Study on separation characteristics of two-phase flow in double helical separator

The helical separator plays an important role in improving the working efficiency of electric submersible pump. Separation efficiency of two-phase flow in double helical separator is studied by numerical simulation and theoretical calculation. It is found that the separation efficiency of helical separator increases with the increase of gas-liquid ratio and flow rate. At the same time, under the condition of constant helical number and gas-liquid ratio, the separation efficiency is best when the even difference of pitch is 10 mm

Two-phase simulation of the pressure loss in helical channel

The CFD simulations are carried out for the flows in a helical gas-liquid separator, which is installed at the inlet of the electric submersible pump (ESP) to separate gas from gas-liquid mixture and keep the efficiency of the pump. The effects of mass flux, curvature and helix angle on two-phase pressure drop have been investigated. Through theoretical analysis and numerical simulation, it is found that the mass flux of two-phase flow and the curvature of spiral passage have influence on pressure drop, while the spiral angle has little effect on pressure loss

Design of a robotic system for battery dismantling from tablets

Due to the rapid increase in sales of mobile electronic devices, the number of batteries ending up in waste electric and electronic equipment (WEEE) is also rapidly increasing. According to the EU legislation, all batteries need to be removed from WEEE, which is currently done manually for tablets, posing potential safety risks for workers and resulting in high processing costs due to the labour intensity of the required dismantling operations. Therefore, a robotic dismantling system is developed in this research to automatically remove both the back covers and batteries from a mixed waste stream of tablets of different models and brands. At the outset of the design process, a total of 47 randomly collected tablets were analyzed to define the location of the battery and the required manual dismantling time. Thereafter, a robotic bending method was tested for removing the back cover. Once the battery is exposed, two different methods are tested: using a heat gun to loosen the glue that fixes the battery to the rest of the tablet and a robotic scraping method with a spatula to mechanically extract the battery. Whereas the required time for only the heating showed to be more than 120s, the results with the bending and scraping tool show that the proposed robotic dismantling system is capable of removing the back cover and battery for 63% of the tested tablets in less than 90s. However, to increase the economic viability and robustness of the proposed method to be able to cope with the high variety in tablet model designs, future work is required to develop algorithms to recognize product models to enable to define and retrieve product specific toolpaths for dismantling.Peer ReviewedPostprint (published version

Effect of ZrO2-toughened Al2O3 ceramic particles on impact abrasive properties of reinforced high-chromium cast iron matrix composites

Traditional wear-resistant steel materials can hardly meet the needs of modern mining equipment for key wear-resistant components, and ceramic particle-reinforced steel-based wear-resistant composites have become one of the most promising wear-resistant materials. ZrO2 toughened Al2O3 ceramic particles reinforced with high chromium cast iron (HCCI) matrix composites were prepared by pre-sintering to obtain ceramic preforms with different volume fractions and particle sizes in combination with the casting and infiltration method. The results show that with the increase of ZTA (ZrO2-toughened Al2O3) particle volume fraction (25%-45%) and the decrease of ZTA particle equivalent diameter (1.7, 1.2, 0.4 mm), the impact wear resistance of the composites improves, with the best at 45% particle volume fraction and 0.4 mm equivalent particle diameter.The main wear characteristic of ZTAp/HCCI composites is the occurrence of microcutting on the wear surface, and its main wear mechanism is abrasive wear

Experimental Study on the Fracturing Behaviors and Mechanical Properties of Cracks under Coupled Hydro-Mechanical Effects in Rock-like Specimens

The artificial fracturing technique under coupled hydro-mechanical effects is widely used in many rock engineering. Therefore, the study on the fracturing behaviors and mechanical properties of hydro-mechanical coupled cracks is very crucial. In this study, a series of fracturing tests were conducted on the cylinder gypsum specimens with single pre-existing cracks using triaxial compression loading system. Water pressure was applied inside the pre-existing cracks and led to the specimen failure with external compression loading. A new type of cracks, namely horizontal coupled cracks (HCC), were found in some specimens. Macroscopic observations reveal that HCC, which were mainly caused by the hydraulic pressure, were different from any tensile wing cracks, shear secondary cracks, or shear anti-wing cracks. Subsequently, a microscopic study was performed using scanning electron microscope (SEM), the outcomes suggest that: (1) Shear fracturing zones (SFZ) and tensile fracturing zones (TFZ) under coupled hydro-mechanical effects displayed distinct characteristics on orientations, length, and independence of gypsum grains; and (2) the HCC were tensile cracks when they just initiated from outer tips of pre-existing cracks. While tensile stress made major contribution to the specimen failure during the whole fracturing processes, the HCC became tensile and shear mixed cracks when the specimen was about to fail

Integration of Vertical and Horizontal Deformation Derived by SAR Observation for Identifying Landslide Motion Patterns in a Basaltic Weathered Crust Region of Guizhou, China

In recent years, due to adverse geological conditions, intense human engineering activities, and extreme weather conditions, catastrophic landslides have frequently occurred in southwest China, causing severe loss of life and property. Identifying the kinematic features of potential landslides can effectively support landslide hazard prevention. This study proposes a remote sensing identification method for rotational, planar traction, and planar thrust slides based on geomorphic features as well as vertical and slope-oriented deformation rates. Rotational landslides are characterized by similar vertical and horizontal deformation rates, with vertical deformation mainly occurring at the head and gradually decreasing along the slope, while horizontal deformation mainly occurs at the foot and gradually increases along the slope. As for the planar slide, the dominant deformation is in the horizontal direction. It is further classified into the planar traction and planar thrust types according to the driving position. The vertical deformation of planar traction slides is concentrated at the foot, while the vertical deformation of planar thrust slides is concentrated at the head of the landslide. We identified 1 rotational landslide, 10 planar traction landslides and 10 planar thrust landslides in the basalt weathering crust area of Guizhou. Field investigations of three landslides verified the method’s accuracy. Combining two-dimensional rainfall and time-series deformations, we found that there is a significant positive correlation between landslide deformation acceleration and precipitation. The landslide kinematic identification method proposed in this paper overcomes the shortcomings of the inability to accurately characterize landslide motion by line-of-sight displacement and realizes the non-contact identification of active landslide motion patterns, which is an essential reference value for geological disaster prevention and control in the study area

DRs-UNet: A Deep Semantic Segmentation Network for the Recognition of Active Landslides from InSAR Imagery in the Three Rivers Region of the Qinghai–Tibet Plateau

At present, Synthetic Aperture Radar Interferometry (InSAR) has been an important technique for active landslides recognition in the geological survey field. However, the traditional interpretation method through human–computer interaction highly relies on expert experience, which is time-consuming and subjective. To solve the problem, this study designed an end-to-end semantic segmentation network, called deep residual shrinkage U-Net (DRs-UNet), to automatically extract potential active landslides in InSAR imagery. The proposed model was inspired by the structure of U-Net and adopted a residual shrinkage building unit (RSBU) as the feature extraction block in its encoder part. The method of this study has three main advantages: (1) The RSBU in the encoder part incorporated with soft thresholding can reduce the influence of noise from InSAR images. (2) The residual connection of the RSBU makes the training of the network easier and accelerates the convergency process. (3) The feature fusion of the corresponding layers between the encoder and decoder effectively improves the classification accuracy. Two widely used networks, U-Net and SegNet, were trained under the same experiment environment to compare with the proposed method. The experiment results in the test set show that our method achieved the best performance; specifically, the F1 score is 1.48% and 4.1% higher than U-Net and SegNet, which indicates a better balance between precision and recall. Additionally, our method has the best IoU score of over 90%. Furthermore, we applied our network to a test area located in Zhongxinrong County along Jinsha River where landslides are highly evolved. The quantitative evaluation results prove that our method is effective for the automatic recognition of potential active landslide hazards from InSAR imagery