Working Cycle Research Articles

ОПРЕДЕЛЕНИЕ НАИБОЛЕЕ ПОВРЕЖДАЮЩИХ ПО КРИТЕРИЮ УСТАЛОСТИ ЭКСПЛУАТАЦИОННЫХ РЕЖИМОВ НАГРУЖЕНИЯ НЕСУЩИХ КОНСТРУКЦИЙ КУЗОВА КАРЬЕРНОГО САМОСВАЛА

A procedure is developed for the calculation and experimental assessment of the operatonal modes damaging effect on the load-bearing structure of a dump truck body. The procedure makes it possible to determine the most dangerous zones of the load-bearing structure according to the multicycle fatigue criterion, as well as to assess the damaging effect of individual operatonal modes forming the dump truck working cycle. Analysis of the loading and fatigue damage accumulation of the load carrying structures of the BELAZ 7558 dump truck body was used for the procedure testing. Structure loadings have been determined for eight operating modes, including loading and unloading the body with bulk cargo during field tests. Processes of change of mechanical axial stresses during the tests were registered in eight zones. Experimental data analysis revealed two zones of the structure where the fatigue damage accumulation happens more than twice as fast as in the others. It is established that dump truck movement modes for technological road and the road in the dump area are characterized by the greatest fatigue damage accumulation. For the truck whole working cycle the most damaging movement mode for body is moving on the technological road. At the same time, the greatest unit equivalent fatigue damaging effect is formed by moving on the dump road and is greater than the corresponding value for the technological road by about 1.5 times. This is explained by the fact that the length of the technological road in the considered working cycle of the dump truck is 7 times more than the length of the dump road.

Analysis of work productivity and compatibility of excavation-loading equipment and transport equipment in soil salvaging activities at Katala Hill area of PT. Amman

Abstract PT. Amman Mineral Internasional Tbk in Katala Hill, West Nusa Tenggara Province, Indonesia, is an open-pit mining company producing copper as its main commodity, followed by gold and silver. The initial stage of mining involves soil removal in land clearing activities for reclamation, waste disposal areas, and construction of other infrastructure. In soil salvaging activities, it is essential to understand the influential factors to productivity and the match factor in mechanical equipment, including work efficiency, delay time, cycle time, fill factor, and swell factor. The objective of this study is to determine the productivity and match factor values of the digging-loading equipment and transportation equipment in soil salvaging activities in the Katala Hill area. This study applied the descriptive quantitative method, involving direct field observations of the digging-loading and transportation equipment activities and interviews with mining workers. Based on the results, the actual work efficiency of the digging-loading equipment was 59% and the transportation equipment was 76%, the actual productivity of the digging-loading equipment was 825.00Bcm/h, the transportation equipment productivity was 611.17 Bcm/h, and the compatibility factor value is 0.7408. After increasing the work efficiency of the conveyance by 83%, the conveyance productivity was 667.46 Bcm/h with the match factor increasing to 0.8090.

General Concept of the Magnetic Reconnection Converter (MRC)

The general concept of the magnetic reconnection converter (MRC) is considered, based on the cyclic combination of two physical processes: 1) controlled turbulence using super-linear Richardson diffusion and/or self-generated/self-sustaining physical processes increases the stochasticity of the magnetic field (MF) in a limited volume of plasma and, accordingly, the global helicity H through the processes of twisting, writhing, and linking of the MF flow tubes to the level of a local maximum (optimally global), which is determined by the plasma parameters, boundary conditions, magnetic tension of the field lines, etc. At this stage of the MF turbulent pumping, the β of plasma will decrease to the minimum possible value with a corresponding increasing in the accumulated "topological" MF energy; 2) upon reaching the local (if possible global) maximum of MF stochasticity, turbulent magnetic reconnection (TMR) occurs in the plasma, which reduces the state of the local (if possible global) maximum of MF stochasticity and increases the kinetic stochasticity of plasma particles, accelerating and heating them, which is used in direct converters of electrical power. At this stage of turbulent discharge, the β of plasma will increasing to the maximum possible value with a corresponding increasing in its kinetic and thermal energy; 3) when the kinetic stochasticity of plasma particles subsequently decreases and reaches a local minimum, the control system repeats the MF turbulent pumping in the plasma and the cycles are repeated. Practically, the basis of the MRC can be the fusion scheme of two anti-spiral spheromaks, the helicity of which is increased in a cycle with the help of controlled turbulence before their fusion and the creation of a field-reversed configuration (FRC) to increase the efficiency of the annihilation of their toroidal and poloidal magnetic fields into kinetic and thermal energy of plasma particles with its subsequent direct transformation into electrical power for industrial use or single-volume plasma (spheromak) with changing beta at turbulent pumping/discharge phases of the working cycle.

Influence of Control Strategy on Heat Recovery Efficiencyin a Single-Duct Periodic Ventilation Device

The subject of the research was a single-duct, decentralised periodic ventilation unit, using accumulative heat exchanger for heat recovery (also called single-core fixed-bed regenerator). It can achieve high efficiency of heat recovery but is vulnerable to pressure differences between the interior of the building and the outside. To counter this, two control strategies were proposed: adjustment of the fan speed based on an air flow sensor and adjustment of the working cycle length based on temperature sensors. The strategies were tested experimentally in actual working conditions. Due to the use of cheap and simple sensors, it was possible to retain the low price of the device. Both control strategies proved to be successful in equalising the amount of supplied and removed air in a single cycle. Moreover, the heat recovery efficiency increased by more than 10% compared to the default working mode.

Design and Optimization of Non-Coplanar Orbits for Orbital Photovoltaic Panel Cleaning Robots

Aiming at the problem that it is difficult for an orbital photovoltaic panel cleaning robot to span a large distance between photovoltaic panels, a method of designing and optimizing a non-coplanar orbit based on Bezier curves is proposed. Firstly, the robot’s motion law is analyzed to obtain trajectory data for a single work cycle. Then, Bezier curves are utilized for trajectory design to ensure a smooth transition during the spanning motion phase. Thirdly, with the average value of the minimum distance between the Bezier curve and the point set data of the spanning motion phase as the optimization objective function, the nonlinear planning based on the SQP algorithm was adopted for the optimization of the upper and lower trajectories. Finally, the results of the case calculations indicate that the standard deviation of the optimized upper and lower trajectories was reduced by 35.63% and 40.57%, respectively. Additionally, the ADAMS simulation validation demonstrates that the trajectory errors of the four wheels decreased by a maximum of 8.79 mm, 23.78 mm, 10.11 mm, and 14.97 mm, respectively, thereby confirming the effectiveness of the trajectory optimization.

Stress Concentration Modelling in Internal Stiffeners of Ship-to-Shore Quay Cranes Legs Due to Structural Heightening

This paper presents a study on the modelling and estimation of stress concentration at the tips of leg stiffeners in ship-to-shore (STS) quay cranes, which is intensified in those on the sea-side leg extensions, which are more prone to crack formation, notably following structural heightening of the cranes. A computer-simulated database was generated, incorporating mechanical parameters and geometric features that impact stress concentration. These variables can then be integrated as inputs into a multiple linear regression model (MLR). This methodology offers an alternative to the finite element method (FEM) for the computation of stress concentration and deformations. At the same time, the statistical significance of the parameters influencing this scenario is determined, ensuring a comprehensive assessment of their impact on the studied phenomenon. The research underscores the importance of incorporating stress concentration and structural geometry considerations into crane design or modification, given their crucial role in preserving the remaining lifecycle of the structure. Crack initiation is significantly intensified in regions characterised by high stress concentrations, particularly in areas where there are geometric changes at the tips of the stiffeners, where local stiffness is altered. All of this is in combination with work cycles under the supported loads.

Thermal optimization of robotic piezoelectric osteotomy motion in porcine trabecular bone

BackgroundPiezoelectric osteotomy represents a potentially viable alternative to conventional techniques for preparing pilot holes for bone screws. However, piezoelectric osteotomes have demonstrated the potential to heat bone beyond 47 °C, which induces necrosis that could contribute to screw loosening, resulting in osteosynthetic material failure and pseudarthrosis. Thus, we sought to determine the working movements of a piezoelectric drill that resulted in the lowest maximum bone temperatures while ensuring that this optimal drilling motion resulted in temperatures below 47 °C. MethodsVertebrae samples were obtained fresh from a local abattoir. A robot was used to drill 15 mm holes through the vertebrae bodies parallel to a sectioned viewing surface, observed with a thermal camera. We tested three significant aspects of the osteotome's movement: the feed rate, retraction speed and working cycle to see which combination resulted in the lowest maximum temperatures. Each factor combination was tested three times for a total of 24 trials. FindingsA feed rate of 2 mm/s, a retraction speed of 2 mm/s and a novel working cycle termed “multi-pass” were found to generate the lowest maximum temperatures (41.5 °C, σ = 1.91 °C). The factors of retraction speed and working cycle demonstrated statistical significance through analysis of variance, with ordinary least squares regression indicating their optimal settings resulted in reductions in maximum temperatures of 4.95 °C and 5.63 °C, respectively. InterpretationRobotic piezoelectric osteotomy appears to represent a safe method of pedicle screw pilot hole preparation from a thermal perspective when using the optimal methods found in this study.

Innovative and self-adaptive energy recovery system in hydraulic cylinders for cyclic operations

Abstract Conventional hydraulic actuation supply and control systems usually work with a very high energy loss, especially in the field of off-road machinery. In particular, during the lowering phase of a boom of a hydraulic excavator, energy dissipated through lamination in thermal heat is a consistent fraction of the energy required for operating the working cycle. In this paper, an innovative system is presented that can recover a significant fraction of this energy, to make it available for the next working cycle, which adapts the level of energy recovery in order to maximise the overall efficiency. In the presented system, the conventional hydraulic actuators that operate the boom of a large size hydraulic excavator are replaced with three-chamber actuators, in which the third chamber, obtained inside the cylinder rod, is connected to a secondary hydraulic circuit that involves a series of accumulators: the compression and the subsequent expansion of the amount of gas inside the accumulator allows to, respectively, store the maximum possible recoverable energy, during load lowering phase in the first cycle and deploy it in the next cycle. The initial gas pressure inside the accumulator is set accordingly to the maximum amount of recoverable energy during the cyclic operation, and can be easily changed via a low-displacement auxiliary pump and a feedback control mechanism, without the need of stopping the machine to vary the amount of inert gas inside the accumulators. A hydraulic manifold has been designed to manage and regulate the flow rates of both the main and the secondary circuits. Pressure losses inside the manifold have been evaluated through CFD analysis, performed in SimericsMP+ environment. The whole system has then been simulated as a lumped parameter model developed in Simcenter Amesim ©. Results from the simulation of the proposed system show that, on a working cycle of 20 s, only 25% of the hydraulic energy required for the conventional system is needed to operate the boom in the proposed configuration. This method can be easily extended to several hydraulic actuators that realise frequent height changes of the load.

Managing Downtime: Actionable Strategies for Productively Filling Slack Periods

This article provides evidence-based strategies for capitalizing on slow work cycles rather than letting productivity suffer. Drawing on over 40 years of scholarly literature across multiple disciplines, the article outlines a framework for constructively navigating periods of lower workload. It advocates first adjusting one's mindset to view downtime positively as opportunity rather than negatively as a problem. Tactics are then presented for comprehensively inventorying available resources and strategically targeting them towards high-impact undertakings. The importance of systematically tracking progress is emphasized. Real-world case examples from marketing and manufacturing industries demonstrate impact. The article concludes by emphasizing how effectively addressing variability through temporary, targeted investments strengthens long-term organizational agility, performance and prosperity.

A steady-state numerical approach for the thermo-structural analysis of a cryogenic piston pump

Abstract The process of liquefaction of gaseous fuels, such as natural gas or hydrogen, is an essential technology that helps reduce transportation costs over long distances. Cryogenic piston pumps play a critical role in these systems, as they compress the fuel up to 700 bar before vaporization and storage in high-pressure vessels. Due to the extreme temperatures and pressures involved, the design of these machines poses a significant challenge from the thermal and structural point of view. This work presents the application of a simplified numerical approach for evaluating the thermally induced stresses and deformations through a de-coupled thermo-structural three-dimensional analysis of a prototype cryogenic piston pump. Thermal simulations of the solid domain are carried out to assess the steady-state temperature distribution of the pump. The heat transfer between the pump and cryogenic liquid is computed using three-dimensional steady-state CFD simulations of the suction and discharge phases. Heat generated by friction during the working cycle of the pump and external natural convection are calculated and imposed as a heat source in the simulations. The steady-state temperature distribution is imposed in a finite-element steady-state three-dimensional structural simulation to evaluate the combined effect of thermal loads induced by the cryogenic temperatures and loads induced by the high working pressures. Results show how the proposed methodology can assist in the design of cryogenic piston pumps by offering valuable insights into the most critical aspects of these machines.

ДАВЛЕНИЕ НА ПОЧВУ БУНКЕРОВ-ПЕРЕГРУЖАТЕЛЕЙ В РАБОЧИХ ЦИКЛАХ ОБСЛУЖИВАНИЯ ЗЕРНОУБОРОЧНЫХ КОМБАЙНОВ

The problem of soil compaction by heavy transport equipment used to transport grain from combines, the solution of which is associated with the use of bunker-loaders (BL), is currently becoming more acute. However, the lack of indicators of the pressure on the soil of their running systems (when moving across fields) and the methodology for assessing the impact of BL on the soil with different body loads of grain, prevent comparative assessments of BL and an objective choice by agricultural producers of samples with the lowest pressure on the soil. The distances of passes across the field in the working cycles of BL for the variants of the number of combines serviced are modeled using original formulas as a result of research. It was found that the total length of the BL run across the field Ltotal in the working cycle is directly proportional to the length of the run Lg of the harvested field and the number of combines serviced. It consists of separate sections-passages characterized by successively increasing soil compaction, the value of which in turn depends on the mass of the loaded grain and the number of support wheels of the BP. The proposed expression for calculating the vertical load on the wheels of the bunker-loader, taking into account the change in the weight of the grain in the body, provides the ability to calculate the maximum pressure on the sections of the BP movement across the field when servicing combines for subsequent comparison with the regulated permissible pressure. It was found that with each loading of grain from the combine bunker, the maximum pressure of the wheels on the soil increases by 104 and 80 kPa for BP with four support wheels and by 38-50 kPa - with eight support wheels, with an increase in pressure to 382-394 kPa and with an excess of the permissible value by 1.8-1.9 times. When working with grain reception in a heavy-duty BP from three bunkers of TORUM combines instead of the possible four, the maximum pressure on the soil is reduced by 9.9% (from 382 to 344 kPa), and when receiving grain from two bunkers - by 20.7% (from 382 to 302 kPa).

Health behaviours and affective states of partners of fly‐in fly‐out workers: A daily diary study

AbstractPartners of fly‐in fly‐out (FIFO) workers face increases in demands, for instance in care and family responsibilities, particularly in the absence of workers; however, little is known about how their daily life experiences influence their health across the FIFO work cycle. This study examined the within‐person effects of workload, job control and social support on affective states and health behaviours of partners of FIFO workers. Forty‐four (N = 44) partners of FIFO workers completed online diary surveys on affective states and health behaviours once a day for 28 consecutive days during on‐and off‐shift periods of the FIFO worker. Multilevel models were used to analyse day‐level data. The results of the study demonstrated significant differences in partners' depressed affect and alcohol consumption during both on‐ and off‐shift periods of FIFO workers. Daily increases in workload were associated with anxious affect, whereas daily increases in job control and social support were associated with low depressed affect and positive affect in partners of FIFO workers. Daily increase in social support was also found to be associated with an increase in daily alcohol intake. Interventions could support partners in managing the daily workload and encouraging the creation of social support networks in partners of FIFO workers.

The Use of Heart Rate Measures to Evaluate Stress Levels among Air Traffic Controllers

This paper looks at the possibility of using a heart rate monitor to evaluate stress levels among Air Traffic Controllers (ATCOs). Air Traffic Control (ATC) service requires constant good planning, situation awareness, and always making sound decisions. A study was conducted on two ATCOs for three complete work cycles: the morning shift from 8 a.m. to 4 p.m., the afternoon shift from 4 p.m. to 12 a.m., and the night shift from 12 a.m. to 8 a.m. Both participants have different roles, with Subject A being a planner controller while Subject B is a radar controller. The study used the NASA Task Load Index (NASA-TLX) survey to collect the subjective workload rating and a heart rate monitor armband to measure the heart rate reading of an ATCO and then compare it with the number of aircraft within the controlled area. Two hypotheses were investigated: the first one is the relationship between the number of traffic and heart rate readings, and the second hypothesis is the relationship between the elapsed working time and heart rate reading. The Spearman correlation test has been used to determine these relationships. Based on the results, a p-value of less than 0.05 and a positive correlation indicates a significant relationship between the number of aircraft and heart rate readings for both subjects. Elapsed time and heart rate measurement, on the other hand, do not significantly correlate with a p-value greater than 0.05 and a negative correlation was produced for both subjects. The unweighted NASA-TLX workload measure confirmed the findings for Subject A but not for Subject B. This might be due to the different roles carried out by both subjects during the experiment. This shows that different work tasks resulted in different workload-induced factors. The results show a promising outcome of using a heart rate monitor to evaluate stress levels among ATCOs. However, more subjects were needed to enable the use of this concept for future purposes of measuring ATCO stress levels to manage workload.

Comparative Study on the Anti Sliding Performance of Circular and Rectangular Cross-section Anti-Sliding Piles

Anti-slide pile is a retaining structure commonly used in large-scale landslide reinforcement. It usually adopts large cross-section rectangle pile by artificial excavation, but the defects of this pile are long work cycle, large excavation disturbances and personnel safety of builders in hole can't get effective guarantee in the rainy season and stratum saturated by water. However, the circle section pile has advantages of applying rotary pile drill into holes, high efficiency pore-forming, small excavation disturbances, and the option of aperture convenient and flexible. The circle section pile has obvious superiority to large cross-section rectangle pile. But the mechanism and design calculation of anti-slide pile group with the space frame structure of circle section has not the existing specification to adopt. This study aims to contrast and discuss the anti-sliding effectiveness between circle and rectangle section anti-pile through experiment.

Von Neumann Entropy and Evolution

In this paper I outline a hypothesis where quantum information in the form of von Neumann entropy provides a universal driving force for increasing complexity of systems and for evolutionary processes. Interference between quantum states of interacting systems allows storage of free energy that can be used to overcome kinetic barriers and accelerate reactions. This informational work cycle is analogous to entanglement in quantum Carnot engines where energy is stored as phase or so-called phaseonium fuel. The von Neumann entropy subadditivity and Araki-Lieb inequality properties of combined states can lower effective entropy and favour routes to increasing complexity of systems. It is proposed that observed macroscopic evolutionary processes are the emergent manifestation of this microscopic informational drive to complexity.

Optimization and performance assessment of Ag@SiO2 core–shell nanofluids for spectral splitting PV/T system: Theoretical and experiment analysis

Ag@SiO2 nanofluid is widely used in spectral splitting PV/T system. Its core–shell structure has great influence on the optical properties. In this work, we focus on the comprehensive analysis and structure optimization of Ag@SiO2 nanofluid to achieve its optimal spectral performance. DDA method is used to predict the optical properties of Ag@SiO2 nanofluid and an optimization model based on filter efficiency is proposed. The effect of the SiO2 shell thickness and Ag core mass concentration is analyzed. It indicates that the spectral performance of Ag@SiO2 nanofluid can be improved with SiO2 shell thickness of 15–40 nm and Ag core mass concentration of 81–135 mg/L. To achieve the same theoretical merit function of 1.46, the usage of Ag mass can be reduced by 25/33/44/62 % with SiO2 coating of 10/20/40/70 nm. The optimal structure to achieve the highest filter efficiency η of 37.8 % is with a shell thickness of 20 nm and a mass concentration of 113.9 mg/L. An indoor PV/T operation testing is conducted to verify the optimization results. The merit function of Ag-based nanofluids increases from 1.58 to 1.598 and a reduction in Ag usage of 17 % is achieved with a SiO2 coating shell of 17.8 nm. Operation stability is also enhanced with no aggregation observed during the working cycle and 7-day static experiment.

Parametric identification of coefficients for a model of fatigue stiffness degradation of a composite material

The problem of finding the fatigue characteristics of a composite material based on test results is considered. The results of endurance tests of unidirectional polymer composite materials with different initial stiffness, breaking stress and working cycle stress were used as the initial data. As a mathematical model of stiffness degradation, a nonlinear ordinary differential equation with five unknown parameters is used, reflecting characteristic changes in the properties of the material. It is required to find such parameter values that the solution of the differential equation should describe the available test results with sufficient accuracy. The solution procedure is reduced to the problem of optimizing the objective function, the value of which characterizes the achieved accuracy. As optimization methods, a method simulating the behavior of a flock of moths and a method of sequential reduction of the search set were used. A step-by-step algorithm for finding unknown model parameters is proposed, and numerical results of processing input data containing information on changing the elasticity modulus of the composite material in the course of applying load cycles are presented.

Mobile Application Development for Prepaid Water Meter Based on LC Sensor

This study presents a novel low-cost and low-power prepaid water meter system that combines tokenization and LC sensors to monitor water consumption accurately with mobile application via Bluetooth Low Energy (BLE) connectivity compared to conventional meters. Water meters play a vital role in monitoring water usage in Indonesia. Postpaid billing methods that rely on manual data recording are a source of concern due to potential inaccuracies caused by human error. This study presents the development of a prepaid water meter system that integrates LC sensors, BLE connectivity, a tokenization mechanism, and a mobile application to address this issue. The system offers a cost-effective solution by utilizing BLE + Global System for Mobile (GSM) from the user’s mobile phone. Using the design thinking methodology, the mobile application for the prepaid water meter achieved a usability testing score of 80. The load testing results for the back-end server, conducted with a sample size of 515 users, revealed a back-end latency of 1.973 milliseconds and an error rate of 8.74%. Furthermore, the LC sensors integrated into the PWM device showed an average error rate of 1.33%. The power consumption during each work cycle was measured at 129 mA and each battery is expected to last six years. Overall, with simple LC sensors, this system can precisely measure water usage.

Radiative heat transfer to enhance the performance of liquid metal-based phase change heat sink under natural convection condition

Liquid metal phase change materials have the advantages of high thermal conductivity and high volumetric latent heat, which are expected to address the growing challenges of thermal management of advanced electronics. In previous studies, the effect of radiative heat transfer from fins of a phase change heat sink on thermal management performance has rarely been considered. In this study, radiative coating materials with high emissivity were prepared and coated on the fins of the liquid metal phase change heat sink. The effect of radiative heat transfer on the performance of liquid metal phase change heat sink was investigated. The experimental results of continuous heating under natural convection conditions show that the introduction of the radiative coating with an emissivity of 0.9298 can extend the time for the surface temperature of the heat source to reach 100 °C by 9.4%, while shortening the recovery time of the phase change heat sink by 14.9%. The results of high-power cyclic heating indicate that the high emissivity coating can reduce the peak temperature by 16.6 °C in the tenth working cycle. A simplified numerical model was subsequently developed and validated to determine the specific effects of phase change and radiative heat transfer on the overall thermal control performance. The radiation-enhanced liquid metal phase change heat sink proposed in this study is simple and maintenance-free. It is expected to address the thermal management issues of electronic devices that cannot use active cooling or operate in thin-air environments.

Organization of safe work on the ice battle

The article presents materials related to the organization of the safe conduct of coastal raft sections of raft bundles in winter on the ice of the water area. The materials presented in the article are based on information from the first of the articles of the planned work cycle, where the basic concepts of sorting bundles and the organization of their manufacture were given.