Edge Quality Research Articles

Intensifying the spatial resolution of 3D thermal models from aerial imagery using deep learning-based image super-resolution

Nowadays, 3D thermal models can play an important role in buildings' energy management while acquiring multisource data to generate a high-resolution 3D thermal model. Consequently, in this article, a method for intensifying 3D thermal model using deep learning-based image super-resolution is presented. In the proposed method, first, the enhanced deep residual super-resolution (EDSR) deep network is re-trained based on thermal aerial images. Second, the resolution of low-resolution thermal images is enhanced using the newly trained network. Finally, the state-of-the-art structures from motion (SfM), semi global matching (SGM) and space intersection are utilized to generate intensified 3D thermal model from the resolution enhanced thermal images. Spatial evaluations indicate a 5% increase in edge-based image fusion metric (EFM) for the intensified 3D model. Besides, the evaluations show that the modulation transfer function (MTF) curves of the intensified 3D thermal model are closer to a reference model against the original 3D thermal model. Highlights A 3D thermal model intensification solution using EDSR is proposed which is independent of hardware techniques and multisource data. Considering the importance of edge sharpness in the intensified 3D thermal model, the quality of edges is assessed using MTF curves and the EFM metric. In comparison to the original 3D thermal model, the MTF curves of the intensified 3D thermal model are closer to the MTF curve of the high-resolution 3D model. The EFM metric shows higher values for MTF curves of the intensified 3D thermal model against MTF curves of the original 3D thermal model.

Characterisation of needle edge quality using diffraction pattern

The performance of hypodermic needlesismainlydependentonquality of theiredges. The quality oftheneedle edges directly impactspenetration forces, tissue healing time, andpatientpain. At present, only subjective techniques are used to access quality of edges of the needles which are not capable to contribute during manufacturing. Thus anappropriatetechnique is desirable to characterize the defects of the needle edges. This study aims to develop a characterization technique for measurement of defects such as roughness, chips and tip bending on the edges of needles. The proposed technique uses the diffraction fringes, obtained from the superposition of diffracted light from needle edges and the direct propagated light from the source. Variations in the fringes and their intensity profiles are utilized to study the defects. Further, the results are compared with results obtained from a standard optical profiler and a microscope. The standard deviation of proposed technique for repeatability and reproducibility of measurements are σ = 0. 104 a.u and σ = 0. 87 a.u, respectively. This technique is simple, non-contact in nature, uses compact configuration and is capable for qualitative and quantitative evaluation of the hypodermic needles.

Optimum blanking clearance choice method by an approach coupling experimental trials and simulations

Blanking process of sheet metal is accomplished by a shearing action on a thin plate placed between two sharp cutting edges, known as “punch” and “die”. The main problem of this sheet metal cutting technology, that causes major shutdowns of the press machine, is the punch wear. Among all blanking parameters, the clearance set between the punch and the die has the major influence on tool wear. In this context, our study focuses on identifying the optimum blanking clearance that guarantees a maximum abrasion and chipping wear reduction for different sheet metal materials and different blanking operations. The developed approach combines experimental blanking tests and numerical simulation of blanking processes. Based on assumptions made in this paper, links are established between the stripping force and the abrasive wear behaviour of punching tools and also between the maximum pressure on the face of the punch and the risk of chipping. Using these links, criteria have been developed allowing to propose an optimum blanking clearance for all the configurations tested in this paper. A next step of this study consists on applying the optimum punch-die clearances in a variable way along a complex blanking shape and realizing experimental tests to compare the results (tool life and edge quality) with a constant blanking clearance.

Modelling stamped edges in FEM breakage analyses of high-strength steel safety components

The development process for new safety components includes break load tests, where the component undergoes very large strains. Besides the mechanical properties of the steel, which are changed by the forming process, the break load depends on the quality of the stamped edges. Target of this paper is to investigate whether a hole-tensile test with a stamped hole can demonstrate the effects of stamped-edge quality on the load bearing capacity – and secondary, how such a test procedure can be reproduced with a multi-scale FEM procedure. A series of Hole Tensile Tests (HTT) has been performed with a HSLA steel grade. Here, only minor differences in break load and total elongation were found. The local strain just prior to breakage at the edge of the stamped hole shows remarkably high values, but little difference is found when comparing a machined sample to stamped samples. The multi-scale FEM approach was demonstrated using literature data for dual-phase steel, which is known to be more sensitive to edge cracks. Indeed, a stamped edge, which includes significant hardening and pre-damage, shows earlier fracture in this FEM calculation – however, the crack propagation, which is needed to capture the full breakage of the HTT sample, is not modelled correctly – this limits the application of the method on safety components.

Stretch flangeability of AHSS automotive grades versus cutting tool clearance, wear, angle and radial strain gradients

Stretch flangeability tests are performed on cold rolled AHSS automotive steel grades for crack sensitivity evaluation. The ISO16630 tests procedure is used with different cutting edge conditions including cutting clearance, cutting tool wear, cutting tool angle and hole expansion punch tool geometry. Among all influence parameters, the cutting clearance is considered to be the most critical to control. Low (<10%) and high (>20%) clearances are significantly detrimental to hole expansion ratio (HER). An optimum in HER is reached around 15% clearance. Both cutting punch wear and cutting die wear each affect negatively the HER values in comparison to new sharp cutting tools. Varying the cutting angle with concave and convex hole punching tool geometries instead of orthogonal cutting has a rather negative effect on stretch flangeability due to irregular cut edge quality along hole perimeter and excessive tool wear in the concave configuration. The influence of hole expansion punch geometry (flat R25, biaxial Nakajima R25 vs. ISO16630 60° conical) on the HER values is also investigated. The (true) HER values are proportional to the FE simulated logarithmic radial strain gradient at fracture.

Soft machining-induced surface and edge chipping damage in pre-crystalized lithium silicate glass ceramics

Soft machining is a key procedure in fabrication of high-strength lithium-based silicate glass ceramic (LS) restorations. This paper reports on the diamond machining-induced surface and edge chipping damage in two pre-crystalized LS materials: pre-crystallized lithium metasilicate/orthophosphate glass ceramic (Pre-LS, IPS e.max CAD) and pre-crystallized zirconia-containing lithium metasilicate glass ceramic (Pre-ZLS, Vita Suprinity). Indentation techniques were used to measure the material mechanical properties. Soft machining was conducted using a robotic controlled apparatus mimicking dental CAD/CAM machining processes at different removal rates and enabling in-process force measurement. Machined surface roughness was assessed using 3D confocal optical profilometry in terms of the average and maximum surface heights. Scanning electron microscopy was used to assess diamond tool and machined surface and edge morphology. Soft machining of both materials was dominated by brittle fracture mixed with localized ductile flow. However, the higher brittleness index of Pre-ZLS than Pre-LS yielded higher degrees of machining-induced conchoidal fractures in Pre-ZLS in comparison with irregular fractures in Pre-LS. Thus, much larger surface roughness and deeper edge chipping damage were produced in Pre-ZLS than Pre-LS. Machining forces for Pre-ZLS were significantly smaller than Pre-LS, due to the lower machinability index associated with a complex relation of the mechanical properties as well as less debris adhesion for Pre-ZLS than Pre-LS. Further, increased material removal rates resulted in significantly increased machining forces, maximum surface roughness and fracture, and edge chipping damage in both Pre-ZLS and Pre-LS materials. Therefore, optimization of soft machining processes needs to be practiced to achieve accepted surface and edge quality at balanced removal rates.

Rising Speed Limits for Fluxons via Edge-Quality Improvement in Wide MoSi Thin Films

Ultra-fast vortex motion has recently become a subject of extensive investigations, triggered by the fundamental question regarding the ultimate speed limits for magnetic flux quanta and enhancements of single-photon detectors. In this regard, the current-biased quench of a dynamic flux-flow regime - flux-flow instability (FFI) - has turned into a widely used method for the extraction of information about the relaxation of quasiparticles (unpaired electrons) in the superconductor. However, the large relaxation times $\tau_\epsilon$ deduced from FFI for many superconductors are often inconsistent with the fast relaxation processes implied by their single-photon counting capability. Here, we investigate FFI in $15$ nm-thick $182$ $\mu$m-wide MoSi strips with rough and smooth edges produced by laser etching and milling by a focused ion beam. For the strip with smooth edges we deduce, from the current-voltage ($I$-$V$) curve measurements, a factor of 3 larger critical currents $I_\mathrm{c}$, a factor of 20 higher maximal vortex velocities of 20 km/s, and a factor of 40 shorter $\tau_\epsilon$. We argue that for the deduction of the intrinsic $\tau_\epsilon$ of the material from the $I$-$V$ curves, utmost care should be taken regarding the edge and sample quality and such a deduction is justified only if the field dependence of $I_\mathrm{c}$ points to the dominating edge pinning of vortices.

Enhancing the accuracy of forging measurement using silhouettes in images

In this study, a new passive camera system for heavy cylindrical forging measurement, based on silhouettes in images, is developed. New methods for making such a system more resistant to the negative effects of the industrial environment have been proposed. This includes weighted edge filtering based on complementary information about the edge quality in an image. The recorded measurement median errors were ±0.12 mm and ±0.14 mm. Moreover, the 95% confidence intervals were ±0.5 mm and ±1 mm for the forging axis and diameter measurements, respectively. Both results were achieved in a measurement volume of 6 × 6 × 2 m during the measurement of glowing hot forgings in industrial conditions. The results surpass those of the state-of-the-art method, mainly in the case of axis straightness measurement, by approximately 50%. The measurement is fast, and it provides feedback about the axis straightness for its subsequent correction.

Nonstationary spin waves in a single rectangular permalloy microstrip under uniform magnetic excitation

Ferromagnetic resonance modes in a single rectangular ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}$ microstrip were directly imaged using time-resolved scanning transmission x-ray microscopy combined with a phase-locked ferromagnetic resonance excitation scheme, and the findings were corroborated by micromagnetic simulations. Although under uniform excitation in a single confined microstructure typically standing spin waves are expected, all imaged spin waves showed a nonstationary character both at and off resonance, the latter being additionally detected with microantenna-based ferromagnetic resonance. The effect of the edge quality on the spin waves was observed in micromagnetic simulations.

A Novel Edge Detection Algorithm Based on Outer Totalistic Cellular Automata

Edge detection is a key technique in image processing. The detected edge quality has a direct and significant impact on performance. There is a multitude of methods for edge detection but they are strongly associated with the application and the quality of the images. However, more precise outcomes and a reduced execution time remain the primary objectives for extracting edges. To address these issues, we propose a novel technique based on a complex system called Cellular Automata (CA). They are successfully applied in edge detection due to their simplicity and local interactions. This undertook shed new light on a novel method using Outer Totalistic Cellular Automata (OTCA) to perform efficiently edge detection. We have tested images from Berkeley dataset. RMSE and SSIM are used as fitness functions for estimating numerical performance of OTCA rules. Comparisons were made with classical edge detectors like: Canny, Scharr, Sobel, Roberts. Experimental results showed that OTCA rules provide excellent performance and outperforms other edge detectors in terms of precision and execution time, particularly when dealing with noisy images.

Operational behaviour of graded diamond grinding wheels for end mill cutter machining

The varying related material removal rate during deep grinding of cemented carbide end mill cutters results in an unevenly wear of the grinding wheel. This study therefore presents a simulation-based model for the load-adjusted design of grinding wheels to achieve balanced radial wear, as well as an evaluation of this model. The related material removal rate along the width of the grinding wheel is determined by a Dexel based material removal simulation for different end mill geometries. Based on these results an equation is derived to adapt the abrasive layer properties to the local load differences. Three grinding wheels with different types of gradients are then manufactured by a grinding tool manufacturer based on this equation. These and two grinding wheels with constant abrasive layer properties are used for deep grinding of ten end mills each. Afterwards the radial wear of each grinding wheel is measured by a confocal microscope. An analysis of the cutting edge chipping is done to evaluate the influence on the graded grinding wheels on the cutting edge quality. It was found that a reduction of the wear difference over the grinding wheel width of 52% and an improved cutting edge quality can be achieved by using graded grinding tools. This allows the time intervals between dressing steps to be increased without compromising the accuracy of the grinding process, thus also increasing its productivity. Finally, this article shows that the presented model allows for a more balanced wear behaviour, but has to be extended by considering further factors influencing radial wear.

Influence of extrusion parameters on drilling machinability of AZ31 magnesium alloy

AZ31 magnesium alloy is mainly used in aerospace applications due to its lightweight and good mechanical properties. The installation of AZ31 alloy in an aircraft usually requires machining operations such as drilling and milling for assembly purposes. The current study aims to investigate the effects of different extrusion ratios (1.77, 2.68, 3.55) on the drilling machinability of AZ31 alloys. The machinability was evaluated with thrust force, borehole surface quality, and chip characteristics. It was found that the thrust force and hole quality depend on the extrusion ratio and cutting parameters. The highest thrust force and surface roughness Ra occurred when drilling AZ31 alloy produced using the highest extrusion ratio of 3.55 in agreement with the improvement in the mechanical properties. The chip length decreased with the increase of the extrusion ratio depending on a decrease in the ductility, while SEM images showed that the AZ31 sample produced using intermediate extrusion ratio had the best hole edge quality and least burr formation.

Study on the edge defects of high volume fraction 70% SiCp/Al composites in ultrasonic-assisted milling

Directing at the hard machinability of high volume fraction 70% SiCp/Al composites, a longitudinal and torsional ultrasonic-assisted milling (LTUAM) method is proposed to improve the edge quality and machining efficiency. By observing the metallographic structure of the material, a three-dimensional (3D) finite element model of random distribution of spherical, elliptical and polygonal SiC particles is established and analyzed by ABAQUS simulation software. The formation mechanism of edge defects, stress distribution, defect characteristics and the effect of machining parameters on milling forces are investigated during ultrasonic-assisted milling. The results show that the edge defects appear at the inlet, outlet and middle edge position, especially is more serious at the outlet position. The SiC particles failure modes mainly include particle pullout, particle shearing, and crushing, moreover, the edge defects mainly include matrix tearing, edge breakage, burrs, bulges and pits. Ultrasonic-assisted milling (UAM) with a certain range of ultrasonic amplitude could effectively reduce the surface fragmentation rate and milling force, and it not only could slow down the expansion of cracks, but also increase the plastic flow of material, and obtain better edge quality compared with the traditional machining method. Comparing the results of finite element analysis and experimental tests, it shows that the simulation results are in good agreement with that of tests.

Enhanced Edge Detection Technique in Digital Images Using Optimised Fuzzy Operation

In image processing, edge detection is a critical issue. Edge detection is a key approach for evaluating the edge of various objects in a digital image. These edges are found using the gradients, which are present in the image. The intensity and value of pixels determine the gradients. In digital images, edge detection lowers the quantity of data and filters out irrelevant data while maintaining the image's key structural features. In this paper, a new edge detection approach based on a fuzzy rule-based system is proposed. In digital image processing, the proposed method typically depends on fuzzy logic systems. The main goal of this system is to show how fuzzy logic may be used in image processing. This paper provides a fuzzy logic-based edge detection technique that uses a sharpening Gabor filter to regulate edge quality and a Gaussian filter to reduce noise caused by sharpening. This is determined by utilizing applications such as “Peak Signal to Noise Ratio (PSNR) F-Measure, and Hausdorff distance (HoD) to prove that fuzzy logic outperforms the proposed system. The findings for edge detection approaches are included in high quality. The proposed approach outperforms most commonly used traditional edge detection methods. The proposed method also reduces the number of noisy features and may be used for a wide range of images.

Experimental study on drilling process of a newly developed CFRP/Al/CFRP co-cured material

The drilling is often applied for a newly developed CFRP (carbon fiber reinforced plastic)/Al/CFRP co-cured material to ensure excellent fastening and accurate assembly. However, because of their different material properties, there are great challenges in one-time drilling of CFRP/Al/CFRP co-cured materials. This paper presents contrast between the TiAlN coating and uncoating for the quality/accuracy of drilling CFRP/Al/CFRP co-cured materials. Considering inhomogeneous behavior, a three-dimensional drilling model is proposed to analyze the drilling process. Then, experiments are taken to prove the effect of the TiAlN coating on the thrust force of the drill bit. Finally, the results show that it helps reduce the maximum thrust force, and improving hole edge quality, surface morphology and roughness during the drilling process of CFRP/Al/CFRP co-cured materials.

Hybrid laser-arc welding of laser- and plasma-cut 20-mm-thick structural steels

It is already known that the laser beam welding (LBW) or hybrid laser-arc welding (HLAW) processes are sensitive to manufacturing tolerances such as gaps and misalignment of the edges, especially at welding of thick-walled steels due to its narrow beam diameter. Therefore, the joining parts preferably have to be milled. The study deals with the influence of the edge quality, the gap and the misalignment of edges on the weld seam quality of hybrid laser-arc welded 20-mm-thick structural steel plates which were prepared by laser and plasma cutting. Single-pass welds were conducted in butt joint configuration. An AC magnet was used as a contactless backing. It was positioned under the workpiece during the welding process to prevent sagging. The profile of the edges and the gap between the workpieces were measured before welding by a profile scanner or a digital camera, respectively. With a laser beam power of just 13.7 kW, the single-pass welds could be performed. A gap bridgeability up to 1 mm at laser-cut and 2 mm at plasma-cut samples could be reached respectively. Furthermore, a misalignment of the edges up to 2 mm could be welded in a single pass. The new findings may eliminate the need for cost and time-consuming preparation of the edges.

Enhanced cold deformability of a marine Cu-Ni-Al–Fe-Mn alloy produced by HCCM vertical continuous casting: effect of deformation mechanism and second phases

ABSTRACT Cu-Ni-Al–Fe-Mn alloy billets were prepared by heating–cooling combined mould (HCCM) continuous casting at different casting speeds. Then, the cold deformation behaviour of billets was studied by multi-pass cold rolling, and the effects of HCCM continuous casting on cold deformability were discussed by comparing with the mould casting (MC) alloy. The results show that HCCM continuous casting significantly improves the cold deformability of Cu-Ni-Al–Fe-Mn alloy billets. When the rolling reduction is 94%, HCCM continuous casting samples have good edge quality without obvious crack, while the MC sample has severe edge cracks. With the rolling reduction increasing from 40% to 94%, the elongation of the MC samples decreases from 6% to 2%, while that of HCCM continuous casting samples maintains in 6%∼9%, showing good continuous deformability. The HCCM continuous casting samples with lower casting speeds have [001] oriented columnar grains along the casting direction, which make the deformation mechanism change from nano-crystallization to parallel stacking faults. In the meanwhile, HCCM continuous casting improves deformation coordination of as-cast grains and restrains intergranular cracking, which is reflected in the influence on misorientation between as-cast grains and distribution of coarse NiAl phases. In addition, nano-twins found in the rolled MC sample promote the initiation and propagation of cracks.

Multi-objective optimization of edge quality and surface integrity when wire electrical discharge machining of polycrystalline diamonds in cutting tool manufacture

This work presents an energy-saving approach to the single-pass wire electrical discharge machining (WEDM) of polycrystalline diamond with no degradation in edge geometry or surface integrity in cutting tool manufacture. The proposed boundary conditions and discharging wavelets enable the least number of pulse-off durations to effectively recover the electrical potential for the extended discharging action and the successively energy saving via a secondary MOSFET circuit. Secondly, the determined pulse-off durations could sufficiently improve the effectiveness of the Joule heat model which did not consider the extrinsic interference from the removed materials in the discharging gap. Full factorial design experiments were performed to validate the effects of the operating parameters on the material removal rate, surface roughness, cutting edge radius, and surface waviness in single-pass WEDM for the shaping of diamond cutting tools. Precision levels in the fitting of analytic models to experiment results were presented. Linear algebra was introduced to evaluate the selection of operating parameter combinations aimed at optimizing of observations with adjustable weightings. Thermal induced defects and alterations in the microstructures were reported and discussed. The proposed ready-to-use diamond cutting tools present a good balance between energy savings and appreciable outcomes.

Experimental and numerical investigation of thick plate laser cutting using dynamic beam shaping

Further improvement of quality and productivity are some of the most relevant laser cutting process challenges. One way of affecting the process performance is manipulating the laser beam intensity distribution. Within this work, the feasibility of enhancing the cutting speed and edge quality using dynamic beam shaping in 4 kW fiber laser cutting of 15 mm stainless steel is investigated. Moreover, in order to evaluate the effect of dynamic beam shaping parameters on the process zone, a simplified thermal simulation model is introduced. As a result, the effect of longitudinal beam oscillation on the cutting efficiency is studied experimentally and explained using numerical calculation. The obtained results have shown a significant improvement for laser fusion cutting compared with a static top-hat intensity distribution. In particular, the cutting speed can be increased up to 45 % with considerably better quality. Finally, further steps to optimize the dynamic beam shaping technology for laser cutting applications are proposed.

Research progress on the quality and efficiency of carbon fiber reinforced thermoplastic polymer composites processed by laser

Carbon fiber reinforced plastics (CFRP) has been widely used in aerospace, military weapons, new energy and high-end vehicles due to its specific and superior strength, low density and long-lasting wear resistance. The processing of CFRP is very different from the traditional metal processing because of its heterogeneous structure, anisotropy and superior wear resistance of CFRP. Usually, CFRP has often various defects in mechanical processing and water jet processing, such as interlayer tearing, fiber pull-out, delamination, tool wear, and abrasive penetration. Through laser processing, the problems of CFRP materials existing in mechanical processing can be overcome. However, due to the huge differences in thermal physical properties such as thermal conductivity and vaporization temperature of carbon fiber and resin in CFRP, its laser processing also turns out to have some issues, such as heat-affected zone and fiber end expansion. This paper summarizes the research results of CFRP laser processing in China and internationally. Research progress was introduced in detail from various aspects including laser and material mechanism as well as laser processing parameters. It reports the experimental and theoretical studies covering the process accuracy in edge quality and the thermal characteristics in terms of heat-affected zone. Eliminating the heat-affected zone in the polymer matrix are considered the major obstacles of CFRP industrial applications. The methods of improving processing efficiency by increasing material removal rate and reducing processing time were reviewed. The influence of different thermal conductivity of carbon fiber and resin matrix in CFRP on the processing quality was discussed. Finally, the development trend and challenges of thermal conductivity of carbon fiber and resin in CFRP in theoretical modeling were proposed.