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Rainbow coloring problems, of noteworthy applications in Information Security, have been receiving much attention in the last years in Combinatorics. In particular, the rainbow connection number of a connected graph G , denoted r c ( G ) , is the least k for which G admits a (not necessarily proper) k -edge-coloring such that between any pair of vertices there is a path whose edge colors are all distinct. When G is disconnected, we define r c ( G ) = ∞ . A graph G is rainbow critical if the deletion of any edge of G increases r c ( G ) . In this paper we determine the rainbow connection number for the shadow graphs of paths, some circulant graphs, and some Cartesian products involving cycles and paths. We also determine conditions for the rainbow criticality and non-criticality of wheels, fans, and some Cartesian products involving cycles, paths, pans, and complete graphs.

Impacts from a changing climate, in particular sea-level rise, will be most acutely felt on small oceanic islands. A common configuration of mid-latitude islands is the sandy barrier island. Sable Island, Nova Scotia, Canada is a vegetated sand island near the shelf edge, 160 km from the nearest point of land, that is morphologically similar to a barrier island. This study uses 60 years of airphoto records to analyse changes in coastline position through digitized shore and vegetation (foredune proxy) lines. Rates of coastal movement are analysed to model the future (2039) coastal configuration. The analyses suggest that the majority of the coastline on Sable Island is in retreat, with net retreat on the south side of the island only partially offset by modest net advance on the north side. The different morphologies of the beach–dune systems of South Beach and North Beach, driven by incident wind and waves, yield these different coastline responses. Projected loss of 10 ha by 2039 of the climax heath vegetative community to shoreline retreat suggests a trend toward island instability due to coastline migration. Island-wide data set trends show support for two different but complementary hypotheses about whole-island evolution: (1) the island is mobile via bank migration driving southern coastline changes and experiencing sediment transport toward the east, or (2) the island is generally immobile and losing subaerial sediments (and thus shrinking) likely due to ongoing (and accelerating) sea-level rise.

Building on earlier results for regular maps and for orientably regular chiral maps, we classify the non-abelian finite simple groups arising as automorphism groups of maps in each of the 14 Graver–Watkins classes of edge-transitive maps.

Let G = ( V , E ) be a simple undirected graph. A set D ⊆ V is called a vertex-edge dominating set of G if for each edge e = u v ∈ E , either u or v is in D or one vertex from their neighbor is in D . Simply, a vertex v ∈ V , vertex-edge dominates every edge u v , as well as every edge adjacent to these edges. The objective of the vertex-edge domination problem is to find a minimum size vertex-edge dominating set of G . Herein, we study the vertex-edge domination problem in unit disk graphs and prove that the decision version of the problem belongs to the NP-complete class. We also show that the problem admits a simple polynomial-time 4-factor approximation algorithm and a polynomial-time approximation scheme (PTAS) in unit disk graphs.

For a given graph $G$, the metric and edge metric dimensions of $G$, $\dim(G)$ and ${\rm edim}(G)$, are the cardinalities of the smallest possible subsets of vertices in $V(G)$ such that they uniquely identify the vertices and the edges of $G$, respectively, by means of distances. It is already known that metric and edge metric dimensions are not in general comparable. Infinite families of graphs with pendant vertices in which the edge metric dimension is smaller than the metric dimension are already known. In this article, we construct a 2-connected graph $G$ such that $\dim(G)=a$ and ${\rm edim}(G)=b$ for every pair of integers $a,b$, where $4\le b, Comment: 12 pages

In this paper, an innovated buried layer rectifier (BLR) breakdown voltage (BV) instability has been tested and analyzed. Under the reverse current stress (RCS) condition, the BV read-out profiles show walk-in and walk-out phenomena. Based on the experimental results and surface traps theory, a sort of time dependent degraded simulation is developed by TCAD tools, which is considered with hydrogen depassivation and diffusion process. In order to explore the inner mechanism, the dynamic electric parameters are analyzed during the degraded period. Due to the hole interface traps, the termination Si-SiO2 surface leakage current is deteriorated and the depletion boundary is shrunk, which reveals the BV values instability. Thus, the proposed physical model could clearly explain the whole process of degradation, while it fits BV and junction temperature curves to the experimental results identically. Furthermore, the investigated mechanism will be helpful to future device design and failure situations analysis.

Reliability evaluation of multiprocessor systems is of great significance to the design and maintenance of these systems. As two generalizations of traditional edge connectivity, extra edge connectivity and component edge connectivity are two important parameters to evaluate the fault-tolerant capability of multiprocessor systems. Fast identifying the extra edge connectivity and the component edge connectivity of high order remains a scientific problem for many useful multiprocessor systems. In this article, we determine the $h$ -extra edge connectivity of the 3-ary $n$ -cube $Q_n^3$ for $h\in [1, \frac{3^n-1}{2}]$ . Specifically, we divide the interval $[1, \frac{3^n-1}{2}]$ into some subintervals and characterize the monotonicity of $\lambda _h(Q_n^3)$ in these subintervals and then deduce a recursive closed formula of $\lambda _h(Q_n^3)$ . Based on this formula, an efficient algorithm with complexity $O(\log _3\,N)$ is designed to determine the exact values of $h$ -extra edge connectivity of the 3-ary $n$ -cube $Q_n^3$ for $h\in [1, \frac{3^n-1}{2}]$ completely. Moreover, we also determine the $g$ -component edge connectivity of the 3-ary $n$ -cube $Q_n^3(n\geq 6$ ) for $1\leq g\leq 3^{\lceil \frac{n}{2}\rceil }$ .

The main objective of the proposed work was to analyse the influence of magnification and focal spot size scan settings on X-ray computed tomography (CT) measurements results under commercial threshold-based algorithms. The relationship between spatial resolution and contrast sensitivity in CT scans of different materials and the accuracy of the resulting CT measurement results is discussed. For that purpose, Aluminium, Copper, Inconel 718 and Titanium disk phantoms were scanned. Preliminary measurements showed that deviations can increase up to 0.48% when the scanning magnification was increased while, for a given magnification, the decrease of a focus size from 1mm to 0.4mm slightly improves the differences up to 0.15%, being negligible at low magnifications. Unsharpness (U T ) and contrast-to-noise ratio (CNR) were calculated for each scanning conditions according to standard ASTM E1695 – 20. A new image quality indicator that includes the combined effect of the U T and CNR was proposed in order to relate measurement error with the image quality. The indicator proves that the influence of CNR is much higher than influence of U T on the CT measurements.

We introduce a natural temporal analogue of Eulerian circuits and prove that, in contrast with the static case, it is NP-hard to determine whether a given temporal graph is temporally Eulerian even if strong restrictions are placed on the structure of the underlying graph and each edge is active at only three times. However, we do obtain an FPT-algorithm with respect to a new parameter called interval-membership-width which restricts the times assigned to different edges; we believe that this parameter will be of independent interest for other temporal graph problems. Our techniques also allow us to resolve two open question of Akrida, Mertzios and Spirakis [CIAC 2019] concerning a related problem of exploring temporal stars. Furthermore, we introduce a vertex-variant of interval-membership-width (which can be arbitrarily larger than its edge-counterpart) and use it to obtain an FPT-time algorithm for a natural vertex-exploration problem that remains hard even when interval-membership-width is bounded., Extended abstract of this paper appeared in IWOCA 2021: Combinatorial Algorithms pp 107-121 (doi: https://doi.org/10.1007/978-3-030-79987-8_8 )

This paper has proposed a novel design of dual PM vernier machine with T-shape consequent pole rotor. The analytical model of T-shape magnet rotor based on differential magnetic network method are firstly derived. Given the additional optimizing parameter, edge arc difference, T-shape consequent pole (TCP) rotor has the potential to produce 6% higher fundamental airgap flux density or 30% higher PM utilization ratio than regular fan-shape consequent pole rotor. The influence of magnet size parameters including magnet thickness, pole pitch ratio and arc difference angle on airgap flux density of TCP rotor is then analyzed. The torque performance of TCP in regular consequent pole and dual PM consequent pole vernier machines are also studied. The comparison shows that T-shape consequent pole can produce higher torque than fan-shape magnet in vernier machines. At last, a prototype of dual-PM vernier machine with TCP rotor is built and tested, which has achieved 28 Nm/L measured torque density.

To suppress the edge crack of the magnesium alloy sheet during the ordinary rolling process, a new rolling process named width-limited rolling was proposed in this paper. Width-limited rolling is a rolling method in which the width of the alloy sheet is limited by modifying the shape of the rollers, allowing a compressive stress field to form at the edge portion of the alloy sheet during rolling, resulting in the reduction of edge cracks. At present work, magnesium alloy sheets were separately subjected to ordinary rolling and width-limited rolling. The microstructure evolution and mechanical properties of the rolled sheets were investigated by EBSD, TEM, and XRD. The results exhibited that under the same rolling conditions, the sheet after ordinary rolling exhibited obvious edge cracks while no crack was found at the edge of the sheet after width-limited rolling. The edge crack suppressing effect was attributed to the reduction of the tensile stress along rolling direction during WLR, promoting the synchronous extension of the edge and center regions to suppress edge crack tendency. Microstructure observation showed that the compressive twins formed in the sheet after ordinary rolling usually exhibited as thin plates and cannot continue to fully develop due to the premature generation of the edge cracks. However, the compressive twins developed maturely in some of which double twins formed and various slip systems with different dislocation Burgers vectors occurred in the rolled sheet after WLR. More twin intersections and shear bands, providing more potential recrystallization nucleation sites, which are beneficial to weaken basal texture. With the cooperation of twinning and dislocation slip, the texture of the sheet after the width-limited rolling is weakened and the mechanical properties are improved.

The Mg-2Zn-1.5Mn alloy (ZM21) sheets were hot-rolled in a single pass at 150 °C with different reductions through on-line heating rolling. Microstructures and edge cracking behavior of the rolled sheets were investigated. The in-situ tensile tests at 150 °C were also carried out, the crack initiation and propagation were compared with the edge cracking behavior of ZM21 sheets prepared by on-line heating rolling. The results reveal that the edge cracks are most likely to originate in the rolling direction and normal direction (RD-ND) plane due to the secondary tensile stress along RD. Edge cracking becomes more severe with an increasing reduction. The edge cracks mainly initiate and propagate in the fine recrystallized grain areas and the junction of recrystallized grains and sub-grains with hard orientation. The in-situ tensile test indicates that micro-cracks mainly initiate at the triple junction of grain boundaries where grains have hard orientation with low basal Schmid factor (SF). Meanwhile, those cracks are more likely to propagate along the grain boundaries with maximum difference in basal Schmid factor. Besides, the crack initiation and propagation during the in-situ tensile deformation at 150 °C are found not to be associated with the recrystallization.

Visual inspection techniques for rail surface defects have become prevalent approaches to obtain information on rail surface damage. However, uneven illumination leads to illegibility of local information, and the change of the wheel-rail area results in the changeful background of the rail surface, both of which pose challenges to the visual inspection. This paper proposes a novel algorithm that detects rail surface defects via partitioned edge features (PEF). PEF eliminates the effect of uneven illumination by effectively extracting edge features and building homogeneous background on the rail surface. In the process of edge feature extraction, the thresholding based on adaptive partition of rail surface (APRS) plays an indispensable role. In APRS, the rail surface is adaptively partitioned into three types of regions according to the wheel-rail contact degree. After that, the dynamic threshold is set adaptively for each region type on the basis of the prior information of defect proportion. Subsequently, based on neighborhood information and fuzzy decision, the spatial information of adjacent pixels and the direction information of fracture edges are utilized to realize the effective recovery of incomplete defect contours. In addition, defect contours are precisely filled via a flexible combination of morphological hole filling operation and defect region extraction based on improved background difference. The accuracy of this PEF algorithm was confirmed by experiments and comparisons with related algorithms. The experiment results show that PEF detects defects with 92.03% recall and 88.49% precision, which achieves higher accuracy than the established detection algorithms for rail surface defects.

This study deals with the behaviour of duplex stainless steel bolted connections. The aim of the study is to respond to the question if the current stainless steel design specifications are able to predict the behaviour of such connections. Firstly, the net cross-section capacity of duplex stainless steel plates subjected to tensile loading are presented. They were conducted to obtain the stress–strain curves and tensile fracture behaviour used to support the finite element (FE) fracture simulations. Secondly, nonlinear FE models are developed for duplex stainless steel bolted connections subjected to tensile loading. The FE models are validated against experimental data in terms of load–displacement curves, failure modes and ultimate loads. Then, a numerical parametric study that consists of 133 duplex stainless steel grade EN 1.4162 bolted connection specimens is carried out. The failure modes of bolted connections are carefully examined, including combined tear out and bearing, bearing and net section, looking at the influence of parameters such as end distance, edge distance and spacing between the bolts in the connections. The results are compared to the design rules prescribed in the current stainless steel design specifications. Generally, it is found that the Australian/New Zealand (AS/NZS), American (SEI/ASCE) Specification and European codes conservatively predict the ultimate strengths of the bolted connections, whereas the strengths predicted by the AS/NZS and SEI/ASCE specifications are overall more accurate and less scattered.

Windows typically account for 30% to 50% of heat losses through building envelopes. Monolithic silica aerogel has thermal properties and physical characteristics which make it an attractive material for high performance glazing. Optimizing the thermal performance of individual window components can improve the thermal performance of windows insulated with monolithic silica aerogel. It is important to consider how the thermal properties can be sustained, especially when in contact with other window components such as edge and intermediate spacers and the window frame. The purpose of this research paper is to analyze French style windows insulated with four panes of monolithic silica aerogel and investigate the thermal bridging of edge and intermediate spacers and window frame in order to assess how they collectively affect the centre of glass and edge of glass regions. The research aims to determine the spacer geometry, materials, and window frame that guarantee the best performing window system.

This paper reports on the possibility of performing Friction Stir Welding (FSW) without the usual immanent shoulder to enable FS processing to deep welding of narrow and labile structures and applications where backing is not possible. Requirements and prerequisites, advantages and limitations for Shoulderless Friction Stir Welding (SLFSW) are discussed and an industrial application of the joining technology is presented. For leaving the shoulder out, its central functions in FSW have to be transferred to the pin. The resulting tool design of SLFSW is comparably small and slim and so reduces contact area and effective lever and in turn forces and heat input during processing. SLFSW allows welding paths almost at the edge of components and enables a complete and gap-free joining while a deformation of overhanging structures can be avoided. Compared to standard FSW processes, force reductions of about 80–85 % and power reductions of about 75-80 % were found in this study for a 6.5 mm deep weld opening up additional potential for integration with other spindle processes like milling. The locally very limited process impact of SLFSW resulted in comparably low distortion with a part precision reached of +/- 0.05 mm., Projekt DEAL

More translucent dental zirconias have been developed by incorporating the cubic phase and reducing the tetragonal phase content that undergoes transformation toughening, leading to reduced mechanical properties. Whether the clinically relevant mechanical property of the edge chipping toughness of the material is also reduced is unclear.The purpose of this in vitro study was to evaluate the edge chipping toughness and translucency of translucent zirconia, 3mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP), and lithium disilicate.Two translucent zirconia products, Katana and Lava Esthetic; one 3Y-TZP, Lava Plus; and one lithium disilicate, IPS e.max Press were prepared and tested for phase composition via X-ray diffraction (XRD) (n=3), translucency via a spectrophotometer (n=20), and edge chipping via a universal testing machine with a custom-machined specimen holder and diamond indenter (n=20). The 3Y-TZP and lithium disilicate served as the optimal control materials for edge chipping and translucency, respectively. Translucency was compared with 1-way ANOVA and edge toughness with ANCOVA (α=.05).The XRD showed the 3Y-TZP to be almost completely tetragonal phase compared with the 2 translucent zirconia products that were predominantly cubic. Katana UTML and IPS e.max Press had a statistically similar (P.05) translucency that was significantly (P.05) greater than that of Lava Esthetic and Lava Plus. The edge toughness of Katana UTML was 304 N/mm, IPS e.max Press was 354 N/mm, Lava Esthetic was 394 N/mm, and Lava Plus was 717 N/mm, with significance rankings of Katana UTMIPS e.max Press=Lava EstheticLava Plus.Some translucent zirconias had translucency similar to that of lithium disilicate; however, as translucency increased with increased cubic content, edge toughness decreased.

Hosoya introduced the concept of graph terminologies in chemistry and provide a modeling for molecules. This modeling leads to predict the chemical properties of molecules, easy classification of chemical compounds, computer simulations and computer-assisted design of new chemical compounds. In this article, we determine the non-commuting graph associated with the dihedral group by using three Hosoya parameters (Hosoya polynomial, reciprocal Hosoya polynomial and Hosoya index). These Hosoya parameters contain a pile of information about distance structure as well as the edge independent structure of the above-mentioned graph.

The diffraction of plane electromagnetic waves by a perfect electromagnetic conductor (PEMC) semi-infinite sheet which is embedded in an anisotropic medium is examined. The anisotropic region is modeled by a dielectric matrix. The external uniform magnetic field is taken as parallel to the edge of the semi-infinite sheet. Upon considering the H-polarized incident wave, the total scattered fields are obtained with the diffracted waves by using an integral theory which is associated with the scattered fields. The results are expressed in terms of the Fresnel functions. Thus, the wave behaviors at the transition boundaries are uniform. The solutions are compared numerically with the literature including limit values.

Pantograph slide is a vulnerable component because of the contact and friction between the pantograph and catenary (PAC) while the train runs with a high speed. Condition monitoring of the slide is a necessary and meaningful work to improve the operation efficiency and reduce the occurrence of accident. It is a hard work to measure the slide abrasion due to the dynamic and complicated environment. In this paper, an accurate edge extraction method based on image analysis is proposed, which aims at providing an image metric property based on vision measurement to detect the wear of slide. First, a subpixel edge detection method is proposed. The gradient in horizontal direction is first taken into account, which filters out the non-horizontal edges. Then, the upper and lower edges of the slide are located using the geometric restriction. The subpixel edge feature are also extracted in the image process, which can be used to the vision measurement system for monitoring the wear condition of the slide. The experiment results shows that the proposed algorithm can precisely detect the subpixel edges of the slide. The measurement error of the slide is less than 2 mm, which demonstrates that the proposed algorithm has a high accuracy in the large field of view.

Given a connected graph $G=(V,E)$ and a length function $\ell:E\to {\mathbb R}$ we let $d_{v,w}$ denote the shortest distance between vertex $v$ and vertex $w$. A $t$-spanner is a subset $E'\subseteq E$ such that if $d'_{v,w}$ denotes shortest distances in the subgraph $G'=(V,E')$ then $d'_{v,w}\leq t d_{v,w}$ for all $v,w\in V$. We show that for a large class of graphs with suitable degree and expansion properties with independent exponential mean one edge lengths, there is w.h.p.~a 1-spanner that uses $\approx \frac12n\log n$ edges and that this is best possible. In particular, our result applies to the random graphs $G_{n,p}$ for $np\gg \log n$.

The renewed interest on Fast Firing has been motivated by the suppressed Li, Na volatilization during the short sintering cycle (a few seconds). Ultra-fast high temperature sintering represents the latest development in Fast Firing with heating rates approaching 104 °C/min. At present, there is no clear indication on how heating rate should be modulated to target a certain physical property. In this work, we compared different heating schedules to consolidate Li1.5Al0.5Ge1.5P3O12 electrolyte. Ultra-fast high temperature sintering carried under a single step current mode promoted the formation of radial cracks around the edge of the sample as a result of the differential shrinkage resulting from the inward heat fluxes. Multistep processing, based on the hybrid combination of conventional sintering (pre-sintering step) followed by UHS resulted in crack free samples. Under a discharge time as short as 160 s, hybrid UHS resulted in a relative density as high as 94.62% and conductivity of 1.72 × 10−4 S/cm, surpassing conventional sintered counterparts.

In this paper, the free vibration of the functionally graded porous (FGP) non-uniform annular-nanoplates lying on Winkler foundation (WF) is studied by using the smoothed finite element method based on the first-order shear deformation theory (FSDT). The combination of the mixed interpolation of the tensorial components for the three-node triangular element (MITC3 element) and the edge-based smoothed finite element method (ES-FEM) creates the ES-MITC3 element. This element is employed to avoid the shear locking problem as well as to improve the accuracy of the original MITC3 element. The small-scale effect is considered based on the nonlocal theory. Applying Hamilton's principle, the governing equation of the FGP non-uniform thickness annular-nanoplate is derived. Material properties of the nanoplate are characterized by two parameters: power-law index ( k ) and maximum porosity distributions ( Ω ) in the forms of cosine functions. The results of the present work are compared with other published work to verify accuracy and reliability. Moreover, the effects of geometry parameters and material properties on the free vibration of FGP non-uniform annular-nanoplates are comprehensively investigated.

To investigate the punching behaviour of edge column–slab connections, 15 tests on full-scale reinforced concrete specimens with and without shear reinforcement are presented. Four slabs were post-tensioned to examine the benefit of curved tendons in the vicinity of edge columns. Besides the discussion of the test results, current code provisions are compared to the ultimate capacities of the present tests as well as tests from the literature. The code provisions are evaluated for reinforced concrete and post-tensioned slabs without shear reinforcement.

At present, the surface precision requirements for mold and die parts are extremely high. Especially in the precision mold and die cavity for ELD lenses, several mirror surfaces for automotive lens parts, and general camera lenses that required a few tens or a single nano-level like a mirror-finished surface. This final process is difficult to achieve with the conventional cutting edge of ball-nose end mills. In addition, it is commonly performing a very long time by manual polishing of the skilled worker after machining. To the problem, we purposed to develop a sintered polycrystalline diamond (PCD) rotary tool with a simple spherical cutting part. This PCD tool is a novel method for the final process of the small molds and dies cavities with high precision. A distinctive feature of its cutting can achieve a mirror-finished surface by full automation on a CNC machining center. This study aims to clarify the basic machining characteristics and verify its effectiveness on the hardened stainless steel commercial STAVAX with the hardness of 54 HRC for small mold and die cavities. As a result, we can clarify the chip generation mechanism, finish surface accuracy, internal crystal structure state, and residual stress characteristic of this processing method. It also shows that the manual problems related to mirror finishing of the precision mold and die cavity can be solved under the actual mold manufacturing process by consecutive conditions.

Silicon carbide fiber-reinforced silicon carbide ceramic matrix composite (SiCf/SiC) is promising for manufacturing aero-engines because of its high-temperature resistance and lightweight. However, since SiCf/SiC is hard and brittle, the machining of SiCf/SiC has been suffering from uncontrolled machining-induced damages, such as edge chipping, cracks, fiber breakage. This paper studies the edge chipping characteristics of SiCf/SiC in brittle removal mode in single grain grinding. It is found that the edge chipping in grinding SiCf/SiC is complicated. The edge chipping in grinding the SiC matrix is dependent on the pre-existed defects rather than grinding parameters. While the edge chipping in grinding SiC fibers is dependent on both fiber orientation and grinding speed. The edge chipping in the grinding perpendicular to the fiber orientation is larger than that in the grinding along with the fiber orientation. It decreases with increasing grinding speed. Increasing grinding speed from 20 m/s to 50 m/s and 90 m/s, the width of the edge chipping area decreases by 30% and 60% respectively. While in the grinding along with the fiber orientation, edge chipping is minor and insensitive to grinding speed. Therefore, this study represents that increasing grinding speed would not enlarge the edge chipping but greatly increase the material removal rate, which is important for the surface finish and damage control of the machining of SiCf/SiC.

Positive geological and geochemical prerequisites have been identified for the purpose of increasing hydrocarbon resource potential in the under-explored study area. A methodology has been developed for assessing the hydrocarbon potential and prospecting for new promising oil and gas accumulation zones using the technology of basin modeling, provided there is a lack of initial data. A high hydrocarbon source rock generative potential and the degree of thermal maturity of the Lower Permian, Mid Carboniferous and Upper Devonian strata of the south-eastern part of the Precaspian depression have been revealed. Seismostratigraphic interpretation and geodynamic analysis were carried out and the main stages of the geodynamic evolution of the study area were reconstructed based on combination of all available geological and geophysical information, recent exploration drilling results and unpublished subsurface studies. The results of thermotectonic modelling confirm the possibility of vertical migration of hydrocarbons generated in Upper Paleozoic source rocks. A revision of the previously performed interpretation of 3D seismic data has been carried out; and for the first time, intrasalt sedimentary packages of presumably Upper Permian age have been identified as independent objects, which can be potential hydrocarbon traps.For the Lower Permian deposits, type III kerogen predominates, which may be associated with an increase in collisional processes in the Late Paleozoic time and an active input of plant organic matter. For Mid Carboniferous sediments, type II or mixed type II / III kerogen prevails. Analysis of the evolution of thermal maturity indicates the unevenness of the entry of potential source rocks into the main zone of oil generation. For kerogen type III of the Lower Permian source rocks, the peak of oil generation falls on the Late Cretaceous. For predominantly carbonate and terrigenous-carbonate Middle Carboniferous source rocks the peak of generation falls on the Jurassic. The most buried Devonian source rocks presumably entered into the zone of wet gas generation.The development of salt tectonics from Late Triassic to Cenozoic contributed to the vertical migration of hydrocarbons into the post-salt complex. The identified petroleum accumulations in the Upper Triassic-Jurassic stratigraphic section are mainly confined to the four-way dip structural closures above the steep flanks of salt diapirs.

Hole-making for Carbon Fiber Reinforced Plastics (CFRP)/Ti-6Al-4 V stacks is crucial for the assembling strength of aircraft structure parts. This work carried out experimental work for helical milling (HM) of the stacks with sustainable cooling/lubrication (dry, MQL and cryogenic) conditions. Cutting forces and temperatures at the CFRP layer, Ti-6Al-4 V layer and the interface of stacks were obtained by a developed measuring system. The temperatures in CFRP machining at cryogenic condition varied from −167 °C to −94 °C, which were much lower than those at dry and MQL conditions. The maximum temperature near the interface of stacks for the ninth hole was higher than 240 °C due to heat conduction from Ti-6Al-4 V layer. The hole quality, hole diameter and tool wear mechanism at different cooling/lubrication conditions were presented and discussed. MQL condition generated mainly extrusion fracture for the fibers, due to the reduced friction effect compared with dry condition. MQL was helpful to reduce the feed mark at the hole surface of Ti-6Al-4 V alloy. The flank wear of cutting edge at MQL condition was better than those at dry and cryogenic conditions. Cryogenic cooling contributed to better CFRP surface with smaller delamination and hole entrance damage due to the increased resin strength and fiber brittleness. The damage near the entrance of CFRP were analyzed by the contact state of cutting edges and fibers. Additionally, hole diameters near the exit of CFPR layer were larger than other test positions. This work provided feasible processes for improving hole quality and tool life in hole-making of CFRP/Ti-6Al-4 V stacks.

A temporal graph is a pair ( G , λ ) where G is a simple graph and λ is a function assigning to each edge time labels telling at which snapshots each edge is active. As recently defined by Mertzios, Molter and Zamaraev (2021), a temporal coloring of ( G , λ ) is a sequence of colorings of the vertices of the snapshots such that each edge is properly colored at least once. We first focus on t-persistent and t-occurrent temporal graphs. The former (resp. the latter) are temporal graphs where each edge of G stays active for at least t consecutive (resp. not-necessarily consecutive) snapshots. We study which values of t make the problem polynomial-time solvable. We also investigate the complexity of the problem when restricted to temporal graphs ( G , λ ) such that G has bounded treewidth.

Second-order photonic topological insulators (SPTIs) featured with topological edge and corner states provide an intriguing way for steering light in integrated optics. However, existing SPTIs have narrow bulk gaps for tightly confining topological edge and corner states. In this paper, we propose a bi-directional evolutionary structural optimization (BESO) method to inversely engineer SPTIs in C3-symmetric lattices. At first, we maximize the first band gap of a photonic crystal (PC) enforced with C3 symmetry. Then, the topological phase transition is achieved by inverting the optimized PC. Highly localized topological edge and corner states are formed at the boundary and corner between the optimized PC and its inversion-symmetry partner. The bandwidth of the topological edge state for TE modes achieves 44.9%, exceeding two times of the current record. The robust of the topological corner states is further demonstrated. Our work provides a new route for designing SPTIs, paving the way towards their practical application.

This paper presents a physical model for monolithic self-rolled-up microtube interdigital capacitors and elaborates their working mechanisms in comparison to on-chip planar interdigital capacitors. Besides the high-frequency phenomena such as the skin effect in thin, wide metal films, the model accounts for the complexities resulting from all possible 3D electrode configurations, such as the inner diameter dependent overlapping capacitances and edge capacitances between electrodes, as well as parasitic inductances within the rolled-up structure between the fingers, for integer and non-integer number of turns. The model is validated by the measured results of fabricated self-rolled-up membrane (S-RuM) interdigital capacitors over a wide range of layout and process parameters. This fully enables the structural design optimization for electrical performance of this 3D device architecture.

This paper presents an efficient multi-objective optimization model for linear induction motors (LIMs) with a novel approximation and prediction strategy. The proposed method can realize the optimization design with speediness and accuracy, while reducing the calculation complexity of eddy current analysis. The sample data in this model are obtained by 3D finite-element method (FEM) considering the skin effect and edge effect. Then, the Latin hypercube sampling (LHS) method is adopted to extract dimensional data including every structural parameter of the secondary. Based on these samples, a multiple analysis model is established using eXtreme Gradient Boosting (XGBoost) method. By employing this analysis model, several optimization structures are provided satisfying the limitation and rationality of designing structure and performance requirements. The precisions of the thrust force, vertical force, eddy current and copper loss of optimal structures are validated by FEM.

This work firstly studies the Steiner tree problem with bounded edge-length d in which d is the ratio of the maximum edge cost to the minimum edge cost. This work analyzes the algorithm of Byrka et al. [19] and shows that the approximation ratio of d ln ⁡ 4 d + ln ⁡ 4 − 1 + ϵ for general graphs and approximation ratio of 73 ⋅ d 60 ⋅ d + 13 + ϵ for quasi-bipartite graphs. The algorithm implies approximation ratio of 1.162 + ϵ for the problem on complete graphs with edge distances 1 and 2. This finding represents an improvement upon the previous best approximation ratio of 1.25. This work then presents a combinatorial two-phase heuristic for the general Steiner tree in greedy strategy that achieves an approximation ratio of 1.4295.

A floating air weapon system (such as airborne floating mines) plays an important role in modern air defense operations. This paper focuses on aerodynamic characteristics of airborne floating mine named inflated pillow. Firstly, the dynamic deployable process of the pillow and characteristics of the local instability of the edge are studied, and the evolution mechanism of wrinkles and kinks is analyzed. Secondly, in the cruising stage, the fluid-structural-thermal coupling analysis is performed on the pillow, and the aerodynamic characteristics are studied. Thirdly, the shape-preserving effect of the inflated pillow during the “negative pressure” slow landing stage is evaluated. It is found that when the wind velocity is higher, the pillow has a collapsed instability (surface extrusion and contact), and when the wind velocity is lower, snap-through instability occurs. Finally, for the collapsed instability, a carbon fiber skeleton is added to discrete the large global collapsed fold into small local folds, thus achieving shape-preserving effect of pillow. For snap-through instability, the critical internal pressure and different shape evolution under different wind velocity are evaluated. Through the analysis of the mechanical mechanism and control of the structural morphological evolution, it provides theoretical guidance for the application of the curved shell structure in floating air weapon system.

The dielectric breakdown strength of solid insulators is usually dependent on the dimensions of the sample. In particular, for "thick" insulating sheets having thicknesses above a certain threshold thickness of typically about 10 micrometer, the dielectric breakdown strength at room temperature is often found to be roughly proportional to the inverse of the square root of the sample thickness. In this contribution, the hypothesis is examined that the latter type of size dependence is related to electric field inhomogeneities associated with the geometrical electrode configuration. In order to test the hypothesis, dielectric breakdown experiments have been performed for alumina ceramic sheets of different thicknesses. In this context, an electrode configuration has been used which allows for an analysis of the local electric field enhancement at the electrode edge in terms of fracture mechanics concepts. It is concluded from a comparison of experimental and theoretical results that the mentioned dependence of the dielectric breakdown strength on sample thickness is, under certain circumstances, likely related to electrode edge effects.

The study introduces the dynamical characteristics of functionally graded porous nanocomposite new plates reinforced with graphene platelets (GPLs). The profiles of the structures are defined by fo...

This letter presents underwater image enhancement using Laplace decomposition. Underwater image undergoes Laplace decomposition resulting in low- and high-frequency bands. Haze is removed from the low-frequency band, and then it is normalized for white balancing. The high-frequency band is amplified for edge preservation. Adding the two frequency images results in an enhanced image. It has improved, in contrast, color, object prominence, edge preservation, reduced artifacts, and naturalness as compared to other methods related to underwater image enhancement.

The components made out of spring steel are usually subjected to different environmental conditions when in service. The hydrogen embrittlement is one such process which is inevitable for spring steel. The embrittlement will make the material brittle and induce cracks at the edges and corners. In the presentation experimental investigation has been focused on the analysis of the behavior of embrittled spring steel with edge and corner cracks, under impact and bending loads. The specimen preparations and experimentations have been carried out according to ASTM standards. The results have revealed that the embrittlement induced side and corner cracks play a vital role in the fracture process of the spring steel. The mechanism of fracture in edge and corner notched samples has been analyzed with the aid of scanning electron microscopy. The microscopic observations have shown that the failure in the edge and corner cracked samples is almost catastrophic, and increase in the rate of crack growth in these embrittled samples is highly influenced by the embrittlement induced cracks.

Random micro-structured surfaces (RSS) have great application potentials as various functional surface elements, such as optical diffusers, with homogeneous surface properties. Conventional fabrication methods for RSS, such as chemical etching, can no longer meet modern requirements of high precision and controllability. In this study, a novel method was proposed for fabricating micro dimple arrays with controllable randomness in dimple size and depth by using fast tool servo (FTS)-based single-point diamond turning. Firstly, for tool path generation, a computer program was developed to periodically arrange small patches of quadratic surfaces over a large surface area. Then the position, height, and size of each quadratic surface were adjusted by applying random values, whose dynamic range was preset, to control the spatial difference among the dimples. Finally, the designed RSS was machined by continuous and segment cutting methods, respectively, to evaluate their effects on dimple edge formation. Results showed that the segmented cutting method improved the edge accuracy, thus was effective for RSS machining. The machined surface matched precisely with the designed surface with a form error of 10 nm level. The machining method proposed in this study enables high-precision patterning of mold inserts for molding/imprinting RSS on polymer materials.

In this work, we experimentally investigate the effects of electric bias on the degradation of few-layer MoS2 back-gated field-effect transistors in ambient air. The devices were fabricated using mechanically exfoliated MoS2 flakes, which were transferred to a Si/SiO2 substrate by a PDMS-based transfer. We report an accelerated electric bias-induced degradation of the devices under investigation and used optical and scanning electron microscopy (SEM) to monitor changes of the morphology of the MoS2 channel. In particular, we found a linear dependency of the degradation on the electric field between the Ti/Au source and drain contacts. In addition, we identify four regions in which morphological changes occur, of which the edges of the MoS2 channel are most affected.

Retrofitting of Engineering marvels/ Structures is very important for preservation of history of mankind. There are various methods available to repair/retrofit the structure depending on type of failure. It was observed that the old structures made up with hard materials like marble, stone etc. which withstand centuries without any sign of failure. But soil underneath the structure is changing day to day due to change in presence and location of water and other physical factors around the structure. This may lead to failure of structure. Pin-pilling is one of the most efficient and economical methods out of several methods available to retrofit the soil underneath the foundation. Piles having diameter less than 30 mm are considered as pin piles. Due to some limitations it is difficult to insert pin piles under the foundation. This paper deals with the study of exact location of insertion of pin piles around the vicinity of existing foundation. A physical model was prepared in lab to simulate the site conditions in which soil is prepared with its natural density and loaded with hydraulic jack and effect of edge distance (Distance of center of pile from edge of foundation) is analyzed as X/B ratio and a notable increase in bearing capacity of soil was observed.

The heterogeneity of soil is an advantage as well as a disadvantage at the same time. The well graded soil possesses more density and stability then uniformly graded soil, but at same time because of uneven distribution of soil underneath the foundation soil may behave differently to different soil conditions. The soil beneath the foundation cannot be accessed directly therefore methods like pin piles came into the picture. The piles having diameter less than 300 mm are termed as pin piles. Under this portion of study the gain in strength by soil under the foundation of existing structure was noted down by an experimental method. The structure and subsequent conditions were simulated in the laboratory. The quantity and spacing of pin pile are interrelated. In the analysis the pin piles are inserted in the periphery of the existing footing in one line and footing size remains constant throughout the experiments, therefore the more spacing means less number of pin piles and vice versa. The distance between pin piles is termed as pitch length as measured from center to center. The distance from the outermost edge of footing is termed as edge distance also taken as variable. The experiments were designed in MiniTab 9.0 for suitable combinations of variables. The settlement of soil at 25 mm was considered a failure and optimized quantity and spacing of pin piles were determined. The positive effects of pin piles were observed when inserted in the periphery of existing footing.

Let G be an edge-colored complete graph on n vertices such that there exist at least n distinct colors on edges incident to every pair of its vertices. In this paper, we first show that every edge of G with n ≥ 6 k − 19 is contained in a properly colored cycle of length k . Further, we prove that if G contains no monochromatic triangles, then there exists a properly colored path of length l for every 1 ≤ l ≤ n − 1 between each pair of vertices of G and every vertex of G is contained in a properly colored cycle of length k for any 3 ≤ k ≤ n .