Edge Width Research Articles

Mapping of axial plastic zone for roller bearing overloads using neutron transmission imaging

Premature failure of wind turbine gearbox bearings is an ongoing concern for industry, with sudden overload events potentially contributing towards raceway damage, significantly hindering performance. Subsurface stresses generated along a line contact cause material yielding, and a probable crack initiation site. Currently, the ability to study subsurface plastic zone evolution using non-destructive techniques is limited. Neutron Bragg edge imaging is a novel technique, allowing for two-dimensional mapping of the Bragg edge broadening parameter, indicative of bulk plastic deformation. An experiment on the ENGIN-X strain scanning instrument, at the ISIS neutron source, UK, was setup for Bragg edge transmission imaging, to measure the effect of in situ loading on the raceway of a bearing, scaled-down from a traditional wind turbine gearbox bearing. Results demonstrate a strong correlation between load and the Bragg edge width, and allow for future experimental development in studying, not only the effect of overloads on fatigue life, but also the use of neutron imaging for evaluating plastic deformation in engineering components.

Effect of 3D depth on the resolution and the observed image for auto‐stereoscopic multi‐view 3D display

AbstractIn auto‐stereoscopic multi‐views, blurring occurs due to the incomplete separation of views for non‐zero depths. How this blur affects a 3D image was investigated using the commercial multi‐view 3D. The 3D input signal consisted of the square pattern and the gratings of various width and gray level values of G1 and G2. The various combinations of G1 and G2 were used to investigate the dependence of blur on gray G1 and G2 values. The 3D depth caused blurring, which caused a decrease in contrast modulation. Hence, the 3D resolution determined from contrast modulation was affected by the depth and became worse with increasing depth. Therefore, 3D resolution may be used to define the depth range within which the image degradation due to blurring is acceptable. Blur edge width values at the boundaries of gray G1 and G2 were measured and found to be similar irrespective of G1 and G2 values at the same depth. This was because blur was caused by the incomplete separation of views that are independent of G1 and G2. Hence, the blurriness of the observed 3D image is determined only by the depth. The 3D resolution and blur edge width might be useful to characterize the performance of auto‐stereoscopic multi‐view 3D.

Design and Optimization of Quadrilateral Shaped PVDF Cantilever for Efficient Conversion of Energy from Ambient Vibration

This paper addresses an efficient way of conversion of ambient vibrational energy to electrical by structure optimization of piezoelectric film. Polyvinylidene fluoride has been used for this study. The effects of shape variations of cantilever beam with multilayer configuration based on Euler–Bernoulli theorem without considering the proof mass attached at the free end has been investigated in this paper. Most of piezoelectric vibrational energy harvesters are designed considering the presence of proof mass and in this paper it has been tried to convey the idea, that with the new optimized shape, the cantilever itself can behave as a flexible proof mass for energy enhancement. The possibility of harvesting energy from three different geometries: 1) near edge width quadratic (NEWQ), 2) half quadratic (HQ), and 3) Trapezoidal has been presented. Scanning electron microscopy is used to measure the thickness of the various layers. The NEWQ design shows the best performance in terms of power and resonance frequency ( $\text{f}_{\text {r}} ) compared with the others. Here, the study of the piezo-film models using finite element method simulation software (COMSOL Multiphysics optimization module) and experimental validation are also presented. Using the models, the generation of voltage/power has been analyzed under various excitation frequency and load resistance. Moreover, stress/strain distribution and the displacement have also been highlighted in this paper.

Numerical investigation of the core outlet temperature fluctuation for the lead-based reactor

The temperature fluctuations induced by incomplete mixing of coolants with different temperature may cause thermal fatigue at the components of the lead-based reactor core outlet. Thus the accurate analysis of the phenomenon is very crucial for reactor safety operation. In this paper, the temperature fluctuations of the lead-based reactor core outlet were simulated by using large eddy simulation (LES) method in the simplified core outlet models. In order to analyze the temperature fluctuation sensitivity for the fuel assembly design parameters, such as the fuel assembly size and the gap between two adjacent fuel assemblies, five geometry models were constructed with different fuel assembly design parameters. The time histories of temperature fluctuations at different monitoring points on the center of three fuel assemblies were obtained. Then the amplitudes and the power spectrum density (PSD) of temperature fluctuations were analyzed, in order to compare temperature fluctuations of different geometry models at the same locations of core outlet. Finally the distribution characteristics of core outlet temperature fluctuations were obtained in axial directions, and the temperature fluctuation sensitivity with fuel assembly parameters was also analyzed based on the amplitudes, PSD and the normalized root-mean square temperature analysis. It is found that the temperature fluctuation intensity is enhanced with the increase of the gap size between adjacent fuel assemblies and the opposite edge width of each fuel assembly. The analysis results could provide important references for optimized design and engineering guidance of lead-based reactor.

Bending-shear performance of column-to-column bolted-flange connections in prefabricated multi-high-rise steel structures

The bolted-flange connection is a new application for mounting rectangular hollow section (RHS) columns in prefabricated multi-high-rise steel structures, which may bear the combination of bending moment and shear under permanent, live, wind loads or earthquake. The performance of the bolted-flange connection used in the structural column is different from that in its popular usage in the pipe because the subjected force is different. To investigate the bearing performance of a bolted-flange connection under the combination of bending moment and shear, this study conducted static tests and finite element analysis (FEA) of 12 column-to-column bolted-flange connections with different flange thicknesses, bolt edge distances, flange edge widths and bolt hole diameters, as well as one column without a connection. The test agreed well with the FEA, which verifies the FEA. The influences of the flange thickness, bolt edge distance, flange edge width and bolt hole diameter on the stiffness and strength of the connections, bolt tension and contact force were studied, and the failure mode and mechanism of the connection were obtained. A significant prying action occurred on the flange contact surface, increased the bolt tension in the tensile region, and caused the bolt shanks to experience tension and bending moment. The flange thickness had a large impact on the prying force, while other factors had less of an effect. Based on the yield line theory, the bearing mechanism of the connection was obtained. The formulas for the yield bearing capacity were proposed and were verified by the test and FEA.

Compression-bend-shearing performance of column-to-column bolted-flange connections in prefabricated multi-high-rise steel structures

The bolted-flange connection is used to connect rectangular HSS columns in prefabricated multi-story and high-rise steel structures. It may subject to coexisting axial compression, bending moments and shearing under the combination of dead, live, wind loads or earthquake action. The bearing performance is different from that of bolted-flange connections used in pipelines, towers and mast structures. To investigate the bearing performance of a connection subjected to coexisting compression, bending moments and shearing, static tests and a finite element analysis (FEA) were applied to 12 column-to-column bolted-flange connections with different flange thicknesses, bolt edge distances, flange edge widths and bolt hole diameters, as well as one column without connection. The effects of flange thickness, bolt edge distance, flange edge width, and bolt hole diameter on the stiffness and strength of connections, bolt tension levels, and contact forces between flanges were obtained as well as effects on the failure mode and mechanisms of the connections. Flange thickness was found to have a considerable impact on the performance of connections, while the bolt edge distance and flange edge width were found to have a lesser effect. The FEA results agree well with the test results, verifying the finite element model (FEM). Some performance results that could not be obtained through testing were obtained. Based on yield line theory and T-stub analogies, the load transfer mechanism of bolted-flange connections was obtained and formulas for yield-bearing capacity are proposed. The results obtained from the formulas agree well with the test and FEA results.

Spatial and temporal patterns of microclimates at an urban forest edge and their management implications.

Fragmented forests generate a variety of forest edges, leading to microclimates in the edge zones that differ from those in the forest interior. Understanding microclimatic variation is an important consideration for managers because it helps when making decisions about how to restrict the extent of edge effects. Thus, our study attempted to characterize the changing microclimate features at an urban forest edge located on Mt. Gwanak, Seoul, South Korea. We examined edge effects on air temperature, relative humidity, soil temperature, soil moisture, and photosynthetically active radiation (PAR) during the hottest three consecutive days in August 2016. Results showed that each variable responded differently to the edge effects. This urban forest edge had an effect on temporal changes at a diurnal scale in all microclimate variables, except soil moisture. In addition, all variables except relative humidity were significantly influenced by the edge effect up to 15m inward from the forest boundary. The relative humidity fluctuated the most and showed the deepest extent of the edge effect. Moreover, the edge widths calculated from the relative humidity and air temperature both peaked in the late afternoon (16:00h). Our findings provide a reference for forest managers in designing urban forest zones and will contribute to the conservation of fragmented forests in urban areas.

An image edge recognition approach based on multi-operator dynamic weight detection in virtual reality scenario

Virtual reality (VR) is based on graphics, images and sensors, and its simulation environment is a real-time and dynamic three dimensions realistic image generated by computer. The detection and extraction method of image edge and contour features is one of the research contents and hotspots in image detection, processing and analysis. Based on the traditional edge detection algorithm, in this paper a dynamic weight edge detection method based on multi-operator is proposed, an image edge detection system based on VR is developed, and the proposed algorithm is compared with the traditional method from the aspects of continuity, smoothness, edge width, positioning accuracy and system performance of the edge. The results indicate that this algorithm is the optimization and supplement of the traditional edge detection algorithm, has certain advantages in continuity and positioning accuracy, and can achieve rapid detection of VR image edge, which provides a theoretical basis for the research of VR image processing in the future.

Super resolution PLIF demonstrated in turbulent jet flows seeded with I2

Planar laser induced fluorescence (PLIF) represents an indispensable tool for flow and flame imaging. However, the PLIF technique suffers from limited spatial resolution or blurring in many situations, which restricts its applicability and capability. This work describes a new method, named SR-PLIF (super-resolution PLIF), to overcome these limitations and enhance the capability of PLIF. The method uses PLIF images captured simultaneously from two (or more) orientations to reconstruct a final PLIF image with resolution enhanced or blurring removed. This paper reports the development of the reconstruction algorithm, and the experimental demonstration of the SR-PLIF method both with controlled samples and with turbulent flows seeded with iodine vapor. Using controlled samples with two cameras, the spatial resolution in the best case was improved from 0.06 mm in the projections to 0.03 mm in the SR image, in terms of the spreading width of a sharp edge. With turbulent flows, an image sharpness measure was developed to quantify the spatial resolution, and SR reconstruction with two cameras can effectively improve the spatial resolution compared to the projections in terms of the sharpness measure.

Solution Growth of Two-Dimensional Bi₂Se₃ Nanosheets for Two-Color All-Optical Switching.

Two-dimensional Bi2Se3 nanosheets with hexagonal shape are synthesized by a solution synthetic route. The Bi2Se3 nanosheets are 120 nm in edge width and 7 nm in thickness. The size of the Bi2Se3 nanosheets can be controlled by choosing different kinds of reducing agents including hydroxylamine and ethylenediamine. Subsequently, we demonstrate a configuration of two-color all-optical switching based on plasma channels effect using the as-synthesized Bi2Se3 nanosheets as an optical media. The signal light can be modulated as two states including dot and ring shape by changing the intensity of control light. The modulated signal light exhibits excellent spatial propagation properties. As a type of interesting optical material, ultrathin two-dimensional Bi2Se3 nanosheets might provide an effective option for photoelectric applications.

Magnetocapacitance and dissipation factor of epitaxial graphene-based quantum Hall effect devices

We investigate the properties of the magnetocapacitance and dissipation factor of epitaxial graphene Hall bars with different electrode configurations to gain insight into the underlying physical mechanisms. The dependence of magnetocapacitance and dissipation factor on the magnetic field shows how the screening ability of the two-dimensional electron gas (2DEG) changes at the transition from the nonquantized to the quantized state. Both magnetocapacitance and dissipation factor exhibit a characteristic and correlated voltage dependence, which is attributed to the alternating contraction and expansion of the nonscreening 2DEG regions due to the alternating local electric field. Two regimes with seemingly different voltage dependencies are explained as the limiting cases of weak and strong electric fields of the same general voltage dependence. Electric fields in the plane of the 2DEG are found to cause about three orders of magnitude more ac dissipation than perpendicular electric fields. This strong directionality is attributed to the fact that the electrons are mobile in the plane of the 2DEG but are confined in the third dimension. In the quantized state, not only the screening edge of the 2DEG but also compressible puddles embedded in the bulk cause ac dissipation, as follows from the measured frequency dependence. Finally, characteristic parameters like the width of the screening edge, the threshold voltage, and the charging time of the compressible puddles are determined.

Positive gate bias stress-induced hump-effect in elevated-metal metal–oxide thin film transistors**Project supported by the Science and Technology Program of Suzhou City, China (Grant No. SYG201538) and the National Natural Science Foundation of China (Grant No. 61574096).

Under the action of a positive gate bias stress, a hump in the subthreshold region of the transfer characteristic is observed for the amorphous indium–gallium–zinc oxide thin film transistor, which adopts an elevated-metal metal–oxide structure. As stress time goes by, both the on-state current and the hump shift towards the negative gate-voltage direction. The humps occur at almost the same current levels for devices with different channel widths, which is attributed to the parasitic transistors located at the channel width edges. Therefore, we propose that the positive charges trapped at the backchannel interface cause the negative shift, and the origin of the hump is considered as being due to more positive charges trapped at the edges along the channel width direction. On the other hand, the hump-effect becomes more significant in a short channel device (L = 2 μm). It is proposed that the diffusion of oxygen vacancies takes place from the high concentration source/drain region to the intrinsic channel region.

Super-resolution reconstruction of 4D-CT lung data via patch-based low-rank matrix reconstruction

Lung 4D computed tomography (4D-CT), which is a time-resolved CT data acquisition, performs an important role in explicitly including respiratory motion in treatment planning and delivery. However, the radiation dose is usually reduced at the expense of inter-slice spatial resolution to minimize radiation-related health risk. Therefore, resolution enhancement along the superior–inferior direction is necessary.In this paper, a super-resolution (SR) reconstruction method based on a patch low-rank matrix reconstruction is proposed to improve the resolution of lung 4D-CT images. Specifically, a low-rank matrix related to every patch is constructed by using a patch searching strategy. Thereafter, the singular value shrinkage is employed to recover the high-resolution patch under the constraints of the image degradation model. The output high-resolution patches are finally assembled to output the entire image.This method is extensively evaluated using two public data sets. Quantitative analysis shows that the proposed algorithm decreases the root mean square error by 9.7%–33.4% and the edge width by 11.4%–24.3%, relative to linear interpolation, back projection (BP) and Zhang et al’s algorithm.A new algorithm has been developed to improve the resolution of 4D-CT. In all experiments, the proposed method outperforms various interpolation methods, as well as BP and Zhang et al’s method, thus indicating the effectivity and competitiveness of the proposed algorithm.

Precise vibrating electrochemical machining of a diamond-shaped hole with side-wall insulation

Electrochemical machining has the advantage of being free of cathode loss, thermal stress, and residual stress, and is suitable for high precision machining of metal structures. Localization of anodic dissolution can be significantly improved by the side-wall insulation of the cathode. However, for shaped-hole machining, the removal of electrolytic products in the machining gap becomes problematic with the increase of machining depth, which may hinder the machining process. The application of vibration to the cathode in an electrochemical machining is considered an effective approach because the frontal gap is periodically changed by the vibration; therefore, the removal of electrolytic products and the refreshment of electrolyte are facilitated. This study is aimed at finding a suitable method for diamond-shaped hole fabrication using electrochemical machining. The influence of vibrating feed, cathode with and without side-wall insulation on the machining stability and accuracy were studied based on the machining system developed in this study. The experimental results reveal that the machining accuracy of the diamond-shaped hole can be improved remarkably by reducing the width of the tool edge. Meanwhile, the machining stability can be improved significantly with a reasonable vibrating feed mode.

A new application of change point analysis reveals extensive edge effects on a temperate mixed forest

AbstractQuestionsHow do landscape changes along edges of protected areas affect forest interiors and stand development? What are the locations, spatial extents and magnitudes of these effects?LocationThe 8500‐ha Sylvania Wilderness Area, Michigan's Upper Peninsula, USA.MethodsWe conducted vegetation surveys in 202 plots in ten transects crossing the Sylvania Wilderness border in 2013 and 2014. We recorded characteristics of forest structure, trees, shrubs, saplings, seedlings and herbaceous species. We constructed GLMM to estimate the location, spatial extent and magnitude of change of edge effects on Sylvania with a range of possible edge effect locations and widths of effect. We selected best‐fit models that minimized the AIC and applied likelihood ratio tests to assess the statistical significance of each edge effect.ResultsOverall, evidence of edge effects occurred up to 625 m into the Sylvania Wilderness, with most significant changes occurring within 400 m of the wilderness border. Wide zones of change occurred across the wilderness border, while zones of change farther from the edge tended to be narrower, suggesting that distinct environments are established beyond the transitional habitats surrounding the border region. Canopy‐level and understorey‐level variables exhibited the largest magnitudes and steepest gradients of change, indicating these communities are strongly influenced by edge effects in this forest system. Canopy‐level heterogeneity also increased approaching the internal core area of Sylvania.ConclusionsIn this case study, we applied a linear change point model and found a minimum buffer zone of 400 m to mitigate edge effects in an old‐growth temperate mixed forest. Regionally, land managers could implement this buffer to existing edges of protected areas or negotiate this buffer zone in land acquisitions. A more stringent buffer zone of 625 m internal and 250 m external to old‐growth forests would be ideal. This application of change point analysis provides a simple, efficient method to establish effective buffer zones and to identify functional groups or ecosystem attributes for which edge effects are of greatest conservation concern. We recommend modifying our open‐source change point package to estimate local edge effects that take into account regional characteristics.

Electronic and magnetic properties of zigzag C2N-h2D nanoribbons: Edge and width effects

Based on first-principles calculations, we have systematically investigated the structural stability, electronic and magnetic properties of zigzag C2N nanoribbons (ZC2NNRs). Different from zigzag graphene nanoribbons (ZGNRs), the ground states of ZC2NNRs present ferromagnetic metal, antiferromagnetic semiconductor and spin semiconductor dependently on the edge configuration and width of nanoribbons. Our results suggest the ZC2NNRs have great potential applications in spintronic, thermoelectric and optoelectronic devices.

Influence of depth and 3D crosstalk on blur in multi‐view 3D displays

AbstractCurrent 3D crosstalk equation was defined from the characteristics of 3D display using glasses. This equation is not suitable for multi‐view 3D display with larger view number as it gives the inappropriately large value. In 3D display using eyeglass, double images occur at large depth. But, in multi‐view 3D display with larger view number, blur occurs to larger width for the larger depth. Hence, blur phenomenon of multi‐view 3D display was investigated to understand the unique characteristics of multi‐view 3D display. For this purpose, ray tracing S/W was used to simulate 3D display image seen at the designed viewing distance, to calculate the relative luminance distribution, and to quantify the relation between blur and depth. Calculated results showed that incomplete image separation caused the overlap of multiple view images and the blur. Blur edge width (BEW) was proportional to the horizontal disparity and related to the depth. BEWR = (BEW) / (binocular disparity) was newly defined, and its usefulness for 3D characterization was investigated. BEW and BEWR might be useful as new measuring items to characterize multi‐view 3D display regarding 3D crosstalk.

Wear of cemented tungsten carbide (WC) router cutters during oak wood milling

The paper presents a study on the performance of non-coated solid cemented tungsten carbide (WC) router cutter when milling oak wood. The tests were done with the oak wood samples. The samples were milled in the CNC milling router. The samples were milled at three different milling modes. The measured micro-geometrical parameter was the width of cutting edge. Actual values of cutting edge width were measured by optical method using optical microscope and digital microscopy camera. Width of cutting edge was measured in the established steps of cutting length. The received images were processed and measured using the computer software. The results are presented in the form of summaries and diagrams.DOI: http://dx.doi.org/10.5755/j01.mech.23.3.18482

ESIM: Edge Similarity for Screen Content Image Quality Assessment.

In this paper, an accurate full-reference image quality assessment (IQA) model developed for assessing screen content images (SCIs), called the edge similarity (ESIM), is proposed. It is inspired by the fact that the human visual system (HVS) is highly sensitive to edges that are often encountered in SCIs; therefore, essential edge features are extracted and exploited for conducting IQA for the SCIs. The key novelty of the proposed ESIM lies in the extraction and use of three salient edge features-i.e., edge contrast, edge width, and edge direction. The first two attributes are simultaneously generated from the input SCI based on a parametric edge model, while the last one is derived directly from the input SCI. The extraction of these three features will be performed for the reference SCI and the distorted SCI, individually. The degree of similarity measured for each above-mentioned edge attribute is then computed independently, followed by combining them together using our proposed edge-width pooling strategy to generate the final ESIM score. To conduct the performance evaluation of our proposed ESIM model, a new and the largest SCI database (denoted as SCID) is established in our work and made to the public for download. Our database contains 1800 distorted SCIs that are generated from 40 reference SCIs. For each SCI, nine distortion types are investigated, and five degradation levels are produced for each distortion type. Extensive simulation results have clearly shown that the proposed ESIM model is more consistent with the perception of the HVS on the evaluation of distorted SCIs than the multiple state-of-the-art IQA methods.

A retinal image sharpness metric based on histogram of edge width

Retinal image sharpness assessment is one of the critical requirements of automatic quality evaluation in telemedicine screening for diabetic retinopathy. In this paper, a new sharpness metric measuring the spread of edges is presented to quantify fundus image clarity. After edge detection on the region of interest of retinal image, the width of each edge is calculated and the histogram of region of interest generated. Based on the histogram, a distance-based factor is introduced to gain the weighted edge width, which is defined as the sharpness metric for the fundus image. The method was tested on Messidor dataset and a proprietary dataset. The results show that the proposed metric performs well over different image distortion levels and resolutions and is of low computational complexity. The weighted edge width value of gradable retinal image, which is irrelevant to resolution, is always within the range of 3–7 pixels.