Edge Of Circle Research Articles

Comparative analysis of tube designs in heat exchangers: A numerical simulation study for enhanced thermal-flow efficiency, "optimizing wavy tubes bundle geometries for enhanced heat transfer in underwater applications"

With the growing challenges of heat transfer in marine vehicles and underwater power stations, the demand for an effective tube heat exchanger has surged. Numerical simulations were conducted on the constant, laminar flow of an incompressible viscous fluid inside a wavy tube while keeping the wall temperature consistent. The laminar flow was modeled in two dimensions using ANSYS FLUENT 19.2. For the water fluid model, an integrated algorithm was used to link the pressure and velocity fields. Primarily examined were circular tube banks organized in a staggered arrangement. The primary equations were approached via a finite volume method based on a combined technique. This study aimed to evaluate and contrast the heat exchange and flow traits of four distinct tube designs: asteroid (ASTB), hypotrochoid (HTB), Wavy edge circle (WCTB), and mixed bundle (MBT). The influence of tube design on a heat exchanger’s thermal-flow efficiency was measured across Reynolds numbers ranging from 100 to 400. The results indicated an improved Colburn factor and a decrease in both the friction factor and tube performance for all scenarios examined. Three key metrics determined the optimal tube design: the performance evaluation criterion (PEC), the global performance criterion (GPC), and the average Nusselt number (Nu). Regardless of the Reynolds number, the conventional HC had the least efficient PEC, while the STB registered the peak PEC value. The highest GPC was attained with the STB. Nu values remained relatively consistent for ASTB, HTB, WCTB, and MBT. In evaluating the average Nusselt number, the ASTB outperformed the STB (92–106% higher), HTB (36–48% higher), WCTB (21–32% higher), and MBT (57–64% higher).

Establishment of Analytical Model for CFRP Cutting Force Considering the Radius of the Edge Circle.

Carbon fiber-reinforced composite material (CFRP) has been widely applied in the aerospace industry, which places demanding requirements on the accuracy and quality of its processing. However, there remains a lack of clarity on the microscopic material removal process of CFRP, despite substantial relevant research. This paper aims to reveal the mechanism of material removal in the CFRP cutting process at different fiber cutting angles and to establish an analytical model for CFRP cutting force by considering the radius of the edge circle. Furthermore, the CFRP cutting force analytical model was established by considering the radius of the edge circle on the basis of the CFRP representative volume unit (RVE). According to the model, the cutting process was divided into three regions, the cutting slip zone, fiber fracture zone, and spring back zone, with consideration given to the effect of residual fibers on the cutter teeth. The CFRP cutting finite element model was defined using the software Abaqus, while the chip removal and single-fiber deformation processes were analyzed using the finite element model. As indicated by the experimental results, the analytical model is reliable and capable of providing cutting force values within a 15% deviation.

Role of processing parameters in CVD grown crystalline monolayer MoSe2.

The quality of as-synthesized monolayers plays a significant role in atomically thin semiconducting transition metal dichalcogenides (TMDCs) to determine the electronic and optical properties. For designing optoelectronic devices, exploring the effect of processing parameters on optical properties is a prerequisite. In this view, we present the influence of processing parameters on the lattice and quasiparticle dynamics of monolayer MoSe2. The lab-built chemical vapour deposition (CVD) setup is used to synthesize monolayer MoSe2 flakes with varying shapes, including sharp triangle (ST), truncated triangle (TT), hexagon, and rough edge circle (REC). In particular, the features of as-synthesized monolayer MoSe2 flakes are examined using Raman and photoluminescence (PL) spectroscopy. Raman spectra reveal that the frequency difference between the A1g and E12g peaks is >45 cm−1 in all the monolayer samples. PL spectroscopy also shows that the synthesized MoSe2 flakes are monolayer in nature with a direct band gap in the range of 1.50–1.58 eV. Furthermore, the variation in the direct band gap is analyzed using the spectral weight of quasiparticles in PL emission, where the intensity ratio {I(A0)/I(A−)} and trion binding energy are found to be ∼1.1–5.0 and ∼23.1–47.5 meV in different monolayer MoSe2 samples. Hence, these observations manifest that the processing parameters make a substantial contribution in tuning the vibrational and excitonic properties.

A vision based method for automated measurement of circular fiber cross-sections

Abstract There are many synthetic fibers with circular cross-sections, and characteristics of the fiber cross-sections have a major influence on the fiber properties. Direct measurements made with microscopic techniques on the fiber cross-sections can output maximum information on transverse dimensions. However, measuring parameters of the fiber sections in the microscopic images is a laborious task. In this paper, a hybrid method based on machine vision is proposed to measure the diameter and ellipticity of the circular fiber cross-sections. The hybrid method consists of modified Circle Hough Transform (CHT) and edge tracing algorithm, and the two sub-algorithms are performed successively. The modified CHT is used for detection and initial measurement of the fiber sections. Then the results are refined by the edge tracing algorithm, outputting elliptical results along with the ellipticity information of each fiber section. Experimental results show that the proposed method outperforms existing methods in circular fiber cross-section measurement.

Microarray spot segmentation algorithm based on integro-differential operator

Microarray technology has increased exponentially in the past few years. Such technology encompasses various applications related to drug design, tumor detection, clinical diagnosis and treatment, and environmental health research. However, the segmentation of the spots in microarray image is still a problem due to variations of spots qualities such as spots shapes and sizes for example. Hence, we have introduced a new microarray spot segmentation algorithm based on Integro-Differential Operator (IDO). Because it includes a spot detection step, this IDO can be used to find any spot regardless of its size and shape within the microarray image. The IDO algorithm is applied on the cDNA microarray images to improve the accuracy and the efficiency of the spots segmentation process. As the IDO is able to segment each spot based on the fact that the illumination difference between the inside and the outside of the pixels in spot edge circle is maximum. We have also tested our algorithm on the Stanford Microarray Database (SMD). The numerical results show that, the IDO is a powerful technique to improve the overall spots segmentation on the microarray image and to also give better results in spot segmentation and analysis process.

Anomalous energy shift of laterally confined two-dimensional excitons

We theoretically investigate the energy of the ground state exciton confined to two-dimensional (2D) monolayers with circular shape. Within an effective mass approach employing a nonlocal screening effect on the Coulomb potential energy, we demonstrate how the exciton energy is correlated with the radius of the circle, electron-hole reduced mass, and 2D susceptibility. In addition, we show that a dead layer around the circle edge, into which the electron-hole pair cannot penetrate, is necessary for understanding the energy shift recently observed in monolayer WSe2 quantum dots.

Fretting fatigue fracture of the supporting shaft in a rotary kiln

Abstract The fracture failure of the supporting shaft in a rotary kiln was analyzed to determine the failure mechanism. The rotary kiln was used to heating and mixing nickel ores and was supported by four group riding wheels with two wheels in each group. One of the supporting shafts was found fractured after it was used for about two years. The fracture was located at the interface between the supporting shaft and the sleeve. This location was 100–120 mm far from the transition arc of the supporting shaft where high stress concentration usually occur. A failure analysis was carried out, using characterization techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and so on. Obvious fatigue propagation zone caused by multi-initial cracks were observed at the circle edge of the fracture surface. Adhesive wear and some circumferential cracks were found on the outside surface of the supporting shaft. It was considered that fatigue due to the fretting wear between the shaft and sleeve was the most probable mechanism.

Influence of the Blade Trailing Edge Profile on the Performance and Unsteady Pressure Pulsations in a Low Specific Speed Centrifugal Pump

The blade trailing edge profile is of crucial importance for the performance and pressure pulsations of centrifugal pumps. In the present study, numerical investigation is conducted to analyze the effect of the blade trailing edge profile influencing the performance and unsteady pressure pulsations in a low specific speed centrifugal pump. Five typical blade trailing edges are analyzed including original trailing edge (OTE), circle edge (CE), ellipse on pressure side (EPS), ellipse on suction side (ESS), and ellipse on both sides (EBS). Results show that the well-designed blade trailing edges, especially for the EPS and EBS profiles, can significantly improve the pump efficiency. Pressure amplitudes at fBPF and 2fBPF are together calculated to evaluate the influence of the blade trailing edge profile on pressure pulsations. The EPS and EBS profiles contribute obviously to pressure pulsations reduction. In contrast, the CE and ESS profiles lead to increase of pressure pulsation amplitude compared with the OTE pump. Vorticity distribution at the blade trailing edge demonstrates that the EPS and EBS profiles have an effective impact on reducing vortex intensity at the blade trailing edge. Consequently, rotor–stator interaction could be attenuated leading to lower pressure pulsation amplitude. It is thought to be the main reason of pressure pulsations reduction obtained with the proper modified blade trailing edges. The results would pave the way for further optimization of the blade trailing edge profile.

Apple detection from apple tree image based on BP neural network and Hough transform

Using machine vision to accurately identify apple number on the tree is becoming the key supporting technology for orchard precision production management. For adapting to the complexity of the field environment in various detection situations, such as illumination changes, color variation, fruit overlap, and branches and leaves shading, a robust algorithm for detecting and counting apples based on their color and shape modes was proposed. Firstly, BP (back propagation) neural network was used to train apple color identification model. Accordingly the irrelevant background was removed by using the trained neural network model and the image only containing the apple color pixels was acquired. Then apple edge detection was carried out after morphological operations on the obtained image. Finally, the image was processed by using circle Hough transform algorithm, and apples were located with the help of calculating the center coordinates of each apple edge circle. The validation experimental results showed that the correlation coefficient of R2 between the proposed approaches based counting and manually counting reached 0.985. It illustrated that the proposed algorithm could be used to detect and count apples from apple trees’ images taken in field environment with a high precision and strong anti-jamming feature. Keywords: apple detecting and counting, BP neural network, Hough transform,color segmentation, edge detection DOI: 10.3965/j.ijabe.20150806.1239 Citation: Xiao C Y, Zheng L H, Li M Z, Chen Y, Mai C Y. Apple detection from apple tree image based on BP neural network and Hough transform. Int J Agric & Biol Eng, 2015; 8(6): 46－53.

Fabrication and Characterization of Electronic and Optical Properties of Polyaniline Nanopatterns.

The authors conducted polyaniline (HA) polymerization on a micro-scale patterned Si water and nano-scale patterned Al surface. Polymerization was performed using a microliter solution droplet made of aniline, HCI and oxidation agent ammonium peroxodisulfate (APS). The droplet was dropped on a flat Si wafer, a micro-patterned Si wafer and a nanostructured Al surface. The SEM image showed that PA was densely polymerized on the circle edge of the dropped 1 mm sized droplet on the flat Si wafer because of large surface tension due to the flat surface. On the other hand, a droplet was broken on a circular trench pattern of 100 µm in diameter fabricated on a Si wafer. The width and depth of the trench were 1 µm and 1 µm, respectively. Tree-like polymer was intensively polymerized along the circular trench. Droplet was also dropped on a lattice trench pattern whose pitch was 10 µm. The width and the depth of the trench were 1 µm and 1 µm, respectively. The SEM image showed that dots of PA were fabricated along the trenches. Far smaller dots of PA were also observed on the flat area of the lattice. Thus, micro-scale structure affects the shape and size of PA in polymerization. Nanoscopic polymerization of PA was conducted locally in a nanoscale highly-oriented line pattern with nanoscale trenches formed on an Al surface. One of the characteristic fabricated patterns was a highly conductive PA line pattern whose pitch was 100 nm. In this case, point-contact IV characteristic measurement, step-like curve was observed. PL spectra of the PA line-pattern exhibited significantly enhanced emission peaks at 380, 450 anc 550 nm due to PA which were overlapped by the rippled PL pattern due to the Al nanostructure.

Accurate projector calibration based on a new point-to-point mapping relationship between the camera and projector images

The mapping relationship between the charge-coupled device (CCD) of a camera and the digital micro-mirror device (DMD) of a projector, together with the algorithm to estimate the parameters of the projector, determines the accuracy of projector calibration. In this paper, a new method is presented to achieve sub-pixel-level mapping between the camera and projector images. Instead of directly mapping the circle centers from the CCD to the DMD, which is pixel-precision-based, a set of pixels on the circle edge are extracted on the CCD and mapped onto the DMD. The locations of the circle centers are extracted on the DMD by the least-squares fitting technique, thus achieving sub-pixel precision. Compared with existing approaches based on the direct mapping of the circle centers on the camera image to the projector image, the proposed method is characterized by higher accuracy in mapping the points and thus the projector calibration. The experimental results are presented to show the effectiveness of the proposed method in the improvement of the accuracy of the projector calibration.

Modeling a Rotating Circle Thermal Field with a Thermal Source on the Edge

The task of circle heating by a thermal source moving along the circle edge with a constant angular velocity is considered. The circle is a cylinder in which the temperature is the same on each straight line parallel to a cylinder axis, i.e. at each point the temperature is a function of time, distances from a cylinder axis and a polar angle. The computing schemes based on numerical methods are usually used for the similar tasks solution. Explicit schemes solve one equation for each time step of each spatial knot. Implicit schemes solve a system of linear algebraic equations for each time step. The number of equations is connected with the number of spatial knots. In the first case the process is rather simple, but the scheme is not absolutely steady. For this scheme the step order by time should not exceed the square of step order by coordinate. In the second case the scheme is absolutely steady, but it is necessary to solve a complex system of equations, especially for a multidimensional case. The purpose of this work is to use absolutely steady differential-difference explicit scheme based on linear equation application with partial derivatives of the first order which analytical solution (an explicit formula) is known.

Adaptive preprocessing algorithms of corneal topography in polar coordinate system

New adaptive preprocessing algorithms based on the polar coordinate system were put forward to get high-precision corneal topography calculation results. Adaptive locating algorithms of concentric circle center were created to accurately capture the circle center of original Placido-based image, expand the image into matrix centered around the circle center, and convert the matrix into the polar coordinate system with the circle center as pole. Adaptive image smoothing treatment was followed and the characteristics of useful circles were extracted via horizontal edge detection, based on useful circles presenting approximate horizontal lines while noise signals presenting vertical lines or different angles. Effective combination of different operators of morphology were designed to remedy data loss caused by noise disturbances, get complete image about circle edge detection to satisfy the requests of precise calculation on follow-up parameters. The experimental data show that the algorithms meet the requirements of practical detection with characteristics of less data loss, higher data accuracy and easier availability.

The Research of Electrical Equipment Identification Technology Based on Image Processing

Insulator is a tiny part in electrical equipment, but whether its working condition is safe or not plays a vital role in the safe operation of the entire power system. In this paper, digital image processing technology based on MATLAB is applied, the obtained image of the insulator is processed through filtering, gray-scale processing and binarization processing. The parameters such as insulator's bottom circle area and edge width are extracted, and compared with the calibration parameters to determine the size of insulators. The method to getting more precise characteristic values of insulators is described in this paper. It provides the evidence of judging the working state by comparing with the calibration value to capture measurements of insulators. The digital image processing technology based on MATLAB can effectively monitor the working status, high efficiency and accuracy of the insulator.

Fast and Accurate Circle Detection Algorithm for Porous Components

Fast and Accurate Circle Detection Algorithm for Porous Components In this paper, a fast and accurate circle detection algorithm is presented. The proposed algorithm satisfies the application requirements on accurate circle localization for porous components with excellent real-time performance. The core idea of the algorithm is to cluster circle edge points by an easy-to-implement image analysis technique. Specifically, the original image is firstly down sampled with uniformly spaced grid to form an image with smaller size. The new image is then analyzed, pixel by pixel, to find the candidate grid points located inside the circle on the original image. Secondly, candidate grid points are evaluated to eliminate the ones which are not inside real circles. Thirdly, grid points located inside one circle are regrouped according to minimum distance between circles. These remaining grid points are the reference points to cluster circle edge points. Finally, parameters for a specific circle including radius and center coordinates are calculated based on the edge points belonging to that circle with Random Sample Consensus (RANSAC) algorithm. Experiment results demonstrate the efficiency of the proposed circle detection method.

Impact Analysis of Geogrid Node Size in Stretch Forming

Numerical simulations are done for stretch forming of uniaxial geogrid. And influence of different punching radius on the stress and strain of geogrid are studied. It shows that the maximum stress and strain in tensile process appear at the corner of the circle and straight edge. And the biggest stress is decreased with the radius. At the same time, radius increases reduce the deformation along the stretching direction on some extent. Based on this, a new optimization method for geogrid stretch forming is proposed. The shapes and sizes of punching can change the stress and strain distribution in the geogrid, which can reduce the probability of defect in the process of stretch forming.

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Dial Instrument Calibration by both Automatic and Half-Automatic Methods

This paper presents a calibration system by video processing technique. The system can calibrate large number of different types of dial instruments. The system is composed of an automatic recog-nition approach and a half-automatic approach. Both the automatic calibration and half-automatic calibration include four steps: 1st, dial plane circle edge extraction and center identification; 2nd, pointer extraction; 3rd, scale start and end position identification; 4th, result reading. For half-automatic method, the 1st step and 3rd step are manually indentified. By experiments and practical application in industry, it proves that our calibration system is effective for more than hundreds of different types of dial instruments.

Vectorization of human pelvis objects in X-ray images

In medical diagnostics visual evaluation of an object or its image is necessary but time consuming operation. Well-known computer vision algorithms or their compilation, or even some new methods should be the right tool in increasing the speed and reliability of this process. This paper introduces situation in this domain and some experiments and their results in extraction of biomechanical parameters of human pelvis from x-ray images using combination of Hough transform for a line, for a circle (arc) and Canny edge detector. The main idea of an algorithm, which was created during this experiment, is to use different levels of noise filter thus making a balance between leaving too much noise and removing too much actual data. The basic steps would be: filter out most of noise and noisy objects using high filter’s threshold value; find sharp and clear objects; narrow the set of possible parameters of noisy objects; apply noise filter with lower threshold value to the original image; find noisy objects. Experiment shows that algorithm works but it needs to be tested on reliability and some bindings with actual biomechanical parameters should be done (see [1–6]).

Electrical behavior of a quartz crystal resonator immersed in a pressurized fluid (gas or liquid)

A network analyzer connected to a high pressure vessel was used to measure the conductance spectrum in a wide range of frequency (1–250 MHz) of an AT-cut quartz crystal resonator of nominal frequency 3 and 5 MHz totally immersed in a fluid under pressure ranging from atmospheric pressure to 80 MPa. Measurements carried out with several gases (methane, nitrogen, argon, carbon dioxide) and various hydrocarbon liquids (toluene, heptane, nonane, decane, dodecane) show that quartz resonators correctly work when they are fully immersed in pressurized fluids whatever the state gas or liquid and whatever the pressure. At constant pressure, both shifts in frequency and bandwidth follow a regular behavior versus overtone number in a domain limited in the lower range by the influence of the circle edge boundary conditions and by the interference with the anharmonic modes in the upper range. In this working domain, experimental observations were well represented by a model that takes into account the effects of hydrostatic pressure, viscous damping as well as interfacial ones through two parameters.