Fan nozzle is an important part of high pressure water descaling system, and its internal structure parameters directly affect the performance of jet. The nozzle flow field was analyzed by using fluid simulation software FLUENT, and the nozzle exit diameter, cone section contraction angle and exit contraction angle were selected as reference factors. The jet impact force was used as evaluation index, and the nozzle structure parameters were optimized by response surface method. The results show that the velocity distribution of the internal flow field is affected by the single factor of the diameter of the outlet section and the conical contraction angle, but the flow rate of the nozzle is little affected. The pressure drop of nozzle is affected by the change of the diameter of outlet section and the contraction angle of nozzle outlet, and the influence of the contraction angle of nozzle conical section on the pressure drop is negligible. When the diameter of the outlet section is 3.15 mm, the taper shrinking angle is 26.17°, and the outlet shrinking angle is 40.93°, it is found that the nozzle striking force is increased from the original 94.91 N to the optimized 143 N by establishing the outflow field and applying the gas-liquid two-phase flow model simulation calculation. The research results provide theoretical guidance for optimizing nozzle structure to enhance jet impact force.

To explore the effects of cardiac magnetic resonance imaging(CMRI) on the assessment of left ventricular function and myocardial changes in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). Thirty-one patients with OSAHS who were admitted to Handan Central Hospital from November 2019 to June 2021 were selected as the observation group, and 30 healthy volunteers who received CMRI monitoring during the same period were selected as the control group.Two sets of parameters related to left ventricular function were compared, including left ventricular ejection fraction (LVEF), left ventricular end diastolic/end systolic volume (LVEDV/LVESV), left ventricular myocardial activity imaging indexes[T1pre value(measurement of T1 relaxation time before enhancement) before mean injection of contrast agent in left ventricular myocardium, 15 min T1post value(T1 value of myocardial tissue measured by T1 mapping technique after using contrast agent in CMRI) and T2 value(transverse relaxation time of myocardial tissue)]after injection,and histological parameter characteristics of different myocardial layers[mean extracellular matrix volume fraction (ECV) of left ventricular myocardium].The left ventricular function parameters (LVEF, LVED) in the observation group are significantly lower than those in the control group, while LVESV and T2 values are significantly higher than those in the control group (P<0.05). There is no significant difference in T1pre, T1post, ECV in basal segment, middle segment and apical segment between the observation group and the control group (P>0.05).CMRI has a significant clinical effect in patients with OSAHS and can effectively assess the left ventricular function, structure and early myocardial lesions.

The Guocheng-Yazi area in the northeastern margin of the Jiaolai Basin is located in the southern section of the Muping-Rushan gold metallogenic belt. It is an important gold metallogenic area in the Jiaodong region. In recent years, medium-sized and large-scale gold deposits such as Pengjiakuang, Tudui-Shawang, Xijingkou, Liaoshang, Xilaokou, and Qianchuiliu have been successively explored. The cumulative amount of gold resources explored exceeds 180 t. Based on the field work of geological mapping, ore-bearing structure investigation, controlled source audio-frequency magnetotelluric sounding (CSAMT) and drilling engineering, the distribution of ore bodies, geophysical characteristics, ore-controlling structure and metallogenic regularity were analyzd. The western extension position of the Pengjiakuang detachment fault was preliminarily clarified. Extending westward from the Xijingkou to the Liaoshang to the Guocheng fault, which is the ore-controlling structure of Pengjiakuang, Xijingkou, Xilaokou, Qianchuiliu, Liaoshang and other gold deposits. The Queshan metamorphic core complex and its detachment faults are the main ore-controlling structures and favorable ore-forming spaces for gold mineralization in this area, and are important prospecting targets in future exploration and prospecting work. The mineralization depth of the gold deposit concentration area in this area is mainly 5.01~7.93 km, and the gold deposit has just been eroded as a whole. The deep and peripheral areas have good prospecting potential.

At present, there are fewer studies on the macroscopic mechanical hysteresis model of magnetically controlled smart magnetorheological elastomer (MRE), which is not conducive to the application control of MRE materials. To improve the control effect of MRE materials, an experimental study on MRE’s magnetostrophic shear mechanical properties based on the Bouc-Wen model was conducted. The influence of magnetic field strength on the mechanical parameters of MRE was analyzed. Firstly, with the assistance of Simulink to establish the Bouc-Wen simulation model was established for MRE parameter fitting. Then, the stiffness, damping, and other material parameters were analyzed with the magnetic field strength change rule. Finally, through the experiments, the model validity was examined. The results show that with the increase of magnetic field strength, the parameters of MRE energy storage and energy consumption have different degrees of increase, in which the equivalent stiffness and maximum damping force increase significantly, respectively, increase 210.61%, 205.41%. In the range of 0.5~0.7 T magnetic field parameter growth rate is faster in the range of 0.7~1.0 T growth tends to be saturated. The dynamic mechanical properties of MRE are better described by the Bouc-Wen model, and the maximum error of the characteristic parameters is 4.42%. The research results can provide theoretical and experimental references for the optimal preparation and algorithmic control of MRE materials.

Due to the unique challenges of deep underground mining environments, such as frequent geological disasters like roof fall, rock bursts, and water inrush, there is a high demand for enhanced safety and stability in mines. The use of downward roadway backfilling methods has shown significant effectiveness in controlling ground pressure activities and rock layer movement. In light of this, the Chambishi Copper Mine in Africa was selected as a case study. Initially, a digital structural plane identification system was employed to conduct a detailed analysis of the ore body structural planes. The findings indicate that the development of structural planes in deep ore bodies significantly impacts the safe extraction of minerals. The high density and narrow spacing of these planes increase the fragmentation of the rock mass, elevating the risk of roof fall and instability in mining areas. Additionally, numerical simulations were performed to study the mechanical behavior and deformation characteristics of the deep zones of the Chambeshi Copper Mine. By optimizing the structure and strength of the bearing layers, the stability of the mining area can be effectively controlled. The simulation results demonstrate that well-structured bearing layers are capable of withstanding the pressure from overlying rock strata, ensuring higher stability in the mining areas. These research outcomes provide effective strategies for the safe extraction of minerals in deep mines, particularly in high-risk geological environments. Adaptable mining methods and safety measures were proposed, which were of significant importance for enhancing the safety and efficiency of deep mining operations.

In the process of oilfield development, the formation of emulsion between crude oil and water is quite common, which increases the difficulty of crude oil treatment. The composition of crude oil, especially the precipitation of paraffin wax, has significant influence on the stability of the emulsion. From the unique perspective that the oil composition affects the phase change and then further determines the emulsion stability, a systematic study was carried out with the methods of emulsion stability test, oil-water interfacial characteristic test, wax precipitation test, asphaltene dispersion stability test, and microscopic observation. It is observed that increasing the amount of liquid paraffin in the solvents leads to a change in the form of wax crystals from fine particles to larger agglomerated wax crystals, and the asphaltenes dispersion stability decreases along with it. Test temperature can significantly affect emulsion stability. At 30 ℃, increasing the percentage of liquid paraffin reduces the interfacial tension, increases the interfacial dilatational modulus, and enhances the structure of the interfacial film. This contributes to the formation of small droplets and improves emulsion stability to a certain extent. At 15 ℃, by contrast, increasing the liquid paraffin content promotes the development of a more structured wax crystals network, which significantly enhances emulsion stability by binding water droplets. Additionally, it is also found that a wax crystal interfacial film could be formed at the surface of the emulsified drops, which improves further the interfacial film strength and emulsion stability. Based on the above findings, an influencing mechanism model is presented concerning the synergistic stabilization of model oil emulsion containing asphaltene and paraffin wax.

In order to efficiently develop the ultra-deep thin interbedded carbonate gas field, the development well of Lei-4 gas reservoir in western Sichuan gas field adopted a three-spud casing program. The first spud section was drilled into the Penglaizhen Formation to the third member of Xujiahe Formation. Due to the large variation of soft and hard sand mudstone, and the existence of mud shale or sand mudstone is easy to be hydrated and denudated, there will be falling block, collapse and other problems. The second spud section was drilled into the formation from the 3rd of Xujiahe Formation to Maantang Formation. The formation shale and coal seam are interbedded frequently, the uncased hole section is long and high pressure fractured gas layer, these factors are prone to risk of wellbore instability, well loss and even blowout. The third spud section was drilled into the fourth member of Leikoupo formation. Due to the alternations of limestone and dolomite, the stress difference between layers is large, and the formation is broken, it is easy to cause local instability of borehole wall, and even collapse, stuck drilling and other downhole complications. In the face of challenges, through theoretical research, laboratory experiments and field application optimization, potassium-based polysulfonic drilling fluid technology was used in the first section, the compound salt strongly inhibited polysulfonic anti-collapsing drilling fluid technology was used in the second spud section, strong plugging white oil base drilling fluid technology was used in the third section, have been formed to solve the technical problems faced by drilling fluids. The successful application of more than 10 wells has achieved remarkable results in speed and efficiency improvement..Among them, well PZ5-1D has a drilling depth of 8 208 m and a drilling cycle of 252.79 days.

The stability of power cyber physical system(CPS) is easily affected by stochastic uncertainty from both the information and physical sides. A stability analysis method for power CPS based on stochastic uncertainty model and a robust wide area feedback frequency control method were proposed. Taking into account the essential differences between the discreteness of the information side and the continuity of the physical side, as well as the mutual influence in terms of functionality, a dynamic model of power CPS in stochastic environment was established from both the information and physical sides. According to the definition of mean square exponential stability of stochastic differential equations, small signal stability analysis was conducted for dynamic model of power CPS. The critical variance based on mean square norm calculation was used to describe the impact of stochastic uncertainty on small signal stability of power CPS. Focusing on the norm optimization problem based on linear matrix inequality constraints, a robust wide area feedback controller was designed based on the distributed control method. Finally, simulation analysis was conducted on an IEEE 39 bus system, and the results verified the correctness and effectiveness of the proposed method.

In order to solve the problems of large training parameters and low text recognition rate of convolutional recurrent neural networks (CRNN) handwritten Chinese character recognition network model, a novel method for handwritten Chinese character recognition based on attention bi-directional long short-term memory network(AT-BLSTM) and knowledge distillation (KD) technology was proposed. By assigning different weights to the input vector features of AT-BLSTM network, the model training data set was more efficient and accurate. Through KD technology, the knowledge acquired from a large high-performance model was transferred to a small model, which ensured the accuracy of the model, reduced the training parameters and internal storage ratio, and obtained a lightweight training model with better performance. Through the comparison of multiple groups of experiments, the accuracy of Chinese character recognition is increased by 6.7%, and the training parameters are reduced by 15.94 M. The recognition accuracy of this network model reaches 97.9%, and the recognition effect of Chinese characters is better.

For the problems of low efficiency and long computational time in the fluid-structure interaction of free-surface flow and elastic structure, an efficient fluid-structure coupling method for free surface flow was developed by combining the volume of fluid method with the fast dynamic mesh method based on the structure-pseudo elastomer. The free surface of the fluid was tracked by volume of fluid (VOF) method. The fluid domain was regarded as a pseudo elastomer, then the structure-pseudo elastomer system was constructed. The multiphase fluid force at the fluid-solid interface was used as the excitation to solve the dynamical equations of the system to obtain the structural vibration displacements and the mesh deformations of the flow field. The fluid flow, structural deformation and the dynamic mesh were solved sequentially at each time step to solve the fluid-structure interaction problem. Based on the developed method, the fluid-structure coupling response of elastic baffle under the impact of dam-breaking flow was calculated. The motion behaviors of the free liquid surface of water and elastic baffle were obtained. The results show that the free liquid surface evolution and elastic baffle vibrational displacements are well in agreement with those of the existing algorithm, under the same mesh size, the method can reduce the computational time by 33.3% compared with the existing algorithms, under the impact of water flow, the elastic baffle is bent slightly to the impact side. Then the water rises along the left side of the baffle and forms a jet, and the baffle is bent greatly to another side. Finally, the amplitude of the baffle gradually decreases due to the damping of the fluid on both sides.