Types Of Loads Research Articles

Effects of the selected factors on cyclic load performance of T-shaped mortise-and-tenon furniture joints

ABSTRACT Furniture commonly fails at joints due to long-term repeated loads. This study aimed to investigate the effects of the selected factors (loading type, tenon fit, and load amplitude) on cyclic load resistance (CLR) and count of the cycle (COC) of mortise-and-tenon (M-T) joints made of beech (Fagus orientalis). The tests were conducted using a self-designed air-operated multi-function fatigue testing machine. The results showed that using a U-shaped circle to apply load on the stretcher was the optimal loading type for testing the cyclic performance of M-T joints. Tenon fit had a greater effect on CLR than loading type, and the effect of load amplitude on COC was more significant than those of loading type and tenon fit at 80% CLR. Although tenon fit had a significant effect on COC, the differences in COC among M-T joints with different tenon fits subjected to the same load amplitude were much greater than those at the same load amplitude. A strong exponential relationship was observed between COC and load amplitude. The fatigue limit load of the M-T joint evaluated was approximately 150 N or 47% CLR. This study provided an efficient method and extensive data for evaluating fatigue life of M-T joints.

Comparative Electromyographic Activity of Hamstrings During Sprinting Versus Strengthening Exercises: Implications for Injury Prevention.

Hamstring injuries are a major problem in sports involving sprinting, such as soccer, rugby, and track and field, and lead to sports stoppages and psychological, social, and financial repercussions. For several years now, these injuries have been stagnating or even increasing. Preventing these injuries is therefore a fundamental issue for at-risk athletes. The aim of this study was to compare the electromyographic(EMG) activity of the hamstrings in athletes during sprinting, Nordic hamstring exercise (NHE), and high-speed concentric exercise on an isokinetic dynamometer. A pilot study was conducted on a population of 15 sprint-exposed field athletes (22.54 ± 3.71 years, Tegner score ≥ 6) with no history of hamstring injury in the last six months. The protocol included a warm-up, followed by three repetitions of the NHE, two sets of 10 repetitions on the isokinetic dynamometer at 300°/sec, and a maximal sprint. Exercises were randomized for each subject, and muscle activity was assessed using wireless EMG sensors during each test. EMG data were normalized to the measured maximum voluntary isometric contraction (MVIC), and test results were statistically analyzed to determine which exercise resulted in maximal hamstring activation. Comparison of hamstring muscle activity between exercises showed a significant difference for most of our results (p-value < 0.05). The results show significantly higher mean hamstring activity during sprinting (0.4800 ± 0.19 μV) compared with strengthening exercises. The NHE (0.3201 ± 0.09 μV) was the second most active exercise. In the last place was the high-speed concentric exercise on the isokinetic machine, which produced less activation than the other exercises (0.2487 ± 0.07 μV). Sports involving sprinting are at risk of a hamstring injury but it appears that its use in rehabilitation and prevention of hamstring injury is relevant, as it would allow high-intensity muscle activation to prepare the hamstring for this type of loading. However, it is also fundamental to integrate strengthening exercises such as NHE in combination with sprinting in our rehabilitation. Finally, the use of the isokinetic dynamometer does not constitute a first-line choice for hamstring injury management.

Cryogenic Investigations into the Effect of Impact-Oscillatory Loading on Changes in the Mechanical Properties and Structural Condition of VT23M Two-Phase Titanium Alloy.

Impact-oscillatory loading of variable intensity was applied to the VT23M high-strength sheet two-phase titanium alloy in liquid nitrogen. This was carried out to investigate the effect of this loading type on changes in the mechanical properties and structural condition of the alloy upon subsequent static tensioning at normal temperature. Dynamic non-equilibrium process (DNP) realized at a temperature of liquid nitrogen proved to be unable to impair the strength properties of the VT23M titanium alloy compared to room temperature; however, they caused a significant decrease in ductility (down to 16%). The impaired plastic properties of the alloy were shown to entail additional defects in the structural components of the alloy. The authors have found patterns of damage accumulation in the structural components of the alloy depending on the DNP parameters. They are in good agreement with the findings of the fractographic research.

A steady-state and dynamic response model for working characteristics prediction of the electromechanical transmission system including eddy-current magnetic coupler

In this paper, a steady-state and dynamic response model is proposed to predict the working characteristics of the electromechanical transmission system including eddy-current magnetic couplers. Considering the influence of mechanical characteristics of motor and load device on the performance of eddy-current magnetic couplers, the system is divided into input and output for kinematic analysis. The expressions of electromagnetic torque versus speed are obtained through layer analysis of the eddy-current magnetic coupler during steady-state and then, the dynamic response model of the system is established by combining the kinematic analysis with the motor, the eddy-current magnetic coupler and three typical loads (constant torque load, quadratic rate load and constant power load). The dynamic characteristics during starting and speed-regulation of the system under constant torque loads are analyzed using the proposed model. The variations of the torque and speed with time of input and output are calculated by numerical integration. Finally, the speed and torque during starting and speed-regulation computed with the dynamic response model are compared with those obtained from the experimental results. The result shows a good agreement.

Abstract Tu097: Titin cleavage induces loss of myocardial tensional homeostasis driving a rapid TGF-beta-independent fibrotic response

Background: Cardiomyocytes (CMs) are subjected to different types of mechanical loads in the myocardium. Depending on its origin these loads can be classified as extracellular (extracellular matrix-ECM towards CMs), intracellular (exerted by the CM contraction machinery, i.e. the sarcomeres) or intercellular (exerted between CMs). In the myocardium, all these loads are actively maintained in tensional homeostasis (TH). In this context, the study of the sarcomere protein titin is essential, because its I-band region is considered as a hub for mechanotransduction, mostly of intracellular mechanical cues. Research Questions: It has been shown that mechanical disruption of the ECM affects the myocardial TH, leading to morphological changes inside CMs. However, potential alteration of TH resulting from defective mechanics of CM proteins remains unknown due to the lack of specific tools for in vivo studies. Aims: Here we explore the in vivo effects on myocardial TH of an abrupt tensional unloading of titin. Methods: We have experimentally challenged CMs to a tensional unloading by means of titin cleavage in vivo using TEVs-TTN mice. In this model, a cassette with a Tobacco Etch Virus protease (TEVp) recognition sequence has been included in the I-band of titin. Transducing TEVp with adeno-associated virus (AAV), we were able to cleave titin in vivo , ceasing only the mechanical properties of the protein. Samples were analyzed using an array of techniques including histology, immunofluorescence, and bulk and single nuclei RNA sequencing. Results: Our results show that a mosaic expression of TEVp, which does not affect cell viability, cleaving no more than 30% of total titin. However, this leads to a fast fibrotic response (less than six days), characterized by an increase in interstitial collagen and a response from cardiac fibroblasts population. Transcriptional and phospo-SMAD2/3 analysis results suggest that this ECM response occurs without noticeable activation of the TGFβ canonical pathway. Conclusion: Taken together, our results show experimentally for the first time that titin is not only a mechanotransducer of intracellular cues. In fact, mechanical abrogation of the I-band leads to a fast ECM response mediated by cardiac fibroblasts.

Reconsidering Museums’ Climate and Seasonal Adjustment for Vulnerable Artifacts

ABSTRACT The paper provides new experimental evidence for vulnerable artifacts on the dependence of failure strain on the loading rate corresponding to typical environmental loads lasting between hours and months. Animal glue-based ground was chosen for this study as an easily available, hygroscopic and brittle material as well as due to its abundance in collections and its relevance when discussing the risk of mechanical damage to objects. Gesso specimens were tested using dynamic mechanical analysis and tensile testing at different frequencies, under a variety of loading rates and temperatures. The time-temperature superposition principle was used to predict the material response to slow deformations (lasting hours to months) that are otherwise inaccessible on laboratory timescales. The results demonstrate that brittle materials such as animal glue-based grounds do not benefit from longer cycles of applied loads as failure strain is not time-dependent within the investigated timescale.

An application of clustering to classify movement patterns in men’s professional grand slam hard court tennis

ABSTRACT The movement cycles from Australian Open player tracking data were analysed using the Lloyd k-means clustering algorithm to classify movement patterns that exist in men’s grand-slam tennis. The elbow criterion method identified six movement patterns, and the k-means model allocated each movement cycle into one of these discrete groups. A description of each movement pattern is presented, outlining three inner range and three end range movement patterns, which are distinguishable by distance, direction, time pressure, and starting location. These findings provide objective details for coaches and athletes to understand tennis movement, overcoming vague descriptions of the inner range and end range in tennis vernacular. The amalgam of distance, direction, and time pressure demands that categorise the six movement patterns can enhance the specificity of training drill design and movement evaluation. Furthermore, evaluating the movement patterns a player typically elicits during match-play can inform typical load exposure and be useful in load monitoring practices. Additionally, understanding the prevalence of movement patterns in a typical match may help understand the strategic approaches players use during match-play.

Shear deformation behavior of additively manufactured 316L stainless steel lattice structures

With the development of additive manufacturing, lattice structures have emerged as a disruptive technology across various fields, including aerospace, automotive, and defense. Lattice structures exhibit exceptional properties for lightweight and energy absorption capacities, especially under compressive loads. However, the lack of experimental data on complex loads, such as shear properties of lattice structures, poses challenges to their broader application across different load types. This study aims to analyze the shear deformation behavior of lattice structures and compare them with their compressive properties, enabling the safe design of lattice structures for various load applications. To achieve this, 316 L stainless steel lattice structures were fabricated using additive manufacturing in three different geometries: body-centered cubic (BCC), face-centered cubic (FCC), and octet truss (OCT), all at the same relative density. The lattice geometries were compared for their mechanical properties and deformation mechanisms under the two types of loading using DIC and FEM analyses, compression and shear tests. It was found that the mechanical properties of the lattice structures under compression and shear loads varied depending on the geometry, showing that each lattice geometry has a unique load-bearing capacity that exhibits superior mechanical properties. Furthermore, under shear loading, the struts of the BCC lattice structure showed a bending-dominated deformation mode due to the rotation of the nodes, whereas the struts of the FCC and OCT structures presented a compression and tension-dominated deformation mode. As a result, the BCC lattice specimens showed a higher shear energy absorption capacity than the other specimens and were capable of bearing higher loads. In addition, the FCC specimens showed lower shear energy absorption. The OCT specimens presented a uniform strain distribution under both compression and shear loading and showed compliant performance. The shear deformation behavior of various lattice structures has been evaluated by considering both geometrical and local strain distribution aspects. Implications for optimization guidelines and potential improvements were also discussed. These results can be used for research and development of the shear properties of lattice structures, the safe design of lattice structures, and industrial applications.

An improved moth flame optimization for optimal DG and battery energy storage allocation in distribution systems

Deploying distributed generators (DGs) powered by renewable energy poses a significant challenge for effective power system operation. Optimally scheduling DGs, especially photovoltaic (PV) systems and wind turbines (WTs), is critical because of the unpredictable nature of wind speed and solar radiation. These intermittencies have posed considerable challenges to power grids, including power oscillation, increased losses, and voltage instability. To overcome these challenges, the battery energy storage (BES) system supports the PV unit, while the biomass aids the WT unit, mitigating power fluctuations and boosting supply continuity. Therefore, the main innovation of this study is presenting an improved moth flame optimization algorithm (IMFO) to capture the optimal scheduling of multiple dispatchable and non-dispatchable DGs for mitigating energy loss in power grids, considering different dynamic load characteristics. The IMFO algorithm comprises a new update position expression based on a roulette wheel selection strategy as well as Gaussian barebones (GB) and quasi-opposite-based learning (QOBL) mechanisms to enhance exploitation capability, global convergence rate, and solution precision. The IMFO algorithm's success rate and effectiveness are evaluated using 23rd benchmark functions and compared with the basic MFO algorithm and other seven competitors using rigorous statistical analysis. The developed optimizer is then adopted to study the performance of the 69-bus and 118-bus distribution grids, considering deterministic and stochastic DG's optimal planning. The findings reflect the superiority of the developed algorithm against its rivals, emphasizing the influence of load types and varying generations in DG planning. Numerically, the optimal deployment of BES + PV and biomass + WT significantly maximizes the energy loss reduction percent to 68.3471 and 98.0449 for the 69-bus's commercial load type and to 54.833 and 52.0623 for the 118-bus's commercial load type, respectively, confirming the efficacy of the developed algorithm for maximizing the performance of distribution systems in diverse situations.

Prediction and sensitivity analysis of embankment dam settlement under earthquake loading using gene expression programming

ABSTRACT A correct understanding of dams’ dynamic behaviour can help improve structures’ design and safety. The settlement of earth dams caused by earthquake shaking can induce instability and destruction. Using white-box machine learning techniques, including gene expression programming (GEP), a numerical relationship has been tried to estimate the settlement of earth dams under different types of earthquake loading, so that this relationship can be used in the design of earth dams. The main input parameters used in this research include the ratio of the yield acceleration of the dam to the maximum horizontal acceleration of the earthquake (ay/amax), the ratio of the fundamental period of the dam to the predominant period of the earthquake (Td/Tp), the magnitude of the earthquake (Mw) and the settlement ratio (S/H) earth dam as the output parameter. The R, MAE, and RMSE values for the proposed relationship in the research were equal to 0.85, 0.058, and 0.127, respectively. The measurement of statistical parameters shows the acceptable accuracy of the GEP method in predicting S/H. However, developing a database containing other effective parameters can be considered for future research.

Working memory load does not interfere with distractor suppression in the additional singleton task.

Over the last decade, the additional singleton task has been widely used to study visual statistical learning. In this paradigm, participants are instructed to find a target while ignoring a series of distractors. In some trials, a salient singleton distractor is added to the search display, making the task more difficult. However, if the singleton appears more frequently in one particular location of the display, participants eventually learn to suppress attention towards this location. It has been suggested that this type of learning is probably implicit and independent of working memory (WM) resources. To our knowledge, only one study has explored the impact of WM in suppression effect (Gao & Theeuwes, Psychonomic Bulletin & Review, 27, 96-104, 2020). However, there are reasons to suspect that the amount and type of WM load used in that study may have been suboptimal to detect any effects on distractor suppression. The aim of the present study was to explore the impact of WM load on distractor suppression addressing these issues. Contrary to our expectations, our results confirm that this type of learning is indeed highly resilient even to strong manipulations of WM load.

A Low voltage AC fault arc detection method based on multi-feature fusion

Abstract The complex electrical environment makes it difficult for most arc detectors on the market to accurately detect faulty arcs. A universal fault arc detection method based on machine learning (ML) algorithms is proposed in this paper. To address the potential hazards of fault arcs in the power system, firstly, the causes, time-domain, and frequency-domain characteristics of fault arcs were analyzed. Then, an arc experiment platform was built according to national standards, and current data was collected under various load conditions. Finally, the arc detection model was trained based on ML. The main contribution of this study is to explore a feature combination that is not affected by load type interference and has strong generalization ability for identifying fault arcs, clarify the key factors and feature extraction methods for identifying fault arcs, and develop a set of high-precision arc detection methods, providing strong guarantees for the stable operation of the power system.

Intuitionistic fuzzy divergence for evaluating the mechanical stress state of steel plates subject to bi-axial loads

The uncertainty that characterizes the external mechanical loads to which any connection plate in steel structures is subjected determines the non-uniqueness of the isochoric deformation distributions. Since the eddy currents induced on the plates produce magnetic field maps with a high fuzziness content, similar to those of the isochoric deformations, their use can be exploited to evaluate the extent of the external load that determines a specific induced current map. Starting from an approach known in the literature, according to which the map-external load association is operated through fuzzy similarity computations, in this paper, we generalize this method by reformulating it in terms of intuitionistic fuzzy logic by proposing a classification based on divergence computations. Our approach, acting adaptively on the fuzzification of the maps, results in a better classification percentage, besides significantly reducing the presence of doubtful cases due to the uncertainty of each applied load. Furthermore, a FEM software tool was developed, which turned out to be, to a certain extent, a substitute for the experimental procedure, notoriously more expensive. Even if the procedure was applied on plates subjected to bi-axial loads, it could be used for other types of loads since the classification operator processes the eddy current maps exclusively, regardless of their cause.

The consequence of ignoring load modeling on the circuit breaker selection in densely-meshed sub-transmission systems

In this paper, the selection of circuit breakers for a densely-meshed sub-transmission system with relatively short transmission lines is investigated. The results highlight the significance of modeling the load at the end of lines for accurately calculating the transient recovery voltage (TRV) following the short-circuit current interruption. According to IEEE standards, assuming load modeling at the end of the transmission lines can result in a maximum discrepancy of 20 % in the calculated TRV. Supposing that the load modeling leads to a moderating effect on the calculated TRV, the difference is considered as a safety margin, and load modeling is ignored. Nevertheless, the results presented here illustrate that this assumption strongly depends on characteristics of the studied network and the load type. In a network possessing the characteristics outlined in this paper, even a passive load as small as 15 % of the nominal capacity can significantly moderate the calculated TRV, with impacts reaching up to 38 %. Conversely, modeling an active load may result in a more severe TRV than if it were disregarded. The simulation results indicate that for networks with transmission lines longer than 70 km, neglecting to model passive loads on the transmission lines still yields sufficiently accurate calculations of TRV.

Buckling behavior of simply supported tapered square plates

Buckling is one of the important design parameters for the design of plate structures. The critical buckling loads and buckling coefficients for a series of different tapered plates are investigated. Buckling analyses of square plates are performed by changing different types of thickness variation by using ANSYS finite element software. Plates are assumed to be thin plate. The loading types and taper ratio of the simply supported square plates considerably affect the critical buckling loads. Some analyses results are compared with the literature results and presented in the form of graphs and tables. It is concluded that the analyses results are in good harmony with the literature results. The graphics proposed in this study could be useful for designers. The formulas obtained from the graphics gives the buckling coefficients for calculating the critical buckling loads for tapered plates with different loadings.

Buckling load optimization of laminated composite plates with elliptical hole under different non-uniform edge loads using bonobo optimizer algorithm

This present work investigates the buckling load optimization of the laminated composite plates with the elliptical hole under different non-uniform edge loads. The design objective is the maximization of the critical buckling load by determining the optimum fiber orientations in the layers. The stability equations are derived based on the first-order shear deformation theory (FSDT) of the laminated plates. The critical buckling loads are calculated using the finite element method with the nine noded rectangular element having five degrees of freedom per node. The bonobo optimizer (BO) algorithm is employed to optimize the laminated composite plates with the elliptical hole. The computer programming is developed in the MATLAB environment. Besides, the parametric studies are conducted for different types of the non-uniform edge loads, boundary conditions, cutout radius ratio and aspect ratios and the obtained numerical results are compared. Finally, the optimum results show that these factors play an imperative role in the optimum pattern and stacking sequence of the laminated composite plates with hole. The new significant findings can aid the designers in the structural design, and other industrial applications.

Types of stress and methods of stress reduction in cattle

Recently, stress has become the most urgent problem of modern animal husbandry. With the industrialization of agriculture, this problem is becoming more and more acute, as a result, livestock enterprises and farms suffer significant economic losses. Throughout its life, the animal is exposed to numerous stressors that have a completely different nature of occurrence, but invariably lead to the same changes in the body. The animal noticeably loses weight, weakens, its resistance to diseases decreases. A review of scientific sources on some types of stress loading on cattle: heat stress, transportation stress, pre-slaughter stress is given. According to many studies, the stress state of an animal depends on feeding and maintenance by 70-80% and only 20-30% on genetics. The body of farm animals is constantly affected by various environmental factors. These include production technology, method of maintenance, density of accommodation, size of groups, microclimate of premises, type and level of feeding, biological full-value of diets, methods of preparation and distribution of feed, quality of drinking water, veterinary and preventive and zootechnical measures (vaccination, sanitary treatment of animals, weighing, castration, etc.). When the above factors change, certain reactions occur in the animal body. The nature of stress can be different: mechanical, physical, chemical, biological, mental. Knowledge of the causes of stress, the patterns of its course, its consequences, outlined in the mentioned scientific sources, will allow rational use of the proposed ways to reduce the adverse effects of various stress factors on animals to preserve their health and high productivity.

Analysis of Improvements to Bank Capacitor Requirements in 20kv Voltage Distribution Network Panels for Power Plant 2 at PT. Toyota Motor Manufacturing Indonesia

This research aims to describe and analyze the effectiveness of using capacitor bank capacity in PT's power plant 2 distribution system. TMMIN. The focus is to analyze the initial design of capacitor bank requirements for each panel in the substation production line, including Painting, Assembly and Welding, to increase capacitor bank requirements according to electrical theory standards. The Power Factor calculation method is used to measure the required capacitor bank capacity. The power factor is influenced by the type of electrical load which is resistive, inductive or capacitive, with a value range between 0 and 1. A power factor close to 1 indicates high active power and better electrical power quality, while a power factor close to 0 indicates high reactive power. reducing power quality and increasing electrical energy use. The current power factor value is obtained from the actual voltage and active power conditions, and the required capacitor bank value is calculated with a target power factor of 0.9 or 0.95. According to calculations, the panels that can be repaired are panels 3, 4, 5, 6 Painting, panel 1 Assembly, and panel 1 Welding. The results show that 2 MDB panels reach ideal conditions with 6 steps of 2x50kVAR capacitor bank, while the other 6 MDB panels require an additional 2 steps of 2x50kVAR capacitor bank to achieve ideal conditions.

Multi‐objective interval planning for 5G base station virtual power plants considering the consumption of photovoltaic and communication flexibility

AbstractLarge‐scale deployment of 5G base stations has brought severe challenges to the economic operation of the distribution network, furthermore, as a new type of adjustable load, its operational flexibility has provided a potential way to promote the consumption and utilization of photovoltaic. In this paper, a multi‐objective interval collaborative planning method for virtual power plants and distribution networks is proposed. First, on the basis of in‐depth analysis of the operating characteristics and communication load transmission characteristics of the base station, a 5G base station of virtual power plants participating in the cellular respiratory demand response model is constructed. In view of the inherent contradiction between system economy and environmental performance, a multi‐objective interval optimization model for collaborative planning of virtual power plants and distribution networks is established with the lowest system investment and operating costs and the lowest carbon emissions as the optimization goals. The established model is transformed into a deterministic optimization problem, which is solved by NSGA‐II algorithm. The modified IEEE‐33 node system is used in the case analysis to analyse the impact of different planning schemes and response characteristics on the system economy. The calculation results verify the effectiveness of the proposed method.

Improving capacity configuration and load scheduling for an integrated multi-sourced cogeneration system

The integration of renewable energy sources and fossil fuel e.g. coal in a heat and power cogeneration system has been proven to be an effective way to reduce CO2 emissions. An integrated multi-sourced cogeneration (IMC) system consisting of wind, solar photovoltaic (PV), and coal-fired combined heat and power (CHP) plant on the energy supply side, is studied in this paper. A bi-level collaborative optimization model for capacity configuration and load scheduling of the wind-PV-coal IMC system is developed. In the upper level, the capacity of wind farm and PV farm are optimized with the enumeration method, while the load scheduling under typical annual conditions is optimized with adaptive particle swarm optimization algorithm in the lower level. The results show that the optimal capacities of wind and PV are 120 MW and 280 MW for the IMC system, respectively. The annual and typical day load scheduling with optimal wind and PV capacities are analyzed. The result of the load scheduling shows that heating and power load distribution unevenly between the two CHP units contributes to reducing total standard coal consumption, which saves 34.96 t in a typical day during the heating season. This study can provide a reference for the capacity configuration and operation scheduling of the IMC system.