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The flexible drill string with hinges is a unique structure for drilling ultra-short radius horizontal wells. In this paper, spatial beam elements are used to simulate the flexible drill string and outer tube, universal joint connection elements are used to simulate hinge joints, and contact gap elements are used to simulate the random contact between the flexible drill string and the outer tube. A nonlinear mechanical analysis model is established for the contact of the flexible drill string with hinges in the outer tube, and the dynamic relaxation method is adopted to solve the model. The correctness of the model and method is verified by an example with analytical solutions. Numerical calculations are conducted on six types of hinge rotation limits and six different single section lengths of flexible drill strings in the inclined section. The results illustrate that the contact force between the flexible drill string and the outer tube is discontinuous and randomly distributed along the axis. The hinge rotation limit is increased from 3° to 5.5°, the axial force transmitted to the bottom of the flexible drill string is reduced from 16.7 kN to 1.5 kN, and the torque transmitted to the bottom has little changed, and its values are close to 1900N·m. When the hinge rotation limit is greater than 5 degrees, the axial force loss rate is greater than 59.5 %. When the hinge rotation limit is 4 degrees, the axial force and torque transmitted to the bottom of the well have little change for flexible drill strings of different single section lengths.

The hub bearing with face spline transmission is a new type of hub bearing. The design method and standards are lack. In this work, the geometric relationship of the tooth profile parameters and the meshing situation are derived for the hub bearing face spline. The outer diameter D, number of teeth Z, and face tooth profile angle φ are key design parameters. The verification conditions for preload, extrusion stress, tooth root bending stress, and shear stress are established based on strength theory and assumption of uniform load distribution. To validate the design, a case study is conducted on the hub bearing face spline in a certain vehicle model, with theoretical calculation and simulation of stress by using Finite Element Method. The present FEM results compare well with those of the literature data. Finally, through the incorporation the torque strength and durability tests of the face spline, the reliability of the design theory in this work is confirmed. The results indicates that, the tooth tip fillet r1 has a significant impact on the meshing area, the maximum principal stress near the tooth root is highest at the arc of the tooth root, proving that the selection of the dangerous section is appropriate. The work has value in promoting the development of automotive wheel hub bearings.

In the process of modifying titanium alloy oral implants using cavitation water jet, the collapse of bubbles releases significant energy. This phenomenon is accompanied by micro-jets and shock waves, which induce changes in the three-dimensional microscopic morphology of the implant surface. The loose and porous surface of the implant will increase the adhesion area of the cells, which is more conducive to the combination of the oral implant with the surrounding bone tissue. In order to explore the coupling mechanism between the instantaneous energy of bubble collapse and the surface deformation of titanium metal, based on different flow field and solid field model parameters, the numerical analysis software Ansys and the fluid-structure coupling simulation method are used to establish the numerical simulation model of single bubble collapse on the near curved wall. In order to explore the coupling mechanism between the instantaneous energy of bubble collapse and the surface deformation of titanium metal, the bubble growth process is ignored. Based on different flow field and solid field model parameters, this paper adopts the numerical analysis software Ansys and the fluid-structure coupling simulation method to establish the numerical simulation model of single bubble collapse on the near curved wall. The effects of flow field parameters and wall morphology on the transient flow field of bubble collapse and the effect of metal surface modification are revealed. The results show that when the initial bubble diameter is 180 μm, the instantaneous collapse high pressure reaches 7.24 GPa, and the maximum stress on the titanium surface is 689 MPa, which is 1.57 times higher than that under the bubble diameter of 60 μm. When the bubble collapses away from the wall, due to the weakened constraint of the wall, more intense energy is released, but the energy decays rapidly in the propagation process, and the energy loss when it reaches the wall is more serious. In this paper, the surface micromorphology is simplified into a near-curved shape. After the modification, the flow obstruction on the near-curved concave wall inhibits bubble collapse, resulting in an increase in bubble collapse time. The stress and deformation caused by a single bubble collapse are concentrated within a radius of 1mm and a depth of 5 μm.

With the advancement of urbanization, two-lay trusses bridges are widely used because of their good traffic capacity and structural performance. However, the aerodynamic behavior of this beam type is still in the exploratory stage. The local microclimate characteristics at the bridge site in mountainous cities are obvious, and it is easy to form a large wind angle of attack, which has a significant impact on the vortex-induced vibration (VIV) performance of the bridge. Therefore, this study takes a long-span two-lay steel trusses bridge in a mountainous city as the engineering background, and uses wind tunnel test and numerical calculation methods to study the changes of the static three-component force coefficient and VIV response of the main beam in the construction and completion state under the action of high wind angle of attack. The results show that the three-component force coefficient curves under different wind speeds are close to each other, and the Reynolds number effect is not obvious. The vibration test shows that the vertical bending VIV first occurs at +3° and +5°, and then two torsional VIV with different amplitudes occur. Both vertical bending and torsional VIV are simple harmonic vibrations with a single frequency, and the vertical bending VIV frequency is locked at 2.227 Hz, and the torsional VIV frequency is locked at 4.289 Hz, which are close to the natural frequency of the test model. Compared with +3°, the maximum amplitude of vertical bending VIV under +5° increases by 30.0 %, while the maximum amplitude of torsional VIV under high and low wind speed increases by 16.6 % and 12.7 % respectively, and the locking range is longer. It can be seen that the wind angle of attack has a significant effect on the VIV response of the main beam in the completion state. Especially, the trusses beam at a large angle is more sensitive to VIV, and it is more prone to large-scale and large-amplitude VIV. The research results can provide a theoretical basis for the aerodynamic shape optimization and provide a reference for the design of related bridges.

Fixed-wing drones generate lift using a wing similar to a conventional airplane, in contrast to rotary helicopters. As a result, these machines use energy solely for propulsion rather than to maintain altitude, making them significantly more efficient. These devices can traverse greater distances and cover larger areas, making them capable of mapping and monitoring specific points over extended periods. This article uses an analytical nonlinear approach to look at how discrete H∞ can be used as a robust controller to manage the path of a quadrotor. The main goal is to create a discrete H∞ nonlinear output feedback algorithm that can accurately track the position of the quadrotor while staying stable, even when there are unknowns, disturbances, or noise. The discrete formulation of this algorithm makes it especially suitable for multi-engine aircraft. By designing the controller in a discrete space first, transitioning to a continuous phase, and then reverting to discrete space for real-world application, more desirable and design-aligned results can be achieved. However, transitioning from continuous to discrete controllers may sometimes cause deviations from the design specifications. Designing the controller directly in the discrete space simplifies the overall process and enhances robustness.

Image recognition, a subset of artificial intelligence, has been applied to various industries, including steel recycling, to enhance efficiency and accuracy in quality control processes. This review paper provides an overview of the current state of image recognition technology in steel recycling, including the types of images used, the algorithms employed, and the benefits and limitations of the technology. The paper also discusses potential future directions for image recognition in steel recycling, such as integrating machine learning and deep learning frameworks to improve accuracy and developing mobile applications for on-site quality control. Overall, image recognition technology has shown great potential in the steel recycling industry, and further research and development in this field could lead to significant improvements in efficiency and quality control. Experimental results show that the precision of steel scrap classification is 0.92, and the precision of steel scrap quality judgment is 0.87. The empirical findings indicate that this technique can swiftly and precisely detect the type of steel scrap and evaluate its quality, it can also identify the existence of dangerous goods. The model can directly help enterprises reduce costs and increase efficiency, is conducive to the full recovery of scrap steel, and positively affects environmental protection and enterprise profits.

Lanes changing is one of the basic behaviors of vehicle driving, which has a significant impact on road traffic safety and stability. Aiming at the problem of slow convergence rate in solving the optimal control problem of vehicle lane changing, an optimal lane changing control method based on hp adaptive pseudospectral method is proposed. By establishing a vehicle kinematic model, boundary constraints, and path constraints, combining with the physical process of vehicle lane changing the proposed method discretizes the control and state variables to transform the multi constraint optimal control problem into a nonlinear programming problem and the minimum vehicle lane changing time is set as the performance objective function. And also, the proposed method is compared with traditional solving methods. The simulation results show that the proposed method can effectively solve the optimal feasible lane changing trajectory and complete the lane changing maneuver process in the shortest possible time.

The accurate assessment of stresses, strains and loads in components under working conditions is an essential requirement of successful engineering design. In particular, the location of peak stress values and stress concentrations, and subsequently their reduction or removal by suitable design, has applications in every field of engineering. The current work presents a technique for experimental strain measurement, where a data acquisition system have been composed of strain gauge sensors and an Arduino microcontroller. The measured signal conditioning is performed by means of strain bending sensor and then discretized by an analog-digital converter external to the Arduino. To realize the full-field measurement, the current measuring approach can be employed to determine the induced strain in multi points simultaneously. The significant features of the proposed measuring system are: sensitive, precise, economical, and compact size. For the purpose of results verification of the designed measuring device, experimental tests have performed on a cantilever beam and on a simply supported thin plate loaded at the center. An average percentage error was 5.7 % between analytical and experimental recorded strains in beam test. Also, in rectangular plate loading, an average percentage errors were 5.8 % and 4.1 % for the measured strains numerically and experimentally in X-direction and Y-direction respectively. The conducted results indicated a good agreement and demonstrate the accuracy of the proposed measuring system.