Convex Edge Research Articles

Evaluation of Delamination Strength of Hard Film by Convex Edge Indent Method

Evaluation of Delamination Strength of Hard Film by Convex Edge Indent Method

Radiating and non-radiating sources in elasticity

In this work, we study the inverse source problem of a fixed frequency for the Navier equation. We investigate non-radiating external forces. If the support of such a force has a convex or non-convex corner or edge on its boundary, the force must be vanishing there. The vanishing property at corners and edges holds also for sufficiently smooth transmission eigenfunctions in elasticity. The idea originates from the enclosure method: an energy identity and a new type of exponential solution for the Navier equation.

Numerical investigation of edge configurations on piston-modal resonance in a moonpool induced by heaving excitations

The renormalization group (RNG) turbulent model is used to investigate the fluid resonance in a moonpool formed by two identical rectangular hulls under synchronous heaving excitation (e.g., a catamaran or dual pontoon). The numerical model is validated against the available experimental data, and accurate numerical solutions are obtained. The present study focuses on the amplitude of the moving hulls and the edge configuration of the moonpool entrance, as well as their influences on the piston-modal resonant wave in the moonpool. The dependence of the resonant wave amplitude in the moonpool on the heaving amplitude, the characteristic moonpool dimensions and the local velocity magnitude is derived based on a theoretical analysis, and the results are in good agreement with the RNG turbulent solutions. Five different edge profiles are considered, including two convex edges, two concave edges (both with various dimensions), and a sharp edge. Numerical examinations show that the edge configuration has a significant influence on the piston-modal resonant responses, a larger opening size leading to a higher resonant frequency and a larger resonant wave amplitude in the moonpool. Various flow patterns of the piston-modal resonance in the vicinity of the moonpool entrance are also identified, mainly depending on the edge profile. More intensive turbulent and vortical flows give rise to more significant dissipation, accounting for the smaller relative wave amplitude in the moonpool. With the increase of the heaving amplitude, the relative piston-modal resonant amplitude is decreased in an approximate power function. Within the scope of this work, the numerical investigations show that the piston-modal resonant frequency is hardly affected by the heaving amplitude.

Research on energy distributions of the lateral swirl combustion system in DI diesel engines

The lateral swirl combustion system (LSCS) can improve the air-use, fuel and emission performance of direct injection (DI) diesel engines. In this study, the differences in energy distributions between the LSCS and the double swirl combustion system (DSCS) were analyzed under different working conditions using a single-cylinder test system. A simulation calculation was used to compare the velocity, mixture equivalence ratio and in-cylinder temperature distributions of the working medium in the two combustion chambers, elucidating the different energy distributions of the two chambers. Additionally, a new idea is proposed herein for the design of LHR engines. The experimental results show that, compared with the DSCS under different operating speeds (1300–2100 r/min) and different loads (21–43 kW), the indicated thermal efficiency of the LSCS was approximately 2% higher, the percentage of the exhaust energy and heat transfer to the total energy was approximately 2% lower, the cylinder head temperature was 2–20.5 K lower, the ratio of the cylinder head heat transfer to the total heat transfer was 2–8% smaller and the heat transferred to the cooling water in the water jacket of the cylinder head was 0.2–1 kW lower. The in-cylinder velocity distribution, mixture equivalence ratio and temperature distribution of both the LSCS and the DSCS were compared through simulation. The results show that the fuel in the LSCS developed along the wall of the combustion chamber circumferentially due to the convex edge, and the high temperature zone distributed along the circumference of the combustion chamber. In the DSCS, most of the fuel moved to the cylinder head due to the circular ridge, and the high temperature zone existed near the cylinder head. The LSCS had a lower cylinder head temperature, a higher exhaust gas temperature, and less heat transferred to the cooling water through the cylinder head. Therefore, the unique shape of the LSCS chamber guided the movement of the fuel and reduced the concentration of the fuel/air mixture near the cylinder head, which reduced the heat transferred to the cooling system through the cylinder head and improved the thermal efficiency. In addition to these findings, this study also provides a foundation for the design of a low heat rejection engine.

A Study of the Materials Removal Mechanism of Grinding-Aided Electrochemical Discharge Machining of Metal Matrix Composites

In order to research the workpiece materials removal mechanism of Grinding-assisted Electro-chemical Discharge Machining(G-ECDM) of Metal Matrix Composites (MMCs), a good deal of single pulse experiments has been performed in this paper. The crater volume, convex edge, debris, machined surface of G-ECDM have been taken into considerationand it turns out to be that the grinding effect removes the convex edge of the Electro-chemical Discharge Machining (ECDM) crater during the machining of MMCs, the result show that the material removal rate (MRR) of G-ECDM is much higher than that of ECDM and Electrical Discharge Machining (EDM). When compared to the normal ECDM process, it is found that though the Al4C3 phase can be detected in this ECDM condition, no Al4C3 are observed in the processed surface, which indicates a better surface quality. The reason of this phenomenonhas been analyzed theoretically and experimentally. Based on these results, mechanism of the G-ECDM of MMCs was disclosed in this study.

A new species of grass spider, Agelenopsis riechertii, from the Southwestern USA, with notes on its courtship behavior (Araneae: Agelenidae).

We describe a new spider species of the genus Agelenopsis Giebel 1869 (Agelenidae) from adult males and females. Agelenopsis riechertii is found in dry desert scrub habitats in the southwestern United States. While A. riechertii is similar to other sympatric congeners (A. aleenae, A. aperta, and A. spatula) in morphology and courtship behavior, it can be distinguished by an examination of its genitalia. Males possess an embolus that gradually narrows into a twisted tip which displays a convex edge from the lateral view. The female epigyna are harder to distinguish from congeners, but have a flatter anterior atrial edge that lacks strong bi-lobing. The spermatheca in female A. riechertii are also more elongate and comma-shaped than the other species. We describe the sequence of courtship behaviors exhibited by males, including the use of web pulses, abdomen waggling, and web flexing, in which males with fewer pauses, longer waggling bouts, and fewer web flexes are more likely to successfully copulate.

Nanojunction Effects on Water Flow in Carbon Nanotubes

We report on the results of extensive molecular dynamics simulation of water imbibition in carbon nanotubes (CNTs), connected together by converging or diverging nanojunctions in various configurations. The goal of the study is to understand the effect of the nanojunctions on the interface motion, as well as the differences between what we study and water imbibition in microchannels. While the dynamics of water uptake in the entrance CNT is the same as that of imbibition in straight CNTs, with the main source of energy dissipation being the friction at the entrance, water uptake in the exit CNT is more complex due to significant energy loss in the nanojunctions. We derive an approximate but accurate expression for the pressure drop in the nanojunction. A remarkable difference between dynamic wetting of nano- and microjunctions is that, whereas water absorption time in the latter depends only on the ratios of the radii and of the lengths of the channels, the same is not true about the former, which is shown to be strongly dependent upon the size of each segment of the nanojunction. Interface pinning-depinning also occurs at the convex edges.

Feasibility studies on manufacturing tailored blanks by rolling partially stacked blanks

Tailored blanks with different blank thicknesses are semi-finished parts that can be used to produce lightweight vehicle parts. This study investigates a manufacturing process that can produce tailored blanks by rolling partially stacked blanks. The process was experimentally and numerically investigated using various processing conditions. To characterize the process, the deformation behaviors of upper and lower blanks were analyzed and quantified. The dimensional variations at the top end and the transition zones were analyzed based on the cross-sectional thickness profiles of formed blanks. The results show that the proposed process is feasible for the production of tailored rolled blanks that have both straight edges with a concave transition zone and convex edges with a straight transition zone.

Intrinsic curvature in wool fibres is determined by the relative length of orthocortical and paracortical cells

Hair curvature underpins structural diversity and function in mammalian coats, but what causes curl in keratin hair fibres? To obtain structural data to determine one aspect of this question, we used confocal microscopy to provide in situ measurements of the two cell types that make up the cortex of merino wool fibres, which was chosen as a well-characterised model system representative of narrow diameter hairs, such as underhairs. We measured orthocortical and paracortical cross-sectional areas, and cortical cell lengths, within individual fibre snippets of defined uniplanar curvature. This allowed a direct test of two long-standing theories of the mechanism of curvature in hairs. We found evidence contradicting the theory that curvature results from there being more cells on the side of the fibre closest to the outside, or convex edge, of curvature. In all cases, the orthocortical cells close to the outside of curvature were longer than paracortical cells close to the inside of the curvature, which supports the theory that curvature is underpinned by differences in cell type length. However, the latter theory also implies that, for all fibres, curvature should correlate with the proportions of orthocortical and paracortical cells, and we found no evidence for this. In merino wool, it appears that the absolute length of cells of each type and proportion of cells varies from fibre to fibre, and only the difference between the length of the two cell types is important. Implications for curvature in higher diameter hairs, such as guard hairs and those on the human scalp, are discussed.

Nonradiating Sources and Transmission Eigenfunctions Vanish at Corners and Edges

We consider the inverse source problem of a fixed wavenumber: study properties of an acoustic source based on a single far- or near-field measurement. We show that nonradiating sources having a convex or nonconvex corner or edge on their boundary must vanish there. The same holds true for smooth enough transmission eigenfunctions. The proof is based on an energy identity from the enclosure method and the construction of a new type of planar complex geometrical optics solution whose logarithm is a branch of the square root. The latter allows us to deal with nonconvex corners and edges.

Prediction of edge profile of plate during hot cross rolling

In rolling, formation of convex or concave like edge shape causes loss of material. For cross rolling, where the rolling direction is changed by 90° and is achieved through the rotation of the plate in the rolling plane, the dimensions of the plate is smaller. So, the percentage loss of material due to the uneven edge shapes may increase in case of cross rolling. Since direct industrial trials would be expensive, physical simulation i.e. laboratory-scale experiments or finite element simulation can be implemented to predict the plate shape for different cross rolling pass sequences so as to minimize the loss of material. In the present work, finite element modeling (FEM) has been performed for hot cross rolling of 304 stainless steel plate. The deformation behavior of the plate is considered as rigid visco-plastic and the work roll is considered as a rigid body. The simulation has been performed for two passes. The direction of rolling for the second pass has been changed by 90° i.e. the transverse direction (TD) of the first pass becomes the rolling direction (RD) of the second pass. Considerable amount of change in dimension along the width direction and bulging along the thickness direction have been observed. Flow of material at the four side surfaces has been analyzed by calculating the spreading and elongation velocities. The FEM predicted profiles are in close agreement with the experimental profiles.

Efficient Algorithm for Sidewall Machining of Aircraft Structural Part

Traditionally, the boundaries of the pocket bottom face are often used as the guide elements of the machining process of sidewall machining. However, for complex pocket, overcutting often occurs due to the incorrectness of the guide elements. To solve this problem, the sidewall machining model is presented at first. Then, terms such as rim convex edge and visible property are introduced in detailed. Finally, the rim convex edges are projected onto the bottom face and the visible guide lines are constructed by sub-lines selection based on the visible property. At last a case study is given to verify the feasibility and effectiveness of the proposed algorithm. The result shows that the algorithm can avoid overcutting for complex pocket.

A functional approach to the use of the earliest blade technology in Upper Paleolithic Hokkaido, northern Japan

To understand the behavioral significance of the emergence and proliferation of blade technology in the northeastern Asian Upper Paleolithic, this paper explores the function of the earliest blade technology in Hokkaido, northern Japan, through an integrated analysis of edge morphology and use-wears on blade tools from the Last Glacial Maximum (LGM) assemblage of Kawanishi C. Although varied edge morphologies (i.e., straight, convex, concave, denticulate) have been distinguished, the results of use-wear analysis suggest that morphological differences of edges are not related to specific functions. Straight and convex edges experienced different use-lives and use-trajectories: both straight and convex edges were principally served for cutting/sawing and whittling, while some edges changed their functions to scraping as edge resharpening blunted the edges. The results of use-wear analysis also suggest that LGM blades were intensively used for performing a narrow range of activities (e.g., skin and meat stripping). Because this blade technology differs from the dominant flake technology in LGM Hokkaido, LGM foragers were able to employ it to perform intensive processing activity to exploit critical faunal resources that may have been sporadically clumped in the landscape.

Mixing and combustion mechanisms within lateral swirl combustion system (LSCS) in a DI diesel engine

The fuel diffusion around the combustion chamber wall is the key to affecting the engine performance. The current enveloping combustion systems (e.g. ω combustion systems) mainly utilize the air in the radial direction of the combustion chamber along the spray track. In these systems, since the combustion chamber wall only envelops the spray without obvious guiding effect, it will cause difficulty in the fuel diffusion around the chamber wall and deteriorate the combustion. On the contrary, the LSCS, as a guiding combustion system, could effectively improve the diffusion around the chamber wall. Therefore, it is necessary to further understand the mixing and combustion mechanisms of the LSCS. In this study, the spray and combustion characteristics of the wall-impinging jet in the lateral swirl (LS) combustion chamber were investigated in a constant-volume combustion vessel through the high-speedphotography. These characteristics were compared between the ω and LS combustion systems through the image processing and the two-color method. The results show that the spray process in the ω combustion system contains free jet and wall jet, while the spray process in LS combustion system contains free jet, formation of LS, and LS & intervening wall jet after the separation of jet head from the convex edge. The LSCS forces the fuel spray to swirl along the circumference of the combustion chamber. As a result, it could strengthen the diffusing and mixing process, and avoid a large quantity of fuel burning near the wall to form a thermos constraint. The LSCS could improve the distribution of the air-fuel mixing and consequently accelerate the combustion and reduce the soot emission through the guiding effect of convex edge on the wall jet.

The effect of Kinesio taping on back pain in patients with Lenke Type 1 adolescent idiopathic scoliosis: A randomized controlled trial

PurposeThis study investigated the short-term effects of KT on back pain (BP) in patients with Lenke Type 1 adolescent idiopathic scoliosis (AIS). MethodsWe chosen Lenke Type 1 scoliosis who have had only back pain (the localization of the pain: the only in the apical convex edge). Forty patients suffering from BP with Lenke Type 1 AIS were randomly separated into two groups, Group 1 (20 patients) and Group 2 (20 patients). Group 1 was given KT with tension and home exercises and Group 2 was given KT without tension and home exercises. KT and home exercises was applied to the thoracic area of the patients in both groups for four weeks. Pain intensity was measured using a visual analog scale (VAS) and SRS-22 (subtotal SRS-20) before and after treatment. ResultsMean age of both groups was 16.1 years. Mean Cobb angle of the thoracic scoliosis was 31.8° (range: 17°–44°) in Group 1 and 32.8° (range: 19°–43°) in Group 2 before the treatment. The decrease in VAS score of Group 1 after taping was higher than that of Group 2. The difference between the pre- and post-treatment VAS scores of both groups was statistically significant (p < 0.05). The increase in mean SRS-20 score of Group 1 following taping application was significantly higher than the increase in the control group (p < 0.05). ConclusionResults demonstrated that KT application with tension effectively leads to back pain relief shortly after application. In addition, KT has a positive impact on quality of life. Thus, KT may be a suitable intervention in treating back pain of patients with AIS. Level of EvidenceLevel 1, Therapeutic study

Evaluation of Delamination Strength of Glass by Convex Edge Indent Method

Evaluation of Delamination Strength of Glass by Convex Edge Indent Method

The Structure of the Gynostegium, Breeding System, and Pollination Ecology of Spider Milkweed, Asclepias viridis Walter (Apocynaceae)

Reproductive structures, flowering phenology, breeding system, and potential pollinators were described in two populations of Asclepias viridis Walter in Oklahoma in 1997 and 1998. Scanning electron microscopy was used to locate the stigmatic surfaces of the gynostegium, and a series of pollination treatments was performed including open-pollination, supplemental pollination, self-pollination, and within- and between-population cross-pollination. Flower visitors, their visitation rates, and numbers of pollinaria carried were recorded. Pollinia were inserted in four ways to determine which type of insertion results in pollen germination, and flowers were collected to determine how pollinia were inserted by insects. The stigmatic surfaces of A. viridis are located at the fusion point of the two styles at the base of the gynostegium. Self-pollinations produced no mature follicles, revealing self-incompatibility. In addition to genetic barriers, the low rate of natural fruit-set (1.87% in 1997 and 1.39% in 1998) is due to follicle abortion and predation of flowers and follicles. Supplemental pollination did not significantly increase fruit and seed set. Fruit-set from hand cross-pollinations at one site, but not the other, revealed a greater crossability between populations than within. A. viridis flowered from early May to late June, with a peak in late May. The mean number of flowers per inflorescence was 34.1, and the mean flowering span per inflorescence was 10.6 days. Over 20 families of insects, including those within the orders Hymenoptera, Lepidoptera, Coleoptera, and Hemiptera, visited flowers. Of the hymenopterans, solitary wasps, large carpenter bees, digger bees, and bumblebees carried pollinaria. Hymenopterans contributed the majority of visitations, and bumblebees ( Bombus spp.; Apidae) were the most important pollinators based on numbers of pollinaria carried and frequency of visitation. The highest percentage of mature follicles was obtained when pollinia were inserted with the convex edge toward the stigmatic surface; natural pollinators almost always insert pollinia in this manner.

The combustion and emission characteristics of a multi-swirl combustion system in a DI diesel engine

In this study, the authors developed a new multi-swirl combustion system (MSCS) and investigated its combustion and emission characteristics. The MSCS combines the structural features of a double swirl combustion system (DSCS) and a lateral swirl combustion system (LSCS) and utilizes the arc structure of the MSCS to lead fuel to (1) form multi-swirls in both a longitudinal and lateral direction, (2) accelerate the fuel/air mixture and (3) improve the combustion process in a diesel engine. An experimental study and simulation analysis was used to verify the MSCS combustion and emission characteristics. In the experimental study, tests at various speeds were conducted using a single-cylinder diesel engine. The experimental results, including the brake specific fuel consumption (BSFC), soot emission, NOx emission and in-cylinder pressure were recorded and compared with results from a DSCS that was operated under the same condition. In the simulation, the fuel spray process was studied using AVL-Fire. The fuel velocity profile and the fuel/air equivalent ratio distribution were studied to verify the formation of multi-swirling fuel in the combustion chamber. The experimental results show that the BSFC of the MSCS was lower by 4–5g/(kWh), and the soot emission was lower by about 60% in comparison to the results from the DSCS. The simulation results show that the fuel formed two longitudinal swirls in opposite directions after touching the circular ridge, and the fuel in the outer chamber formed two swirls in lateral space after touching the convex edge. This multi-swirl enlarged the diffusion space of the fuel in both the inner and outer combustion chamber and accelerated the formation of the fuel/air mixture, which led to a decrease in soot emission and fuel consumption from the MSCS.

Analytical and finite-element study of optimal strain distribution in various beam shapes for energy harvesting applications

Owing to the increasing demand for harvesting energy from environmental vibration for use in self-powered electronic applications, cantilever-based vibration energy harvesting has attracted considerable interest from various parties and has become one of the most common approaches to converting redundant mechanical energy into electrical energy. As the output voltage produced from a piezoelectric material depends largely on the geometric shape and the size of the beam, there is a need to model and compare the performance of cantilever beams of differing geometries. This paper presents the study of strain distribution in various shapes of cantilever beams, including a convex and concave edge profile elliptical beam that have not yet been discussed in any prior literature. Both analytical and finite-element models are derived and the resultant strain distributions in the beam are computed based on a MATLAB solver and ANSYS finite-element analysis tools. An optimum geometry for a vibration-based energy harvesting system is verified. Finally, experimental results comparing the power density for triangular and rectangular piezoelectric beams are also presented to validate the findings of the study, and the claim, as suggested in the literature, is verified.

Automatic Keyline Recognition and 3D Reconstruction For Quasi‐Planar Façades in Close‐range Images

AbstractCritical keylines, such as concave and convex edges of a building façade, can be lost in photogrammetric recognition procedures. To solve this problem and to reconstruct quasi‐planar 3D façades automatically and precisely, a set of algorithms and techniques for the automatic recognition of lines and 3D reconstruction is proposed. This includes: (1) a procedure for line‐segment matching that satisfies the spatial requirements of a 3D scene based on “global independence” and “local dependence”; (2) a technique of generalised point bundle block adjustment combined with spatial line constraints (in the form of virtual observations) to control the propagation of error; and (3) the methods of perceptual organisation, plane fitting and plane–plane intersection are suggested to acquire the critical keylines corresponding to concave and convex building edges. Experimental results show that these new algorithms are feasible and applicable to recognition and 3D reconstruction. Recommendations for recognition methods are provided depending on whether or not a priori topological relationships are available between the planes under consideration.