Skew Angle Research Articles

Experimental Investigation of the Effect of the Pier Group Skew Angle on Local Scour Around the Piers under Steady Flow

Experimental Investigation of the Effect of the Pier Group Skew Angle on Local Scour Around the Piers under Steady Flow

Paratextual mediation and (re)framed narratives: a case study of Ganxiao liuji

ABSTRACT Translation is not merely a textual transformation but involves paratextual mediation. Linking Genette's notion of paratext to Baker's narrative theory, this paper examines Yang Jiang's Ganxiao liuji, a personal narrative set during the Cultural Revolution but focusing on everyday occurrences, to uncover how three publishing houses mediate paratextual materials (titles, prefaces, blurbs, notes and afterwords, and visual images) in their translations of this book, and what larger narratives are (re)framed and reinforced in this process. It discloses that while the Hong Kong publishing house prioritises the original personal narrative content and style in its paratextual presentation, its American counterparts foreground the political background while overshadowing Yang's personal narrative and reframing it as part of the larger narratives of a repressive, inhumane China with an authoritarian government and suppressed masses. Such mediation responds to and reinforces Western narratives of the problematic, dystopic China, and directs readers to understand it through a skewed angle, thereby perpetuating established stereotypes of this non-Western country. This research further unveils how paratextual mediation resonates with and contributes to the larger narratives circulating beyond the immediate text, guiding receivers into (re)framed narratives which impact their perceptions and behaviour in the society, and ultimately shape the social world.

The Effect of Connection Ductility on Composite Steel–Concrete Bridges

Connection behavior significantly influences the design efficiency of steel–concrete composite bridges. This study investigates the impact of shear connectors, specifically headed stud connectors, on the structural response of symmetric and skewed composite steel–concrete bridges. Utilizing bilinear or trilinear slip–shear strength laws for studs, in line with the existing literature and code provisions, a finite element (FE) model is developed. This FE model is applied to a case study for composite deck analysis, incorporating variations in connection strength and ductility for nonlinear analyses. The study assesses ductility demands in connections for symmetric and skewed bridges of varying lengths and angles, considering both ductile and elastic designs. Results emphasize the importance of stud capacity, ductility, and strength on the overall bridge response, analyzing slip and shear trends at the interface. Skewed bridges, crucial for non-orthogonal crossings of roads, are integral to modern transportation infrastructure. However, skewness angles exceeding 20° can result in undesirable effects on stresses in the deck due to vertical loads. The results indicate that shear distribution in studs changes significantly as the skew angle increases, contributing valuable insights into optimizing bridge design. Thus, this research provides a comprehensive analysis of principles, design methodologies, and practical applications for both symmetric and skewed steel–concrete composite bridges, considering various parameters.

Accurate prediction of the through plane effective thermal conductivity of GDB-MPL composite region in PEMFC with a layered model

In the field of proton exchange membrane fuel cell (PEMFC), precise determination of through plane (TP) effective thermal conductivity (keff) of the composite region of the gas diffusion backing and microporous layer (GDB-MPL) holds significant importance for effective hydrothermal management. This study presents the establishment of a keff prediction model for the composite region based on X-ray computerized tomography (XCT). The model incorporates various inputs, including the equivalent pressure PGDB, average fiber angle θ¯, average skewed angle ϕ¯, the distribution of carbon fiber volume fraction εC, MPL volume fraction εMPL and other relevant information derived from XCT scans. By leveraging these inputs, the model facilitates the accurate prediction of keff. To explore the impact of different solid contents in MPL, the composite region, comprising CeTech GDS210 carbon paper, was categorized into three groups: 0 wt% (no MPL), 10 wt% and 13 wt% group. The theoretical values computed by the developed model were then compared with experimental values. Impressively, all the results demonstrated variations within the range of 1.5%. Such consistency indicates a high level of agreement between the predicted and experimental keff values. Moreover, it was noted the accumulation of MPL within the inter-fiber contact region significantly impeded the expansion of this area under escalating pressure, resulting in a pronounced limitation on heat transfer compared to the additional heat flux pathway facilitated by MPL. This work provides a new idea for studying the intrusive effects of water and polytetrafluoroethylene etc. on GDB, thereby contributing to a more accurate simulation and the commercialization of PEMFC.

Measuring the Roller Skew Angle in the Loading Zone of a Cylindrical Roller Bearing With Strain Gauges for Long-Term Monitoring

Abstract Roller skew in roller bearings can cause heat generation in roller–race and roller–rib contacts, thus reducing bearing life. It is significant to obtain the roller skew angle in situ for guiding the bearing design and adjusting the operating conditions. In this study, a method for measuring the roller skew angle in the loading zone of a cylindrical roller bearing with strain gauges is presented. The measurement principle is that the roller skew angle is related to the movement of the contact line between the roller and raceway. The strain gauge array on the outer surface of the outer ring shows temporally separated responses when roller skew occurs. An experimental system is developed to validate the effectiveness of the proposed method for cylindrical roller bearing measurements. A laser measurement system is incorporated into the experimental system to detect the horizontal displacement of the reflected spot using a high-speed camera, which is then converted into the roller skew angle. The calculated roller skew angle from the time shift of the strain response agrees well with the value of a specially modified roller independently measured with the laser detection system. Compared with other measurement methods, the proposed method provides a potential way to achieve the nondestructive measurement of the roller skew angle in actual service for long-term purposes.

Soil-structure interaction of Huge RC Box Culvert under High Embankment

Two huge RC concrete box culverts are constructed underneath the Dhoho Kediri airport runway embankment. These multi-cell culverts serve as the main infrastructure facilitating the diversion of two crossing rivers and several irrigation channels, and one of them is under 24-meter-high fill, penetrating the slope at a skewed angle and creating huge unbalanced soil pressure. The seismic design loads for underground structures are characterized in terms of the deformations and strains imposed on the structure by the surrounding soil. Soil-structure interaction plays an important role in defining static and seismic loads. Finite element method with dynamic time history analysis considering three selected and modified ground motions has been performed for the seismic design of the RC box culverts, in addition to the racking deformation method. A comparison of both methods is presented.

Parametric study on prestressed skewed box-girder bridge

This study employs the finite element-based CSiBridge v.20.0.0 software to examine the response of a single-cell prestressed box-girder bridge subjected to Indian loading conditions. The analyses is carried out on a simply supported bridge considering the specifications of Indian Road Congress (IRC) 6:2017, IRC 18:2000 and IRC 21:2000. An existing model of prestressed skewed bridge is validated with the published one. A convergence study is conducted for determining the model’s mesh size. An extensive parametric study is carried out to gain a better understanding of the response of a skewed prestressed bridge. The parameters variables are: Skew angle (0°, 10°, 20°, 30°, 40°, 50°, and 60°); Span (35, 40, 45, 50, 55, and 60 m); and Span-depth ratio (10, 12, 14, 16 and 18). The results of this study are presented as ratios of Bending moment, Shear force, Torsional moment, and Vertical deflection. Finally, equations for estimation of these ratios for different span and span-depth ratio are also deduced from the statistical approach so that the results of skewed bridges may be evaluated directly. It is determined that the skewed bridge outperforms the straight bridge because of its higher span-depth ratio, which results in less bending moment development. Evidence suggests that the skewness may help to lessen the prestress load’s dominance. The findings of this study may be helpful to engineers and designers in the analysis and design of prestresssed skewed box-girder bridges.

Thermal and hygrothermal buckling characteristics of porous magneto-electro-elastic skewed plates using third-order shear deformation theory

The implementation of third order shear deformation theory using finite element method is presented in the current article to analyze the stability characteristics of porous magneto-electro-elastic (MEE) plates. This study aims to present the obscure behavior of FGMEE plate considering the loading to be hygrothermal in nature for buckling. Several temperature and porosity distribution are involved in this study in order to understand their influence on the buckling characteristics. The material properties of the porous MEE plate are assumed to vary continuously throughout its thickness according to rule of mixture. The porosity is considered as a locally distributed density estimated using the modified power law. The effect of temperature and moisture on buckling of MEE plates is of interest in this study. Skewness is incorporated through a transformation matrix to account for the angle. The stability characteristics of the porous FGMEE plate are examined under thermal, hygrothermal, electric, and magnetic loads to determine the critical buckling temperature. The influence of various variables, such as porosity, porosity distribution, and porosity volume, on the buckling behavior is extensively studied to realize that as porosity increases, the critical buckling temperature decreases in both load forms and noticed to be highest in Vo and Vx porosity distribution. Skew angle directly influenced the critical buckling temperature and was seen to be increasing with increase in skew angle between the plates. The study is also extended to assess the effect of geometrical parameters, such as aspect ratio, thickness ratio, and boundary conditions, on the stability characteristics that established an inverse relation between the parameters.

Computer Vision-Based Autonomous Method for Quantitative Detection of Loose Bolts in Bolted Connections of Steel Structures

In this study, an autonomous computer vision-based method is presented to quantitatively detect loose bolts. The method integrates keypoint detection via YOLOv5 and PIPNet, distortion correction via perspective transformation, and rotation angles quantification via geometric imaging. Distortion correction is incorporated to address skewed angles and improve the accuracy of rotation angles. A representative experiment on bolted connection of steel structures is conducted to evaluate the presented approach. The effects of the focal distance, skewed angle, and lighting conditions on the detection and quantification performance are evaluated by varying the imaging conditions. The results demonstrate that the presented approach automatically detects all bolts and their corners, irrespective of the imaging conditions. No false detection occurs, and the quantification errors are lower than 1°. The proposed method can be deployed for automatic detection of loose bolts and quantification of rotation angles in bolted connections under different imaging conditions.

Control mechanism of vortex-generator jet on turbulent separation in a highly loaded compressor cascade

The active flow control technique of vortex-generator jet (VGJ) was used to control the turbulent separation of a highly loaded compressor cascade at a high incidence. VGJ schemes on suction surface with different jet locations, skewed angles, pitch angles were numerically performed and the control mechanism of VGJ parameters on the flow field of the cascade was revealed. For avoiding the effect of endwall boundary layer, both endwall surfaces of the cascade were set to translational periodicity boundary (TPB). Results show that VGJ significantly eliminates the turbulent separation and improves the performance of cascade. The overall loss coefficient of cascade is reduced by 52.3% at most. The optimal VGJ location in this study is not separation location but 7% axial chord downstream of it, which is probably due to the ultra-high loading of the cascade. The spanwise location and intensity of jet vortices are mainly affected by skewed angle, and will increase with the skewed angle. The VGJ case with a higher pitch angle features better control effect on suction surface but increases the pitchwise scale of the low-velocity region. In addition, as pitch angle increases, the mixing loss between mainstream and jet flow increases, which brings a negative effect on cascade performance. In order to enhance the momentum transporting between mainstream flow and separation flow, counter vortex-generator jet (CVGJ) schemes were designed and studied. Though CVGJ strengthens the jet vortices near the trailing edge and achieves minimum loss near TPB sections at 150% axial chord section, the interaction of jet vortices with opposite rotating direction brings extra loss, which leads to the control effect of CVGJ is weaker than that of VGJ.

Skew angle estimation and alleviation based multi-layer perceptron in V-shaped read-head array BPMR systems

The demand for a massive storage device has kept rising and it has led to the emergence of advanced technology with a vast storage capacity. Achieving this idea might bring some obstacles called two-dimensional interference as well as a skew angle (SA). Array-reader-based magnetic recording can be the potential to give a better performance in the system by reading multiple tracks simultaneously. This paper investigates a V-shaped read-head array (VRA) with three read sensors performance on five levels of skew angle consideration in three different zones of hard disk drive. VRA with three read sensors is being grouped; therefore, SA can be considered as the change in this group movement. To achieve a good system performance, we propose an SA estimation method for bit-patterned media recording systems by computing a specific target by three readback sequences before estimating the SA value and finally detecting the data. Both estimation and detection processes are carried out using a neural network method known as multilayer perceptron.

Modeling sound transmission through apertures with diffraction

Sound transmission through an aperture in a thin wall is a classical scattering problem with various applications in building and room acoustics. In particular, the use of active noise control for open windows can be viewed as an aperture scattering problem. Diffraction-based modeling of scattering is very efficient and accurate for convex scattering objects but has been shown to be less accurate for the transmission through circular apertures, at low frequencies. In this study we investigate the accuracy of edge-diffraction based modeling of sound transmission through rectangular apertures. Reference solutions are computed with a boundary element formulation for this case. Results confirm that the diffraction modeling gives accurate results for mid-to-high frequencies. For low frequencies and skewed transmission angles, the diffraction-based method gives larger errors. For aspect ratios between 1:1 and 10:1, the sound power transmission ratio predicted by the edge diffraction approach is maximally ±1.5 dB in error for very low frequencies.

Analysis of Skewing Effects on Radial Force for Different Topologies of Switched Reluctance Machines: 6/4 SRM, 8/6 SRM, and 12/8 SRM

Reducing vibration and noise in electrical machines for a given application is not an easy task, especially when the application imposes some restrictions. There are many techniques for reducing vibration based on design or on control. Switched reluctance motors (SRMs) have a double-saliency structure, which results in a radial pulsation force. Consequently, they cause vibration and acoustic noise. This paper investigates the correlation between the radial force and the skew angle of the stator and/or rotor circuits. The analysis is computed from two-dimensional (2D) transient magnetic finite-element analysis (FEA) of three machine topologies, namely the 12/8 three-phase SRM, the 6/4 three-phase SRM and the 8/6 four-phase SRM. Compared to SRM, these topologies have the same basic dimensions (stator outer diameter, rotor outer diameter, and length) and operate in the same magnetic circuit saturation. The flux linkage and torque characteristics of the different motors are presented. The radial force distributed on the stator yoke under various skewing angles is studied extensively by FEA for the three machines. It is also demonstrated the effect of skewing angles in the reduction of radial force without any reduction in torque production.

Optimizing Designed Variable Speed Control Moment Gyroscopes with Variable Skew Angle

Optimizing Designed Variable Speed Control Moment Gyroscopes with Variable Skew Angle

Effect of Skew Angle on the Dynamic Response of a Reinforced Concrete Bridge under Blast Loading

Accidental explosions and subversive blasts are on rise. The recent devastating Beirut explosion witnesses this fact. Performance of the structures such as bridges in cities and strategic boarder areas is of paramount importance. With this concern the effect of skew angle on the performance of a single span reinforced concrete (RC) bridge deck supported on three symmetrically placed RC girders under blast loading generated by1000kgTNT charge located above and below the mid-section of the central girder at a standoff distance of 0.5 m has been investigated using ABAQUS/CAE. Analyses have been performed at different skew angles i.e. 0º, 10º, 20º, 30º, 40º, and 50º. Several empirical relations from the literature have been used to estimate the blast parameters such as peak overpressure, positive phase duration, the arrival time of blast wave, and decay coefficient. Blast pressure P(t), has been modeled using modified Friedlander’s equation. Distributions of damages have been evaluated with a mesh size of 300 mm using concrete damage plasticity (CDP) model. Maximum displacements have been computed and are compared with those obtained from the provisions of AASHTO: Load Resistance and Factor Design (LRFD) - Bridge Design Specifications (2014). It has been found that the midspan displacement and the stresses of the deck increase for 10º skew angle but decrease for subsequent increase in skew angle for the explosive charge loaded above the mid-section of the central girder. However, tensile as well as compressive damages in girders increase with increase of skew angle irrespective of the location of the blast. Side girders suffer more damage with increase in skew angle than uniform damage for ‘under the deck’ location of explosive charge.

Model experiments on hydraulic properties around multiple piers with reproduced 3D geometries

The effects of multiple piers with 3D geometries on water levels during floods, as well as riverbed fluctuations and local scour after floods were examined via hydraulic model experiments. The Kintaikyo Bridge in Japan, a world-famous historical triple-wooden-arch bridge, was modeled at a scale of approximately 1/276. The number of model piers was set to four, as in the real bridge, and they were 3D printed and installed in the sand layer of an open channel. To provide adequate information on the pier installation conditions and hydraulic response, four cases were studied in the experiments, primarily considering present pier conditions; the previous conditions of the Kintaikyo Bridge were also considered. The experimental conditions in these four cases depended on whether foundations were present, the piers were skewed against the flow center, and the shape was spindle or similar to that of the present case. In the current bridge condition where foundations are present and there is no skew, water level rise, riverbed fluctuation, and local scour were suppressed. Furthermore, the statistical analysis of the results suggested that riverbed fluctuations are more stable after flooding. The two piers with foundations had smaller scour areas than those without. Further, those with foundations generally had lower mean scour at the pier perimeters. Regarding those without foundations, there were no differences in riverbed fluctuations or local scour due to the skewed pier angle. In addition, the representative length of the pier with a 3D geometry was determined by dividing the projected area of the pier below the initial sand surface in the main flow direction by the pier height, and the relationship between the Froude number or the mean water depth and the maximum scour depth was investigated.

A Lower Bound on the Estimation Variance of Direction-of-Arrival and Skew Angle of a Biaxial Velocity Sensor Suffering from Stochastic Loss of Perpendicularity.

The biaxial velocity sensor comprises two nominally perpendicular particle velocity sensors and a collocated pressure sensor. Due to real-world imperfections in manufacturing or setup errors, the two axes may suffer from perpendicularity losses. To analytically study how skewness affects its direction-finding performance, the hybrid Cramér-Rao bound (HCRB) of the directions-of-arrival for the polar angle, azimuth angle and the skew angle of a biaxial velocity sensor that suffers from stochastic loss of perpendicularity were derived in closed form. The skew angle was modeled as a zero-mean Gaussian random variable of a known variance, which was assumed to be very small, to capture the uncertainty in the orthogonality of the biaxial velocity sensor. The analysis shows that for the polar and azimuth angle, the loss of perpendicularity introduces the variation of the HCRB along the azimuth angle axis, which is independent of the skew angle, but on its variance. The dynamic range of this variation increases as the variance of the skew angle increases. For the estimation of the skew angle, the HCRB of the skew angle is bounded upwards by the variance of the skew angle and varies with the azimuth angle. The hybrid maximum likelihood- maximum a posterior (hybrid ML/MAP) estimator was used to verify the derived bounds.

Thermal operation by nanofluids with various aspects: a comprehensive numerical appraisal

This research is a good understanding of unsteady convective transport of nanofluids inside a skewed cavity considering MHD, different combinations of base fluids and nanoparticles, shapes, sizes (1–50 nm), volume fractions, and with/without Brownian effects. The right and left sidewalls of the enclosure are heated at low and high temperature, respectively, whereas the bottom and top walls are insulated. The finite element technique with Galerkin’s residual has been implemented for solving non-linear PDEs that govern the flow for the current problem. The numerical simulations have been presented using streamlines, isotherms, and temperature transport rates for different parameters, non-dimensional time, skewed angles, base fluids, nanoparticles, shapes, sizes, and volume fractions. The outcomes show that heat transport rate augments about 12.55% with an additional 2.5% nanoparticles into the base fluid for Cu-H2O nanofluid. An optimal thermal transport rate is observed for kerosene-based nanofluid, blade shape, and 1 nm size of nanoparticles. Magnetite nanoparticles show a greater thermal performance of 4.72% than higher thermal conductivity nanoparticles (copper and cobalt). Thermal transport enhances about 110.78% with Brownian motion for 5% concentrated blade-shaped kerosene-Fe3O4 nanofluid than without Brownian effects. In addition, a new linear regression equation with multiple variables has been derived from the obtained results.

Variable Weighting Coefficient of EMF-Based Enhanced Sliding Mode Observer for Sensorless PMSM Drives

In the field of permanent magnet synchronous motor (PMSM) control, the sliding mode observer (SMO)-based sensorless control is widely used; however, the actual control input of the current observation function is asymmetric. It can lead to different velocities of the estimated currents approaching to the actual currents and will make the current and back EMF fluctuations more severe, and result in more skewed angle and speed estimates, especially at a lower carrier ratio. In response to the above problems, this paper proposes a variable weighting coefficient of an EMF-based sliding mode observer (VWC-SMO). Unlike the traditional sliding mode observers, the weighted sliding mode switching variables and their bandpass-filtered values are used as the input of the current observer in the VWC-SMO. Thereby, the asymmetry of the control input in the current observation function can be well-suppressed, and almost the same approaching velocity on the two sides of the sliding surface can be obtained. Therefore, chattering near the sliding surface can also be suppressed. The method is verified on a motor controller experimental platform, and the comparative results shows that the VWC-SMO can reduce chattering of the observed currents and mitigate back EMFs fluctuations and improve the dynamic and steady-state performance.

YOLO and Mask R-CNN for Vehicle Number Plate Identification

Abstract: License plate scanners have grown in popularity in parking lots during the past few years. In order to quickly identify license plates, traditional plate recognition devices used in parking lots employ a fixed source of light and shooting angles. For skewed angles, such as license plate images taken with ultra-wide angle or fisheye lenses, deformation of the license plate recognition plate can also be quite severe, impairing the ability of standard license plate recognition systems to identify the plate. Mask RCNN gadget that may be utilized for oblique pictures and various shooting angles. The results of the experiments show that the suggested design will be capable of classifying license plates with bevel angles larger than 0/60. Character recognition using the suggested Mask R-CNN approach has advanced significantly as well. The proposed Mask R-CNN method has also achieved significant progress in character recognition, which is tilted more than 45 degrees as compared to the strategy of employing the YOLOv2 model. Experiment results also suggest that the methodology presented in the open data plate collecting is better than other techniques (known as the AOLP dataset)