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This paper investigates the failure mechanism of the rear drive shaft in a modified pickup truck which had operated for about 3000 km. The investigation included macroscopic and microscopic evaluation to document the morphologies of the fracture surface, measurement of the material composition, metallographic preparation and examination, mechanical testing, and finite element modelling and calculations. The results obtained suggest that rotation-bending fatigue was the primary cause of the drive shaft failure. The crack initiation is located in the root of the machined threads on the drive shaft surface and expanded along the side of the machining line surface. The main cause of fatigue cracks is attributable to a high stress concentration owing to a large unilateral bending impact under overload. Meanwhile, the bidirectional torsional force also produces a higher stress concentration and thus accelerates the fatigue crack to expand radially along the surface. Furthermore, the hardness of the central section of the drive shaft was marginally below standard. This deficiency results in harm to the bearings and other mechanical components, as well as expediting the enlargement of cracks. Finite element analysis revealed significant contact stress between the bearing and drive shaft, with stress levels exceeding the fatigue limit stress of the parent material. This highlights the need for reevaluation of the heat treatment process and vehicle loading quality to enhance the drive shaft's longevity. [ABSTRACT FROM AUTHOR]

Achieving precise stopping of electric locomotives is crucial for the realization of intelligent and unmanned auxiliary transportation systems. Presently, human drivers play a central role in ensuring accurate stopping, presenting obstacles to automation and cargo location precision, especially within the coal mining sector. This article centers on achieving the precise stopping of electric locomotives under various conditions through the utilization of permanent magnet synchronous motor-driven locomotives. This approach introduces a novel stopping control method that integrates a fuzzy proportional–integral–derivative (F-PID) controller with a vector control model for permanent magnet synchronous motors (PMSM). Subsequently, we develop the F-PID controller using the PMSM technique, incorporating new fuzzy rules for each subsystem to enhance control accuracy and efficiency. Finally, extensive simulations and real-world experiments are conducted on an electric locomotive stopping test bed to validate the effectiveness of the proposed control method. The results show that the method consistently achieves precise stopping under diverse working conditions, with an error of less than 0.3 m, confirming its robustness and reliability. [ABSTRACT FROM AUTHOR]

Currently, the main solution for braking systems for underground electric trackless rubber-tired vehicles (UETRVs) is traditional hydraulic braking systems, which have the disadvantages of hydraulic pressure crawling, the risk of oil leakage and a high maintenance cost. An electro-mechanical-braking (EMB) system, as a type of novel brake-by-wire (BBW) system, can eliminate the above shortcomings and play a significant role in enhancing the intelligence level of the braking system in order to meet the motion control requirements of unmanned UETRVs. Among these requirements, the accurate control of clamping force is a key technology in controlling performance and the practical implementation of EMB systems. In order to achieve an adaptive clamping force control performance of an EMB system, an optimized fuzzy proportional-integral-differential (PID) controller is proposed, where the improved fuzzy algorithm is utilized to adaptively adjust the gain parameters of classic PID. In order to compensate for the deficiency of single-close-loop control and adjusting the brake gap automatically, a cascaded three-closed-loop control architecture with force/position switch technology is established, where a contact point detection method utilizing motor rotor angle displacement is proposed via experiments. The results of the simulation and experiments indicate that the clamping force response of the proposed multi-close-loop Variable Universe Fuzzy–PID (VUF-PID) controller is faster than the multi-closed-loop Fuzzy–PID and cascaded three-close-loop PID controllers. In addition, the chattering of braking force can be suppressed by 17%. This EMB system may rapidly and automatically finish the operation of the overall braking process, including gap elimination, clamping force tracking and gap recovery, which can obviously enhance the precision of the longitudinal motion control of UETRVs. It can thus serve as a BBW actuator of mine autonomous driving electric vehicles, especially in the stage of braking control. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) shows promise in tumor treatment, particularly when combined with nanotechnology. This study examines the impact of deep learning, particularly the Cellpose algorithm, on the comprehension of cancer cell responses to PDT. The Cellpose algorithm enables robust morphological analysis of cancer cells, while logistic growth modelling predicts cellular behavior post-PDT. Rigorous model validation ensures the accuracy of the findings. Cellpose demonstrates significant morphological changes after PDT, affecting cellular proliferation and survival. The reliability of the findings is confirmed by model validation. This deep learning tool enhances our understanding of cancer cell dynamics after PDT. Advanced analytical techniques, such as morphological analysis and growth modeling, provide insights into the effects of PDT on hepatocellular carcinoma (HCC) cells, which could potentially improve cancer treatment efficacy. In summary, the research examines the role of deep learning in optimizing PDT parameters to personalize oncology treatment and improve efficacy. [ABSTRACT FROM AUTHOR]

It is urgent for automated electric transportation vehicles in coal mines to have the ability of self-adaptive tracking target constant deceleration to ensure stable and safe braking effects in long underground roadways. However, the current braking control system of underground electric trackless rubber-tired vehicles (UETRVs) still adopts multi-level constant braking torque control, which cannot achieve target deceleration closed-loop control. To overcome the disadvantages of lower safety and comfort, and the non-precise stopping distance, this article describes the architecture and working principle of constant deceleration braking systems with an electro-mechanical braking actuator. Then, a deceleration closed-loop control algorithm based on fuzzy neural network PID is proposed and simulated in Matlab/Simulink. Finally, an actual brake control unit (BCU) is built and tested in a real industrial field setting. The test illustrates the feasibility of this constant deceleration control algorithm, which can achieve constant decelerations within a very short time and maintain a constant value of − 2.5   m / s 2 within a deviation of ± 0.1   m / s 2 , compared with the deviation of 0.11   m / s 2 of fuzzy PID and the deviation of 0.13   m / s 2 of classic PID. This BCU can provide electric and automated mine vehicles with active and smooth deceleration performance, which improves the level of electrification and automation for mine transport machinery. [ABSTRACT FROM AUTHOR]

Beyond diffraction limit, multitrapping of nanoparticles is important in numerous scientific fields, including biophysics, materials science and quantum optics. Here, we demonstrate the 3-dimensional (3D) shell-like structure of optical trapping well induced by nonlinear optical effects in the femtosecond Gaussian beam trapping for the first time. Under the joint action of gradient force, scattering force and nonlinear trapping force, the gold nanoparticles can be stably trapped in some special positions, or hop between the trap positions along a route within the 3D shell. The separation between the trap positions can be adjusted by laser power and numerical aperture (NA) of the trapping objective lens. With a high NA lens, we achieved dual traps with less than 100 nm separation without utilizing complicated optical systems or any on-chip nanostructures. These curious findings will greatly extend and deepen our understanding of optical trapping based on nonlinear interaction and generate novel applications in various fields, such as microfabrication/nanofabrication, sensing and novel micromanipulations.

Continental shale in China is a key exploration target with regard to unconventional hydrocarbons. Systematic research on the mineral composition, organic geochemistry, and hydrocarbon mobility has been performed in the Da'anzhai (J1dn) lacustrine shale oil reservoirs, clarifying the factors controlling shale oil accumulation. The results suggest that J1dn consists of three sub-members, with an organic-rich interval developed within the second sub-member. Three types of lithological associations have developed within the organic-rich interval: Type 1 represents the interbedding relationship between shale and shell limestone and Type 2 represents shale with intercalated limestone, followed by Type 3. The brittleness index of the J1dn continental organic-rich shale is relatively low. The porosity of the Da'anzhai lacustrine shale ranges between 0.5% and 10.5% (average value of 5.89%). The porosity is predominantly due to inorganic pores, with a small amount being attributable to nanoscale microfractures and organic pores. The average porosity of the shell limestone is only 1.2%, but fractures at the micron and centimeter scales are well developed. The organic matter in the J1dn continental shale is mainly II1–II2, with maturity in the oil generation stage. The average oil saturation of the J1dn continental shale is 3.15%, with most samples having oil saturation of less than 4%. The J1dn continental shale has great exploration potential with regard to shale oil. Type 1 shale oil is affected by multiscale fractures, including bedding fractures, and has the best mobility. The high hydrocarbon generation capacity of lacustrine shale, coupled with the multiscale fractures within shell limestone and shale, is the principal controlling factor for hydrocarbon enrichment. Based on exploration practices, the Type 1 shale association may represent the optimal interval for future shale oil exploration in the Da'anzhai Member. [ABSTRACT FROM AUTHOR]

Micro- and nano-scale pores develop in shale reservoirs, and the associated pore structure controls the occurrence state, gas content, seepage capacity, and micro-migration and accumulation mechanisms of shale gas. For this study, we mainly conducted tests, using field emission-scanning electron microscopy, of the isothermal methane adsorption of powder-sized samples under high temperatures (60–130 °C) and pressures (0–45 MPa), along with methane-saturated nuclear magnetic resonance tests of plug-sized samples under different temperatures (60–100 °C) and pressures (0–35 MPa). These samples were from Longmaxi shale cores from strata at different burial depths from the Zhaotong, Weiyuan, and Luzhou areas. As the burial depth increases, organic pores transform from complex networks to relatively isolated and circular pore-like structures, and the proportion of organic matter-hosted pores increases from 25.0% to 61.2%. The pore size is influenced by the pressure difference inside and outside the pores, as well as the surface tension of organic matter in situ. As the burial depth increases to 4200 m, the main peak of the pore size first increases from 5–30 nm to 200–400 nm and then decreases to 50–200 nm. This work establishes an NMR method of saturated methane on plug-sized samples to test the free gas content and develop a prediction model of shale reservoirs at different burial depths. The gas content of a shale reservoir is influenced by both burial depths and pore structure. When the burial depth of the shale gas reservoir is less than 2000 m, inorganic pores and microfractures develop, and the self-sealing ability of the reservoir in terms of retaining shale gas is weak, resulting in low gas content. However, due to the small pore size of organic pores and the low formation temperature, the content of adsorbed gas increases, accounting for up to 60%. As the burial depth increases, the free gas and total gas content increase; at 4500 m, the total gas content of shale reservoirs is 18.9 m3/t, and the proportion of free gas can be as high as 80%. The total gas content predicted by our method is consistent with the results of the pressure-holding coring technique, which is about twice our original understanding of gas content, greatly enhancing our confidence in the possibility of accelerating the exploration and development of deep shale gas. [ABSTRACT FROM AUTHOR]

The Ediacaran Dengying Formation fourth member in Central Sichuan Basin is the deep dolomite gas reservoir with the largest natural gas reserves in China, providing an excellent example for understanding the effect of hydrothermal silicification on deep dolomite reservoir quality. By integrating petrology, geochemistry and physical property measurement, this study aims to reveal the genesis of different quartz phase and their corresponding diagenetic events, and to discuss the temporal relationship of diagenetic events and their effects on the quality of deep dolomite reservoir in Dengying fourth member. Three phases of quartz cement are identified in Ediacaran Dengying Formation deep dolomite reservoirs of Central Sichuan Basin as follows: (1) first‐stage quartz filled in primary reservoir spaces, (2) second‐stage quartz mainly filled in secondary reservoir spaces, and (3) third‐stage quartz filled in secondary reservoir spaces with Mississippi Valley‐Type minerals. By analysing petrographic and temporal relationships between these fabrics, it is suggested that the first‐stage quartz precipitated during the syndiagenetic stage, the second‐stage quartz precipitated during middle diagenetic stage, and the third‐stage quartz precipitated during middle diagenetic stage as well. Silicification during syndiagenetic stage is characterized by replacement of cryptocrystalline quartz and cementation of first‐stage quartz within matrix dolomite (MD). After syndiagenetic silicification, the mineral composition of the MD changed from magnesium calcium carbonate to silica, and the later constructive diagenetic alterations were almost ineffective. The distribution of syndiagenetic silicification during syndiagenetic stage gradually decreases from the platform‐interior to the platform‐margin. The second‐stage and third‐stage quartz cements, derived from two‐stage hydrothermal silicification in the middle stage, are both destructive for reservoir preservation. This study, combined with coeval vapour–liquid inclusions Th data and thermal‐burial models, constrains the time of the second‐stage quartz to ca. 403–408 Ma, suggesting an hydrothermal silicification related to the Caledonian movement. The time of the third‐stage quartz cement is constrained to ca. 259.4 Ma, associated with Late Permian eruption of Emeishan flood basalts. [ABSTRACT FROM AUTHOR]

The pore‐throat structure and fluid mobility are the key factors of tight sandstone reservoir classification and evaluation. Taking the Jurassic Shaximiao Formation tight sandstone reservoir in Central Sichuan Basin as an example, 19 samples were analysed by casting thin sections, scanning electron microscopy, high‐pressure mercury injection and nuclear magnetic resonance to clarify the pore‐throat structure, the fluid motility and its controlling factors. The results show that the pore type of Shaximiao Formation tight sandstone reservoir consist of intergranular pores, dissolved pores and a few microfractures. Based on the feature of capillary pressure curve, the pore‐throat structure was classified into three types, corresponding to different movable fluid characteristics. The Type I has large pore and throat radius, good pore‐throat connectivity, small fractal dimension, weak reservoir heterogeneity and strong fluid motility. The distribution range of pore‐throat radius is mainly from 0.3 to 1.1 μm and the average movable fluid porosity (MFP) and movable fluid saturation (MFS) are 6.04% and 49.93%. The Type II has poor pore‐throat sorting, weak fluid motility and the distribution range of pore‐throat radius is 0.01–0.03 μm and 0.2–0.8 μm. The average MFP and MFS of Type II are 1.13% and 14.3%. The Type III has the smallest pore‐throat radius and the largest fractal dimension, corresponding to the most complex pore‐throat structure, which lead to the worst fluid mobility. The average MFP and MFS are 0.49% and 12.76%. The fluid mobility of the tight sandstone reservoir is affected by physical properties and pore‐throat structure. The reservoirs with large pore‐throat size, good connectivity between pore and throat, and low heterogeneity have higher MFP and saturation. Moreover, the mineral compositions have different effects on fluid mobility of the tight sandstone. The feldspar positively affects fluid mobility, while the clay minerals negatively affect fluid mobility. [ABSTRACT FROM AUTHOR]

Organic-rich continental shale, widespread in the Sichuan Basin during the deposition of the Jurassic Dongyuemiao Member (J1d), is considered the next shale hydrocarbon exploration target in southern China. To identify a shale gas sweetspot and reduce exploration risk, it is of great significance to determine the organic matter (OM) enrichment mechanism of J1d shale. In this study, based on sedimentological characteristics and organic matter content, high-resolution major and trace elements were systematically analyzed to demonstrate terrigenous influx, paleoredox, paleosalinity, paleoproductivity, and paleoclimate. The 1st section interval of the J1d 1st submember is dominated by shallow lake subfacies, while the other intervals have the characteristic of semideep to deep lake subfacies. The 1st submember interval of J1d lacustrine shale is characterized by the warmest-humid paleoclimate, strongest weathering degree, highest terrigenous input, moderate paleoproductivity, and paleoredox condition. Within the Dongyuemiao 1st submember, the 4th section interval has the highest paleoproductivity and the most oxygen-deficient condition in bottom water. During the deposition period of the 2nd submember, the sedimentary environment turned to a cold-dry paleoclimate, weak weathering degree, low terrigenous input, low paleosalinity, and high paleoproductivity. Under the background of semideep and deep lake, the terrigenous OM input plays the most critical role in controlling OM enrichment. Moreover, the high primary productivity of lake surface water and the suboxic condition of lake bottom water contribute to the formation of relatively higher TOC lacustrine shale interval in the 4th section of 1st submember. [ABSTRACT FROM AUTHOR]

Deeply buried (>3500 m) marine shale has become a focus point for the future exploration and exploitation of shale hydrocarbon in China. Low-temperature nitrogen adsorption (LTNA), scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), and other experiments were combined to characterize the pore structure and fluid division in deep-marine shale of the southern Sichuan Basin in this study. The results suggest that the deep-marine shale had a relatively developed nanopore network, especially with honeycomb organic pores. These organic pores were largely macropores with good connectivity in three-dimensional space and constituted the major reservoir space of the deep-marine shale gas. Microfractures were predominantly clay-mineral-related fractures, and the development degree of microfractures connected with organic pores was low, which contributed to the preservation of organic pores. Within the deep-marine shale interval, the pore volumes of Section 1 and Section 3 were higher. Pore volume was predominantly contributed by pores above 10 nm, where macropores accounted for a large proportion. Based on a combination of high-speed centrifugation and gradient temperature drying, the pore fluid of deep-marine shale reservoirs was quantitatively classified into four types: clay-bound fluid, capillary-bound fluid, free-flowing fluid, and closed-pore fluid. The clay-bound fluid existed in pores of less than 4.25 nm, which cannot be exploited. Quantitative division of the shale pore system could be realized by using the pore space differences of different types of fluids. [ABSTRACT FROM AUTHOR]

Lacustrine shale oil has the potential to lead the development of China's oil and gas industry. By integrating scanning electron microscopy, low-temperature CO2 and N2 adsorption, high-pressure mercury intrusion, and nuclear magnetic resonance with centrifugation at different speeds, the pore system and pore fluid distribution of Da'anzhai Member lacustrine shale in the Sichuan Basin are studied. The results show that: (1) The reservoir space is mainly inorganic pores and micro-fractures. Nano-micron scale pores are commonly found and widely distributed in the Da'anzhai shale with multiple peaks of 28 nm, 200 nm, 900 nm, and 3.5 µm. The total pore volume ranges from 0.00849 to 0.02808 cm³/g, and the pores ranging from 100 nm to 1000 nm are the main contributors to total pore volume. (2) Pore fluid can be divided into movable oil, bound oil, and adsorption oil. The proportion of movable oil, bound oil, and adsorbed oil is 21.4%, 12.4%, and 66.2% in Da'anzhai shale, respectively. Movable oil mainly occurs in pores larger than 350 nm, bound oil is 30–350 nm, while adsorbed oil mainly exists in pores below 30 nm. (3) The higher the total organic carbon content and clay minerals content, the smaller the pore size, resulting in the low content of movable oil. The higher the content of brittle minerals such as quartz, the better the development of intergranular pores and microfractures, and the higher the content of movable oil. Through the grading evaluation of shale pore structure and pore fluid, it is conducive to guide the exploration and development of Da'anzhai shale oil, which has important theoretical and practical significance. [ABSTRACT FROM AUTHOR]

This article concentrates upon the adaptive secure containment control problem for a class of uncertain nonlinear multi‐agent systems with the output constraint requirements under denial‐of‐service (DoS) attacks. At first, to overcome the difficulty that the tracking performance of the nonlinear multi‐agent systems under the DoS attacks is disturbed seriously, a novel adaptive secure containment control approach is presented by applying a DoS attacks detection mechanism and introducing the barrier Lyapunov functions, which enables the system to achieve the security control objective that the output of each agent eventually converges to the convex hull spanned by the dynamic leaders' outputs, while never violating the output constraints. Then, a state estimator is designed, which reconstructs the immeasurable states of the multi‐agent systems and approximates the completely unknown nonlinearities arising from the agents. In addition, the dynamic surface control technique is used to solve the "explosion of complexity" problem. It is demonstrated that the proposed anti‐attack controller ensures that all the signals of the closed‐loop system are semi‐globally uniformly ultimately bounded. Finally, a simulation example is provided to illustrate the effectiveness of the theoretical results. [ABSTRACT FROM AUTHOR]

Self-piercing riveted (SPR) joints in automobiles inevitably suffer from corrosion damage and performance reduction. In this work, the influence of salt spray corrosion on the mechanical properties of TA1-Al5052 alloy SPR joints was studied. The TA1-5052 SPR joints were prepared and salt spray tests were carried out for different durations. The static and fatigue strengths of the joints after salt spray corrosion were tested to analyze the effect of salt spray duration on the performance of the joints. The results show that the joints' static strength and fatigue strength decrease with prolonged salt spray time. The salt spray duration affects the joint's tensile failure mode. The tensile failure without corrosion and with a short salt spray time is the fracture failure of the lower aluminum sheet, and the tensile failure of the joints after a long time of salt spray corrosion is the failure of the rivets. The fatigue failure form of the SPR joint is the formation of fatigue cracks in the lower aluminum sheet, and salt spray time has little effect on the fatigue failure form. Salt spray corrosion can promote the initiation and propagation of fatigue cracks. The fatigue crack initiation area is located at the boundary between the lower aluminum sheet and the rivet leg. The initiation of cracks originates from the wear zones among the sheet metal, rivets, and salt spray particles. [ABSTRACT FROM AUTHOR]

Currently, there are no suitable means to measure the composite vibration response of mine hoisting rope. However, machine vision-based measurement technology is a potential way to solve this problem. Therefore, a non-contact and non-intrusive stereovision method is proposed to obtain the 2D vibration displacement of a moving hoisting rope. In this methodology, a novel 3D digital image correlation (DIC) method that combines digital image processing (DIP) algorithm with 2D-DIC algorithm is developed, and the method can simplify the procedure of rope target stereo matching in two synchronous image sequences. In order to confirm the correctness of the stereovision method, some free vibration responses of a rope are measured in a hoist experimental system. Test results demonstrate that the stereovision measurement technique can keep satisfactory consistency with the laser displacement sensor for vibration data identification. The method is verified to have high adaptability to different lighting conditions and be reasonable to measure the vibration parameters of dynamic mine hoisting rope. [ABSTRACT FROM AUTHOR]

The Xixiangchi Formation is a significant replacement stratum for natural gas production of deep marine carbonate in the Sichuan basin, which is mainly composed of grain shoal. Basic characteristics and corresponding major controlling factors of the Xixiangchi reservoir are of great importance for hydrocarbon exploration, but the diagenesis sequence and evolution of the reservoir are poorly understood because of their complexity. Based on core and thin-section observations, cathodoluminescence (CL), scanning electron microscopy (SEM), and microbiologically induced calcium carbonate precipitation (MICP) data, it is suggested that the Xixiangchi reservoir is comprised of medium crystalline dolostone and grain dolostone in the Central Sichuan basin, with an average porosity of 3.6% and 2.2%, respectively. The corresponding pore-throat type is an intercrystalline pore with a flaky throat and a dissolved intergranular pore with a necking throat. The majority porosity ranges from 2% to 4% (with a distribution frequency of 64.9%), but the permeability distribution is relatively scattered (with a distribution frequency between 10% and 30%). The capillary pressure curve of medium crystalline dolostone is characterized by coarse skewness, relatively flat plateaus, low displacement pressures, and high mercury saturation at relatively low injection pressures. The capillary pressure curve of grain dolostone is characterized by fine skewness, which exhibits relatively poor connectivity and a small value of median pore radius. The deposition of intraplatform grain shoals determines the original property of the Xixiangchi Formation reservoirs. Destructive diagenesis, including compaction and multistage cementation, decreases the physical properties of the Xixiangchi reservoir. Constructive diagenesis, including Caledonian supergene karstification and late-stage burial dissolution, tremendously improves the reservoir quality. [ABSTRACT FROM AUTHOR]

Based on comprehensive analyses of occurrence, petrological observation, pore structure and geochemistry, the different reservoir characteristics and reservoir evolutionary pathways between different oolitic shoal reservoir types of the Feixianguan Formation on the west side of the Kaijiang‐Liangping Trough have been studied. There exist three stages of high‐energy slope break belts in the Feixianguan period, the corresponding three stages of oolitic shoals gradually migrating in the direction of the trough. Three types of oolitic shoal reservoirs, namely, residual‐oolitic dolomite, mold‐oolitic dolomite and sparry oolitic limestone, were formed during sedimentary‐diagenetic evolution, the pore types being intergranular dissolved pore, mold pore (or intragranular dissolved pore) and residual intergranular pore, respectively. The petrology, physical properties and pore structure of the different types of oolitic shoal reservoirs are quite different. Residual‐oolitic dolomite reservoirs have the best quality, while sparry oolitic limestone reservoirs have the poorest. Combined with analyses of trace elements, rare earth elements and carbon‐oxygen isotopes, it is suggested that the formation of residual‐oolitic dolomite reservoirs is jointly controlled by penesaline seawater seepage‐reflux dolomitization and hydrothermal dolomitization. Mold‐pore oolitic dolomite reservoirs are controlled by penesaline seawater seepage‐reflux dolomitization and meteoric water solution. The burial dissolution of organic acid not only further improves the reservoir qualities of previously formed oolitic dolomite reservoirs, but also preserves residual intergranular pores in the sparry oolitic limestone reservoirs. [ABSTRACT FROM AUTHOR]