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The sleeve valve is a crucial component of the integrated water distributor utilised in offshore oilfields for waterflooding. Spool offset is highly correlated with sticking. However, the existing design does not consider the opening frequency, leading to elevated offset and deviating from the design goal. Therefore, a novel design method is proposed herein. The frequency of operation opening is categorised into the primary and the secondary operating conditions. The sensitivity of design parameters was identified using Morris sensitivity analysis, and genetic algorithms were used to optimise target variables for different operating conditions. The simulation results show that an average of 65.06% reduces the offset, and an average of 19.5% increases the mass flow rate. In particular, the offsets are near zero under the primary working condition. This approach can offer significant guidance for valve design under unique operation conditions of openings. [ABSTRACT FROM AUTHOR]

Downhole turbine generators (DHTG) installed within drill-string are susceptible to internal and external excitation during the drilling process, causing significant dynamic loads on bearings, and thereby reducing the bearing's service life. In this study, a finite element model of an unbalanced rotor-bearing system (RBS) of DHTG with multi-frequency excitations, based on the Lagrangian motion differential equation, is established. The responses of the RBS under different drill-string excitations in terms of time-domain response, whirl orbit, and spectrum are analyzed. For a constant rotor speed, lateral harmonic translational and lateral oscillation both transform the whirl orbit to quasi-periodic, while axial rotation only changes the response amplitude. Changing the duration of pulse excitation leads to different response forms. Then, the dynamic characteristics of the RBS supported by a squeeze film damper (SFD) are investigated. The results indicate that SFD effectively reduces the displacement response amplitude and bearing force near the critical speed. As the axial rotation angular velocity of the drill-string increases, the first critical speed and displacement response decrease, while the variation of lateral oscillation frequency and amplitude has limited impact on them. The established model provides a means for analyzing the dynamic characteristics of DHTG's RBS under drill-string excitations during the design stage. [ABSTRACT FROM AUTHOR]

The article presents a comprehensive summary of Intelligent Ship Marine Object Detection (ISMOD) based on the RGB Camera. Marine object detection plays a pivotal role in enabling intelligent ships to acquire crucial data and security assurances for autonomous navigation. Among the various detection sensors, the RGB Camera is an informative and cost‐effective tool with a wide range of civil applications. In the beginning, the ISMOD metrics based on the RGB camera is analyzed from three significant aspects, namely accuracy, speed, and robustness. Subsequently, the latest research status and comparative overview are presented, encompassing three mainstream detection methods: traditional detection, deep learning detection, and sensor fusion detection. Finally, the existing challenges of ISMOD are discussed and future development trends are recommended. The results demonstrate that forthcoming development will predominantly concentrate on deep learning approaches, complemented by other techniques. It is imperative to advance detection performance in domains such as deep fusion, multi‐feature extraction, multi‐fusion technology, and lightweight detection architecture. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel pipeline cleaning method utilizing slurry. The reason why slurry can be used for pipeline cleaning is that the collisions between the particles and the contaminant in the pipe wall can enhance the cleaning effect. A slurry with polypropylene particles embedded in water is used to cleaning a horizontal pipe is conducted to realize this method. Because the flow characteristics of the slurry is crucial for the cleaning process, it is valuable to conduct a simulation and investigate the influence of several different factors including the convey velocity and the particle size. A 3D CFD-DEM model has been established. The indicators including pressure loss, particle accumulation level at the top of the pipe are choses to characterize the slurry flow and the influence of convey velocity and particle size has been investigated accordingly. In addition, an effective method is proposed to determine the critical convey velocity for each size of the particle.

This study proposes a system to detect the phases of gait. It consists of an intelligent shoe equipped with an inertial measurement unit (IMU) and force-sensitive resistors (FSRs), and it uses a compound method to recognize gait. The continuous wavelet transform is applied according to accelerations obtained via the IMU to identify heel strike and toe-off events. These events are used to calculate the pressure threshold and proportional factor via the Lopez–Meyer (LM) method by using minimal leave-one-out for training and validation. The LM method can identify the entire sub-phase of the stance of the gait based on ground contact forces measured by using the FSRs and rules of gait event detection. The proposed system was tested on five healthy volunteers who used the intelligent shoe. The results show that it can detect all sub-phases of the gait with an overall accuracy (96%) higher than the LM method. The proportional factor was adaptable to variable body weights, and the reported average errors of competing systems in the literature significantly exceeded the average variation of the proposed system for all phases of gait. The range of errors in the swing phase and sub-phases of stance was also acceptable for application purposes. When the size of the subject's foot was close to that of the intelligent shoe, the error between normative data and phases of gait identified by the detection system was minimal. Furthermore, the proposed system detected abnormalities in the gait circle, and thus, it can be used to monitor the walking activity and measure the motor recovery. [ABSTRACT FROM AUTHOR]