Search Results (83)

High-precision 6D pose estimation for pick-and-place operations remains a critical problem for industrial robot arms in manufacturing. This study introduces an analytics-based solution for 6D pose estimation designed for a real-world industrial application: it enables the Staubli TX2-60L (manufactured by Stäubli International AG, Horgen, Switzerland) robot arm to pick up metal plates from various locations and place them into a precisely defined slot on a brake pad production line. The system uses a fixed eye-to-hand Intel RealSense D435 RGB-D camera (manufactured by Intel Corporation, Santa Clara, California, USA) to capture color and depth data. A robust software infrastructure developed in LabVIEW (ver.2019) integrated with the NI Vision (ver.2019) library processes the images through a series of steps, including particle filtering, equalization, and pattern matching, to determine the X-Y positions and Z-axis rotation of the object. The Z-position of the object is calculated from the camera’s intensity data, while the remaining X-Y rotation angles are determined using the angle-of-inclination analytics method. It is experimentally verified that the proposed analytical solution outperforms the hybrid-based method (YOLO-v8 combined with PnP/RANSAC algorithms). Experimental results across four distinct picking scenarios demonstrate the proposed solution’s superior accuracy, with position errors under 2 mm, orientation errors below 1°, and a perfect success rate in pick-and-place tasks. Full article

Differential planetary roller lead screw (DPRS) serves as a quintessential actuating mechanism within the electromechanical braking (EMB) systems of vehicles, where its operational reliability is paramount to ensuring braking safety. Considering different braking intensities, how assembly errors affect the contact stress in DPRS was analyzed via the finite element method. Firstly, the braking force of the EMB system that employed DPRS was verified by the braking performance of legal provisions. Secondly, a rigid body dynamics model of DPRS was established to analyze the response time, braking clamping force, and axial contact force of DPRS under varied braking intensities. Finally, a finite element model of DPRS was constructed. The impact of assembly errors in the lead screw and rollers on the contact stress were investigated within the DPRS mechanism based on this model. The results indicate that as braking intensity increases, the deviation of the lead screw exerts a greater influence on the contact stress generated by the engagement between the lead screw and rollers compared to that between the nut and rollers. The skewness of the rollers also affects the contact stress generated by the engagement of both the lead screw with rollers and the nut with rollers. When assembly errors reach a certain threshold, the equivalent plastic strain is induced to exceed the critical value. This situation significantly impairing the normal operation of DPRS. This study provides guidance for setting the threshold of assembly errors in DPRS mechanisms. It also holds significant implications for the operational reliability of EMB systems. Full article

This study investigates the impact of hydrogen supplementation on the performance, efficiency, and emissions of a spark-ignition internal combustion engine, with a specific focus on knock phenomena. A Nissan HR16DE engine was modified to operate in a dual-fuel mode using gasoline (E95) and high-purity hydrogen. Hydrogen was injected via secondary manifold injectors and managed through a reprogrammable MoTeC ECU, allowing precise control of ignition timing and fuel delivery. Experiments were conducted across various engine speeds and loads, with hydrogen mass fractions ranging from 0% to 30%. Results showed that increasing hydrogen content enhanced combustion intensity, thermal efficiency, and stability. Brake specific fuel consumption decreased by up to 43.4%, while brake thermal efficiency improved by 2–3%. CO, HC, and CO₂ emissions were significantly reduced. However, NO_x emissions increased with higher hydrogen concentrations due to elevated combustion temperatures. Knock tendency was effectively mitigated by retarding ignition timing, ensuring peak in-cylinder pressure occurred at 14–15° CAD aTDC. These findings demonstrate the potential of hydrogen supplementation to reduce fossil fuel use and greenhouse gas emissions in spark ignition engines, while highlighting the importance of precise combustion control to address challenges such as knock and NO_x formation. Full article

Herein, a three-dimensional mathematical model was established to investigate the metallurgical behavior of liquid steel in a funnel-shaped mold equipped with single-ruler electromagnetic braking (EMBr). The effects of mold thicknesses, electromagnetic intensity, and casting speed in flow behavior were investigated. The results indicate that with EMBr, multiple pairs of induced current loops are present in the horizontal section of the magnetic pole center, distributed in pairs between the jets and broad faces. The Lorentz force acting on the main jet, which impacts the downward and upward flow at adjacent broad faces, is opposite in direction. Increasing mold thickness results in a larger jet penetration depth, leading to a higher meniscus temperature near the narrow faces accompanied by elevated velocity and turbulent kinetic energy. EMBr can lead to a decrease in shell thickness and an improvement in its uniformity at mold exit. For the thickened mold, as the magnetic flux density increases and the casting speed decreases, the penetration depth of jets and velocity near the narrow faces and meniscus decreases. The shell thickness decreases as the casting speed increases, with the lowest non-uniformity coefficient of 6.78% observed at a casting speed of 5.0 m/min. Full article

BEVs (Battery Electric Vehicles) have received widespread attention from various countries for their potential in combating global warming, the energy crisis, and environmental pollution. The driving range and energy consumption of BEVs vary significantly under different driving cycles, which often results in discrepancies between the values reported by manufacturers and real-world data. To address this issue, this paper establishes a modular simulation model of a BEV on the Matlab/Simulink platform and conducts simulation experiments and analyses of driving range and energy consumption under three different standard driving cycles, namely, the NEDC (New European Driving Cycle), WLTC (World Light Vehicle Test Cycle), and CLTC-P (China Light-duty Vehicle Test Cycle for Passenger Car), and compares the results with data from vehicle manufacturers and consumers. The results of the study show that the NEDC conditions are more ideal, the CLTC-P conditions are the most intense vehicle driving, and the WLTC conditions require the highest overall vehicle performance. Compared with other standard cycles, the WLTC conditions show better alignment with real-world driving range data. The two main factors affecting the energy consumption in each condition are driving range and acceleration. The energy recovery strategy, braking frequency, and average deceleration speed of the driving cycle conditions are important factors affecting the braking energy recovery. This study provides a theoretical basis for driving range and energy consumption testing and driving cycle condition improvement of BEVs. Full article

This study aimed (1) to explore the spatio-temporal phases of the execution of the bench press (BP) exercise based on barbell acceleration and power; (2) to describe barbell velocity, acceleration, mechanical power, and mechanical work at different load intensities; and (3) to analyse differences in kinematic and mechanical parameters. Twenty-one men (21.4 ± 1.5 years; 175.1 ± 6.7 cm; 75.8 ± 7.7 kg; 1RM: 91.7 ± 13.7 kg) and nine women (21.7 ± 2.3 years; 163.3 ± 10.8 cm; 57.2 ± 6.8 kg; 1RM: 38.9 ± 10.5 kg) were evaluated during the eccentric and concentric phases of the BP at different load intervals: interval 1 (55 to 75% 1RM), interval 2 (>75 to 85% 1RM) and interval 3 (>85 to 100% 1RM). Both temporal (duration) and mechanical variables (velocity, acceleration, mechanical power and mechanical work of the barbell) were determined using the Xsens MVN Link System. Mechanical variables were compared among the three different intervals. Interval 3 displayed greater duration compared to intervals 1 and 2. Barbell acceleration and power showed four different phases of BP movement, corresponding to the second and third phases of the exercise, bar braking (eccentric) and bar acceleration (concentric), respectively; the first and fourth phases are mainly determined by gravity instead of muscle intervention. Velocity and acceleration were different among the three different intervals during both the eccentric and concentric phases (p < 0.05). No differences were found between intervals 2 and 3 in mechanical power or mechanical work during the eccentric phase. In conclusion, the BP exercise has four phases considering barbell acceleration and power. The maximum and mean velocity and acceleration during BP performance decrease as load intensity increases. Maximum and mean mechanical power, and mechanical work, decrease progressively in the second and third intervals for both the eccentric and concentric phases. Thus, kinematics and mechanical parameters vary depending on load intensities. Full article

In various applications, dry friction could induce vibrations. A well-known example is frictional braking systems in ground transportation vehicles involving a sliding contact between a rotating and a stationary part. In such scenarios, the emission of high-intensity noise, commonly known as squeal, can present human health risks based on the noise’s intensity, frequency, and occurrences. Despite the importance of squeal in the context of advancing urbanization, the parameters determining its occurrence remain uncertain due to the complexity of the involved phenomena. This study aims to identify a relevant operando indicator for predicting squeal occurrences. To this end, a pin-on-disc test rig was developed to replicate various contact conditions found in road profiles and investigate resulting squealing. Each test involves a multimodal instrumentation, complemented by surface observations. It is illustrated that the enhanced thermal indicator identified is relevant because it is sensitive to the thermomechanical and tribological phenomena involved in squealing. Full article

To investigate the propagation behavior of thermal cracks on the wheel tread under the conditions of long downhill ramps, a three-dimensional finite element model of a 1/16 wheel, including an initial thermal crack, was developed using the finite element software ANSYS 17.0. The loading scenarios considered include mechanical wheel–rail loads, both with and without the superposition of thermal wheel–brake shoe friction loads. The virtual crack closure method (VCCM) is employed to analyze the variations in stress intensity factors (SIFs) for Modes I, II, and III (K_I, K_II, and K_III) at the 0°, mid, and 90° positions along the crack tip. The simulation results show that temperature is a critical factor for the propagation of thermal cracks. Among the SIFs, K_II (Mode II) is larger than K_I (Mode I) and K_III (Mode III). Specifically, the thermal load on the wheel tread during braking contributes up to 23.83% to K_II when the wheel tread reaches the martensitic phase transition temperature due to brake failure. These results are consistent with the observed radial propagation of thermal cracks in wheel treads under operational conditions. Full article

Wind plays a crucial role in the formation of coastal dunes, and in China, these dunes are shaped by the combined effects of typhoons and winter monsoons. However, the unique characteristics of Chinese coastal dunes impacted by these forces remain poorly understood, as prior research has predominantly focused on their separate impacts. This study employed RTK-GPS technology to conduct 14 high-precision morphological assessments of coastal dunes in Tannan Bay, Pingtan Island, Fujian, China, between 2014 and 2017, aiming to investigate the response patterns of coastal dunes to typhoons and winter monsoons. Our findings indicate that coastal dunes respond variably to typhoons of differing intensities, with considerable height changes across different sections; however, winter monsoons contribute to an overall increase in dune height. Both dune volume and height increased due to continuous sediment accumulation at the base of the windward slopes. Additionally, the average high-water level advanced seaward by 3.0–4.0 m. We concluded that in Tannan Bay, typhoons exert only a temporary “braking” effect on dune morphology, whereas the winter monsoon is the primary driver of its long-term evolution. These findings contribute to a comprehensive understanding of coastal dune dynamics and provide insights for effective coastal sand management and disaster prevention strategies. Full article

This study investigates magnetic flux density (B) and radiofrequency electromagnetic field (RF-EMF) measurements on electric buses operating in Samsun, Turkey, focusing on two bus routes (called E1 and E4) during the morning and evening hours. Measurements were taken under diverse operational conditions, including acceleration, cruising, and braking, at locations of peak passenger density. Along the E1 route, the magnetic field intensity varied significantly based on the bus position, road slope, and passenger load, with notable increases during braking. In contrast, the E4 route showed a lower magnetic field intensity and RF-EMF values due to its straighter trajectory and reduced operational stops. The highest RF-EMF measurement recorded was 6.01 V/m, which is below the maximum levels established by the ICNIRP guidelines. In 11 out of the 12 different band-selective RF-EMF measurements, the highest contribution came from the downlink band of the base stations, while in only one measurement, the highest contribution originated from the uplink bands of the base stations. All data were subject to the Anderson–Darling test, confirming the generalized extreme value distribution as the best fit for both B and RF-EMF measurements. Additionally, the study assessed B levels inside and outside the bus during charging, revealing heightened readings near the pantograph. These findings significantly contribute to our understanding of electromagnetic field exposure in electric bus environments, highlighting potential health implications and informing the development of targeted mitigation strategies. Full article

Prolonged exposure to high-intensity noise environments in urban rail transit systems can negatively impact the health and work efficiency of drivers. However, there is a lack of comprehensive understanding of the noise pattern and, therefore, effective mitigation strategies. To control the noise in urban rail transit systems, this study proposes a comprehensive noise assessment framework, including metrics such as average sound pressure level, peak sound pressure level, percentile sound pressure levels, dynamic range, main frequency component, and cumulative time energy to evaluate the noise characteristics. We also employ a density-based spatial clustering of applications with noise (DBSCAN) method to identify the noise patterns with the evaluation of their hazard to urban rail transit drivers. The results have revealed that: (1) The equivalent continuous sound pressure level (Leq) in the cab of Lanzhou Urban Rail Transit Line 1 averages 87.12 dB, with a standard deviation of 8.52 dB, which reveals a high noise intensity with substantial fluctuations. (2) Ten noise patterns were identified, with frequencies varying from 14.47 Hz to 69.70 Hz and Leq varying from 60 dB to 115 dB. (3) The major noise sources from these patterns are inferred to be the train’s mechanical systems, wheel–rail interaction, aerodynamic effects, and braking systems. Combined with the noise patterns and urban rail transit’s operation environment, this study proposes tailored mitigation strategies for applications aimed at protecting drivers’ hearing health, enhancing work efficiency, and ensuring driving safety. Full article

Researchers have hypothesized that high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MOD) lead to different patterns of shear stress in the brachial artery. These differing patterns of shear stress are thought to partially explain the differing chronic adaptations to these two types of exercise. No study has directly compared blood flow characteristics during HIIE and MOD. Sixteen healthy males (Age: 23 ± 3 years) completed two randomly assigned exercise visits: HIIE (10 × 1 min intervals at 90–95% of HR_max with 1 min of recovery between) or MOD (30 min at 70% of HR_max) on an electronically braked cycle ergometer. Brachial artery blood flow velocity and diameter were measured for a total of 12 min during each of the exercise sessions. Both anterograde blood flow (MOD: 191.3 ± 80.3 mL/min, HIIE: 153.9 ± 67.5 mL/min, p = 0.03) and shear rate (MOD: 203.5 ± 78.1 s⁻¹, HIIE: 170.8 ± 55.5 s⁻¹, p = 0.04) were higher during MOD compared to HIIE. Both retrograde blood flow (MOD: −48.7 ± 21.3 mL/min, HIIE: −63.9 ± 23.3 cm/s, p < 0.01) and shear rate (MOD: −51.5 ± 19.8 s⁻¹, HIIE: −73.8 ± 28.4 s⁻¹, p < 0.01) were of greater magnitude during HIIE compared to MOD. During exercise, brachial artery diameter (p = 0.34) did not differ between HIIE and MOD. Continuous moderate cycling exercise leads to higher brachial artery anterograde shear rate and blood flow, but lower retrograde shear rate and blood flow when compared to high-intensity interval exercise. These differences during exercise in blood flow characteristics could shed light on the differing chronic adaptations to these two types of exercise. Full article

Assessing the effects that nonstationary dynamic processes have on the durability of structural elements belongs to an important trend in modern dynamics and technical diagnostics of machines. Normally, fatigue strength calculations are performed taking into account only periodically variable stresses, as steady operating modes of machines are much longer in comparison with transient modes. However, a significant role in fatigue failure in machines and engineering structures is also played by nonstationary loads. This is explained by emerging intensive oscillations in the mechanical system during accelerating, braking, or changing the operation mode of a machine unit, which often lead to the accumulation of fatigue damages in the materials of parts in heavy loaded assemblies. The combination of stationary and nonstationary dynamic loads manifests itself, particularly in drilling rigs, where technological cycles include steady motion modes, starts, and stops. This paper represents a generalized mathematical model describing nonstationary processes in the lift system of a drill rig, which considers the relationship between electromagnetic processes in asynchronous motors and mechanical oscillatory phenomena, with the purpose of determining dynamic loads and stresses in structural elements of the rigs. Nonlinear physical systems include mechanical members with both concentrated and clearly expressed distributed parameters. The durability of structural elements is evaluated by means of a computer algorithm for analysis of crack growth rates using the NASGRO equation obtained with the presence of plastic deformation zones. An example of the crown block axis illustrates the influence of nonstationary dynamic processes in drill rigs on the durability of structural elements. Full article

The magnetorheological brake (MRB) epitomized a revolutionary modification in the braking systems because of its extremely efficient and well-controlled performance. To increase the safety and controllability of automotive braking system, researchers have developed a different MRB structures. Although much research on magnetorheological brakes has shown positive results in terms of brake torque, braking time, thermal efficiency, etc., the ability to increase braking force by expanding the disc surface, through which the magnetic field operates in a compact structure, is restricted. To address this issue, a new multipole MRB configuration with a unique pole head design that maintains compactness. Initially, the conceptual design was achieved by leveraging the combined impact of the twin disc-type structure and multipole concept. The model was used in a dynamic simulation to show how the braking torque of a magnetorheological braking system varies with coil current. The effects of circular sector pole head shape on braking performance were investigated using COMSOL Multiphysics software (version 5.5). A three-dimensional electromagnetic model of the proposed MRB was developed to examine the magnetic flux intensity and the impact of magnetic field dispersion on the proposed pole head structure of a magnetorheological brake. Based on simulation results, the circular sector pole head configuration is capable of increasing the active chaining regions for the MR fluid on the rotor surface, allowing for a more effective use of magnetic flux throughout the whole surface of a rotating brake disc, thereby increasing the magnetic field usage rate. The acquired simulation results show an increase in braking torque while keeping a compact and practical design structure. Full article

Braking systems are extremely important in any vehicle. They convert the kinetic energy of motion into thermal energy that is dissipated into the atmosphere. Different vehicle groups have different nominal and maximum speeds and masses, so the amount of thermal energy that needs to be absorbed by the friction pads and then dissipated can vary significantly. Conventional friction materials are composite materials capable of withstanding high temperatures (in the order of 500–600 °C) and high mechanical loads resulting from braking intensity and vehicle weight. In small vehicles traveling at low speeds, where both the amount of thermal energy and its density are limited, the use of slightly weaker friction materials with better ecological properties can be considered. This work proposes a prototype composite friction material using flax fibers as reinforcement instead of the commonly used aramid. A number of samples were prepared and subjected to laboratory tests. The samples were prepared using components of plant origin, specifically flax fibers. This component acted as reinforcement in the composite friction material, replacing aramid commonly used for this purpose. The main tribological characteristics were determined, such as the values of the coefficients of friction and the coefficients of abrasive wear rate. For this purpose, an authorial method using ball-cratering contact was used. The results were analyzed using statistical methods. It was found that the composite material using flax fibers does not differ significantly in its tribological properties from conventional solutions; so, it can be assumed that it can be used in the vehicle’s braking system. Full article