Horizontal And Vertical Research Articles

Microscopic deformation mechanism and characteristics of carbonaceous slate during the creep process

Carbonaceous slate exhibits a significant creep deformation that seriously affects the construction and operation of underground projects. To investigate the microstructural changes characteristics and reveal the microscopic deformation mechanism of the carbonaceous slate during the creep process, multiple methods were performed, including the triaxial creep test, SEM and MIP. The following conclusions were drawn: The rock samples underwent three stages during the creep test: microporosity closure at a low-stress level, material densification at an intermediate stress level, and microcracks emerging and expanding to failure at the high stress. The creep deformation was particularly significant in the first and third processes. The lamellar particles are compressed or bent under stress in parallel and vertical directions, showing the anisotropic properties of deformation. The deformation of the rock sample is related to the angle between the bedding and the orientation of major principal stress, and the effect of the anisotropy decreases with the increased stress level. The sprouting and expansion of microfractures occur at high-stress levels, showing pressure dissolution of mineral particles, migration of very fine particles, and cement damage between lamellar particles. Finally, the horizontal samples formed a combined rupture surface composed of the laminar surface and the fracture surface intersecting it, showing brittle damage, while the vertical samples formed a fracture surface parallel to the laminar surface, showing a ductile damage pattern. Those results could provide the basis for a further understanding of the mechanical properties of carbonaceous slate and the improvement of its creep model and parameters. It was significant for the stability analysis and deformation prediction of engineering structures using numerical simulation.

Analysis of contaminant dispersion in constructed wetland flows with absorptive boundaries

Pollution in wetland flows poses a significant challenge to ecosystem preservation, underscoring the importance of wetland restoration. Constructed wetlands have emerged as a widely embraced solution for contaminant mitigation. In this study, we focus on the contaminant removal process within the wetland flows to contribute to wetland restoration. A constructed wetland with ecological floating and bottom absorptive beds has been employed to enhance the capacity of contaminant removal within wetland flows. However, the environmental dispersion in constructed wetland flows is further complicated by the presence of irreversible first-order absorptive boundaries at the upper and bottom beds. Therefore, our work focuses on comprehending the expansion processes of contaminant clouds under absorptive boundaries through a multiscale analysis to demonstrate the removal effects of constructed wetlands. The findings highlight significant deviations in the spatial distribution of contaminant clouds, particularly in the vertical dimension, attributed to absorptive effects. To analyze the impact of removal mechanisms on the dispersion patterns of contaminant clouds, variations in the vertical concentration peak are examined. A predictive model is developed to estimate the position of the concentration crest in the vertical direction based on changes in absorptive ratios between the upper and bottom boundaries. Furthermore, in order to explore the key factor on removal capacity and efficiency within constructed wetland flows, we look into the process of contaminant depletion by examining variations in removed mass and local absorptive and removal efficiency along the streamwise direction in response to deviations in absorptive strengths at the upper and bottom beds. The ratios of the two boundary removal intensities play a significant role in the absorptive dynamics within wetland flows, particularly during the early stages of cloud expansion. By adjusting the absorption ratio between two absorptive beds to 1:1 with a certain total depletion strength in wetland flows, the enhancement ratio of depletion efficiency can increase by nearly 30%. It has been proven that employing identical absorption strengths at two absorptive beds is an economical and efficient means to amplify the absorption efforts within designed constructed wetland flows. This study provides guidelines for the design of constructed wetlands aimed at enhancing their capacity for sewage treatment.

Reflection and transmission of ultrasonic waves in a layered structure with a functionally graded porous piezoelectric base

The phenomenon of reflection and transmission of waves offers valuable insights into the internal composition and structural characteristics of materials. This study investigates the reflection and transmission of waves in functionally graded porous piezoelectric materials. These materials, distinguished by their customised electromechanical attributes and gradual property variations, present a promising avenue for optimizing performance across diverse applications, including ultrasonics. The reflection and transmission of ultrasonic waves in a novel structure, consisting of a fluid half-space (FHS) positioned above n porous piezoelectric layers, situated on top of a functionally graded porous piezoelectric half-space (FGPPHS) is studied in this paper. The material properties of FGPPHS are considered to vary along the vertical direction and and resulting equations are solved analytically and numerically. The transfer matrix method is employed to analytically determine the energy ratios and amplitude ratios for reflected and transmitted waves. Numerical computations are performed to study the impacts of frequency, gradation, angle of incidence, and porosity on the energy ratios. Furthermore, the influence of stacking of the number of porous piezoelectric layers above FGPPHS, and the choice of materials (Barium Titanate (BaTiO 3), PZT − 5H, PZT − 7H) in layers and half-space, on the energy ratios are studied. The absolute value of acoustic impedance is plotted for various angles of incidence and porosities. From the graph, it is found that the acoustic impedance can be controlled by adjusting porosity in the structure. This will be helpful in minimizing the energy loss at ceramic-medium interface and improving the mismatch of acoustic impedances at the interfaces of medical ultrasonic imaging devices or underwater sonar detectors, and NDE applications. Further, because of lower acoustic impedance, lower density and stiffness of porous piezoelectric materials, the outcomes of this study will be helpful in designing SAW devices.

Edge-preserving image deraining network using cumulative feature aggregation

This study proposes an edge-preserving image deraining network using a wavelet feature aggregation method. Wavelet subbands re correlated with each other, and the high-frequency subband in the horizontal direction is the least affected by rain streak contamination. On this basis, we introduce a single image deraining network that cumulatively aggregates wavelet subband features according to their importance. The network architecture primarily comprises a wavelet feature aggregation block and a residue channel guide block. The aggregation of features with the cumulative wavelet feature aggregation block moves downward and upward, and a long short-term memory-based multiscale attentive rain streak removal block is developed to serve as the backbone for rain streak removal. We use a residual channel map based on the low-frequency subband to construct guide features that assist in rain streak removal. A repetitive image restoration framework that incorporates two proposed blocks is used to iteratively improve rainy images. We test the proposed network on various image datasets and compare the deraining performance with those of existing methods The experimental results demonstrate that the performance of the proposed scheme is superior to that of other tested deraining methods. https://github.com/SYChoi98/CWFANet/

Experimental study on dynamic deformation and breaking mechanism of high-temperature hard rock cutting by abrasive water jet

The development of deep geothermal resources encounters challenges related to high temperatures and hard reservoir rocks. Abrasive water jets (AWJ) offer a potential solution to enhance the efficiency of breaking high-temperature hard rocks in deep ground. This mainly originated from their combined characteristics of jet cooling impact and high-speed abrasive grinding. In order to investigate the dynamic deformation process and rock-breaking mechanism of high-temperature hard rocks cut by AWJ, laboratory tests were conducted on high-pressure abrasive water jets cutting granite, sandstone, and marble. Rock strains were monitored using dynamic strain gauges and the digital image correlation (DIC) technique. The results indicate that in the process of abrasive jet cutting high-temperature hard rock, the rock strain is divided into three stages: compression deformation, deformation release, and stable deformation. The strain response zone can be divided into strain concentration zone, strain transition zone, and strain weak response zone. The high strain region and heat exchange region of high-temperature hard rock during AWJ cutting process are almost consistent. Jet vaporization weakens the water cushion effect during the water hammer stage, leading to high strain concentration at the stagnation point of the jet. During the stagnation stage, the fluid weakens the binding of particles, the abrasive becomes more divergent, and the range of high strain response region expands. Unlike the dynamic strain generated by jet erosion of hard rock, when jet cutting rocks, the strain in the vertical jet direction is generally greater than that along the jet direction. The cutting effect increases with the increase of rock temperature. When the rock temperature is 300 °C, the cutting depth of sandstone, granite, and marble increases by 50 %, 120 %, and 180 %, respectively. Under the combined effects of high-frequency jet impact, high-speed abrasive grinding, and thermal stress, hard rock undergoes varying degrees of damage and failure.

Development of state space models for underwater gliders equipped with embedded actuators in vertical and horizontal planes

Nowadays, underwater gliders (UGs) are known as efficiency vehicles to observe and quantify water properties concerning marine environments, seabed characteristics, and water depths. The development of appropriate dynamic and state space models is necessary for designing an effective control system. This study aims to develop state space models for UGs equipped with embedded actuators based on a non-linear dynamic model that takes into account the hydrodynamic characteristics of the body and wings. The method involves utilizing sensitivity analysis and assumptions to construct two distinct state space models, along with the linearization of the non-linear model in horizontal and vertical plane motions. The presented models are compared with simulation and experiment results to enhance validity. Furthermore, the linear models, when compared with the non-linear model and experimental tests, exhibit suitable performance. The results indicate the maximum observed differences of −9.7% in the period of the first cycle, −12.02% in the yaw angle, and 15.5% in the advance length between linear and non-linear models during zigzag, course-changing, and helical maneuvers, respectively. Through the presented linear models, LQR controllers are designed for the SUT glider and are subjected to testing in a real-world environment, experiencing suitable performance.

Research on the Relative Placement Angle of the Induction Heater and the Channel in a Four-Channel Induction-Heating Tundish.

In order to optimize the application effect of induction heating (IH) tundishes, a four-channel IH tundish is taken as the research object. Based on numerical simulation methods, the influence of different relative placement angles of induction heaters and channels on the electromagnetic field, flow field and temperature field of the tundish is investigated. We focus on comparing the magnetic flux density (B) and electromagnetic force (EMF) distribution of the channel. The results show that regardless of the relative placement angle between the heater and the channel, the distribution of B in the central circular cross-section of the channel is eccentric. When the heater rotates around channel 1 towards the bottom of the tundish, the distribution of B in the central circular cross-section of the channel changes from a horizontal eccentricity to a vertical one. Through the analysis of the B contour in the longitudinal section of the channel, the difference in effective magnetic flux density area (ΔAB) between the upper and lower parts of the channel can be obtained, thereby quantitatively analyzing the distribution of B in this section. The distribution pattern of ΔAB is consistent with the distribution pattern of the electromagnetic force in the vertical direction (FZ) of the channel centerline. The ΔAB and FZ of channel 1 gradually increase as the heater rotates downwards, while those of channel 2 reach their maximum value at a rotation angle of 60°. Compared to the conventional placement, when the heater rotation angle is 60°, the outlet flow velocities at channel 1 and channel 2 decrease by 15% and 12%, respectively. However, the outlet temperature at channel 2 increases by 1.96 K, and the molten steel flow at the outlet of channel 1 and channel 2 no longer exhibits significant downward flow. This shows that when the heater rotation angle is 60°, it has a dual advantage. On the one hand, it is helpful to reduce the erosion of the molten steel on the channel and the bottom of the discharging chamber, and on the other hand, it can more effectively exert the heating effect of the induction heater on the molten steel in the channel. This presents a new approach to enhance the application effectiveness of IH tundish.

Deteksi Tepi Sederhana Pada Citra Menggunakan Operator Sobel

implemented and evaluated the edge detection method using the Sobel Operator, which calculates the gradient of image intensity through two convoluted kernels for horizontal (Gx) and vertical directions. (Gy). The magnitudo gradient is obtained from the combination of both such directional gradients to represent the edge force on each pixel. The main steps include image pre-processing, the application of the Sobel kernel, the calculation of magnitudo gradients, and the filtering of results to extract significant edges. The results show that the Sobel Operator is effective in highlighting intensity differences that indicate the boundary of the object, although it is sensitive to noise and less accurate for fine edges. Despite its limitations, this method is simple to implement and useful as an initial step in image processing applications such as segmentation, pattern identification, and object shape analysis.

A Vertical Surface Flow Analysis of MHD Nanofluids Influenced by Radiation, Viscous Dissipation, and Joule Heating with Soret and Dufour Effects

The purpose of this study is to investigate the effects of radiation and activation energy on mass transfer nanofluids flowing across an expanding sheet in a vertical direction, as well as joule heating, viscous dissipation, Soret and Dufour, and magnetohydrodynamic (MHD) flow. The boundary layer (BL) equations for nonlinear momentum, energy, solute, and nanoparticle volume fraction are reduced by using similarity transformations. After that, the shooting technique and bvp4c are used to numerically solve the boundary layer equations. Schmidt and Eckert’s numbers, along with Soret effects on velocity, temperature, and the volume percentage of nanoparticles, cause an increase in skin friction. Fluid temperature rises significantly with Eckert number. As the Dufour and Schmidt numbers rise, so does the local Nusselt number. A greater thermophoresis parameter, enhanced skin friction, and an increased Schmidt number.

Eyebox expansion of a lensless near-eye display using diverging spherical wave illumination and a multiplexed holographic optical element

We expand the eyebox size of a lensless holographic near-eye-display (NED) using passive eyebox replication technique that incorporates a spatial light modulator (SLM) and a holographic optical element (HOE). In holographic NEDs, the space-bandwidth product (SBP) of the SLM determines the exit pupil dimensions and corresponding eyebox size. The base eyebox size is replicated in the horizontal direction by using the horizontal high-order diffractions of an SLM under spherical wave illumination and a multiplexed HOE combiner. When a digital blazed grating and a digital lens phase are added to the computed phase hologram sent to the SLM, two spatially separated, horizontal high-order diffraction terms with identical intensity and information can be uniformly formed without the zero-order term. When the eyebox size is expanded, the field-of-view (FOV) is not sacrificed; spherical divergence wave illumination alleviates the need for a tradeoff between FOV and eyebox size. The astigmatism introduced during HOE fabrication is counterbalanced by pre-correcting the target image using a computer-generated, holographic computation algorithm. The prototype system shows simple and effective, distortion-free eyebox expansion of a wide-angle, lensless, holographic NED.

Taking inspiration from the natural tubular sponge to enhance momentum exchange in marine environments

Coral reefs consist of various alive elements with specific biological functions. Tubular sponges, as the main coral reefs' constituents, have a marvelous mechanism. They receive nutrients by suctioning from the perforated body (Ostia) and pumping the un-digested materials through the water column from the top mouth (Osculum). This mechanism can be an inspiration for making a device to control or improve sediment/pollutant transport. In the current study, an attempt has been made to evaluate an inspired concept's effects on flow hydrodynamics. In this regard, OpenFOAM® V. 1812 (interFOAM solver) and image processing technique were deployed. The perforated finite-height cylinders (height to diameter ratio of 2.5) with various suction/pump discharges (i.e., J = 150, 300, 350, 400, 450, and 600 lit/h) were considered. The results indicated that increasing the outflow discharge (J ≥ 600 lit/h) could widen the wake by flapping the shear layer. In the vertical plane, the results showed that dipole vortices turned into quadrupole vortex. On the free surface, tip-vortices and counter-rotating vortex pairs (CRVP) generated saw-toothed vortices on two sides of the cylinder. Generating these unique vortices is proof of enhancing the momentum exchange through the water column.

Interlayer Delocalized Electrons Activate Basal Plane for Ultrahigh-Current-Density Hydrogen Evolution.

The basal plane of transition metal dichalcogenides (TMDCs) is inert for the hydrogen evolution reaction (HER) due to its low-efficiency charge transfer kinetics. We propose a strategy of filling the van der Waals (vdW) layer with delocalized electrons to enable vertical penetration of electrons from the collector to the adsorption intermediate vertically. Guided by density functional theory, we achieve this concept by incorporating Cu atoms into the interlayers of tantalum disulfide (TaS2). The delocalized electrons of d-orbitals of the interlayered Cu can constitute the charge transfer pathways in the vertical direction, thus overcoming the hopping migration through vdW gaps. The vertical conductivity of TaS2 increased by 2 orders of magnitude. The TaS2 basal plane HER activity was extracted with an on-chip microcell. Modified by the delocalized electrons, the current density increased by 20 times, reaching an ultrahigh value of 800 mA cm-2 at -0.4 V without iR compensation.

Simulation of landslide dam failure due to overtopping considering vertical soil particles distribution

Accurate prediction of potential landslide dam breaches is crucial for timely and effective emergency responses to the resulting flood. Although many models for landslide dam overtopping have been proposed in past studies, most of these models did not consider the heterogeneity of dam materials, which is important in reflecting the erodibility of soil. In this study, a new mathematical model for landslide dam breaches due to overtopping was proposed based on a constructed vertical distribution model of dam particle size. Two real-world dams, the Tangjiashan landslide dam and Baige landslide dam, were used to evaluate the performance of the proposed model. In addition, the proposed model was compared with four existing dam failure models, and sensitivity analysis was conducted on the median particle size and particle size distribution. The results demonstrate that the computational outcomes of the proposed model align more closely with the actual results, indicating that the proposed model outperforms the four existing models in accurately simulating the landslide dam failure process. It also suggests that ignoring the variation of dam material particle size along the vertical direction inside the dam body would increase the prediction relative errors of key breach outcomes.

Sensor-Less Control of Mirror Manipulator Using Shape Memory Polyimide Composite Actuator: Experimental Work.

Integrated thin film-based shape memory polyimide composites (SMPICs) are potentially attractive for efficient and compact design, thereby offering cost-effective applications. The objective of this article is to design and evaluate a mirror manipulator using an SMPIC as an actuator and a sensor with control. A sensor-less control strategy using the SMPIC (a self-sensing actuator) with a proportional derivative combined variable structure controller (PD-VSC) is proposed for position control of the mirror in both the vertical and angular directions. The mirror manipulator is able to move the mirror in the vertical and angular directions by 3.39 mm and 10.5 deg, respectively. A desired fast response is obtained as the performance under control. In addition, some benefits from the proposed control realization include good tracking, stable switching, no overshoot, no steady state oscillations, and robust disturbance rejection. These superior properties are experimentally validated to reflect practical feasibility.

Kinematic characteristics analysis of highly difficult movements "324C+1D" of the first level Wushu athletes

Background "324C+1D” movements are key techniques and winning factors in Wushu competitions. It is necessary for scientific training to analyze the kinematic characteristics of “324C+1D” by using the method of sports biomechanics. Methods In this study, 3D high-speed camera and 3D motion analysis software were used to study “324C+1D” completed by three Chinese wushu first-level athletes, and the kinematic characteristics of this movement were obtained. Results The run-up speed of completing the “324C+1D” is not high; The lift Angle of the center of gravity is close to 90°. The vertical height of the center of gravity is significantly higher than the vertical height of the center of gravity when landing, and the vertical moving distance of the center of gravity in the lifting stage is significantly less than the vertical moving distance of the center of gravity in the descending stage. The vertical height of the center of gravity at departure is significantly higher than that at landing. Conclusions In the take-off stage, increase the twisting Angle of shoulders and hips, speed up the swing arm speed and squat speed of the center of gravity in the vertical direction, and shorten the take-off time. Increase the vertical speed of the center of gravity before the patting foot and the vertical moving distance between the center of gravity lifting stage and the descending stage, extend the air time, accelerate the swing speed of the right leg, move the foot patting time forward to the rapid rising stage of the center of gravity lifting, accelerate the rotational angular speed of the shoulder shaft in the air stage and improve the strength of the leg, which is conducive to the athletes to complete the movement.

Lightweight polyimide composite foams with anisotropic hierarchical pore structure for enhanced mechanical, flame retardancy and thermal insulation purposes

In this study, lightweight polyimide foam (PIF) with anisotropic pore structure were fabricated by adopting microwave-assisted foaming technique. Afterward, lightweight PIF/PI aerogel/silica aerogel (PIF/PIA/SiA) composite foams with anisotropic hierarchical pore structures was prepared by impregnation and directional freeze-drying method. The directional growth of foam pores and ice crystals endowed PIF/PIA/SiA composite foams with anisotropic skeleton structures and hierarchical porous filling structures, leading to anisotropic mechanical and thermal insulation performances. PIF/PIA/SiA composite foams presented mechanical robustness in vertical direction and mechanical flexibility in horizontal direction due to its unique pore structure. In addition, PIF/PIA/SiA composite foams showed outstanding thermal stability and flame retardancy, suggesting a promising application in the field of high temperature fire protection. The PIF/PIA/SiA composite foams exhibited superior thermal insulation performance with thermal conductivities ranging from 0.0253 to 0.0523 W/(m·K) between 25 and 300 °C. Therefore, a facile strategy was developed to fabricate PIF-based composite foams for mechanical, flame retardancy and thermal insulation applications in high-end engineering fields.

Internet street view image fusion method using convolutional neural network

The use of image fusion technology in the area of information processing is continuing to advance in depth thanks to ongoing hardware advancements and related research. An enhanced convolutional neural network approach is developed to fuse visible and infrared images, and image pre-processing is carried out utilising an image alignment method with edge detection in order to gain more accurate and trustworthy image information. The performance of the fast wavelet decomposition, convolutional neural network, and modified convolutional neural network techniques is compared and examined using four objective assessment criteria. The experimental findings demonstrated that the picture alignment was successful with an offset error of fewer than 3 pixels in the horizontal direction and an angle error of less than 0.3∘ in both directions. The revised convolutional neural network method increased the information entropy, mean gradient, standard deviation, and edge detection information by an average of 46.13%, 39.40%, 19.91%, and 3.72%. The runtime of the modified approach was lowered by 19.42% when compared to the convolutional neural network method, which enhanced the algorithm’s performance and boosted the effectiveness of picture fusion. The image fusion accuracy reached 98.61%, indicating that the method has better fusion performance and is of practical value for improving image fusion quality.

The role of muscle function and pointe shoe characteristics in Arabesque movement among ballet dancers with non-specific low back pain

ABSTRACT This study aimed to investigate posterior chain muscle function and the influence of pointe shoes in ballet dancers with and without low back pain (LBP) in the Arabesque. Twenty-nine young professional ballet dancers (17 with LBP and 12 healthy controls) were recruited. Muscle strength and mechanical properties of the erector spinae and hamstrings were assessed. The displacement of centre of mass (COM) during Arabesque under different shoe conditions (R-class, Chacott, and own shoes) was measured with a motion capture system. The LBP group exhibited greater dynamic stiffness and decreased mechanical stress relaxation time in the lateral hamstring compared to the control group. During Arabesque, the LBP group demonstrated significantly greater anterior-posterior displacement of the COM and a larger percentage of time to achieve maximal trunk extension angle. The COM displacement in vertical and medial-lateral directions was smaller in the R-class than in their own shoes. LBP impacts muscle mechanical properties, particularly in the lateral hamstring. The compromised muscle function resulted in a longer time to spinal extension during Arabesque, signifying that reduced trunk control contributed to greater COM displacement. Hence, it is essential to emphasise that evaluating muscle properties and dynamic postural control is imperative for dancers experiencing LBP.

Shape of a Rotating Slinky

If a Slinky suspended in a U-shape is rotated horizontally, it will have the shape of an upside-down [Formula: see text], like [Formula: see text], due to the centrifugal force in the horizontal direction acting on each point of the Slinky. In this paper, we discuss the shape of a rotating Slinky in both theoretical and experimental aspects. The rotating Slinky has the shape described by a multi-valued function if the angular velocity of the rotation satisfies [Formula: see text]. Our theoretical results are in good agreement with experimental observations. The video of the experiments can be viewed at https://youtu.be/rpu9Ol2jdAM .

Gradient catalyst layer design towards current density homogenization in PEM water electrolyzer with serpentine flow field

The inhomogeneous current density distribution might cause irreversible damage to the membrane electrode assemblies of proton exchange membrane water electrolyzers. Herein, the impact of gradient catalyst distribution on the current density uniformity inside the electrolyzer with serpentine flow field is investigated using a three-dimensional model. The gradient catalyst distribution in parallel and vertical flow directions is considered. It is found that, at low working voltage (1.8 V), gradient catalyst loading in the vertical flow direction would enhance the current density distribution uniformity by 77.6 %, and at the same time improve the electrolyzer performance by up to 4.0 %, whereas in parallel flow direction the corresponding improvement is by 34.5 % and 4.17 %, respectively. At high working voltage of 2.4 V, due to the pronounced impact of mass transportation process, similar and limited improvement in the current density uniformity (11.47–11.87 %) and electrolyzer performance (1.3–1.45 %) is found under the gradient catalyst loading design in both flow directions. This study provides important guidance for the design of proton exchange membrane water electrolyzer using serpentine flow field.