Explore the vast range of titles available.

A MEMS thin-film getter–heater unit has been previously proposed for the vacuum packaging of a Micro-Electro-Mechanical System (MEMS) device, where the floating structure (FS) design is found to be obviously more power-efficient than the solid structure (SS) one by heat transfer capacity simulation. However, the mechanical strength of the FS is weaker than the SS by nature. For high temperature usage, the unit structure must be optimized in order to avoid fracture of the cantilever beam or film delamination due to strong excessive stress caused by heating. In this paper, COMSOL is used to simulate the stress and deformation of the MEMS thin-film getter–heater unit with the cantilever structure. By comparing various cantilever structures, it is found that a model with a symmetrically-shaped heater and edge–center-located cantilever model (II-ECLC model) is the most suitable. In this model, even when the structure is heated to about 600 °C, the maximum stress of the cantilever beam is only 455 MPa, much lower than the tensile strength of silicon nitride (Si3N4, 12 GPa), and the maximum deformation displacement is about 200 μm. Meanwhile, the interfacial stress between the getter and the insulating layer is 44 MPa, sufficiently lower than the adhesion strength between silicon nitride film and titanium film (400–1850 MPa). It is further found that both the stress of the cantilever structure and the interfacial stress between the getter and the insulating layer beneath increase linearly with temperature; and the deformation of the cantilever structure is proportional to its stress. This work gives guidance on the design of MEMS devices with cantilever structures and works in high temperature situations.

Electric vehicles are growing to replace petroleum-fuelled vehicles because of environmentally friendly. The manufacture of electric tricycle must consider the planning of frame construction that is able to support all loads such as passenger loads, engines and other equipment components. Therefore, it must be ensured that the strength of the frame is able to withstand static loads. In this study, a simulation of static load on the frame of an electric tricycle was carried out by varying the size and thickness of the frame pro-file. The frame used is a hollow square with a size of 40x40 with a thickness of 0.8mm, 1.0mm and 1.2mm and a size of 40x60 with a thickness of 1 mm. This study uses Fusion 360 software to simulate static loading with a load of 500 Kg. The recommended safety factor is 3.5. So, based on the simulation results, the eligible frames are hollow steel 40 x 40 with a thickness of 1 mm and hollow steel 40x60 with a thickness of 1 mm. Both of these materials have the same frame weight. Both of these materials have almost the same Von Misses stress, it is 51.34 MPa and 50.37 MPa respectively. The 40 x40 hollow steel has a larger displacement of 0.84 mm while 40x60 hollow steel with a thickness of 1 mm only has a displacement of 0.44 mm. Therefore, 40x60 hollow steel with a thickness of 1 mm is more recommended to be used as a frame for this electric tricycle.

This study focuses on the pin shaft failure accidents occurring during the construction of concrete pump trucks and hypothesizes that the accidents are caused by improper installation of the pin shaft mounting angle (defined as the angle between the oil passage axis and the horizontal plane). First, the actual operating conditions were simplified to design an equivalent test, through which the stress distribution of the pin shaft under the 360° rotation condition was measured and understood. Then, simulation analysis was conducted to verify the stress concentration phenomenon under different pin shaft mounting angles. The results show that the pin shaft mounting angle at the accident site falls within the high-stress zone centered on the oil cylinder axis, verifying the hypothesis. In addition, the high-stress zone of the pin shaft does not change with the rotation angle of the pin shaft; it is only related to the position of the oil cylinder axis and distributed symmetrically around the oil cylinder axis. Therefore, to prevent the pin shaft failure accidents, the mounting angle of the pin shaft can be adjusted to keep it away from the high-stress zone near the oil cylinder axis.

The purpose of this study is to investigate the buckling behavior and failure mechanism of the boom of large-scale elevating jet fire trucks, so as to provide support for its safety design and service life improvement. In terms of research methods, a combination of double-version control tests and refined finite element simulations was adopted to carry out a systematic study. The research results show that the boom base plate exhibits typical sinusoidal wave buckling deformation when the load coefficient is between 0.45 and 0.5, and the wavelength is highly consistent with the theoretical prediction; under the critical load, the strain amplitude shows a significant nonlinear jump, which confirms the buckling mechanism of the coupling between geometric nonlinearity and material plasticity; under the ultimate load, the structure undergoes local buckling failure, the failure location is in good agreement with the simulation prediction, and the test results are highly consistent with the simulation results within the engineering allowable range, which verifies the reliability and applicability of the model. The research conclusion is the establishment of evaluation criteria for buckling failure of box-type knuckle arms: visible buckling waves appear, and the strain exceeds 40%. Based on this conclusion, optimizing the width-thickness ratio of the plate, strengthening the web constraint and improving the manufacturing process can effectively enhance the anti-buckling performance of the thin-walled box structure.

Aiming at the current bottleneck problem that restricts the practical application of robot system engineering in transmission line live operation, in order to improve the on-line and off-loading efficiency of live working robots on transmission lines and improve the practical level of the robot system as a whole, this paper proposes a design and operation method of autonomous on-line and off-loading mechanism of double-arm live working robots based on UAV assistance. Firstly, the realization process of autonomous up-and-down of the robot was analyzed, based on which the structure of the auxiliary hook of the up-and-down system and the lifting winch were designed. Then, the force analysis was carried out on the up-and-down process of the robot, and the appropriate winch drive motor was selected through theoretical calculation. In order to ensure the rationality of the up-and-down process, the operation motion planning was carried out on the up-and-down of the robot. Stress analysis and simulation were carried out on the maximum load bearing point of the auxiliary hook and the walking wheel mechanical arm under different states, and the results showed that the hook and the robot arm could meet the requirements of the robot loading and unloading, and the whole robot loading and unloading system was designed reasonably. Compared with the traditional loading and unloading system designed in this paper, the loading and unloading efficiency could be improved. It has important theoretical significance for the development of the physical system of robot uplink and down.

With the development of UHV transmission technology, large-tonnage disc-type suspension porcelain insulators have been widely used. Insulators with cylindrical heads have the advantages of light weight and high strength compared with traditional insulators with conical heads. Cement is an important part of disc-type suspension porcelain insulators. The drying shrinkage of cement can lead to sliding between cement and porcelain. It can also transform the stress distribution of the porcelain, thus influencing the overall long-term mechanical performance of the insulators. In this paper, the effect of the shrinkage of cement on the stress distribution of porcelain insulators was studied by simulation. In addition, the effect of the drying shrinkage rates of cement on insulators with cylindrical and conical heads were compared. The simulation results show that cylindrical-head insulators can better resist the stress change caused by cement shrinkage than the conical-head insulators, which was beneficial to the long-term performance of the insulators. Based on the tensile stress of porcelain parts, the recommended range of the drying shrinkage rate of cement for insulators with cylindrical heads was presented. The research results are of practical value for the selection of cement.

The aim of this study is to analyze the stress exerted on a four-bar link-type transplanting device using two distinct methods: stress measurement performed during a field test and stress simulation. A field test is conducted to measure stress using a strain gauge positioned at 15 specific points on the transplanting device. Subsequently, the measured strain data are converted into calculated stress data. In another method, stress is simulated using specialized multibody dynamic simulation software. The simulation results are compared with the stress measured during field tests to verify the simulation model. Based on the results, the maximum stress derived from the simulation correlates with the measured results, although notable discrepancies are shown, particularly at strain gauge positions 11 and 13. The maximum stress derived from the simulation is used to calculate the static safety factor of the transplanting device. The peak stress derived from the simulation aligns with the measured results, although significant discrepancies are observed at positions corresponding to strain gauges 4 and 10. The maximum stress (150.82 MPa) is observed on the link of the transplanting device, and the static safety factor determined via the simulation is 1.39.

Abiotic stress and low resource-use efficiency are among the main challenges in agricultural production systems. Stress management is key to sustainable production. It is still challenging to identify and manage prevailing stresses under field conditions due to limited knowledge of the mechanisms of multiple abiotic stressors in crops. Crop models are becoming popular in agriculture because of their diversified nature in identifying multiple abiotic stresses and resource-use management in the complex nature of agricultural production systems. This study combined field measurements and crop modeling to improve the understanding of below- and above-ground resources use (water, nutrients, and light) and their impact on crop productivity and stress management under various planting conditions. A two-year field trial was conducted in the Thai uplands, comparing six treatments: (T1) maize sole crop with tillage and fertilization; (T2) maize-chili intercropping with tillage and fertilization; (T3) same as T2 but with minimum tillage and Canavalia ensiformis relay cropping; (T4) same as T3 plus Leucaena hedgerows; (T5) same as T3 without fertilization; and (T6) same as T4 without fertilization. The Water Nutrient and Light Capture in Agroforestry Systems (WaNuLCAS) model was calibrated using data from T1, T4, and T6 and evaluated against independent observations from T2, T3, and T5. Row-wise aboveground biomass, grain nitrogen (N) and phosphorous (P) concentrations, δ¹³C values, soil volumetric water content, and root length density were measured over two growing seasons. Grain δ¹³C values were significantly less negative in rows near the hedge (−10.33‰) than in distant rows (−10.64‰). More negative grain δ¹³C values (−9.32‰, p ≤0.001) were observed in T6. Both field observations and model simulations showed reduced maize biomass and lower grain N and P concentrations in rows closest to the hedgerows, driven by root competition for nutrients. Soil moisture was consistently higher in intercropped systems, and hedgerow height control prevented shading, indicating no water or light limitations. From the results it is concluded that WaNuLCAS model accurately reproduced spatial biomass patterns ( EF = 0.95 , RMSE = 0.98 , and R2 = 0.96 ) and correctly identified nitrogen and phosphorus stress in maize rows planted closely with leucaena hedgerows. Scenario simulations demonstrated that balanced increases in both N and P inputs most effectively alleviated nutrient competition and improved the long-term system productivity. This integrated field-model approach provides a robust framework for diagnosing resource competition and optimizing nutrient management in hedgerow-based agroforestry systems under upland conditions.

Stress measurements play a crucial role in safety analyses of transplanting devices. Strain gauges for stress measurements during field tests can be expensive and time-consuming. The aim of this study was to investigate the stress on the transplanting device of a cam-type semiautomatic vegetable transplanter using a simulation method. A three-dimensional simulation model was established, considering the dimensions and material properties of the transplanting device. The stress distribution and maximum stress values were obtained through simulations. The maximum stress values at 15 points within the transplanting device determined via the simulation were compared with the experimental stress data to verify the stress simulation model. The results show that the maximum stress obtained from the simulation correlated with that of the measured results, although differences were observed at different locations, particularly at strain gauge positions 11 and 13. Based on the simulation results, the maximum stress occurs at the upper link of the cam-type transplanting device, reaching a magnitude of 201.21 MPa, and the static safety factor is 1.04.

The growing burial depth increases the potential risk of ground stress-induced coal and rock dynamic disasters in coal mining. This study attempts to use microseismic and computed tomography (MS-CT) to quantitatively characterize the stress field in coal seam areas. A comprehensive approach encompassing laboratory experiments, numerical simulations, and field investigations was employed to accomplish this objective. The experimental findings suggest a power function relationship between the wave velocity of coal and stress. The model relating wave velocity ratio to stress proves more suitable for research on stress field quantification. This model captures the positive correlation between wave velocity and stress changes and eliminates the influence of sample differences through normalization, rendering the fitting parameter b applicable in the field. This paper takes the No.22 coal seam of Jinjia coal mine as the research object; MS-CT technology was used to generate the cloud map of wave velocity field distribution in the 11224 working face and combined with the experimentally established relational model to relate the wave velocity ratio to the stress and calculate the results of quantitative characterization of the regional stress. At the same time, a detailed three-dimensional numerical model was established and simulated to obtain the stress distribution in the 11224 working face area. Comparison of the simulated stress field results with the quantitative results of MS-CT shows that the general trend is basically the same, and the stress is higher in the area with greater burial depth. The area affected by the overlying goaf has lower stress in the coal seam. The maximum error value of the two is within ± 2 MPa, and the correlation coefficient is 0.79, indicating a strong correlation. Therefore, the MS-CT technique combined with the experimental wave velocity-stress coupling relationship model can determine the stress field distribution and realize the quantitative stress characterization. This provides a crucial foundation for analyzing the mechanical model of coal seam instability and calculating the judgment index of coal-rock dynamic disaster excitation.