The redundant system reliability simulation is based on Simulink. Through calling simulink module and compiling and calling S function and using subsystem encapsulation, establish the distribution function module base for index distributing, Wbell distributing, minus logarithm Γ distributing and also establish the model for redundant system reliability simulation. This method is used for complex redundant system reliability research.
Machine vibration, noise and cylinder barrel wearing are produced when ordinary piston air compressor driven by crank link mechanism is working. Piston air compressor driven by double-crank link mechanism is proposed in this paper to eliminate these problems. Secondary pressurized double-acting air compressor and two-stage double-acting air compressor based on symmetrical double-crank link mechanism are designed in this paper to increase air compressors output pressure and flow rate and to achieve output control of low pressure high flow and high pressure low flow. It can remove effects generated by lateral force, reduce the vibration and noise and the wearing of cylinder barrel, and improve the steadiness and the service life of the air compressor.
On 23 January 2024, an Mw 7.01 earthquake struck the Wushi County, Xinjiang Uygur Autonomous Region, China. The occurrence of this earthquake provides an opportunity to gain a deeper understanding of the rupture behavior and tectonic activity of the fault system in the Tianshan seismic belt. The coseismic deformation field of the Wushi earthquake was derived from Sentinel-1A ascending and descending track data using Differential Interferometric Synthetic Aperture Radar (D-InSAR) technology. The findings reveal a maximum line-of-sight (LOS) displacement of 81.1 cm in the uplift direction and 16 cm in subsidence. Source parameters were determined using an elastic half-space dislocation model. The slip distribution on the fault plane for the Mw 7.01 Wushi earthquake was further refined through a coseismic slip model, and Coulomb stress changes on nearby faults were calculated to evaluate seismic hazards in surrounding areas. Results indicate that the coseismic rupture in the Mw 7.01 Wushi earthquake sequence was mainly characterized by left-lateral strike-slip motion. The peak fault slip was 3.2 m, with a strike of 228.34° and a dip of 61.80°, concentrated primarily at depths between 5 and 25 km. The focal depth is 13 km. This is consistent with findings reported by organizations like the United States Geological Survey (USGS). The fault rupture extended to the surface, consistent with field investigations by the Xinjiang Uygur Autonomous Region Earthquake Bureau. Coulomb stress results suggest that several fault zones, including the Kuokesale, Dashixia, Piqiang North, Karaitike, southeastern sections of the Wensu, northwestern sections of the Tuoergan, and the Maidan-Sayram Fault Zone, are within regions of stress loading. These areas show an increased risk of future seismic activity and warrant close monitoring.
Vibration control is important in maintaining the silence of the underwater vehicle. Among the many methods of vibration control, isolation is by far the most efficient approach. However, as one of the major vibration sources in underwater vehicle, the vibration isolation of the sea-water pump has not been well explored. The sea-water pipe is the primary vibration transmit path from the sea-water pump to the housing. In order to realize the vibration isolation of the sea-water pump, the sea-water pipe must have certain flexibility and damping. In this study, scaled model tests were carried out to investigate the isolation effectiveness of flexible pipes in isolated sea-water pump. Specifically, three types of flexible pipes, i.e., double layer metal bellows (DLMB), rubber pipes (RP) and bellows coated rubber (BCR) were designed and tested. Tests were carried out under the operation rotate speeds of the sea-water pump. Our results show that compared with single layer metal bellows (SLMB), the isolation effectiveness of DLMB and BCR were significant and stable in high frequency regions. The optimal pipe can be chosen for different vibration reduction requirements in practical engineering.
The impact of the viscosity and the density of transmission fluids on the performance of a hydraulic torque converter was examined. Four different transmission fluids were evaluated under different operating conditions by fluid temperature and speed ratio. The study utilized the computational fluid dynamics (CFD) method, which modeled the transmission fluid as an incompressible and Newtonian fluid and simulated the flow field inside the torque converter by numerically solving the governing equations of the fluid flow. The simulated flow fields of four different fluids were examined via mechanical performance parameters of the torque converter, including the k-factor and the efficiency. The transmission fluids were also experimentally evaluated using the modeled torque converter at two independent laboratories. Comparisons of the model predictions with the experimental results showed that the computational data agree well with the test data. A parametric study was performed by using the validated CFD model. The results indicate that the viscosity and density of the fluid have opposing effects on the performance of the torque converter studied.
Abstract In various engineering projects such as mineral extraction, hydropower resource utilization, railway construction, and geological hazard mitigation, rock engineering is often encountered. Furthermore, dynamic loads and moisture content exert notable influence on the energy transformation processes within rocks. Yet, the specific interplay of dynamic loading and water's impact on the energy conversion mechanism within the sandstone remains unexplored. To address this gap, this study conducted impact loading experiments on sandstone, elucidating the rock’s mechanical response under these conditions and unraveling the underlying energy conversion mechanisms. It was observed that the strength of sandstone exhibits a direct correlation with impact velocity. Moreover, employing energy calculation principles, we established a connection between moisture content and the sandstone’s internal energy conversion properties. The study also delved into the microscopic fracture mechanisms within the sandstone, ultimately concluding that both water content and dynamic loading have a significant impact on these microscopic fracture mechanisms.
The scraper conveyor is the unique transport equipment in coal mining face. Its chain drive system is the core subsystem. The dynamic characteristics of the chain drive system need monitoring for a safe mining. Existing monitoring methods include controlling the chain tension, chain speed and motor current. However, the above-mentioned methods have many disadvantages, such as difficult and costly to implement in mining face, due to the poor working environment and the limitations of the scraper conveyor's structure. This study proposes a monitoring method for the dynamic characteristics of the scraper conveyor on the basis of the speed difference between the head and the tail sprockets. Such an initiative is carried out to study the dynamic characteristics of the scraper conveyor under real working conditions and describe its running state. The speed difference of the head and tail sprockets under different chain speeds, terrains, and loads is monitored and studied. Research results show that the average and maximum speed differences are 0.797% and 0.990%, respectively. Due to the complex terrain, the tighter the scraper chain gets, the smaller the difference of the rotational speed is, compared with the flat working condition. The speed difference under load greatly increases compared with no load. Research results provide data support for the research of the chain drive system dynamics of the scraper conveyor. These results will also provide a new idea for the monitoring of the operating state of the scraper conveyor.
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