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In the process of long-term water flooding in the Gaoqian Southern Area with an average porosity of 30% and an average permeability of 1333.5 × 10 − 3 μm2, the fluid-solid interaction among oil, water, and rock has a great influence on the pore structure. It has resulted in changes in reservoir parameters with the extension of time. This paper used electron microscopy scanning, mercury injection, X-ray diffraction, physical properties, and oil-water relative permeability curves to study the variation of clay mineral content, pore throat structure, porosity, permeability, and relative permeability curves of high-permeability sandstone after high-pressure water flooding. The results showed that clay minerals such as montmorillonite and kaolinite were dissolved, hydrated, and migrated after long-term water flooding, which resulted in the decrease of clay mineral content in fine sandstone and medium sandstone, the increase of pore throat radius, and the decrease of displacement pressure, median pressure, and separation coefficient. The saturation of the isotonic point of the oil-water relative permeability curve was obviously shifted to the right, the hydrophilicity was significantly enhanced, and the porosity and permeability were effectively improved, but there was a blockage of the throat less than 2 μm in the fine sandstone. In addition, this paper established the equations of water injection, permeability, irreducible water saturation, residual oil saturation, and oil-water relative permeability curve coefficient and establishes the initial permeability model with the well data before water flooding. The logging interpretation results of development wells in the process of water flooding as verification data were used, and the relative error of permeability far lower than the general requirement of permeability error within an order of magnitude was less than 30%, which verified the rationality of the method. [ABSTRACT FROM AUTHOR]

The axial deployment force is an indispensable parameter of a lanyard-deployed coilable mast, which reflects its load capacity in practical applications. However, research on the axial deployment force in the literature is very limited, and there are no mature numerical methods to determine this parameter in the design stage of coilable masts. In this paper, a numerical method for determining the axial deployment force of a lanyard-deployed coilable mast in the local coil mode is presented. Through this method, the designer can quickly obtain the estimated value of the axial deployment force in the design stage, which is convenient for the quantitative design of parameters. To verify the correctness of the proposed method, a dynamic simulation of the coilable mast is carried out, and a microgravity test is performed. The comparison results show that the error between the numerical method and the simulation and experimental results is less than 5%, which proves the correctness of the proposed method. In addition, the coilable mast studied in this paper has been verified by an actual microsatellite deployment in orbit. [ABSTRACT FROM AUTHOR]

This paper examines the dynamic behavior of a particular category of discrete predator-prey system that feature both fear effect and refuge, using both analytical and numerical methods. The critical coefficients and properties of bifurcating periodic solutions for Flip and Hopf bifurcations are computed using the center manifold theorem and bifurcation theory. Additionally, numerical simulations are employed to illustrate the bifurcation phenomenon and chaos characteristics. The results demonstrate that period-doubling and Hopf bifurcations are two typical routes to generate chaos, as evidenced by the calculation of the maximum Lyapunov exponents near the critical bifurcation points. Finally, a feedback control method is suggested, utilizing feedback of system states and perturbation of feedback parameters, to efficiently manage the bifurcations and chaotic attractors of the discrete predator-prey model. [ABSTRACT FROM AUTHOR]

In this paper, the limit cycles and local bifurcation of critical periods for a class of switching Z 2 equivariant quartic system with two symmetric singularities are investigated. First, through the computation of Lyapunov constants, the conditions of the two singularities to become the centers are determined. Then, we prove that there are at most 18 limit cycles with a distribution pattern of 9-9 around the two symmetric singular points of the system. Numerical simulation is conducted to validate the obtained results. Furthermore, by calculating the period constants, we determine the conditions for the critical point to be a weak center of finite order. Finally, the number of local critical periods that bifurcate from the equilibrium point under the center conditions is discussed. This study presents the first example of a quartic switching smooth system with 18 limit cycles and 4 local critical periods bifurcating from two symmetric singular points. [ABSTRACT FROM AUTHOR]

In this paper, finite element simulation of asymmetric rolling in relief rolls of C11000 copper alloy in order to analyze the effectiveness of possible roll profiles and technological schemes of deformation was performed. The scientific innovation of this work lies in determining the patterns of development of stress-strain state parameters for various configurations of rolls, as well as determining the effectiveness of metal processing using various technological schemes. It was found that the use of trapezoidal relief makes it possible to increase the level of metal processing by almost 5 times compared with the use of radial relief. Comparison of technological schemes of deformation showed that deformation with 180° workpiece turning between passes significantly reduces the influence of the asymmetry factor. Deformation without changing the workpiece position between the passes has the opposite effect, and such a scheme significantly increases the influence of the asymmetry factor. Deformation with a transverse workpiece shift for the relief period between passes has the effect of a "golden mean." The conducted laboratory experiment for lead billet showed that the shape change of lead billet during computer simulation has a high level of convergence with real conditions. At each stage of deformation, the difference in the geometric parameters of the workpiece between the model and the experiment did not exceed 3-5%. When deforming a copper billet, the maximum difference level was 8%, which is the result of the low rigidity of the rolling cage with smooth rolls. [ABSTRACT FROM AUTHOR]

Background. The deterministic fiber tracking method has the advantage of high computational efficiency and good repeatability, making it suitable for the noninvasive estimation of brain structural connectivity in clinical fields. To address the issue of the current classical deterministic method tending to deviate in the tracking direction in the region of crossing fiber region, in this paper, we propose an adaptive correction-based deterministic white matter fiber tracking method, named FTACTD. Methods. The proposed FTACTD method can accurately track white matter fibers by adaptively adjusting the deflection direction strategy based on the tensor matrix and the input fiber direction of adjacent voxels. The degree of correction direction changes adaptively according to the shape of the diffusion tensor, mimicking the actual tracking deflection angle and direction. Furthermore, both forward and reverse tracking techniques are employed to track the entire fiber. The effectiveness of the proposed method is validated and quantified using both simulated and real brain datasets. Various indicators such as invalid bundles (IB), valid bundles (VB), invalid connections (IC), no connections (NC), and valid connections (VC) are utilized to assess the performance of the proposed method on simulated data and real diffusion-weighted imaging (DWI) data. Results. The experimental results of the simulated data show that the FTACTD method tracks outperform existing methods, achieving the highest number of VB with a total of 13 bundles. Additionally, it identifies the least number of incorrect fiber bundles, with only 32 bundles identified as wrong. Compared to the FACT method, the FTACTD method reduces the number of NC by 36.38%. In terms of VC, the FTACTD method surpasses even the best performing SD_Stream method among deterministic methods by 1.64%. Extensive in vivo experiments demonstrate the superiority of the proposed method in terms of tracking more accurate and complete fiber paths, resulting in improved continuity. Conclusion. The FTACTD method proposed in this study indicates superior tracking results and provides a methodological basis for the investigating, diagnosis, and treatment of brain disorders associated with white matter fiber deficits and abnormalities. [ABSTRACT FROM AUTHOR]

Multiple hypersonic gliding vehicles' (HGVs') formation control problems with obstacle and collision avoidance are investigated in this paper, which is addressed in the stage of entry gliding. The originality of this paper stems from the formation control algorithm where constraints of dynamic pressure, heating rate, total aerodynamic load, control inputs, collision avoidance, obstacle avoidance, and the terminal states are considered simultaneously. The algorithm implements a control framework designed to be of two terms: distributed virtual controller and actual control input solver. The distributed virtual controller is based on distributed model predictive control with synchronous update strategy, where the virtual control signals are derived by the optimization simultaneously at each time step for each HGV under directed communication topology. Subsequently, according to the virtual control signals obtained, a coupled nonlinear equation set is solved to get actual control signals: each HGV's bank angle together with the angle of attack. The actual control input solver adopts a feasible solution process to calculate the actual control signals while dealing with constraints. Finally, extensive numerical simulations are implemented to unveil the proposed algorithm's performance and superiority. [ABSTRACT FROM AUTHOR]

Space close-range inspection can be used to carry out close-range observation and monitoring of targets for identifying the target's types and working states, which is of great significance for space missions such as in-orbit services. The effectiveness evaluation of space inspection tasks will significantly affect the studies on the trajectory design, orbit motion control, and task termination conditions. However, the evaluation models in previous studies are too simple such as that they are usually without considering dynamic changes in the satellite orbit relative motion. Besides, these studies fail to build a comprehensive evaluation model for the whole inspection task process. In this paper, taking the most commonly used optical inspection as an example, the novel multifactor inspection task effectiveness evaluation models were investigated, including the constraint models of observation, the relative distance evaluation model, the effective observation time evaluation model, and the target observation angle evaluation model. These models solve the effectiveness evaluation problem for the complete process of an inspection task, which can support the design of inspection strategies and trajectories better by using the evaluation results. In addition, numerical simulations and 20 semiphysical experiments were carried out to validate the proposed evaluation models. [ABSTRACT FROM AUTHOR]

As one of the main hydrogen production devices, the performance of the proton exchange membrane electrolytic cell (PEMEC) is directly related to the geometric design of the flow channel. In this paper, a new orthogonally sinusoidal channel with periodic fluctuations in both horizontal and vertical planes is proposed. The effects of amplitude and angular frequency in two orthogonally sinusoidal channels with the same or opposite frequency on PEMEC performance are studied by numerical simulation. The results show that the spatial amplitude and angular frequency effectively improve the electrochemical performance and mass transfer performance of PEMEC. Compared with Case 1-1, the polarization performance of Case 7-2 is increased by 16.39% because of the largest spatial amplitude. The oxygen content at 40 mm away from the inlet in the diffusion layer is also decreased by 42.63%. The horizontal angular frequency can increase the hydrogen content by 11.07% at most in Case 5-2. However, the increase in vertical angle frequency will inhibit the oxygen removal on the anode side. The sinusoidal flow channel in orthogonal spaces will provide a particular reference for the design of PEMEC in the future. [ABSTRACT FROM AUTHOR]

Understanding the mechanical properties of rock is of great significance for the development of unconventional reservoirs. However, a large number of bedding makes the mechanical laws of rock unclear. To investigate the effect of bedding properties on the uniaxial mechanical properties of rock, the coal model containing bedding is developed based on the continuous–discontinuous method, and the effect of bedding angle, bedding strength, bedding number, and loading rate on the uniaxial mechanical properties of rock is investigated. The failure morphology, stress–strain evolution, peak stress, and fracture degrees are analyzed and discussed in detail. The reliability of the numerical model in this paper has been verified by comparison with the indoor experiments. The results show that when the bedding angle is 0°, the peak stress of the rock is maximum, 8.16 MPa, and when the bedding angle is 90°, the fracture degree of the rock is maximum, 3.74%. For the different bedding strengths, the peak stress first decreases linearly with the decrease of the bedding strength. The peak stress barely varies when the bedding strength is less than 0.5 MPa. The fracture degree of the rock shows a nonlinear increase with the increase in bedding strength. For different bedding numbers, the activation of the bedding is not related to the bedding number. The loading speed also has a great influence on the mechanical properties of rock. With the increase in loading rate, the difficulty of bedding activation gradually increases, and the complexity of fractures gradually increases. This study aims to further improve the understanding of the effect of bedding properties on the uniaxial mechanical properties of rock. [ABSTRACT FROM AUTHOR]

This paper studies the distribution characteristics of acoustic emission (AE) events in supporting roadways under different dynamic load conditions through numerical simulation and theoretical analysis. According to the principle of AE numerical simulation, the roadway model is established by FLAC3D software, and the supporting structure of the bolt cable is established by editing the Fish function. According to the model dynamic load application criterion, the relationship between the peak velocity of the particle, the distance from the source center to the dynamic impact damage point, and the dynamic load intensity is introduced. The velocity-distance-energy relationship is deduced from the relationship to determine the magnitude of the dynamic load energy. The simulation results show that the intensity of the dynamic load source and the distance of the dynamic load source directly impact the AE events. The larger the dynamic load intensity and the closer to the dynamic load source, the more concentrated the AE events. The roadway has a blocking effect on the transmission of the dynamic load stress waves. According to this characteristic, the roadway can be protected by a high-pressure relief roadway. Rock lithology greatly influences the transmission of dynamic load stress waves and the number of AE events. When the dynamic load stress wave passes through the rock strata of different lithologies, the attenuation of the dynamic load energy and the number of AE events are large. However, when the dynamic load stress wave passes through the rock strata of the same lithology, the attenuation of the dynamic load energy and AE events is small. The surrounding rock structure in the bottom corner area of the roadway is susceptible to disturbance from dynamic load sources above the roadway. The results are greatly significant for studying the AE characteristics of support roadways with disturbance-typeimpact failure. [ABSTRACT FROM AUTHOR]

In this paper, we study a reaction-diffusion nutrient-phytoplankton model with nutrient recycling delay and toxin-producing phytoplankton. For the delay-free case, we prove that the release rate of toxic chemicals by the toxin-producing phytoplankton can destabilize the system and cause periodic oscillation. For the time-delayed case, we observe that nutrient recycling delay may bring about stability switches and Hopf bifurcation. Moreover, we derive the formula for determining the direction and stability of the bifurcating periodic solutions. Finally, we give some numerical simulations to support the theoretical analyses. [ABSTRACT FROM AUTHOR]

This paper presents synchronization of mixed continuous-discrete complex network via impulse-quantizing approach. A delay-partitioning group strategy is proposed and impulse-quantizing control is designed to derive theoretical criteria ensuring scale-type synchronization of complex networks. Our results show that synchronization of mixed continuous-discrete complex networks can be realized by controlling delay-partitioning subgroup nodes with impulsive quantization. The theoretical results give scale-limited sufficient conditions for quantized synchronization relying on control gains, impulsive intervals, and delays. A numerical simulation is given to demonstrate the effectiveness of the theoretical results. [ABSTRACT FROM AUTHOR]

The large-scale space structure during on-orbit assembly is a time-varying system. The dynamic modeling problem of such incrementally increasing space structure is investigated, and a modular dynamic modeling approach is proposed in this paper. The dynamic model of each substructure is first established, and then, a database is designed to store substructure models, which is used for subsequent dynamic modeling in the assembly process. The fixed connection relationship between adjacent substructures is described by constraint conditions, which lead to the coefficient matrices of adjacent substructures being decoupled. The substructures are assembled in a given sequence, and then, the dynamic modeling, to describe the large-scale space structure on-orbit assembly, is gradually completed via using the proposed modeling approach. The numerical simulation is finally presented. The results demonstrate that the extra calculation resulting from the coefficient matrices coupling of adjacent substructures is avoided. Moreover, the proposed dynamic model can accurately describe the dynamic characteristics of the large-scale space structure during on-orbit assembly. [ABSTRACT FROM AUTHOR]

This paper aims to study the law of pressure behavior and the characteristics of mutual influence in the process of steeply inclined coal seam mining. Based on the geological and engineering conditions of the B8 coal seam in Nanshan coal mine, this paper explores the law of mine pressure behavior in the process of steeply inclined coal seam mining by means of theoretical analysis and FLAC3D numerical simulation. Based on this, this paper also examines the influence of the interaction range between coal seams, the reasonable setting size of the section coal pillar, and the mining distance of the working face on the return air roadway. The results suggest as follows: (1) With an increase in the coal seam dip angle, the difference in the abutment pressure plastic zone between upper and lower coal pillars increases, and when mining in steeply inclined coal seams, the stress concentration in the lower and upper part of the working face deviates to the roof and floor respectively, which is obviously different from that of gently inclined coal seams. (2) The vertical stress above the section coal pillar changes in three stages with an increase in the width of the coal pillar, and the width of the coal pillar in the second stage can be taken as the reasonable size of the width of the coal pillar. The numerical simulation results are consistent with the theoretical calculation results, which indicate the high reliability of this method in determining the reasonable coal pillar size. (3) With an increase in the mining distance in steeply inclined coal seams, the maximum pressure around the working face and above the return air roadway has gone through three stages. When the distance between the working face and the adjacent return air roadway is close, the pressure above the return air roadway increases sharply, and disturbance is stronger. [ABSTRACT FROM AUTHOR]

The ice crystal supercooled droplet mixed phase icing problem is an important research direction in aircraft icing and has received more attention in recent years. The thermodynamic process of the water film after the ice crystals impact on the surface determines the final ice shape, which is an important part of the accurate prediction of aircraft icing. In this paper, a thermodynamic model of ice crystal supercooled droplet mixed phase icing is proposed based on the extended Messinger model, according to the results of flow field and particle trajectory calculations. In this model, the mass and energy conservation equations of ice crystals, supercooled droplets, and liquid water are considered. The equations take the process of ice crystal adhesion and erosion into account, and the solution method of the equations is given. Ice shapes are calculated under various ice crystal supercooled droplet mixed phase conditions and compared with experimental results to demonstrate the validity of the numerical method. The effects of ice crystal erosion rate, melting ratio, and adhesion coefficient on the calculation results are analyzed by a numerical method. The results show that the ice crystal erosion rate has little effect on the ice shape, while a larger melting ratio and adhesion coefficient lead to more ice accretion. [ABSTRACT FROM AUTHOR]

Offshore wind turbines (OWTs) are considered vital to the promotion of the development of renewable energy. Especially, floating OWTs can be deployed over a larger area than bottom-fixed OWTs. The floating OWTs, however, are vulnerable to vibration induced by disturbances and require a backup power supply in the case of power outage. On the one hand, various kinds of inerter-based devices have been proposed especially for vibration suppression of civil structures subjected to earthquake loadings. Recently, combined with electromagnetic devices, the inerter technologies have also been applied in the field of vibration energy harvesting such as point absorber wave energy converters. Thus, this paper proposes a novel floating OWT consisting of two bodies combined with inerter-based power take-off (PTO) devices which accomplishes vibration suppression and wave energy conversion at the same time. To investigate the vibration suppression and energy conversion capabilities of the proposed floating OWT with a variety of inerter-based PTO devices for ocean waves, numerical simulation studies employing WEC-Sim are conducted, and the performance of each system is compared for regular and irregular waves. Results show that the proposed floating OWT with the appropriately designed inerter-based PTO devices for the incident wave period has great potential for both vibration suppression and wave energy conversion in a specific frequency range. [ABSTRACT FROM AUTHOR]

This paper focuses on simulating the collision breakage process between the agglomerate and hammer in a hammer crusher by the discrete element method (DEM) as the interaction between particles. This enables us to consider the energy change in the collision breakage process of the hammer. The agglomerate model is built by using the EDEM 2.7 software according to the principle of closest packing in crystallography, while the hammer model is modeled into an assembly of different sizes of spherical particles to make the collision breakage process between the agglomerate and hammer as the one of interrelation of particles. With these models, we mainly investigated collision force, collision impulse, energy breaking agglomerate, and the relationship between the specific breakage energy and agglomerate damage ratio. The collision force is represented as Gaussian function, the collision impulse is represented by the function of the mass ratio of agglomerate to hammer and the product of agglomerate mass and collision velocity, and the relationship between the specific breakage energy and agglomerate damage ratio is represented by exponential function. Finally, it can be seen from this study that, when crushing the agglomerate by hammer impact, it is necessary to increase the specific breakage energy by 1.75 times in order to increase the agglomerate damage ratio from 85% to 90% but 2.13 times in order to increase 95%. The proposed method can be used for the further development and design of the various types of crusher. [ABSTRACT FROM AUTHOR]

During alloy solidification, many free grains in the melt have important effects on the final microstructure and composition distributions. In this paper, grain motion is calculated based on an interface tracking method coupled with a cellular automata (CA) method. First, the interface tracking capabilities of the level set, simple linear interface calculation (SLIC), and piecewise linear interface calculation (PLIC) methods are compared, and the fidelity of the three models is explored. Then, the coupling degrees of these three models with the CA method are analyzed. Finally, the PLIC method is used to simulate various behaviors of grain movement and to verify the authenticity of the dendrite motion calculation. The simulation results show that the VOF methods more readily coupled with the CA model than the level set method, and it is more suitable for calculating the motion behaviors of dendrites. Among the VOF methods, the interface reconstructed by the SLIC method is relatively rough and can only calculate objects with simple morphologies. The PLIC method has a fine interface and small error in the calculation of dendrite movement, and it does not significantly impact the subsequent calculations. [ABSTRACT FROM AUTHOR]

Driven by the aesthetic pursuit of the urban landscape, pedestrian bridges become longer, lighter, and slender, which may be susceptible to unacceptable vibrations induced by human activities. This paper presented on-site vibration tests of a pedestrian bridge with a very low height-to-span ratio (1/60). The vibration characteristics and dynamic responses were analyzed using environmental, heel-drop, and walking tests. Then, a verified finite model was established to investigate the effect of the height-to-span ratio and the concrete filling ranges of tree-like steel piers on the vibration characteristics and acceleration responses of this kind of pedestrian bridges. Moreover, the relationship between different peak accelerations under heel-drop and walking at various frequencies by the same person was detailed and studied experimentally and by computer simulation, after which the ratios of the peak acceleration during walking and the one under heel-drop were recommended. Finally, a method that demonstrates the feasibility of predicting the peak acceleration of pedestrian bridges of a small height-to-span ratio across a range of walking frequencies was proposed based on a simplified heel-drop load model developed according to 60 time-history records. [ABSTRACT FROM AUTHOR]

This paper analyzes the modeling of a computer-aided piano music automatic notation algorithm, combines the influence of music on psychological detachment, and designs the piano music automatic notation algorithm in psychological detachment model construction. This paper investigates the multiresolution time-frequency representation constant Q-transform (CQT), which is common in music signal analysis, and finds that although CQT has higher frequency resolution at low frequencies, it also leads to lower temporal resolution. The variable Q-transform is introduced as a tool for multibasic frequency estimation of the time-frequency representation of music signals, which has better temporal resolution than CQT at the exact frequency resolution and efficient coefficient calculation. The short-time Fourier transform and constant Q-transform time-frequency analysis methods are implemented, respectively, and note onset detection and multibasic tone detection are implemented based on CNN models. The network structure, training method, and postprocessing method of CNN are optimized. This paper proposes a temporal structure model for maintaining music coherence to avoid manual input and ensure interdependence between tracks in music generation. This paper also investigates and implements a method for generating discrete music events based on multiple channels, including a multitrack correlation model and a discretization process. In this paper, the automatic piano music notation algorithm can play an influential role in significantly enhancing the actual effect of psychological detoxification. [ABSTRACT FROM AUTHOR]

The occurrence probability of freak waves is related to the sea wave spectrum. In this paper, different wave spectrums are used to simulate time-invariant three-dimensional freak waves. Freak waves that meet the international standards are generated at fixed time and location by adjusting the energy of the wavelets. We studied the occurrence probability of freak waves under the conditions of different wave spectrums, different wind speeds, and different modulation ratios and optimized the calculation speed of the model. Simulation data show that the difference in the shape of the wave spectrum affects the probability of freak waves occurrence. The model conforms to the Benjamin–Feir index (BFI), and the ratio of wave steepness to spectrum bandwidth is the key. In this paper, the Kirchhoff approximation theory is used to study the electromagnetic scattering (EM scattering) properties of freak waves on the large scale. We ideally calculate the Normalized Radar Cross-Section (NRCS) from the sea surface with freak waves, under different wind speeds and different grazing angles. The NRCS of freak waves is extremely low, and the increase of wind speed and the decrease of the grazing angle will make the detection of freak waves more difficult. The possibility of detection of freak waves is higher at high grazing angles (low incidence angles). The numerical simulations provide reference for engineering. [ABSTRACT FROM AUTHOR]

For large-spanshallow-buried tunnels in composite strata of urban metro, the study on the distribution characteristics of surrounding rock pressure is a necessary prerequisite for the reliability analysis of tunnel structure. In this paper, through numerical simulation, the random joint file generated by MATLAB is combined with the discrete element software to establish the corresponding random network model. According to the network model calculation, the influence of surrounding rock pressure on the support structure system is discussed, and the reasonable support parameter types are given. Comparing the whole section excavation with the subsectional excavation, the subsectional excavation can effectively control the internal stress self-adjustment of the surrounding rock and effectively restrain the plastic zone. It provides some theoretical guidance and reference for tunnel reliability design. [ABSTRACT FROM AUTHOR]

While promoting the development of the Internet of Things, cloud-fog hybrid computing faces severe information security risks. The intrusion detection system deployed in the fog node has lower latency but needs to be more lightweight. In response to the abovementioned problems, this paper proposes a lightweight intrusion detection model based on ConvNeXt-Sf. First, the two-dimensional structure of the latest computer vision model ConvNeXt is reduced to a one-dimensional sequence. Then, the design criteria of the lightweight computer vision model ShuffleNet V2 are used to improve ConvNeXt to make the latter more lightweight. Finally, the max-min normalization and label encoder are built into the data preprocessing model to convert the network traffic into a form conducive to ConvNeXt learning. The proposed model is evaluated on the TON-IoT and BoT-IoT datasets. The params of ConvNeXt-Sf are only 1.25% of that of ConvNeXt. Compared with the ConvNeXt, the ConvNeXt-Sf shortens the training time and prediction time by 82.63% and 56.48%, respectively, without reducing the learning capability and detection capability. Compared with the traditional models, the accuracy of the proposed model is increased by 6.18%, and the FAR is decreased by 4.49%. Compared with other lightweight models, the ShuffleNet V2 is better at making ConvNeXt lightweight. [ABSTRACT FROM AUTHOR]

This paper studies the aircraft air circulation system and proposes a new architecture of the aircraft air circulation system. Combined with the neural network algorithm, the numerical simulation results of turbine, compressor, and heat exchanger are fitted and predicted, and the accuracy of the simulation model is verified by comparing with the experimental results. Comparing and analyzing the booster, F-15, F-35, and the newly proposed air circulation system, the engine bleed air volume consumed by the system under different flight conditions is obtained. The results show that the newly proposed air circulation system can save up to 71.4% of the engine bleed air compared with the simple boost and 29.8% of the engine bleed air compared with the F-35. The new air circulation system proposed in this paper can effectively improve the energy utilization rate of the system and reduce the consumption of engine bleed air. [ABSTRACT FROM AUTHOR]

This study focuses on a differential wheeled robot's (DWR) prescribed-time fractional order position control. Firstly, based on the kinematic model of DWR, a distance-related orientation error is designed using the inverse sine function. Based on this, an improved linear velocity constraint function is proposed. Compared with existing methods, while ensuring the correlation between velocity and orientation error, the multibalance point risk caused by large angle errors is avoided. Then, a prescribed-time fractional order position controller based on a time-varying scaling function is proposed to stabilize the kinematic system of DWR in the prescribed time. This controller can stabilize the position control system of the DWR in a prescribed time by adjusting the prescribed-time parameter, avoiding the infinite gain risk in traditional prescribed-time controllers. Finally, through numerical simulation, we verify that the proposed control law can converge the system status of DWR to the bounded interval in the prescribed time. [ABSTRACT FROM AUTHOR]

In recent years, due to the increase in the incidence of traffic accidents, the number of people with limb injuries has also increased. At the same time, among the aging population, neurological diseases or cardiovascular and cerebrovascular diseases have caused many people to have limb hemiplegia. It has been clinically proven that the use of rehabilitation equipment can help patients with limb injuries to restore limb motor function. This paper takes wearable lower limb rehabilitation exoskeleton as the research object, and its main contents are mechanical structure design, kinematics analysis, gait planning, virtual prototype simulation, and experimental verification and analysis. Based on the physiological characteristics of human body and the principle of comfortable and reliable wearing, this paper designs wearable exoskeleton for lower limb rehabilitation. Firstly, the physiological structure characteristics and movement mechanism of human lower limbs were studied and analyzed. By referring to the rotation range and height and size of each joint of human lower limbs, the overall scheme of wearable lower limb rehabilitation exoskeleton was designed and the degree of freedom was allocated. At the same time, Solidworks was used to establish a three-dimensional model. On the basis of a 3D model, a kinematics model was established, and the forward kinematics solution was obtained by using homogeneous coordinate transformation. Since the inverse kinematics solution was relatively complicated, the inverse kinematics solution was conducted in this paper according to the geometric relations of the joints of the lower limbs. Kinematics analysis of the exoskeleton structure of wearable lower limb rehabilitation was carried out to lay a theoretical foundation for gait planning. The off-line gait planning was carried out by using the method based on ZMP stability criterion, and the gait planning was divided into five stages: squat, start, middle step, stop and rise, and the motion trajectory of the center of mass and ankle joint was planned. Based on the inverse kinematics formula, the function of the change of joint angle with time in walking process is derived. The virtual prototype is established in ADAMS, and the simulation of virtual prototype is carried out by using the function of gait planning's joint angle and time. The correctness of structural design and gait planning was verified by measuring the trajectories of the centroid and ankle joints in each gait stage and the functional relationship between the rotation angle of each joint and time. Then, using a 3D dynamic capture system to capture the human lower limb motion trajectory of each joint, each joint trajectory data output, using the MATLAB software to output data, gets the joint trajectory change over time function curve and is used to verify feasibility and applicability of human gait planning. Through the research and analysis of the joints of the lower limbs of the human body, it can be concluded that the hip joint and the knee joint have 3 degrees of freedom, respectively, and the knee joint has 1 degree of freedom. [ABSTRACT FROM AUTHOR]

Based on computer vision technology, this paper presents a human motion analysis and target tracking technology based on computer vision. In terms of moving target detection, the current moving target detection technology is summarized, and some experimental results of the algorithm are given. The background difference method under monocular camera is emphatically analyzed. The preliminary human contour is obtained by the background difference method. In order to obtain a smoother target contour, the mathematical morphology is used to remove the noise, and the judgment algorithm of the size of the image connected domain is added. A specific threshold is set to remove the connected domain of the noise block less than the threshold. In the aspect of human motion recognition, this paper selects human motion features, including minimum external rectangle aspect ratio, rectangularity, circularity, and moment invariant. The criteria for selecting human motion features are strong noise resistance and obvious distinction. Then, the three types of human motion images are classified and recognized. After cross-validation and parameter optimization, the recognition accuracy is significantly improved. The experimental results show that the video sequence collected in the field has a total of 376 frames, and the frame rate is 10 frames/s. Due to the small traffic, the mean shift algorithm based on adaptive feature fusion is used to track the target every 2-3 frames. And set the inverse X direction as the direction of entering the scene and the X direction as the direction of moving out of the scene so that the allowable error of the distance between the detection and tracking results is 10. The weight of each feature is dynamically updated by the similarity between the candidate model and the target model, which solves the problem that the mean shift algorithm is not robust enough when similar objects are occluded and interfered and achieves more accurate tracking. [ABSTRACT FROM AUTHOR]

With the rapid development of the Internet era and the high popularity of computers, China's economy, politics, and culture have made rapid progress in recent years. In order to adapt to this era of rapid change, China's higher education has also undergone great changes and carried out reform and innovation. As the top priority in the Internet era, computers should be reformed first. The traditional education model is mainly teacher-centered and classroom-centered. The disadvantages of this teaching mode are that students' subjective initiative cannot be fully developed and brought into play. Traditional teaching pays attention to knowledge teaching and ignores ability training. It emphasizes speaking and neglects practice. Therefore, in order to meet the development needs of the new era and cultivate modern talents, colleges and universities began to explore the innovation and entrepreneurship education mode. There is an application of TRIZ theory to the cultivation of innovation and entrepreneurship education, and TRIZ theory is a theory for solving invention problems. Its main content is to find its own laws in the process of technological evolution and analyze the laws to get a general solution, but there are many obstacles in exploring the mode of innovation and entrepreneurship education; for example, many governments do not support this education reform and do not broadcast relevant education and teaching funds for schools, resulting in uneven configuration of software and hardware in schools. According to the survey, the proportion of innovation and entrepreneurship education in the eastern coastal areas is as high as 70%, while the proportion of innovation and entrepreneurship education in the central and western regions is only 10%. This set of data shows that regional differences are the main reason for the differences in education development. In terms of the proportion of education funds, although the annual education funds will gradually increase in recent years, the proportion is still a drop in the bucket in front of huge fiscal revenue, with the highest being only 0.1%. Therefore, in order to improve the current situation of innovation and entrepreneurship education mode in colleges and universities, according to their own characteristics, the reform is carried out from the aspects of practical ability, competition participation, and training plan, and the BP neural network model is introduced to predict and analyze the effect of teaching methods. The results of this paper are investigated and analyzed. Finally, the investigation on the development of KAB course and SYB course and the analysis on the stability and error of BP neural network are within the allowable range, this shows that the model established in this paper is more favored by students than the traditional teaching methods, more in line with the social reality, the effect is more ideal, and the result is more stable. [ABSTRACT FROM AUTHOR]

As a supplement to traditional teaching methods, computer-assisted teaching methods can reflect modern educational concepts, such as creating student-led, teacher-led environments. The goal of college English education is to enable them to communicate effectively in English in their future academic, work, and social interactions, while also developing students' self-learning skills. Chinese society improves overall cultural competence and adapts to the needs of international communication. Self-directed learning is not static and will increase or decrease with time, discipline, and conditions and is an evolving process. Understanding learning, taking responsibility for one's own learning, and learning how to learn are all beneficial. Students abound in school life and even throughout their lives. In this paper, we try to propose a computer-based method for constructing an independent English learning model based on a practical study of computer network technology for the development of self-learning ability of non-English majors in a university. This paper uses comparative analysis techniques to compare traditional paper-and-pencil examinations and computer-based online evaluations and analyzes the effects of each. The survey showed that 81% of the students preferred the computer-based assessment. Therefore, the focus of this research is to strengthen the oral English training in college and create an authentic English learning environment for students to really feel the standard English pronunciation, intonation, and knowledge of grammar, listening, reading, writing, and translation. [ABSTRACT FROM AUTHOR]

Previous studies mainly used statistical methods to analyze the impact of traffic composition on saturation flow rate from the mesolevel, and there is insufficient research on how traffic composition affects driving behavior. Thus, the purpose of this paper is to establish a more accurate car-following model, establish the relationship between microbehavior and mesostatistical regularity, and explain the influence of vehicle composition on saturation headway. In this paper, an improved full velocity difference (FVD) model is proposed, which abstracts the driver characteristics of a heterogeneous flow into four scenarios: car-car, car-bus, bus-car, and bus-bus. The measured data are used to calibrate and verify the basic FVD and the improved FVD models. The performance of the improved model is significantly improved. The RMSE and RMSPE are reduced by 15.29% and 22.32%, respectively. Finally, through numerical simulation experiments, the variation of saturation headway with different proportions of buses is analyzed. The saturation headway increases with the increase of the proportion of heavy vehicles. Moreover, another important finding is that the saturation headway is not significantly influenced by the position of the buses but only by the proportion of the buses. The research results could provide theoretical support for the control and management of fleets composed of different vehicles at intersections. [ABSTRACT FROM AUTHOR]

For a long time, college English instruction has emphasised language skills training and information transfer while neglecting to emphasise the development of cross-cultural communication skills. Theoretical study on cross-cultural communication ability, on the other hand, has grown in various dimensions and lacks empirical research methodologies. Meanwhile, in real teaching, a cross-cultural communicative competence training framework that is adequate for Chinese college English teaching practise and has a high degree of recognition and operability has yet to be constructed. This paper uses computer simulation technology to construct the teaching system of college English cross-cultural knowledge. At the same time, this paper proposes a cross-cultural communicative competence training model suitable for Chinese college English teaching based on the Chinese language communication environment and foreign language teaching environment. Finally, this paper constructs a cross-cultural university English teaching system model through computer simulation. Through teaching experiments, we can see that the system constructed in this paper has a certain effect. [ABSTRACT FROM AUTHOR]

Interwell connectivity assessment in polymer-driven reservoirs is critical for setting appropriate injection rates and improving oil recovery. Traditional deep learning techniques often lack accuracy and reliability when applied to short-term oilfield production data. In response, the A-LSTM algorithm is proposed, which integrates the attention mechanism with a long- and short-term memory network (LSTM). The predictive accuracy of A-LSTM is assessed and juxtaposed with LSTM and support vector regression (SVR) algorithms for short-term single-well daily oil production analysis. The Huber loss function was utilized to quantify the difference between predicted and actual results, resulting in a dynamic production prediction model. An interwell connectivity (IWC) assessment model is then obtained by fusing the dynamic production prediction model with the EFAST method, thus demonstrating the superior prediction accuracy of A-LSTM in oil production prediction and connectivity assessment. Moreover, the credibility of the assessment is further corroborated through numerical simulations and interwell tracer tests. The study results showed that the interwell connectivity evaluation model based on the A-LSTM algorithm and EFAST method is not only capable of accurately predicting the single-well daily oil production using a small sample dataset but also a highly reliable method for interwell connectivity evaluation, and the application of the interwell connectivity assessment model can further guide polymer flooding work in oilfields. [ABSTRACT FROM AUTHOR]

In this study, the vibration characteristics of a bullet-loaded recorder's vibration damping system under various preload conditions are investigated through theoretical analysis, numerical simulations, and experimental verification. The findings indicate that the inclusion of a polyurethane elastomer vibration damping buffer layer between the cartridge and the recorder, along with the application of a specific preload, significantly reduces the amplitude of vibration acceleration transmitted to the recorder's interior. This, in turn, enhances the overload resistance of the cartridge's internal circuit. Numerical simulation results and theoretical analysis suggest that increasing the preload on the buffer material between the elastomer and the recorder reduces both the frequency ratio and damping ratio of the damping system. This reduction further decreases the amplitude of vibration transmitted to the recorder. However, excessively high preload generates substantial compressive stress within the recorder under static conditions, intensifying during the projectile's accelerated movement. As a consequence, deformation and damage occur to the internal circuitry. Therefore, ensuring that the recorder possesses the structural strength necessary to withstand increased preload is crucial. This balancing act improves the recorder's resistance to shock, vibration, and overload, while also preventing excessive stress-induced damage. [ABSTRACT FROM AUTHOR]

Focusing on the phenomenon of the crack on the autoclave flange, a three-dimensional model of the autoclave was established based on the Ansys Workbench platform. A new finite element analysis flow for optimizing the design of autoclave teeth was established using the Fluent, Static Structure, and Direct Optimization modules. The paper analyzed and discussed the maximum stress and minimum fatigue life at the corresponding position. The variation trend of stress and fatigue life at the corresponding position after fillet optimization was also discussed. The results showed that the equivalent stress of autoclave teeth without fillet optimization reached the maximum under different fillet sizes. The equivalent stress and fatigue life of the autoclave tooth were the same as the rounded corner size obtained by the optimization design. The optimal global solution could be obtained through the optimization design process. [ABSTRACT FROM AUTHOR]

The interval section of the Liuyang River flood control levee project of the Changsha Metro Line 6 is used as the engineering background of this study. A three-dimensional finite element numerical model of a tunnel shield containing complex interfaces is established by using the multifield coupling software COMSOL. The paper studied the deformation of flood control levees under shield tunnel excavation working conditions. The results show that when the left line shield machine is excavated below the Liuyang River flood control levee, the deformation of the flood control levee and the surrounding rock of the tunnel is biased towards the built right line tunnel. And it has an impact on the bridge pile near the tunnel. When the shield of the left line crosses the flood control levee, it can easily cause a large deformation and displacement of the levee above the area between the two shields. To ensure the controlled deformation of the levee, the construction should ensure the spacing between the two tunnel palm faces as far as possible and should be far away from other structures on the levee. When the shield crosses the levee, the deformation that occurs at the base of the levee is significantly higher than the deformations that occur at other locations of the levee. Displacement monitoring and secondary reinforcement at the base of the flood control levee appear to be necessary. The numerical simulation results validate the feasibility of using the multifield coupling software COMSOL to study the construction modeling of shield tunnels through rivers and its advantages. This method provides a practical framework for similar tunnel performance engineering or displacement monitoring in future projects. [ABSTRACT FROM AUTHOR]

The squeezed multiple-branch pile is a variable section pile that was built by adding a bearing branch cavity to a constant section pile using expansion and extrusion equipment. It is widely used in engineering practice for its high bearing capacity, small settlement deformation, high economic benefits, strong adaptability, and simple pile forming process. In this paper, a new type of squeezed multiple-branch pile is proposed and its forming tool is invented. The forming tool of the pile has applied for an invention patent and is authorized by the China National Intellectual Property Administration. Multiple groups of comparison models of the new squeezed multiple-branch piles are established by using FLAC3D numerical simulation software to investigate the influence of the number and spacing of branches on the bearing mechanism in response to uplift load. The results indicated that the number and spacing of branches have a significant effect on the uplift bearing capacity, load–displacement curves, side friction resistance, and stress distribution law in the new pile and soil around the pile. The suitable number and spacing of branches maximize the uplift bearing capacity and minimize the settlement of a single pile. [ABSTRACT FROM AUTHOR]

This paper addresses the control problem of the flexible joint manipulator (FJM) with unmeasurable system states and mismatched uncertainties. First, the control system is transformed as a matched uncertain system with unmeasurable states based on differentiation method. Then, the uncertainties and unmeasurable states are estimated by designing a fixed-time observer (FTO). Based on the integral sliding-mode control (SMC), the bi-limit homogeneity technique and the estimation of FTO, a finite-time SMC is proposed for FJM. Compared with the existing finite-time SMC method for FJM, the most attractive feature of the proposed method is that not only the finite-time convergence is guaranteed but also the two angular velocity sensors for rotation angles of link and motor are simplified. Moreover, the proposed SMC can suppress the mismatched and matched uncertainties by using chattering-free control input. The fixed-time stability of FTO and finite-time stability of proposed controller are proved. Finally, the efficiency of proposed scheme is shown by the numerical simulation. [ABSTRACT FROM AUTHOR]

In this paper, we consider a general time-space discrete host-parasitoid model with the periodic boundary conditions. We analyzed and obtained some usual conditions, such as Turing instability occurrence, Flip bifurcation occurrence, and Neimark-Sacker bifurcation occurrence. We also find several multiple bifurcation phenomena, such as 1 : 2 Resonance, Neimark-Sacker-Flip bifurcation, Neimark-Sacker-Neimark-Sacker bifurcation, Neimark-Sacker-Flip-Flip bifurcation, induced by diffusion. In a modified Nicholson-Bailey model, employing the mutual interference and diffusive interaction as bifurcation parameters, there appear route from standing Turing instability to multiple bifurcations by changing diffusive parameters. Some numerical simulations of the modified Nicholson-Bailey model support these corollaries. [ABSTRACT FROM AUTHOR]

It is of great significance to identify structural state-parameters and the unknown seismic inputs using partial measurements of structural acceleration responses for the rapid evaluation of structures after unknown seismic excitations. However, unknown seismic inputs do not directly appear in the observation equations of measured absolute floor accelerations of building structures, i.e., there is no direct feedthrough of unknown seismic inputs in the observation equations. Current methods for the identification of joint structural systems and unknown inputs are either inapplicable or greatly influenced by measurement noises. In this paper, a method so-called smoothing extended Kalman filter with unknown input without direct feedthrough (smoothing EKF-UI-WDF) is proposed. The identification algorithm is derived in the framework of minimum-variance unbiased estimation (MVUE), and the smoothing technique is adopted to introduce subsequent observation steps in the current identification step. Then, structural states, parameters, and unknown seismic excitations without direct feedthrough are simultaneously identified recursively with only a few steps delay, and the identification results are tolerant to measurement noises. The proposed method is verified by a numerical simulation model and a practical engineering case study. Both identification results validate the effectiveness of the proposed method for the simultaneous identification of structural systems and seismic inputs without direct feedthrough. [ABSTRACT FROM AUTHOR]

This paper studies Lyapunov stability at a point and its application in the Cournot duopoly game. We first explore the relationship between Lyapunov stability at a point, nonsensitivity and non-Devaney chaos and find that a dynamical system is nonsensitive and non-Devaney chaotic if there is a point in this system such that it is Lyapunov stable at that point. We next prove a group of equivalent characterizations of Lyapunov stability at a point to deduce the composite theorems and product theorems of Lyapunov stability at a point, and then we prove three equivalent characterizations of the Cournot duopoly system to demonstrate that this system is Lyapunov stable at its unique nonzero fixed point (Cournot equilibrium point) when the unit costs of the Cournot double oligarchies satisfy certain conditions. Therefore, we conclude that the Cournot duopoly system is safe relative to both sensitivity and Devaney chaos. The robustness of our results are also verified by conducting numerical simulations in the Cournot duopoly game. [ABSTRACT FROM AUTHOR]

A guidance approach with obstacle avoidance is proposed for maneuvering target interception. Firstly, by decomposing the constrained optimal guidance problem into two associated subproblems, the overall scheme of guidance is presented. Secondly, to improve the guidance accuracy against the maneuvering target, an MPC controller with disturbance estimation is designed, which transforms the global optimization problem into a finite-horizon optimal control problem. An auxiliary controller is also developed to ensure the system's stability. Then, to achieve obstacle avoidance without affecting the guidance accuracy, a unified function is built to assess the threats from obstacles of different shapes, based on which the optimal guidance-obstacle avoidance model is established. Finally, to solve the above optimization problems, a hybrid solver is developed based on the adaptive moment estimation (Adam) algorithm, whose output will serve as the real-time guidance command. The numerical simulation results show that the guidance approach presented in this paper can achieve precise guidance and obstacle avoidance in various scenarios, and the Monte Carlo experiment further demonstrates the robustness and computation efficiency of the approach. [ABSTRACT FROM AUTHOR]

In this paper, a novel Kenics static mixer applied in a direct-contact heat exchanger (DCHE) was proposed in order to enhance the heat transfer efficiency. The computational fluid dynamics (CFD) simulation method was adopted to investigate the effect of the continuous phase and dispersed phase on direct-contact heat transfer (DCHT) in the Kenics static mixer. The perforation index (PI) was introduced to depict the performance of the Kenics static mixer, and the effect of different numbers of openings at three initial heat transfer temperature differences (at the inlet of the continuous and dispersed phases) was studied. The simulation results showed that under the same working conditions, a larger initial temperature difference would result in greater differences in the fluid uniformity index (UI), turbulence intensity, and time evolution of a gaseous working substance. The increase of hole numbers and decrease of hole diameters can optimize the DCHT. Under three initial temperature differences, the heat transfer efficiency for the 6-hole and 9-hole Kenics DCHEs was about 20% higher than the Kenics DCHE without holes. [ABSTRACT FROM AUTHOR]

Considering the stringent requirement of the pointing accuracy up to 2.5″ of the world's largest full steerable radio telescope, this paper studies the welding experiment of the azimuth track of the antenna. First, the opposite deformation jig and welding process were designed for the QTT's azimuth track. Then, the welding process was numerically simulated using a finite element model. The simulation results show that a better welding effect will be obtained by appropriately reducing the opposite force on the basis of the original. The three deformation processes of the track are regulated by the opposite deformation jig. The results show that the opposite deformation jig designed for QTT's azimuth track can make the amount of deformation and flatness meet the design requirements. Finally, nondestructive testing was carried out to check the welding quality of the track surface and interior. The results show that there are no obvious defects in the welds of the azimuth track. The constraint jig and welding processes designed for QTT are effective and feasible. [ABSTRACT FROM AUTHOR]

In this paper, considering the mooring system can be taut-slack in the motion, the dynamic equations of the mooring system are derived by using the theory of large deformation. The nonlinear dynamic response of semitensioned mooring line is numerically simulated. Assuming the platform motion is known, the effect of platform on mooring line is simplified as an end-point excitation. Directly using the finite difference method for numerically solving partial differential equations of mooring line, the dynamic responses can be obtained. Then, the causes about the nonlinear state are analyzed, and the location where the taut-slack phenomenon occurs can be located by calculating the tension of mooring. The results show that the mooring line is more likely to be taut-slack under tangential excitation with the tension change, while the mooring remains taut under normal excitation. The taut-slack state of the mooring line is concentrated near the anchor point. Through the amplitude-frequency curve and bifurcation point set, it is found that the taut-slack region is accompanied by multiperiod motion. And the taut-slack phenomenon will lead to the unstable motion. [ABSTRACT FROM AUTHOR]

In this paper, a saltwater intrusion model, in view to study the dynamics of the interface between the saltwater and the freshwater in a coastal aquifer, is established. This dynamic is caused by an injection of saltwater and a freshwater pumping through a well located in a given position. From the flow model in each phase, we defined an appropriate hypothesis to obtain our global model based only on the height of the interface. The numerical simulation of our model led us to study the effect of the parameters and obtain some empirical laws of the pollution time versus the distance well-injection area and pollution time versus the pumping flow. [ABSTRACT FROM AUTHOR]

In this paper, a saltwater intrusion model, in view to study the dynamics of the interface between the saltwater and the freshwater in a coastal aquifer, is established. This dynamic is caused by an injection of saltwater and a freshwater pumping through a well located in a given position. From the flow model in each phase, we defined an appropriate hypothesis to obtain our global model based only on the height of the interface. The numerical simulation of our model led us to study the effect of the parameters and obtain some empirical laws of the pollution time versus the distance well-injection area and pollution time versus the pumping flow. [ABSTRACT FROM AUTHOR]

In order to study the influence of bedding structure on the mechanical properties of rock mass structure, this paper takes the layered carbonaceous slate in the Muzhailing tunnel as the research object, and studies the mechanical properties of layered slate under uniaxial compression and Brazilian splitting. In the numerical simulation, the discrete element software MUSEN (bonded particle model, BPM) is used to simulate the failure behavior of layered rock mass in the process of quasi-static compression. The main research contents of this paper are as follows: (1) the relationship between the microscopic Young's modulus and the macroscopic Young's modulus. (2) Influence of tangential shear strength and normal tensile strength on particle model. (3) The influence of different particle distributions on the simulation results. (4) The particle model with different bedding inclinations was simulated numerically. Through the comparative analysis of simulation and experiment, the results show that the mechanical response and failure mode have good consistency, and the splitting evolution process of layered slate with different bedding inclination angles is reproduced. [ABSTRACT FROM AUTHOR]

Summary: The proportion of groundwater‐related diseases in the operational high‐speed railway tunnels in China is increasing and rapid and accurate disease monitoring is urgently needed. Therefore, it is a new attempt to monitor 5‐ to 10‐m water‐bearing anomalies in operating tunnel structures by using train‐borne transient electromagnetic method. The stationary interference source train tracks in the tunnel environment have serious electromagnetic interference to the monitoring of water‐bearing anomalies. Thus, this paper combines numerical simulations and indoor experiments to carry out research on the minimum water‐bearing anomalies that can be monitored at such close distances by train‐borne transient electromagnetic method under electromagnetic interference from train tracks. First, a comparative study of the electromagnetic characteristics of the water‐bearing anomalies when their own parameters change is carried out by numerical simulation, followed by a comparative analysis of the electromagnetic response of the water‐bearing anomalies under the interference of train tracks. For the missing electromagnetic response of the coil‐metal‐anomaly in the numerical simulation, a full‐scale physical model experiment is conducted to obtain the time range of the three interferences. Also in the experiments, the feasibility of existing instruments for close range water‐bearing anomalies detection is verified by comparing different transient electromagnetic instruments. Finally, the minimum water‐bearing anomalies that can be monitored in close proximity under the interference of train tracks are obtained experimentally. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of nonlinear uncertainties when tracking an infrared dim small target with fast maneuvers. The particle filter (PF)-based methods are mostly considered. The existing improvement methods for the PF can handle the infrared dim small target with the conventional maneuver, the motion state of which changes slowly and in most cases is assumed to be linear. However, when fast maneuvers appear on the target, the PF-based method will soon suffer from particle degeneracy, or even loss of the target. In this paper, a robust exact differentiator (RED)-based particle generating method is proposed to improve the PF. New birth particles are produced by the proposed method, which can keep up with the fast maneuvers, and ensure the particle diversity of the PF, so as to avoid the particle degeneracy and depletion, meanwhile the number of particles required can be decreased. Numerical simulations are conducted, showing that the proposed algorithm has more advantages than the state-of-the-art method. [ABSTRACT FROM AUTHOR]