, heat, and gas. To analyze the flexible characteristics of multi energy systems at multiple time scales, a multi-scale flexibility evaluation method based on morphological decomposition is proposed. The net load curve is decomposed using mathematical morphology methods, and a multi-scale energy storage configuration method based on the flexibility of electric heating systems is proposed. The analysis data shows that the probability of insufficient upward flexibility, margin expectation, and insufficient expectation of the scale weighted flexibility index are 1.12%, 3.98%, and 1.16%, respectively, while the probability of insufficient downward flexibility, margin expectation, and insufficient expectation are 0.73%, 4.54%, and 0.56%, respectively. The introduction of energy storage and controllable load simultaneously results in an overall downward flexibility index of 0.92% for the system. The results indicate that controllable load can improve the economy of system peak shaving, providing more options for energy storage and configuration in multi energy systems.

Enhancement of power quality in grid-connected HRES using UPQC with self-improved Battle Royal Optimizer in IEEE 14 bus system

The integration of hybrid renewable energy systems (HRES) in grid-connected load systems has become popular due to its ability to enhance reliability and reduce losses. However, this integration can lead to power quality (PQ) issues caused by non-linear, critical, and unbalanced load conditions. To address these PQ issues and compensate for load demand in HRES systems, a new method called Self-Improved Battle Royal Optimizer (SI-BRO) has been proposed. This method involves the use of a Unified Power Quality Conditioner (UPQC) device, which is designed to improve the system’s PQ performance. To enhance the performance of the UPQC device, an optimized fuzzy logic controller is introduced in the series and shunt active power filter, and its parameters are optimized using the SI-BRO model. The proposed method is implemented in MATLAB/Simulink, and its effectiveness is evaluated through different scenarios in IEEE 14 Bus system. These scenarios include the introduction of a nonlinear load to create PQ issues, and the comparison of Sag, Swell, and fluctuation of proposed technique i.e. SI-BRO optimizer with BRO,HHO ,EHO optimizer and calculation of THD in proposed technique.In all cases of Sag,Swell, Fluctuation , the proposed techniques gives better results in comparison to BRO,HHO & EHO.

Combined effects of axial and lateral loading for Glued-In steel rods in laminated veneer lumber

Glued-in rod timber connections are used to achieve structural continuity in timber structural members and as moment connections due to their high efficiency, stiffness and axial load transition. Existing studies have focused on axial withdrawal load capacity but there is limited research on laterally loaded glued-in rods and combined effects of lateral and axial loading which is common loading condition for all connections. This study investigates the relationship between axial and lateral loading in the ductile failure modes of glued-in steel rods in hardwood LVL. In all specimens an unbonded length was provided based on the latest design recommendations to mitigate splitting failure. The experimental findings suggest that the introduction of lateral load had no effect on the axial load capacities of the rods when the governing failure mode was rod yielding. This is not currently addressed in Eurocode 5. The lateral force capacity exceeded the design code prediction by 82%, and design recommendations are discussed for more accurate estimation of the lateral capacity. The use of the component method can be adopted to estimate accurately the rotational stiffness of moment connections with glued-in rods in LVL.

Functional Characterization of the A414G Loss-of-Function Mutation in HCN4 Associated with Sinus Bradycardia

Patients carrying the heterozygous A414G mutation in the HCN4 gene, which encodes the HCN4 protein, demonstrate moderate to severe bradycardia of the heart. Tetramers of HCN4 subunits compose the ion channels in the sinus node that carry the hyperpolarization-activated ‘funny’ current (If), also named the ‘pacemaker current’. If plays an essential modulating role in sinus node pacemaker activity. To assess the mechanism by which the A414G mutation results in sinus bradycardia, we first performed voltage clamp measurements on wild-type (WT) and heterozygous mutant HCN4 channels expressed in Chinese hamster ovary (CHO) cells. These experiments were performed at physiological temperature using the amphotericin-perforated patch-clamp technique. Next, we applied the experimentally observed mutation-induced changes in the HCN4 current of the CHO cells to If of the single human sinus node cell model developed by Fabbri and coworkers. The half-maximal activation voltage V1/2 of the heterozygous mutant HCN4 current was 19.9 mV more negative than that of the WT HCN4 current (p < 0.001). In addition, the voltage dependence of the heterozygous mutant HCN4 current (de)activation time constant showed a −11.9 mV shift (p < 0.001) compared to the WT HCN4 current. The fully-activated current density, the slope factor of the activation curve, and the reversal potential were not significantly affected by the heterozygous A414G mutation. In the human sinus node computer model, the cycle length was substantially increased, almost entirely due to the shift in the voltage dependence of steady-state activation, and this increase was more prominent under vagal tone. The introduction of a passive atrial load into the model sinus node cell further reduced the beating rate, demonstrating that the bradycardia of the sinus node was even more pronounced by interactions between the sinus node and atria. In conclusion, the experimentally identified A414G-induced changes in If can explain the clinically observed sinus bradycardia in patients carrying the A414G HCN4 gene mutation.

Characterization Method of Damage Information Based on Heterogeneous Network.

Damage is the main form of conflict, and the characterization of damage information is an important component of conflict evaluation. In the existing research, damage mainly refers to the damage effect of a damage load on the target structure. However, in the actual conflict environment, damage is a complex process that includes the entire process from the initial introduction of the damage load to the target function. Therefore, in this paper, the transfer logic of the damage process is analyzed, and the damage process is sequentially divided into being discovered, being attacked, being hit, and being destroyed in succession. Specifically, first considering the multiple types of each process, the transmission of damage is likened to the flow of damage, a network model to characterize damage information based on heterogeneous network meta-path and network flow theory (HF-MCDI) is established. Then, the characteristics of damage information are analyzed based on the capacity of the damage network, the correlation of the damage path, and the importance of the damage node. In addition, HF-MCDI can not only represent the complete damage information and the transmission characteristics of the damage load but also the structural characteristics of the target. Finally, the feasibility and effectiveness of the established HF-MCDI method are fully demonstrated by the example analysis of the launch platform.

Structural optimization and dynamic calibration for load sharing dynamic force measurement platform based on MIGA and SVR

In order to quantify dynamic forces/moments on the ground, a high-performance platform is necessary. This article improves the performance of the measurement platform from both structure and calibration. The platform’s loading capacity and base frequency have been significantly increased by the introduction of an innovative load sharing ring, which also allows the platform to have other important and practical characteristics. Further improvements in platform performance are then achieved by optimizing the platform parameters using a multi-island genetic algorithm (MIGA). In addition, the calibration method is improved. The maximum relative error and cross-coupling error for the novel non-linear support-vector-regression-based (SVR) method are 3.42% and 6.54%, respectively, which are much superior than the 9.98% and 15.39% for the traditional linear least-squares-based (LS) calibration method, indicating better accuracy and decoupling performance of the SVR-based dynamic calibration. This has important implications for measuring dynamic forces and improving the stability of equipment in spacecraft.

Resilience of HP/HT pipelines to combined seismic and thermal loadings

Resilience of unburied high pressure/high temperature (HP/HT) pipelines with different outside diameter-to-wall thickness (OD/t) ratios and subjected to the combined action of both earthquake and thermal loads is studied numerically. Unlike most of the existing research on buried or trenched pipelines, the current work analyses the resilience to combined seismic-thermal actions of an unburied pipeline laid on the seabed and resting on a sleeper. By using finite element analyses (FEA), the thermal and seismic responses of pipelines with different OD/t ratios are captured. The pipeline-soil and pipeline-sleeper interactions are modelled using Mohr-Coulomb constitutive contact behaviour. Empirical equations of critical temperatures causing lateral buckling in pipelines with OD/t between 10 and 50 are developed. Rayleigh damping coefficients are calculated following modal analyses, whereby the pipeline-soil system frequencies are found. Resilience to failure under combined seismic and thermal actions is load-path dependent; the earthquake imposed on a laterally buckled pipeline represents the most detrimental scenario. It is understood that the introduction of seismic load can amplify the buckle amplitudes beyond the pre-defined controlled buckle amplitude and thus cause overstressing and/or local buckling in the buckle crown segment. Local buckling due to the interaction between thermal and seismic loading is found to be more pronounced in pipelines with OD/t > 40.

Applications of Clustering Methods for Different Aspects of Electric Vehicles

The growing penetration of electric vehicles can pose several challenges for power systems, especially distribution systems, due to the introduction of significant uncertain load. Analysis of these challenges becomes computationally expensive with higher penetration of electric vehicles due to various preferences, travel behavior, and the battery size of electric vehicles. This problem can be addressed using clustering methods which have been successfully used in many other sectors. Recently, there have been several studies published on applying clustering methods for various aspects of electric vehicles. To summarize the existing efforts and provide future research directions, this contribution presents a three-step analysis. First, the existing clustering methods, including hard and soft clustering, are discussed. Then, the recent literature on the application of clustering methods for different aspects of electric vehicles is reviewed. The review concentrates on four major aspects of electric vehicles: the behavior of the user, driving cycle, used batteries, and charging stations. Then, several representative studies are selected from each category and their merits and demerits are summarized. Finally, gaps in the existing literature are identified and directions for future research are presented. They indicate the need for further research on the impact on distribution circuits, charging infrastructure during emergencies, equity and disparity in rebate allocations, and the use of big data with cluster analysis to assist transportation network management.

Control and cooling of electronic load based on FET-transistor

The introduction of electronic load for testing high-precision low-voltage sources (solar panels) requires careful review not only of the circuit design, but also thermal and mechanical design. Modern advances in the development of solar cells and other low-voltage energy sources have led to the need to create compact and express systems for testing them, which cannot be implemented on existing solutions. The article considers the principle of creating and calculating the optimal solution for the implementation of electronic load. To achieve this goal, methods of analysis of modern electronic database, calculations of basic physical and electrical parameters and their modeling are used. Based on the considered physical and circuit solutions for the implementation of the electronic load unit, a corresponding electrical circuit was developed. The transistors are controlled by four unipolar operational amplifiers integrated into the LM324 chip. Control of the electronic load unit is implemented by controlling the voltage at the positive feedback terminals, which is further stabilized by the TL431 chip. The device is powered by a source of DC stabilized current of 12 V (provides additional filtering from voltage fluctuations). On the basis of the previously considered physical and circuit solutions for the implementation of the electronic load unit, its cooling and control system was developed. The calculation of the heat balance allows you to choose the right cooling system for stable operation of the system. The control of the electronic load unit is implemented using INA219 and Xicor X9C microcircuits, and a method for their calibration is proposed. These solutions will make it possible to create a universal electronic load solution for researching semiconductor devices and solar cells. Adherence to the indications and principles set out in this article will provide the load with the ability to work at high power, while maintaining good performance and reliability.

Calculation of the electronic loading scheme for testing low voltage sources

Purpose. The introduction of electronic load for testing high-precision low-voltage sources (solar panels) requires careful review not only of the circuit design, but also thermal and mechanical design. The article considers the principle of creating and calculating the optimal solution for the implementation of electronic load. Methodology. To achieve this goal, methods of analysis of modern electronic database, calculations of basic physical and electrical parameters and their modeling are used. Findings. Based on the considered physical and circuit solutions for the implementation of the electronic load unit, a corresponding electrical circuit was developed. The transistors are controlled by four unipolar operational amplifiers integrated into the LM324 chip. Control of the electronic load unit is implemented by controlling the voltage at the positive feedback terminals, which is further stabilized by the TL431 chip. The device is powered by a source of DC stabilized current of 12 V (provides additional filtering from voltage fluctuations). Originality. Modern advances in the development of solar cells and other low-voltage energy sources have led to the need to create compact and express systems for testing them, which cannot be implemented on existing solutions. Practical value. Adherence to the indications and principles set out in this article will provide the load with the ability to work at high power, while maintaining good performance and reliability. The developed scheme allows to create a compass device for express testing of solar panels.

Artificial neural network model for predicting the local compression capacity of stirrups-confined concrete

The local compression capacity is a key mechanical property for several constructions, such as the post-tensioned prestressed concrete. Due to the disordered stress distribution caused by the introduction of the concentrated load, it is a huge challenge to predict accurately the local compression capacity of stirrups-confined concrete to avoid the whole structure damage caused by local failure. This study explored a new approach to obtain the local compression capacity for stirrups-confined concrete using artificial neural networks (ANN). The ANN model was trained by a reliable database consisting of 180 samples from previous literature, which had a large application range, covering concrete strengths 15–112 MPa while the stirrup yield strengths 230–660 MPa. The main parameters, including the concrete strength, the local area aspect ratio, the core area aspect ratio, the ratio of duct diameter to the section width, the yield strength of stirrups, and the volumetric ratios of stirrups, were selected as input variables. To evaluate the proposed ANN model, the k-fold cross-validation approach was adopted to determine the generalization and reliability, and the sensitivity analysis was conducted to investigate the importance of the input parameters. Moreover, an empirical ANN equation was generated based on the proposed ANN model for design. Finally, the ANN model and the ANN equation were evaluated and verified against experimental data and existing models. The findings indicated that the ANN approach was highly applicable and reliable for estimating the local compression capacity of stirrups-confined concrete.

Research on discrete element modeling and numerical simulation of cutting rock behavior under impact load

AbstractCombining well‐drilling hammers with polycrystalline diamond compact bits to break rock under cutting load and impact load is an effective way to improve drilling efficiency. Although impact load can enhance the cutting efficiency of the cutter, excessive impact can also cause the cutter to be subjected to additional vibrations, which can decrease its working life. Knowledge of laws governing the changes in the cutting force of the cutter under impact load is essential for the design and selection of well‐drilling hammers. Based on rock scratch tests and finite element rock cutting model, a discrete element modeling (DEM) rock cutting model was established to analyze the rock breaking and cutting force. Then, the material parameters of rock samples were determined, and the simulation parameters were corrected. Finally, a DEM rock cutting model under an impact load was established. The results showed that when there was an obvious difference between the average cutting force and mean peak cutting force, which corresponded to the rock‐breaking transition from ductile to brittle, with introduction of the impact load leading to an earlier transition. The cutting force variance was proportional to the impact amplitude, and the increase in the cutting force variance became more obvious when the static load exceeded the critical transition weight. When the ratio of the impact amplitude to the static load was greater than 50%, the mean and variance of the cutting force increased rapidly. Under the same impact amplitude, the impact frequency had little effect on the average cutting force, but a higher frequency could significantly reduce the variance of the cutting force under a high static load (i.e., it could alleviate the fluctuation of the cutting force). These results provide a reference for the selection of well‐drilling hammers and optimization of the impact load.

Microstructural and load hold effects on small fatigue crack growth in α+β dual phase Ti alloys

Microstructurally small crack growth was monitored in Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo with equiaxed and bi-modal microstructures. The influence of the microstructure was assessed to obtain an improved understanding of the lifetime variability observed in Ti alloys. Primary α grains, basal plane cracking and misalignment across boundaries were identified as key features for high crack growth rates. The origin of life debits encountered under dwell-fatigue loadings was also investigated through crack growth monitoring with the introduction of load holds at peaks stress. Dwell periods were found to induce a substantial small crack acceleration.

Thermal stress analysis in a hemispherical shell made of transversely isotropic materials under pressure and thermo‐mechanical loads

AbstractThis article deals with the study of thermal stress in a hemispherical shell made of transversely isotropic material under the effect of thermal, pressure and mechanical load. Seth's transition theory and generalized strain measure are used for finding the governing equation. Mathematical modelling is based on stress–strain relation and equilibrium equation. Analytical solutions are presented for the hemispherical shell made of transversely isotropic material and isotropic material. The effects of different pertinent parameters (i.e., temperature, pressure and load) are considered for the spherical shell made of transversely isotropic material. The behaviour of stress distribution, mechanical load, pressure rise, and temperature distribution are investigated. From the obtained results, it is noticed that carbon fiber material hemispherical shell requires higher pressure at the internal surface in comparison to magnesium/polypropylene material. With the introduction of mechanical load, the value of pressure decreases at the internal surface, but reverse results are obtained in the case of thermal condition for the hemispherical shell made of carbon fiber/magnesium/polypropylene material. By applying thermal condition, the hemispherical shell made of carbon fiber material requires maximum hoop stress at the external surface as compared to the magnesium/polypropylene material. The transversely isotropic material hemispherical shell more convenient than that of isotropic material hemispherical shell. Results have been discussed numerically and graphically.

Study on Power Quality Evaluation of Traction Power Supply System of High-speed Railway

With the continuous development and progress of China's high-speed railway system, the power supply of high-speed railway has become an important load of the power system. The introduction of large load will bring certain voltage fluctuation, harmonic interference and other random problems to the power system. In this paper, the positive sequence, negative sequence and zero sequence component models of current and voltage are established to solve the problem of equivalent modeling for power quality assessment of high-speed railway power supply system. Firstly, the positive sequence, negative sequence and zero sequence component models of current and voltage based on symmetric component method are established. Through Fourier transform, the phase Angle of fundamental wave is solved, and the positive sequence, negative sequence, zero sequence component, sequence component diagram and current spectrum diagram of current and voltage under three actual working conditions are obtained Through the analysis of the whole train operation process, the amplitude graphs of the positive sequence, negative sequence and zero sequence components of the current and the curves of the third harmonic possession with time are obtained by using the above methods.

Integrated Control Strategy for Electrolytic Aluminum Load Participation in Frequency Modulation

The introduction of electrolytic aluminum load in a large-scale power system with complex power station structure is essential for load frequency control (LFC). In this paper, we propose a control strategy for electrolytic aluminum load to participate in the frequency modulation of the power grid based on the IEEE standard two-region LFC model. Besides, a fractional-order PID (FOPID) controller is designed and compared with traditional PID, and the parameters of the FOPID controller are optimized by PSO algorithm. In addition, a two-region LFC model was built to verify the integrated control strategy for electrolytic aluminum load participation in frequency modulation, which show that the FOPID controller optimized by the PSO algorithm has stronger robustness in the LFC.

Muscle loaded stability reflects ligament-based stability in TKA: a cadaveric study.

This paper aims at evaluating the effects of muscle load on knee kinematics and stability after TKA and second at evaluating the effect of TKA surgery on knee kinematics and stability; and third, at correlating the stability in passive conditions and the stability in active, muscle loaded conditions. Fourteen fresh frozen cadaveric knee specimens were tested under passive and active condition with and without external loads involving a varus/valgus and internal/external rotational torque before and after TKA surgery using two in-house developed and previously validated test setups. Introduction of muscle force resulted in increased valgus (0.98°) and internal rotation of the femur (4.64°). TKA surgery also affected the neutral path kinematics, resulting in more varus (1.25°) and external rotation of the femur (5.22°). All laxities were significantly reduced by the introduction of the muscle load and after implantation of the TKA. The presence of the implant significantly affects the active varus/valgus laxity. This contrasts with the rotational laxity, in which case the passive laxity is the main determinant for the active laxity. For the varus/valgus laxity, the passive laxity is also a significant predictor of the active laxity. Knee stability is clearly affected by the presence of muscle load. This points to the relevance of appropriate rehabilitation with focus on avoiding muscular atrophy. At the same time, the functional, muscle loaded stability strongly relates to the passive, ligament-based stability. It remains therefore important to assess knee stability at the time of surgery, since the passive laxity is the only predictor for functional stability in the operating theatre. Case series, Level IV.

Strategically plug-in electrical vehicle load management in radial distribution system (A case study)

Objectives: To present a Plug in electric vehicle load model to integrate its maximum loading and distributed generations (DGs) units by maintaining maximum voltage profile value and lesser active and reactive power losses drop in the distribution system. Methods/Statistical analysis: This study comprises in two phases, in first phase IEEE 33-bus radial distribution system with standard data available is simulated using ETAP software. In the second phase, different PEV load model scenario and distributed generation units will be designed and integrated. At each scenario, the voltage profile, active and reactive power losses are observed and strategy is proposed in the manuscript. Findings: The test system gives convincing results even with adoption of new generation and plug-in electrical vehicles load without violating system performance. Novelty/Applications: The proposed study is best suited for practical application of distribution system such as introduction of DG units (i.e.solar PV) and plug-in electrical vehicle load with proper loading. Additionally, this study uses backward-forward sweep method to manage PEVs load with optimum size of DG units; it improves system losses and minimum per unit bus voltage within acceptable limits, unlike other studies. Result of this study allows to use smaller size of DG units with minimum cost. Keywords: Plug-in electric vehicle; radial distribution system; recharging stations; load management; distributed generation

Relevance of the glycemic index control of products and dishes for school meals

The eff ect of adolescent nutrition on various diseases is considered. Rationing of the amount of sugars in the diet is the main problem. Glycemic index (GI) is used for this purpose in the world practice. Glycemic curves for various cereals and derived products are presented. It is shown, that GI is an individual characteristic of each product. Introduction of GI and glycemic load (GL) values as indicators of food product quality and placing values on the consumer packaging label is confi rmed.