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During gas drilling, the drill string friction is directly related to the safety of drilling and tripping. When the drill string reaches the horizontal section, the friction problem is prominent, which greatly increases the risk and difficulty of trajectory control in the horizontal section. The purpose of this paper is to study the frictional characteristics between drill string and wellbore wall. Firstly, the dynamic mathematical model of drill string in gas drilling is established, a new boundary conditions between wellhead and bottom hole is proposed. Secondly, the governing equation of drill string system is established by using Lagrange equation. Thirdly, the improved Generalized-α method is used to solve the dynamic equation of drill string system. Finally, the effects of weight on bit (WOB) and rotational speed on friction torque of drill string system are analyzed, as well as the effects of different borehole curvature and friction coefficient on friction characteristics of drill string. The findings indicate that as the WOB and rotational speed increase, the lateral motion range and friction torque of the drill string gradually rise; With an increase of borehole curvature and friction coefficient, the friction resistance of the drill string increases obviously. Additionally, it is observed that the average friction resistance of the drill string is greater in horizontal sections compared to vertical and deflecting sections. The average lifting friction on the drill string is less than the lowering friction. Theoretical research plays a crucial role in guiding the optimization of drilling parameters and the implementation of friction reduction.

The study of the acoustic characteristics of sound-absorbing structures (SAS) seems to be an urgent task aimed at solving the problem of noise both in the cabin of aircraft and aircraft engine noise. Results of experimental study of the effect of the size of the cell edges of a fiberglass honeycomb core and the degree of perforation on the acoustic characteristics of single-layer sound-absorbing structures are presented. Tests of samples of sound-absorbing structures were performed on an interferometer type installation with a normal incidence of sound waves. The dependence of the acoustic characteristics of SAS on the size of the edge of the honeycomb filler is shown, in connection with the overlap of the holes of the perforated sheet of SAS with the edges of the honeycomb block. The dependence of the resonant frequency and the efficiency of the structure on the diameter of the holes of the perforated sheet are shown.

The results of full-scale acoustic tests of a Ptero-G0 unmanned aerial vehicle (UAV) in an anechoic chamber are presented. The aim of the work is to determine the acoustic characteristics of a Ptero-G0 UAV and to assess the influence of various parameters on the noise level of the device. A unique aspect of the experiment is that a full-scale apparatus with a power plant including a single-cylinder 4-stroke piston engine and 2-bladed fixed-pitch propeller, was studied. Data on the spectral, energy and directivity characteristics of the UAV and its power plant were obtained. The tests assessed the effects of incoming flow velocity, power condition of the power plant, pitch angle of the UAV, propeller diameter, and vibrations of the bonnet on the UAV noise. In particular, increase in the power condition (engine speed) and incoming flow velocity led to an increase in spectral noise levels in the 1/3-octave frequencies bands ranging from 40 to 10,000 Hz. At the same time, background levels up to 40 Hz were determined by background noise. The influence of engine speed and incoming flow velocity on the directivity pattern has not been established. An increase in propeller diameter at a constant speed resulted in higher circumferential speed of the propeller and thrust, as well as increased load on the engine. As a result, intensity of the tonal components of propeller and engine noise increases. A slight decrease in diameter (by 6 %) led to a decrease in the overall noise level by 1.3 dB. Placing the engine in the bonnet without a vibration insulation system led to an increase in the overall sound pressure levels by up to 2.5 dB.

In the context of intelligent vehicles, low- and medium- precision Inertial Measurement Units (IMU) are plagued by high levels of noise and considerable output uncertainly. When positioning and attitude estimation rely solely on IMU data, errors rapidly accumulate over time. To address this issue, this paper introduces a Convolutional Neural Network (CNN)-based noise-adaptive invariant extend Kalman filter (IEKF) vehicle localization. The proposed approach develops CNN models tailored for IMU measurement data as well as the process noise and observation noise in the IEKF. An enhanced CNN architecture and convolution mechanism are designed to dynamically adjust the covariance matrices associated with both process noise and observation noise in response to varying IMU input. This integration with IEKF principles ensures real-time positioning while achieving high accuracy in position prediction. The proposed method was tested and validated on 16 IMU sequences from the KITTI dataset, resulting in a relative translation error performance improvement ranging from a minimum of 10 % to a maximum of 24 % when compared to four existing methods. Additionally, its performance was further evaluated through various metrics including cumulative distribution of errors, root mean square error, and absolute position error. Trajectory tracking experiments further demonstrated that the proposed method produces smoother localization curves and more stable positioning performance.

This study evaluates the fatigue properties of corroded weathering steels to assess their long-term structural safety, durability, and economic feasibility. The fatigue life of two groups of weathering steel is measured by experiment. The first group consists of non-corroded specimens, while the second group is subjected to atmospheric corrosion for a duration of one year. The fatigue life of weathering steel is predicted by numerical calculation. It is found that the fatigue life of numerical simulation can accurately predict the fatigue life of butt weld specimens and provide a certain safety margin. The difference between the two is 2.5 %, which is a strong validation of the method. Then, Utilizing the ABAQUS and FRANC3D interactive platforms, the study achieves numerical computations for initial crack insertion and crack propagation under fatigue loading, and the influence of stress amplitude, initial crack size, initial crack shape, initial crack position, and welding dislocation on fatigue life is analyzed. Nine different stress amplitudes are simulated, and the fatigue life difference between the stress amplitudes of 117 MPa and 189 MPa being 31.72 %. Six different initial crack sizes are simulated. The initial crack sizes are 0.075 and 0.5 mm, and the difference in fatigue life between the two is 48.58 %. Four different initial crack shapes are simulated, and the fatigue life difference between the short axis and the long axis ratio of 1/4 and 1/1 of the initial crack is 30.70 %. Three initial crack positions are simulated, and the difference in fatigue life at different positions is less than 10 %. The effects of four different sets of angular dislocations on fatigue life are simulated. Angular misalignment in butt weld specimens has a minimal effect on fatigue performance, approximately 1 %, provided that the flatness requirements of the specifications are met. However, when the flatness requirements exceeded the specification, the effect on the specimen was greater than 30 %, and its effect cannot be ignored. Based on fatigue detail tests of corroded weathering steel, this paper proposes and validates a method for evaluating the fatigue life of weathering steel after corrosion, and clarifies the factors influencing the fatigue life of weathering steel structures, the proposed method can provide support for the design of fatigue details of weathering steel bridges.

Understanding the potential distribution in liquids is critical due to its significant differences from general media. The main problem addressed in this research is the lack of clarity on how electrode polarization affects potential distribution in liquid electrolytes. To investigate this, we experimentally measured the potential distribution characteristics in liquids under DC and AC voltages, explaining the variability through electrode polarization theory. Our action included introducing electrode polarization potential correction in COMSOL software simulations, which showed strong agreement with our experimental results. Further, we investigated the potential distribution characteristics in Na2SO4 solutions with varying concentrations, using ionic potential to explain voltage formation inside the liquids. The results highlight the improved accuracy in modeling potential distributions in liquid electrolytes, which is significant for advancing various electrochemical processes.

The multi-degree-of-freedom engine mount system presents a coupling issue that significantly impacting its vibration isolation performance. Although the optimization theories for decoupling 6-degree-of-freedom (6-DOF) and 12-degree-of-freedom (12-DOF) engine mount systems are relatively well-developed, previous studies have predominantly focused on engine response and often overlook the impact of car body vibrations. To address this gap, this article conducts an in-depth investigation into how the elasticity of the car body affects the vibration isolation performance of the engine mount system. Initially, the dynamics of the engine mount system are modeled with 6 degrees of freedom, incorporating an elastic base with 9 and 12 degrees of freedom, respectively. The study then analyzes how body elasticity influences the natural frequencies and modal shapes of the engine mount system. Subsequently, the sensitivity of the engine mount system is assessed using Isight analysis to evaluate the three directional stiffnesses of the mount. Finally, the decoupling optimization of the 12-degree-of-freedom engine mount system is performed using the NLPQL (Sequential Quadratic Programming) method. The findings indicate that: (1) considering the car body’s influence directly affects the natural characteristics and decoupling efficiency of the engine mount system; (2) body elasticity in the Z-direction has the greatest impact on the system’s vertical natural frequency; and (3) the NLPQL method effectively enhances the decoupling rate of the engine mount system.

In CCUS ZEN project one of value chains considered includes emission sources located in the region of northern Poland. The value chain is intertwined with the scope of ECO2CEE Project of Common Interest on CO2 terminal in Port of Gdańsk. The ECO2CEE project in its first stage is to include railway transport of CO2 captured in two of the installations of the studied value chain. Carbon dioxide delivered to the terminal is to be transported by ship and stored under North Sea. However, within the region and its immediate vicinity there is notable storage potential. About 120 km north of Gdańsk, offshore, there is saline aquifer in Cambrian sandstones of storage capacity likely sufficient to store emissions of all selected 16 emitters of the region. The main barrier to such approach is the interpretation of Article 11 of Helsinki Convention suggesting ban of CO2 storage under the Baltic Sea. In southern part of the region where also ECO2CEE emitters are located there are several saline aquifer structures in Lower Jurassic and Lower Cretaceous of estimated storage capacity significantly exceeding the possible demand of emitters of the local cluster. Hence, the work is to propose the further development of the PCI value chain in northern Poland, beyond the original concept.