Edges Of Line Research Articles

SOME MORE ON LOGARITHMIC SINGULARITY INTEGRATION IN BOUNDARY ELEMENT METOD

The accuracy of calculations of integrals with logarithmic singularities for two methods, namely the method of ignoring singularities and the method of subtraction (consisting in separating the singular part from the remaining non-singular), are presented in this paper. Only two-dimensional problems, like Dirichlet's problems, as well as acoustic problems formulated in the frequency domain are considered. Problems related to the accuracy of calculations are discussed and the influence of frequency, as well as the influence of the geometry of the analysed area on the accuracy of calculations, are indicated. When we talk about the influence of geometry, we mean not only discretization, but also the configuration of the area, such as the sharp edges of the boundary line, assuming the use of the classic, without any modifications, Boundary Element Method.

Numerical Study of the Effect of the Ignition Procedure on the Front of a Surface Fire from a 3D Numerical Model

In instrumented prescribed fires, the ignition procedure requires much attention. In this paper, we investigate the effects of two ignition procedures on the fire head using a 3D numerical model. The first procedure is to ignite the fire from the edges of the fire line towards the centre of the line. The second procedure consists of igniting the fire from the centre of the fire line to the edges of the line. The 3D numerical model used is based on the modelling of the fuel layer from Lagrangian particles, and the fire propagation is based on a two-phase model. The model was tested on an experimental fire in a wheat field in southern Australia. The model predicted the experimental fire front well. Analysis of the impact of the ignition procedure on the fire head showed that the quasi-steady-state rate of fire spread was the same for both procedures. However, before the quasi-stationary state, the front of the first procedure spread faster than that of the second procedure. The fire front in the first procedure was wider than in the second procedure. It was also found that the length of the head fire in the first procedure remained the same as that of the ignition line. In the second procedure, the length of the head fire was one-third of that of the ignition line.

Influence of accelerated corrosion on bi-material steel-CFRP double-lap joints bonded with thick adhesive

Bi-material steel-composite joints attract interest for marine applications. The marine environment imposes corrosion which is a prolonged process. This work presents a two-electrode electrochemical setup for accelerating free corrosion of the steel surfaces of bi-material joints. It is used to study the impact of accelerated corrosion on the mechanical performance of bi-material double lap specimens subjected to quasi-static tensile testing. Several test series have been conducted to evaluate the influence of overlap length and bond line thickness on shear strength and failure mode. Sixty specimens with a thick layer of methyl methacrylate adhesive have been fabricated and cured at room temperature for at least 24 h. Subsequently, 30 specimens were aged by subjecting them to electrochemical corrosion for 24 h. All specimens were tested for failure in quasi-static tensile loading while monitoring the strain fields in the joint area using digital image correlation. The measurements reveal a homogeneous shear strain field at the onset of loading, with a rapidly increasing shear strain concentration near the edges of the bond line preceding final failure. Both a decrease in the adhesive thickness and an increase in the overlap length increase the shear strength. Higher shear strength was observed for the electrochemically aged specimens than that of non-aged specimens. This is attributed to the faster residual curing of the adhesive during ageing because an increasing percentage of copper ions (released from the anode) accelerates the curing of the MMA adhesive. The electrochemically aged specimens showed mixed failure modes, i.e. cohesive failure and adhesive failure at the interface between steel and adhesive, and skin failure within the composite laminates.

Functions of the audio background in the film version of L.N. Tolstoy’s novella “The Kreutzer Sonata” (director M. Schweitzer, composer S. Gubaidulina)

The author of the article analyzes the film “The Kreutzer Sonata” (director M. Schweitzer, composer S. Gubaidulina) and defines the role of audio background consisting of music and sound effects in the development of the concept of the film version of the same-name novella by L.N. Tolstoy. Based on the comparison of the piece of writing and its screen adaptation, the author describes the functions of the audio background and the role of music as a drama factor. The author emphasizes the importance of timbre and sound principles since the sound characteristics help to define the edges of the event line of the story (the past and the present), and the railway and urban noises become a marker outlining the key phrases of the dialogue of Pozdnyshev with his companion. For the film, the role of citations is important, which are used for describing the characters and interpreting them. Citations accompany the images of Liza (classic piano pieces, romance and French song), Pozdyshev (Strauss waltz, Offenbach’s cancan, and a prison song), and Trukhachevsky (P. Satasate’s gypsy songs). Three main characters are united by L. Beethoven’s Kreutzer Sonata which creates the psychological subtext in representing the relations between Liza, Trukhachevsky and Pozdyshev.  S. Gubaidulina’s music, using the minimum primary musical expressive means, and mostly by timbers characterises the range of Pozdnyshev’s emotions from love to hate and comments the inner dialogue of the character. The audio background in the film fulfils the illustrative, characterizing, subtextual and drama functions. The specific peculiarity of introducing music into the synthetic text is a frequent usage of the intraframe principle determined by both Tolstoy’s prose and the very title of the novel. The author proves that Schweitzer’s “Kreutzer Sonata” is more authentic as compared with other screen versions since it preserves the dialogues and remarks of characters, the unanimity of real events and flashbacks corresponds with the primary source, and the drama of the film is equal to that of the literary text; at the same time, the expression of culmination points is supported by music and sound effects thus helping to understand the idea of the novella.   

The possible role of PtdIns(4,5)P2 and PtdIns(3,4,5)P3 at the leading and trailing edges of the breast cancer cell line

The possible role of PtdIns(4,5)P2 and PtdIns(3,4,5)P3 at the leading and trailing edges of the breast cancer cell line

The possible role of PtdIns(4,5)P2 and PtdIns(3,4,5)P3 at the leading and trailing edges of the breast cancer cell line

Introduction: Phosphoinositides play a key role in the regulation of focal adhesions (FAs) turnover during cell adhesion and migration. However, their potential role in FA turnover at leading and trailing edge of cell are not yet fully understood. In this study, we investigate their spatial co-localisation with paxillin directly at leading and trailing edge of MDA-MB-231 breast cancer cell line. Materials and methods: Cell lines and cell culture experiments were done using MDA-MB-231human adenocarcinoma cells. Co-trnasfection and confocal microscopy were performed to visualise phosphoinositides and FAs by using GFP-C1-PLCdelta-PH/Btk-PH-GFP and 3 μɡ paxillin-RFP as biosensors. Then, ImageJ was used to measure co-localisation point between Phosphatidylinositol 4,5-trisphosphate (PtdIns(4,5)P2) or Phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) and paxillin Spearman's rank correlation value was taken between PtdIns(4,5)P2/PtdIns(3,4,5)P3. Results: Our results demonstrate that the spatial co-localistion of PtdIns(4,5)P2 and PtdIns(3,4,5)P3 with FA at leading and trailing age of cell were slightly changed. Conclusions: This suggests that PtdIns(4,5)P2 and PtdIns(3,4,5)P3 play an equal role at the leading and trailing edges of the cancer metastasis through interaction with FA proteins.

Development of Mechanisms for Automatic Correction of Industrial Complex Tools in the Preprocessing of Laser Welding for Small-Scale and Piece Production Using Computer Vision

This paper is devoted to the development and improvement of mechanisms for the functioning of an automated system for correcting the points of the planned trajectory of the tool of a laser robotic welding complex in the pre-process. Correction of the points of the planned trajectory is carried out in two stages: in the first stage, the focal laser radiation is corrected; in the second stage, the position of the tool is corrected. Correction of the focal laser radiation is carried out in conjunction with the automated focusing of the camera by moving the tool of the industrial complex along its own axis. The functioning of position correction mechanisms is based on methods for recognizing the edges of the gap line to be welded from the image obtained from the charge-coupled device (CCD) camera. The edges of the gap to be welded in the image are segmented using threshold selection. The boundaries of the threshold selection segment are the extreme values of the pixel distribution of the entire image in brightness. For unambiguous recognition of the desired edges based on the segmentation result, the features defining them as a pair of continuous, conditionally parallel lines are formalized. Relative to the recognized pair of edges, the correct position of the planned trajectory point relative to the current position of the welding head is determined. To transfer the correct position, we formalized the calculation model and chose an arbitrary point in the flat image in the workspace laser robotic welding complex, considering the orientation of the tool and the position of the camera. The results obtained made it possible to develop a correction system and successfully test it in the industrial complex.

Detecting Deformation on Pantograph Contact Strip of Railway Vehicle on Image Processing and Deep Learning

An electric railway vehicle is supplied with electricity by an OCL (Overhead Contact Line) through the contact strip of its pantograph. This transmitted electricity is then used to power the electrical equipment of the railway vehicle. This contact strip wears out due to contact with the OCL. In particular, deformations due to chipping and material loss occur because of friction with the fittings on the OCL. These deformations on the contact strip affect its power transmission quality because of contact loss with the OCL. However, it is difficult to monitor the contact strip during operation and judge its condition in order to implement accident prevention measures. Thus, in this study, we developed a contact strip monitoring method based on image processing for inspection. The proposed method measures the deformation in the contact strip based on an algorithm that determines the wear on the deformed contact strip using deep learning and image processing. The image of the contact strip is acquired by installing a camera and laser to capture the pantograph as it passes the setup. The proposed algorithm is able to determine the wear size by extracting the edges of the laser line using deep learning and estimating the fitted line of the deformations based on the least squares method.

Theoretical solution for the axial vibration of functionally graded double-lap adhesive joints

Adhesively bonded joints have widely been used in a number of engineering applications, owing to their improved mechanical performance as compared with other mechanical joining techniques, such as rivets or bolts. In this study, a theoretical solution of double-lap joints is established, with functionally graded adhesive and isotopic adherends, under harmonic loads. Assuming a parabolic distribution of the adhesive shear modulus along the overlap length, the analytical harmonic solution is expressed in terms of the solution of the nonlinear Heun differential equation. Furthermore, a two-dimensional finite-element model was developed to validate the analytical solution. We show that using softer adhesive at the edges of the bond line leads to less stress concentration. We also conclude that the adhesive’s shear modulus gradient along the bond line should be greater as the ratio of the adhesive’s shear stiffness to the adherends’ shear stiffness increases. An equation has also been established to determine the optimal shear modulus gradient in terms of the stiffness ratio.

Linkage among ice crystal microphysics, mesoscale dynamics, and cloud and precipitation structures revealed by collocated microwave radiometer and multifrequency radar observations

Abstract. Ice clouds and falling snow are ubiquitous globally and play important roles in the Earth's radiation budget and precipitation processes. Ice particle microphysical properties (e.g., size, habit and orientation) are not only influenced by the ambient environment's dynamic and thermodynamic conditions, but are also intimately connected to the cloud radiative effects and particle fall speeds, which therefore have an impact on future climate projection as well as on the details of the surface precipitation (e.g., onset time, location, type and strength). Our previous work revealed that high-frequency (> 150 GHz) polarimetric radiance difference (PD) from passive microwave sensors is a good indicator of the bulk aspect ratio of horizontally oriented ice particles that often occur inside anvil clouds and/or stratiform precipitation. In this current work, we further investigate the dynamic and thermodynamic mechanisms and cloud–precipitation structures associated with ice-phase microphysics corresponding to different PD signals. In order to do so, collocated CloudSat radar (W-band) and Global Precipitation Measurement Dual-frequency Precipitation Radar (GPM DPR, Ku–Ka-bands) observations as well as European Centre for Medium-Range Weather Forecasts (ECMWF) atmosphere background profiles are grouped according to the magnitude of PD for only stratiform precipitation and/or anvil cloud scenes. We found that horizontally oriented snow aggregates or large snow particles are likely the major contributor to the high-PD signals at 166 GHz, while low-PD magnitudes can be attributed to small cloud ice, randomly oriented snow aggregates, riming snow or supercooled water. Further, high-PD (low-PD) scenes are found to be associated with stronger (weaker) wind shear and higher (lower) ambient humidity, both of which help promote (prohibit) the growth of frozen particles and the organization of convective systems. An ensemble of squall line cases is studied at the end to demonstrate that the PD asymmetry in the leading and trailing edges of the deep convection line is closely tied to the anvil cloud and stratiform precipitation layers, respectively, suggesting the potential usefulness of PD as a proxy of stratiform–convective precipitation flag, as well as a proxy of convection life stage.

Numerical modelling of functionally graded adherends

The development of lighter structures and materials has been one of the main research concerns of the transportation industry during the last decade, driven by the necessity to decrease fuel consumption and emissions. Therefore, the use of several different new lightweight materials, such as special metal alloys, reinforced polymers and new advanced composite materials has been explored, leading to optimized structures which combine these novel materials. To manufacture these multi-material structures, adhesive bonding is one of best joining techniques available, as fasteners add weight to the structure and require holes to be drilled and welding is not easily applicable to reinforced plastics, composites and some high strength metal alloys. However, adhesive bonding also presents some limitations that need to be considered, such as the appearance of singularities and the resultant stress concentration at the edges of the bond line, which result in a reduction of the joint strength. In order to mitigate this effect, several techniques have been proposed, being the use of functionally graded adherends one of them. Functionally graded adherends consist in an adherend where the mechanical properties gradually change throughout the material, usually in the thickness or length direction. The present work introduces the concept of a layered functionally graded adherend, varying the flexibility of each layer through the thickness direction. Different ratios of stiffness variation, combined with different adhesive properties, were numerically evaluated for single lap joints, comparing the stress distribution of the adhesive layer and the resultant joint strength, using cohesive zone modelling. Moreover, an optimization process of typical graded material properties, where different distribution laws that consider material weight and strength are considered, is presented.

Design of Series-Fed, Single-Layer, and Wideband Millimeter-Wave Microstrip Arrays

A series-fed millimeter-wave (mm-wave) microstrip linear array with single-layer structure and wide operating bandwidth is proposed and investigated. The antenna array simply consists of a microstrip line and a series of short stubs that are periodically introduced on one edge of the microstrip line, at an interval of about one guide wavelength. Owing to the perturbation of the additional stubs, the original symmetrical E-field distributions on the two opposite edges of the microstrip line become asymmetrical, and the intensities of the equivalent magnetic currents are unequal and unable to cancel each other out as in a pure microstrip line. As a result, the stub-loaded microstrip line can radiate effectively, producing broadside radiation patterns. The introduction of stubs can also generate an extra resonant mode, which combines with the resonant mode of the microstrip line, yielding a wide bandwidth of over 20%. In addition, the microstrip array is simply fed by a coaxial probe, without involving any complex feeding network. Therefore, the array configuration is very simple and compact. For demonstration, a $1 \times 4\,\,1$ -D microstrip linear array operating at 27 GHz is fabricated and tested. The measured results show that the array has an impedance bandwidth of 21.40%, an average realized gain of 12.18 dBi, and a first sidelobe level (FSLL) of about −13 dB. Moreover, the FSLL can be decreased to −28.4 dB by tapering the width of the microstrip line. Finally, the design is extended to realize a $4 \times 4\,\,2$ -D microstrip planar array. This planar array can achieve an impedance bandwidth of 19.15% and an enhanced gain of 18.30 dBi.

Fracture of the corpus cavernosum of the penis

Penile fracture is a rare urological emergency requiring immediate surgery, ideally in the first 24h, to prevent complications which are dominated by erectile dysfunction and penile curvature. The highest rates are reported in the Middle East and the Maghreb, most often secondary to false step in coitus or penile manipulations during erection such as the “taqaandan” maneuver. We report the case of a 34-year-old patient with no specific pathological history presenting to the Emergency Department with penile pain associated with swelling and deformity. The patient reported cracking sound during false step in coitus followed by acute penile pain with complete detumescence of the penis, with no associated urinary signs. Clinical examination revealed swollen penis, the seat of a hematoma, suggesting aubergine sign and a small painful induration on the dorsal side of the right corpus cavernosum on palpation. Emergency ultrasound confirmed the presence of a fracture line in the albuginea of the corpus cavernosum at 5 cm from the suspensory ligament of the penis. Direct approach based on elective incision of the induration was performed, which revealed longitudinal fracture measuring 18 mm in length involving the albuginea of the dorsal face of the right corpus cavernosum. After evacuation of hematoma, suture of the edges of the fracture line was performed with separate stitches of Vicryl 3-0. The post-operative suite was simple. At the follow-up visit the patient had recovered normal erectile function, with no induration or fibrosis at the level of the incision or penile curvature.

Stressed State of the Axisymmetric Adhesive Joint of Two Cylindrical Shells under Axial Tension

The research of the deflected mode of the construction, composed of two coaxially-glued cylindrical pipes, is done. Pipes are considered as thin-walled axisymmetric shells, which are joined by adhesive layer of a certain thickness. The shearing stresses in the glue are considered to be constant over the thickness of the adhesive layer, and normal stresses are linearly dependent on the radial coordinate. The shearing stresses in the adhesive layer are considered to be proportional to the difference in the longitudinal displacements of the shell sides that are faced to the adhesive layer. Normal stresses are proportional to the difference in radial displacement of the shells. It is supposed that the change in the adhesive layer thickness under deformation does not affect the stress, that is, the linear model is considered. The problem of the joint deflected mode finding is reduced to the system of four ordinary differential equations relative to the radial and longitudinal displacements of the layers. The system is solved by the matrix method. Displacements of layers outside of the adherent area can be found by the classical theory of axisymmetric shells. Satisfaction of boundary conditions and conjugation conditions leads to a system of twenty two linear equations with twenty two unknown coefficients. The model problem is solved; the results are compared with the computation made by the finite element method. The tangential and normal stresses in the glue reach the maximum values at the edges of the adhesive line. It is shown that the proposed model describes the stressed state of the joint with high accuracy, and this joint has an influx of glue residues at the ends of the adhesive line but can not be applied in the absence of adhesive influxes. Because in this case, the tangential stresses due to the parity rule reach maximum values not on the edge, but at some distance from the edge of the line. As a result, the distribution of normal stresses at the edge of the line also substantially changes. Thus, the proposed model with certain restrictions has sufficient accuracy for engineering problems and can be used to solve design problems.

An extremal property of lattice polygons

We find the critical number of vertices of a convex lattice polygon that guarantees that the polygon contains at least one point of a given square sublattice. As a tool, we prove Diophantine inequalities relating the number of edges of a broken line and the coordinates of its endpoints.

Practical Mitigation of Passive Intermodulation in Microstrip Circuits

This paper presents new experimental evidence and a novel practical approach for mitigation of passive intermodulation (PIM) in microstrip circuits fabricated on commercial printed circuit board laminates. The mechanisms of distributed PIM in microstrip circuits are reviewed and a phenomenology of PIM generation due to locally enhanced electromagnetic fields at the fringed etched edges of microstrip transmission lines is presented. Reducing the magnitude of the local fields is shown to be an effective means for mitigating PIM distortions. The effect is demonstrated experimentally by selectively coating the edges of a microstrip transmission line with a thin layer of high-permittivity dielectric, which resulted in more than 10 dB reduction of the PIM level without compromising the linear characteristics of the circuit, while avoiding the need for additional signal processing. Our approach has proved to be a new practical and effective means for PIM mitigation suitable for a wide range of commercial printed circuits.

Analysis of Arbitrarily Curved Microstrip Lines for Radiated Emission

In the context of printed circuit design, microstrip interconnects pose a great challenge in terms of radiated emission, signal integrity, and intertrace interference. Curved and bent microstrip lines are integral part of such high-frequency circuit design. In this paper, internal fields of an arbitrarily curved microstrip line are calculated using a sequential mode matching technique with piecewise circular discretization. Transverse asymmetry of the electric field is observed due to unequal curvatures of the two side edges of the microstrip line. A dynamic co-ordinate system based on Serret–Frenet reference frame is developed. A simple transmission line model is formulated in this new co-ordinate system to calculate the radiated far fields from the line. The developed model is applied to compute radiation from a sinusoidal line as well as that of a planar spiral. The model is also applied to compute the radiation efficiencies from various microstrip bends and it is observed that circular bends exhibit minimum leakage amongst others. A sinusoidal line and a planar spiral are fabricated and measured. Results are shown to be in good agreement with those predicted by the analytical model.

Improved second harmonic suppression in a compact coupled-line bandpass filter with triangular corrugations

This paper presents the design of a miniaturized coupled-line bandpass filter centered at 5.25 GHz with a fractional bandwidth of 20% for wireless local area network applications. Size reduction has been achieved by incorporating two different approaches in which symmetrical folding techniques have been employed. Periodic triangular corrugations have been introduced in the coupled edges of line for compensating the asymmetry in even- and odd-mode phase velocities . Accordingly, two different filter structures have been designed and optimized: folded V-shaped with five corrugations and in-line W-shaped with four corrugations. Second harmonic suppression of 62 and 30 dB and size reduction of 62 and 74% are achieved for folded and in-line filter respectively.

A Comfortable Solution To Tracheal Anastomosis Protection: Tracheal Retention Sutures

Fixation of the chin to the anterior chest wall is the most commonly used method of reducing anastomotic tension following a segmental resection of the trachea and reconstruction with primary anastomosis. However, the sutures required for this method may lead to various organic and psychological problems. In five patients who underwent tracheal resection and primary anastomosis, retention sutures were placed on the proximal and distal-lateral edges of the anastomotic line rather than placing a Guardian chin stitch. All patients were mobilised in the early postoperative period and were able to perform their routine daily activities without restrictions. During their average 14.4 months of follow-up, no complications were found in their anastomotic lines during their clinical, radiological, and bronchoscopic assessments. The placement of tracheal retention sutures proved an inexpensive and reliable method to reduce anastomotic tension without additional surgical burden, and was effective in terms of patient comfort.

A modified DOI-based method to statistically estimate the depth of investigation of dc resistivity surveys

Abstract Several techniques are available to estimate the depth of investigation or to identify possible artifacts in dc resistivity surveys. Commonly, the depth of investigation (DOI) is mainly estimated by using an arbitrarily chosen cut-off value on a selected indicator (resolution, sensitivity or DOI index). Ranges of cut-off values are recommended in the literature for the different indicators. However, small changes in threshold values may induce strong variations in the estimated depths of investigation. To overcome this problem, we developed a new statistical method to estimate the DOI of dc resistivity surveys based on a modified DOI index approach. This method is composed of 5 successive steps. First, two inversions are performed by using different resistivity reference models for the inversion (0.1 and 10 times the arithmetic mean of the logarithm of the observed apparent resistivity values). Inversion models are extended to the edges of the survey line and to a depth range of three times the pseudodepth of investigation of the largest array spacing used. In step 2, we compute the histogram of a newly defined scaled DOI index. Step 3 consists of the fitting of the mixture of two Gaussian distributions (G1 and G2) to the cumulative distribution function of the scaled DOI index values. Based on this fitting, step 4 focuses on the computation of an interpretation index (II) defined for every cell j of the model as the relative probability density that the cell j belongs to G1, which describes the Gaussian distribution of the cells with a scaled DOI index close to 0.0. In step 5, a new inversion is performed by using a third resistivity reference model (the arithmetic mean of the logarithm of the observed apparent resistivity values). The final electrical resistivity image is produced by using II as alpha blending values allowing the visual discrimination between well-constrained areas and poorly-constrained cells. The efficiency of the proposed methodology is assessed on synthetic and field data. By using synthetic benchmark analysis, we demonstrate that the selected well-constrained cells are well-reconstructed in size and shape as well as in resistivity contrasts. Compared to the existing image appraisal tools, the proposed statistical method allows the identification of the statistically well-constrained cells of the model without using any arbitrary cut-off value. Using this statistical method in combination with the resolution, when interpreting dc resistivity surveys, provides the geophysicist valuable information to avoid over- or misinterpretation of ERT images.