In applications such as marine rescue, marine science, archaeology, and offshore industries, autonomous underwater vehicles (AUVs) are frequently used for survey missions and monitoring tasks, with ...most operations being performed by manned submersibles or remotely operated vehicles (ROVs) equipped with robotic arms, as they can be operated remotely for days without problems. However, they require expensive marine vessels and specialist pilots to operate them. Scientists exploring oceans are no longer satisfied with the use of manned submersibles and ROVs. There is a growing desire for seabed exploration to be performed using smarter, more flexible, and automated equipment. By improving the field operation and intervention capability of AUVs, large-scale and long-range seafloor exploration and sampling can be performed without the support of a mother ship, making it a more effective, economical, convenient, and rapid means of seafloor exploration and sampling operations, and playing a critical role in marine resource exploration. In this study, we explored the integration technology of underwater electric robotic arms and AUVs and designed a new set of electric manipulators suitable for water depths greater than 500 m. The reliability of the key components was analyzed by finite element analysis and, based on the theory of robot kinematics and dynamics, simulations were performed to verify the reliability of the key components. Experiments were conducted on land and underwater, trajectory tracking experiments were completed, and the experimental data in air and water were compared and analyzed. Finally, the objectives for further research on the autonomous control of the manipulator underwater were proposed.
Gravity sampling is of vital importance for sampling seabed sediments and understanding submarine sedimentary environments and resources. In this study, a new bionic sampler tube (BST) with ...non-smooth surface for low-disturbance and rapid sampling is presented. The BST with depressions and swellings on its surface was designed on the model of the non-smooth surface of the dung beetle. Sufficient theoretical calculations, numerical simulations, and experimental tests were carried out to study its sampling performance. The penetration depth, sample length, and frictional drag of the sampler tube were calculated. The finite element model and the coupled Eulerian-Lagrangian (CEL) method were used to analyze and compare its sampling performance. Laboratory and field gravity sampling tests were conducted and the results demonstrated the advantages of the BST in improving sampling performance and in reducing adhesion and drag.
Robotic subsea stratum drilling robot is a method for new subsea stratigraphic geological investigation and resource exploration. Resistance at the front end is the main source of resistance to the ...robot’s motion in the strata. Since there is no continuous and strong downward drilling force as in conventional drilling rigs, robot movement relies heavily on the drill bit to reduce the drilling resistance. In this study we propose a self-propelling drill bit that can discharge soil debris to provide propulsive force and reduce the resistance. The key parameter of the drill bit design, the spiral blade lead angle, was determined by theoretical analysis of the drill bit’s soil discharging effect. To verify the structural advantages of the self-propelling drill bit in reducing resistance, a comparative analysis with a conventional conical drill bit was conducted. The drilling process of both bits was simulated using finite element simulation at various rotation speeds, the penetration force and torque data of both drill bits were obtained, and tests prepared accordingly in subsea soil were conducted. The simulations and tests verified that the penetration force of the self-propelling drill bit was lower than that of the conventional conical drill bit. The self-propelling drill bit can reduce the resistance effectively, and may play an important role in the stratum movement of drilling robots.
The northwestern sub-basin of South China Sea (SCS) is a unique tectonic unit formed in the early spreading of the SCS. The northwestern Sub-basin has a series of complex geological structures such ...as seamounts and fault zones surrounded by the Xisha Trough, the Zhongsha Massif, and the Pearl River Valley. These extensional structures and magmatic activity in the northwestern sub-basin are closely related to the lithospheric structure and its deformation. However, details of the deep lithosphere structure are still poorly known. Here, we obtained detailed data of water and Moho depth using sonar buoys, Extended Spread Profiles (ESP), Ocean Bottom Seismometer (OBS), both Multi-beam and land-sea joint seismic surveys in the northwestern sub-basin and its surrounding areas. Then we adopted a thermal isostasy method to calculate the depth of the Lithosphere-Asthenosphere Boundary (LAB) in the northwestern sub-basin of the SCS and its surrounding regions. Results show that the range of LAB depth is ~25–110 km. The shallowest burial depth is 25–60 km occurring in the ocean basin. The depth increases to 60–110 km toward the continental margin. The lithospheric structure on the north and south sides of the Xisha Trough is symmetrical and shows the deep structure and thermal features of aborted rifts. The LAB depth in the Zhongsha Trough and the Zhongsha Massif increased from 60 to 70 km southwestwards, consistent with the trend of surface morphology. The LAB depth to the west side of the Pearl River Valley is 60–80 km, and the thinning of the lithosphere is related to the distribution of faults, depressions and the magmatic activity. The LAB depth in the northwestern sub-basin and the eastern sub-basin is less than 60 km with the thinnest part being less than 46 km. Combining ocean drilling, seismic investigation, and seafloor topography, we show that the ocean basin of the northwestern sub-basin of the SCS locates within the 46 km isobath of the LAB. The formation of the rifted valleys and discrete blocks surrounding the ocean basins is both controlled by the regional tectonic movement and the deep thermal state, where their lithospheric structures show strong heterogeneity.
As the central component of prognostic and health management (PHM) field, remaining useful life (RUL) estimation approaches based on degradation modeling have played an extremely significant role in ...recent years. For the newly developed systems working in complex environments, the associated degradation processes not only lack historical data and prior information but also have strong nonlinearity and three-source variability. Therefore, this paper proposes an adaptive RUL estimation approach for the newly developed system based on a nonlinear model. Specifically, a general nonlinear Wiener-process-based degradation model is established to simultaneously characterize three-source variability and nonlinearity, and the associated RUL distribution is derived with an explicit form. In order to utilize the condition monitoring (CM) data of the service system up to date, we present a parameter estimation method based on the expectation maximization algorithm to adaptively estimate and update the model parameters online. As such, the RUL distribution can be updated once the new CM data are available. Finally, the effectiveness and superiority of the proposed method are demonstrated by the numerical example an empirical study for battery data. The results show that the proposed method can provide accurate and robust RUL prediction for the newly developed system.
Graves' orbitopathy (GO) is an autoimmune disease that involves complex immune systems. The mainstays of clinical management for this disease are surgery, targeted drugs therapy, and no-targeted ...drugs drug therapy. targeted drugs can improve therapeutic efficacy and enhance the quality of life for GO patients. However, as a second-line treatment for GO, targeted drugs such as tocilizumab and rituximab have very limited therapeutic effects and may be accompanied by side effects. The introduction of Teprotumumab, which targets IGF-IR, has made significant progress in the clinical management of GO. The pathophysiology of GO still remains uncertain as it involves a variety of immune cells and fibroblast interactions as well as immune responses to relevant disease targets of action. Therfore, learning more about immune response feedback pathways and potential targets of action will assist in the treatment of GO. In this discussion, we explore the pathogenesis of GO and relevant work, and highlight four potential targets for GO: Interleukin-23 receptor (IL-23 R), Leptin receptor (LepR), Orbital fibroblast activating factors, and Plasminogen activator inhibitor-1 (PAI-1). A deeper understanding of the pathogenesis of GO and the role of potential target signaling pathways is crucial for effective treatment of this disease.
The geomorphology of the deep-sea environment is complex, including seamounts based on hard rocks and seabeds based on rare soft sediments. Therefore, the frame of the benthic lander needs to be ...shock and subsidence resistant. In this paper, the static model of the benthic landers is established to analyze their force and deformation under different loads, and the dynamic model of the benthic landers is established to derive the motion equation of their landing on the sediment. Some typical frame structure of benthic landers is analyzed with the ANSYS Workbench static analysis module and Explicit Dynamics module. The sea trial data of the benthic lander prototype were analyzed to provide reference for the design and application of the lander’s framework. The research done in this paper provides the basis for the impact resistance design and bottom speed design of the benthic lander and proposes a simulation analysis method for the calculation of the bottom subsidence of the benthic lander.
Precise pressure core motion, including translation and rotation, is the basis and core part of the Analysis and Transfer System of Natural Gas Hydrate Pressure Core, which is crucial to ...nondestructive analyses, core cutting, and transfer. This paper mainly proposes a driving device, whereby a pressure core, up to 3 m long, can be transferred from pressure core drilling tools to proceed to nondestructive analyses and transferring the cores into other chambers. The lead screw is one of the most important components of this driving device. Therefore, the modal analyses of the lead screw are performed, which can help researchers to analyze the stability of this device. The analyzed data shows that the different positions of the slider have a great impact on the natural frequency of the lead screw. Furthermore, the lead screw with a support slider has a larger natural frequency than that without a support slider. According to data analysis, we can derive that the device with the support slider has a much larger rigidity, which can contribute to the stability of the device. To verify the feasibility of this device, the deformation of the lead screw was tested by the Micro-Electro-Mechanical Systems (MEMS) accelerometer array. Experimental results show that the deformation of the lead screw with the support slider is much less than that without the support slider.
The seabed Cone Penetration Test (CPT) system is a common method for investigating offshore soil. This paper focuses on a new subsea CPT method for assessing physical and mechanical properties of ...marine sediments. The new method enables automatic docking and dismantling of the probe rods underwater. The constant-rate penetration mechanism is the basis and core component of the seabed CPT, allowing the probe rod and cone to penetrate the seafloor sediment. Double hydraulic cylinders are used to meet the high penetration force requirements. To maintain a constant penetration rate of 20 ± 5 mm/s, the model identification of the electro-hydraulic servo system is performed using Simcenter AMESim and MATLAB software, and the relevant transfer function is obtained using the PID method. Based on this transfer function, the sliding mode variable structure controller of the electro-hydraulic servo system is designed to regulate the constant penetration rate of the hydraulic cylinder against varying penetration resistance.
In-situ
measurements were operated using the new seabed CPT rig in Zhoushan Island. The simulation and testing results confirm that the sliding mode variable structure controller is suitable for controlling the system during actual operation.
Remaining useful life (RUL) estimation is the key of prognostics and health management (PHM) technology and is an effective way to ensure the safe and reliable operation of equipment. Aiming at the ...lack of historical data and prior information for the newly developed small-sample systems, an adaptive RUL estimation method based on the expectation maximization (EM) algorithm is proposed with three-source variability. First, a degradation model based on a Wiener process is established to incorporate three-source variability and dynamic sampling interval, and the analytical solution of RUL distribution is derived in the sense of the first hitting time. Second, an adaptive parameter estimation method based on the EM algorithm is proposed to update the model parameters by using the condition monitoring (CM) data from one working system running up to the current moment. Finally, a practical example of a gyroscope in an inertial navigation system is provided to substantiate the effectiveness and superiority of the proposed method. The results indicate that the proposed method can efficiently improve the accuracy of the RUL estimation.
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