Ideal Circle Research Articles

New Insight into Quantity-Dependent Self-Assembly Pattern of Light Levitating Droplet Clusters.

It has been reported that the self-assembly pattern of light levitating droplet clusters above the hot gas-liquid interface is dependent on the quantity of droplets. However, the already-reported theoretical explanation of the quantity-dependent self-assembly pattern cannot work well when the quantity of the light levitating droplet exceeds 15. Herein, we propose a new theoretical perspective to understand the self-assembly of a light levitating droplet cluster by referring to the classical densest packing problem of identical rigid circles in a larger circle with the introduction of the minimum total potential energy principle. Amazingly, the theoretical results obtained by this new approach agree well with experimental results, even though the quantity of the light levitating droplet is up to 142. This study deepens our understanding of the quantity-dependent self-assembly pattern of the light levitating droplet clusters and provides significant inspiration for other analogous self-assembly phenomena.

Numerical and Experimental Study on Nonlinear Phenomena and Thermal Deviation Control in a 1000 MW Tower-Type Boiler

Numerical and experimental studies were conducted to study the nonlinear phenomena of a 1000 MW ultra-supercritical four-corner tangential pulverized coal boiler. In this paper, (1) a 3D model of a furnace with a symmetrical structure was established to analyze the asymmetric flow phenomenon and multi-solution phenomenon of flow for multiple timepoints under the same boundary conditions. (2) The visual experiment verified that the flow in the furnace also behaved asymmetrically. (3) On the basis of correctly predicting the nonlinear law, the “diagonal start up” method and the “sequential start up” method are proposed. (4) An uneven coefficient of velocity distribution M, deviation coefficient of flue gas mass flow rate Eq and gas temperature deviation coefficient ET are proposed to quantitatively analyze the degree to which the actual tangent circle deviates from the ideal tangent circle. The tangent circle under the “sequential start up” method is the closest to the ideal, which can reduce the thermal deviation of the furnace outlet from 67 K under the “simultaneous start up” method to 41 K. In this paper, the initial steady-state flow field in the furnace is established by using the initial value sensitivity of the nonlinear system through different burner-opening methods, so as to reduce the thermal deviation at the furnace outlet and achieve the purpose of accurate control.

A combinatorial curvature flow in spherical background geometry

In [12], the existence of ideal circle patterns in Euclidean or hyperbolic background geometry under combinatorial conditions was proved using flow approaches. It remains as an open problem for the spherical case. In this paper, we introduce a combinatorial geodesic curvature flow in spherical background geometry, which is analogous to the combinatorial Ricci flow of Chow and Luo in [4]. We characterize the sufficient and necessary condition for the convergence of the flow. That is, the prescribed geodesic curvature satisfies certain geometric and combinatorial condition if and only if for any initial data the flow converges exponentially fast to a circle pattern with given total geodesic curvature on each circle. Our result could be regarded as a resolution of the problem in the spherical case. As far as we know, this is the first combinatorial curvature flow in spherical background geometry with fine properties, and it provides an algorithm to find the desired ideal circle pattern.

Экспериментальные исследования подвесного точечного тросового параллельного робота

A prototype of a suspended point cable parallel robot with a control interface and three translational degrees of freedom was designed and manufactured. The prototype of a point cable parallel robot consists of a metal frame in the shape of a rectangular parallelepiped; winches with servo motors are located near the base of each vertical post, designed for winding (or winding) cables. The other ends of the cables passing through the pulleys are connected to the working body. The direction of rotation, as well as the rotation speed of winches with servomotors, are set by a control unit that has three translational degrees of freedom. Four force sensors were used to determine the tension in the cables of the suspended point cable parallel robot. The force sensors are connected to the ZET 058 strain gauge measuring system, which, together with the ZETLAB TENZO software, allows you to collect information in real time through four channels simultaneously. Experimental studies of a prototype of a suspended point-cable parallel robot were carried out by drawing a circle trajectory with an end-effector. It has been established that the deviation of the trajectory from an ideal circle occurs as a result of tension fluctuations in the cables. Experimental graphs of the tension in the cables were obtained using force sensors connected to the ZET 058 strain gauge measuring system. It was established that in order to increase the accuracy of the operation of the suspended point cable parallel robot, constant monitoring of the tension of its cables is necessary.

Research on the Application of Motor Field-Oriented Control in Vehicles

The motor application of the FOC strategy of the hybrid system in this text is the battery heat control. The specific contents are as below: SVPWM control. SVPWM is based on the three-phase symmetrical sine wave voltage supply and three-phase symmetrical motor stator ideal flux circle as a reference standard, with different switching modes of three-phase inverter for appropriate switching, to form PWM wave and to form the actual flux vector to track its accurate flux circle. By applying reactive voltage with high-frequency variation and using the FOC control strategy, the inductance characteristic of the motor winding is constantly utilized to generate alternating current on the bus. By taking advantage of the high internal resistance of the cell at low temperatures, the joule heat is constantly generated on the cell. While avoiding the risk of lithium analysis of the cell, heat is generated from the cell itself, and the temperature of the cell is raised. The vehicle results are conducted and show that the battery heat performance is enhanced.

Çift taraflı park edilmiş dar sokaklarda paralel park için geometrik yol planlaması

The aim of the paper is to propose collision-free path planning algorithm for autonomous parallel parking based on Ackermann steering geometry. A geometrical path planning algorithm has been employed for generating a path that is based on two straight lines and two identical circles. The algorithm is taking into account that the left side of the street is taken as another parking slot occupied by full of cars. The ego’s kinematics model appropriate for the low-velocity parking scenario and the maximum allowable steering angle for the narrow streets is used in the path planning stage by considering mechanical and environmental limits. According to the steering angle, required length of the parking space is obtained. The algorithm can adapt itself according to the lateral position of the ego in case it is parallel to other parked cars. The steering angle to be used and the required parking space length according to the lateral position of the vehicle in the environmental model are given with graphics.

Semantics of Verbs of Rotation in the Khanty language

The article is devoted to the identification of the national specifics of the representation of rotational movement in the Khanty linguoculture, the analysis of the semantics of verbs of rotation, the possibility of their lexical compatibility on the material of the Western dialects of the Khanty language (Kazym, Shuryshkar, Uralic) and one of the eastern (Surgut) by the types of situations described by them. The purpose of our study is to identify the parameters relevant to the lexical rotation zone. The article uses the method of corpus research: a sample of examples with verbs of rotation is analyzed and the boundaries of their compatibility are determined. The method of field research is used. There is a difference between movement along a trajectory close to an ideal circle (rotation in a circle) and movement along a chaotic trajectory, i.e. rotation of a set of homogeneous objects / gaseous particles (deer, snow vortex, smoke). In this case, the second type of rotation is marked. The subject performs multiple or single rotations around its axis or causates a rotational movement. The key parameter for distinguishing verbs of rotation and skating is animateness. Verbs of rotation around a landmark reflect the way of movement. Verbs of rolling and rotation do not reflect the environment of movement, but may reflect the direction of movement, which is regulated by the special compatibility of the subject and the predicate, or the word-formation capabilities of the predicate. The rolling zone reflects rotation in contact with the plane during translational motion and multidirectional rotation (about natural phenomena and about the movement of deer). The selected parameters and values are not lexicalized into separate verbs, but are combined inside lexemes. One lexeme describes situations of rotation in the same plane with and above the landmark, however, skating on the surface and rotation around the landmark is marked in dialects by separate lexemes.

An Inference of Plot Design Method Applied to Pavilions in the Rear Garden of Changdeokgung Palace as World Cultural Heritage

Background and objective: It is necessary to study traditional plot design methods or manners that the engineers in Joseon Dynasty were inferred to have conventionally applied to garden spaces or buildings. This study aimed to infer a conventional plot design method practiced by the engineers who created pavilions in Joseon Dynasty.Methods: The four pavilions were selected, whose original design drawings or documents are still unavailable to reveal the method or manner. The actual measurement plot design layouts measured and drawn on the spot by Cultural Heritage Administration (CHA) were analyzed. A geometrical approach was adopted to infer a method that drew the plot design layout on the ground using only non-gauged rulers (or strings). In the analysis, basic figure frames such as circles or lines were overlaid on the actual measurement drawings, and whether they matched was checked. Then, we inferred the sequential processes of the plot design method to implement the layout on the paper or the ground.Results: It was inferred that the plot design layouts of the four pavilions might have the same method. The results suggested that the engineers in Joseon Dynasty, without accurate numeric scale bars or protractors, might apply a geometrical method to determine the position of each pavilion pillar with the figures and intersections created in composing two identical circles overlapping by the radius. Two drawing processes implemented by the method inferred to reproduce the layout of Buyongjeong pavilions with a complex structure coincided with the actual measurement plot design drawing.Conclusion: The result could infer a plot design method and process applied to the four pavilions in the Rear Garden of Changdeokgung Palace in Joseon Dynasty. It may be a drawing method using string as a numeric scale bar or protractor, which could be used to interpret and reproduce the plot design of traditional Korean garden pavilions built in Joseon Dynasty.

Perturbation-Based Thresholding Search for Packing Equal Circles and Spheres

This paper presents an effective perturbation-based thresholding search for two popular and challenging packing problems with minimal containers: packing N identical circles in a square and packing N identical spheres in a cube. Following the penalty function approach, we handle these constrained optimization problems by solving a series of unconstrained optimization subproblems with fixed containers. The proposed algorithm relies on a two-phase search strategy that combines a thresholding search method reinforced by two general-purpose perturbation operators and a container adjustment method. The performance of the algorithm is assessed relative to a large number of benchmark instances widely studied in the literature. Computational results show a high performance of the algorithm on both problems compared with the state-of-the-art results. For circle packing, the algorithm improves 156 best-known results (new upper bounds) in the range of [Formula: see text] and matches 242 other best-known results. For sphere packing, the algorithm improves 66 best-known results in the range of [Formula: see text], whereas matching the best-known results for 124 other instances. Experimental analyses are conducted to shed light on the main search ingredients of the proposed algorithm consisting of the two-phase search strategy, the mixed perturbation and the parameters. History: Accepted by Erwin Pesch, Area Editor for Heuristic Search & Approximation Algorithms. Funding: This work was supported by the National Natural Science Foundation of China [Grants 61703213 and 61933005]. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplemental Information ( https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2023.1290 ) as well as from the IJOC GitHub software repository ( https://github.com/INFORMSJoC/2022.0004 ) at ( http://dx.doi.org/10.5281/zenodo.7579558 ).

Experimental Investigation on Turbulent Flow Deviation in a Gas-Particle Corner-Injected Flow

An experimental model of a corner-injected flow is built to investigate the turbulent flow behavior by employing the PIV technique. The influences of the ideal tangential circle, the additive particles and the initial gas mass flux on the corner-injected flow are analyzed systematically. To be specific, the flow deviation, the velocity profile, the vortex evolution and the turbulent flow development are discussed quantitatively. The influences of the increasing ideal tangential circle on the turbulent jet deviation are shortened gradually, and the impinging circles are obviously narrowed with the injection of particles. The gas-particle corner-injected flow can obtain a good rotation when the ideal tangential circle is 0.25 times the width of the impinging chamber. The momentum decay of the corner-injected flow diminishes with the increasing ideal tangential circle and the decreasing initial gas velocity. The rotation strength of the vortex is more affected by the injection of laden particles, while the angular distortion enhances when increasing the ideal tangential circle. The increasing initial gas mass flux plays a dominant role in the development of the corner-injected flow, secondly the increasing ideal tangential circle, and last the injection of particles. All these findings can provide theoretical support in the design of a corner-fired furnace.

Virtual constraint control of Knee-Ankle prosthesis using an improved estimate of the thigh phase-variable

In the human gait cycle, virtual constraints enforce a robust relationship between the thigh phase-variable and the knee/ankle angle. These constraints enable an accurate estimation and control of angular trajectory when the input phase-variable profile is low in gait aperiodicity and sensor noise. In this work, we present discrete Fourier transform (DFT) based virtual constraint schemes for estimating the knee/ankle trajectories using an improved monotonic and linear trajectory of the thigh phase-variable. To minimize the likely aberrations in the desired trajectory of the phase-variable, the contour of the thigh angle and its integral is amplitude scaled, time shifted, and interpolated over the complete stride. The processed contour is then refitted to an ideal circle using polynomial optimization via two different schemes. For both proposed schemes, estimated knee/ankle trajectories are compared with the benchmark gait kinematics of healthy persons and an amputee wearing three commercial prostheses. Simulation results, based on realistic prosthesis actuator parameters, show a 2.18 ± 0.83 times reduction in the mean trajectory tracking error for three contrasting walking speeds, validating the efficacy of proposed schemes.

Application of method of discontinuous basic and enhanced smoothing solutions for 3D multibranched cable

The paper is devoted to the development of new algorithm of form finding for 3D multibranched cable under static loading. Each cable is presented as a number of elements. For each element the looking for Ultimate solution, US, is presented as a sum of Basic solution, BS, and Smoothing solution, SS. BS present itself as the part of ideal circle with embedded axial force, the length of which corresponds to this force and initial length. The radius, axial force and initial position of BS is gradually refined at each iteration to maximally equilibrate the outer forces. BS is discontinuous one, it does not exactly equilibrate outer forces, there are no continuity at the border between two neighboring elements, and the boundary conditions are not fulfilled for it. All this is solved by SS, which is derived in local coordinate system related to the basic geometry. Here new analytical SS for 3D cable is proposed, which takes into account the uniformly and linearly distributed both normal and tangent forces. Algorithm of the accelerated or decelerated refinement of BS based on the current convergent or divergent behavior of SS is further elaborated. A lot of practical examples are considered, which show a very good accuracy of the proposed approach for the form finding with no relation to the initial random placement of basic geometry.

Geometric characteristics of bicuspid aortic valves.

ObjectiveWe studied the coaptation angles α and β in bicuspid aortic valve geometry from computed tomography scan images.MethodsIn 45 patients, we calculated the coaptation angle α (the angle between the nonfused commissures crossing the center of coaptation), angle β (between the nonfused commissures crossing the center of the reference circle), angles γ1 and γ2 and ε1 and ε2 (angle between the nonfused commissures and the coaptation point at the raphe or the perfect midpoint, respectively), the length of the raphe, the absolute and relative sinuses' surfaces (relative to the perfect circle and the percentage exceeding the ideal circle). Spearman correlation was employed to investigate the associations among all parameters.ResultsThe coaptation angles α and β were significantly different (P < .001). We found a significant correlation of α with the length of the raphe (P = .008), whereas β was dependent on the position of the commissures. Both γ1 and γ2 (P = .04), or ε1 and ε2 (P < .001) significantly differed from each other and ε2 was the most constant angle, although its size geometrically depends on β. The noncoronary was the largest sinus, and β was the primary determinant of its increased size in bicuspid aortic valves with righ/left fusion pattern.ConclusionsThe coaptation angle α is influenced by the length of the raphe, whereas angle β is dependent on the position of the commissures. The position of the raphe can vary and is not always situated in the middle of the free edge. The position of the right/non commissure is variable, whereas the right/left commissure is more fixed.

A Low-complexity OSNR monitoring scheme based on amplitude variance analysis

In this work, we have proposed and verified a low-complexity optical signal-to-noise ratio (OSNR) monitoring scheme based on amplitude variance analysis (AVA). The key feature for OSNR monitoring is extracted from the variance between the received symbols and the corresponding ideal amplitude circles. The simulation results have demonstrated that the obtained mean absolute errors (MAEs) of OSNR monitoring achieve 0.1176 dB, 0.2064 dB, 0.2179 dB, 0.2249 dB, and 0.2631 dB for 28 GBaud polarization-division-multiplexing (PDM) quadrature-phase-shift-keying (QPSK), PDM-8-quadrature-amplitude-modulation (QAM), PDM-16QAM, PDM-32QAM and PDM-64QAM, respectively. Meanwhile, the proposed AVA scheme presents good tolerances to chromatic dispersion (CD) and polarization-mode dispersion (PMD). Furthermore, the OSNR monitoring performances have been verified by a 28 GBaud PDM-QPSK/8QAM/16QAM/32QAM experimental transmission system. The obtained MAEs are 0.1293 dB, 0.3105 dB, 0.3214 dB, and 0.3823 dB, respectively. Compared with the moment estimation (MEB) and deep-neural-network (DNN)-based schemes, the accuracy of the proposed AVA scheme has been improved and its computation complexity is well reduced.

Accuracy Assessment of Two Electromagnetic Articulographs: Northern Digital Inc. WAVE and Northern Digital Inc. VOX.

Purpose This study compares two electromagnetic articulographs manufactured by Northern Digital, Inc.: the NDI Wave System (from 2008) and the NDI Vox-EMA System (from 2020). Method Four experiments were completed: (a) comparison of statically positioned sensors, (b) tracking dynamic movements of sensors manipulated using a motor-driven LEGO apparatus, (c) tracking small and large movements of sensors mounted in a rigid bar manipulated by hand, and (d) tracking movements of sensors rotated on a circular disc. We assessed spatial variability for statically positioned sensors, variability in the transduced Euclidean distances between sensor pairs, and missing data rates. For sensors tracking circular movements, we compared the fit between fitted ideal circles and actual trajectories. Results The average sensor pair tracking error (i.e., the standard deviation of the Euclidean distances) was 1.37 mm for the WAVE and 0.12 mm for the VOX during automated trials at the fastest speed, and 0.35 mm for the WAVE and 0.14 mm for the VOX during the tracking of large manual movements. The average standard deviation of the fitted circle radii charted by manual circular disc movements was 0.72 mm for the WAVE sensors and 0.14 mm for the VOX sensors. There was no significant difference between the WAVE and the VOX in the number of missing frames. Conclusions In general, the VOX system significantly outperformed the WAVE on measures of both static precision and dynamic accuracy (automated and manual). For both systems, positional precision and spatial variability were influenced by the sensors' position relative to the field generator unit (worse when further away). Supplemental Material https://doi.org/10.23641/asha.14787846.

Global exact optimization for covering a rectangle with 6 circles

We address the problem of covering a rectangle with six identical circles, whose radius is to be minimized. We focus on open cases from Melissen and Schuur (Discrete Appl Math 99:149–156, 2000). Depending on the rectangle side lengths, different configurations of the circles, corresponding to the different ways they are placed, yield the optimal covering. We prove the optimality of the two configurations corresponding to open cases. For the first one, we propose a mathematical mixed-integer nonlinear optimization formulation, that allows one to compute global optimal solutions. For the second one, we provide an analytical expression of the optimal radius as a function of one of the rectangle side lengths. All open cases are thus closed for the optimal covering of a rectangle with six circles.

Combinatorial Ricci flows for ideal circle patterns

This paper considers Chow-Luo's combinatorial Ricci flows in the setting of ideal circle patterns. We establish several equivalent conditions regarding long time behaviors of these flows. As consequences, Rivin's and Bobenko-Springborn's theorems are obtained. Moreover, this approach suggests a computational method to find the desired ideal circle patterns (and ideal hyperbolic polyhedra).

Optimizing 3D printing parameters: Evaluating infill type and layer height effects on tensile fracture force

While the concept of 3D printing has existed for decades, only recently has it expanded into our homes, workplaces, and everyday lives. In fact, 3D printing is already being used in a variety of important applications, ranging from prosthetics to automobiles. Nowadays, people can purchase a 3D printer and start 3D printing gadgets from their own homes for under $200. As the concept of 3D printing inevitably continues to develop, it is important that products that are 3D printed are strong and durable, especially if these products are designed to be used frequently or are subject to high loads of stress or pressure. Therefore, this study evaluated the effects of the infill pattern and layer height on the tensile fracture force of tensile testing specimens. To evaluate strength in the XY-directions, we printed tensile testing specimens in the horizontal orientation with different infill patterns and a constant layer height. We hypothesized that the gyroid infill pattern would have the highest tensile strength because it maintains a constant curvature in all directions, therefore having the longest path of least resistance and the maximum tensile strength in a given volume. In order to evaluate strength in the Z-direction, we printed testing specimens in the vertical orientation with varying layer heights and a constant infill pattern. We hypothesized that the lowest layer height of 0.08 mm would yield the highest fracture force because, in the Z-direction, the lowest layer height allows the shapes of extrusions to resemble elongated rectangles instead of ideal circles, which results in larger contact area between the layers. On average, specimens with the gyroid infill pattern exhibited the highest tensile fracture force (mean = 583.14 N) in the XY-directions, and specimens with a layer height of 0.08 mm showed the highest tensile fracture forces in the Z-direction (mean = 526.49 N). Both sets of data supported the hypotheses, showing that the gyroid pattern and 0.08 mm layer height are most practical in terms of strength when 3D printing objects.

679. Predominance of Acinetobacter baumannii Sequence Type 2 (ST2) among Clinical Isolates from Two Detroit Hospitals using Whole Genome Sequencing

BackgroundHealthcare-associated infections (HAIs) caused by Acinetobacter baumannii, an opportunistic gram-negative pathogen, often contribute to morbidity and mortality among hospitalized patients. To determine molecular epidemiology of circulating hospital Acinetobacter strains in Detroit area in a non-outbreak situation, we performed whole genome sequencing (WGS) and whole genome multilocus sequence typing (wgMLST) analysis to characterize genomic diversity.MethodsWe performed WGS on patient isolates from two disparate, geographically distinct tertiary care Detroit hospitals admitted to 16 intensive care units (ICU) and non-ICU wards between 2017-2019. The samples were obtained 48 hours following admission and WGS was performed using the Illumina NextSeq instrument. The contigs were de novo assembled using SPAdes and WgMLST analysis was performed using BioNumerics software v7.6. Minimum spanning tree (MST) was constructed to demonstrate the clusters in each hospital and their wards.ResultsWgMLST analysis was performed on a total of 62 Acinetobacter baumannii patient isolates, 33 of which were from hospital # 1 (H1) and 29 were from hospital # 2 (H2). ST2 (52%) was the predominant sequence type for both hospitals. In addition to ST2, ST93 (8%) and ST406 (8%) clusters were also found in H1. Most of the isolates were predominantly clustered in the intensive care unit (ICU) setting. Several identical sequence types of ST93 (2 identical in H1), ST36 (2 identical in H1) and ST2 (5 identical for H1 and 2 identical for H2) were also observed from different patients in both hospitals. Unlike H1, H2 only has ST2 as a predominant cluster. Other sporadic sequence types such as ST119, ST36, ST49, ST212, ST667 for H1 and ST395, ST214, ST427 and ST268 for H2 were also observed.Figure 1. MInimum Spanning Tree of Acinetobacter strains in hospitals (H1 and H2) and different wards (U1-U12). For identical strains circles are marked with dividing lines. Different sequence types (STs) are marked om the side bar. ConclusionOur data suggests that ST2 is the predominant sequence type circulating in both the geographically distinct hospitals and is endemic to the ICU. There was in hospital spread of this distinct Acinetobacter sequence type from one patient to the other, raising concerns about infection control practices and the role of environment in the spread of these infections. Early detection of these endemic strains within the hospital may be critical in preventing healthcare-associated infections in the future.Disclosures Chetan Jinadatha, MD, MPH, AHRQ (Research Grant or Support)Department of Veterans Affairs (Other Financial or Material Support, Owner: Department of Veterans Affairs. Licensed to: Xenex Disinfection System, San Antonio, TX)Inventor (Other Financial or Material Support, Methods for organizing the disinfection of one or more items contaminated with biological agents)NiH/NINR (Research Grant or Support)NSF (Research Grant or Support)Xenex Healthcare Services (Research Grant or Support) Mark Stibich, PhD MHS, Xenex Disinfection Services, Inc (Board Member, Employee)

A sub-pixel circle detection algorithm combined with improved RHT and fitting

Circle extraction is usually a pre-completed task used in different applications related to medical, robotics, biometrics image analysis among others. Randomized Hough Transform (RHT) determines the parameters of the circle by randomly obtaining three edge pixels, if they are not precisely located on the circumference. The detected circle will not perfectly match the ideal circle. At the same time, three random points are largely not on a circle, which leads to some invalid sampling and parameter accumulation. In this paper, an improved RHT combined with fitting subpixel circle detection algorithm is proposed. The improved RHT algorithm calculates and accumulates parameters by using 1 point obtained from random sampling and another two points obtained from horizontal and vertical search respectively. The algorithm introduces the edge map of the de-soliton point and small region, and improves the probability that three points belong to the same circle. Then, the set of edge pixels corresponding to the identified circle is fitted to reduce the bias effect caused by only using three edge pixels to calculate the circle parameters. In this way, the reliability of the fitting and the precision of the parameters are improved while removing the noise. Experimental tests were conducted for detection performance, accuracy of parameter estimation and noise robustness. Compared with other methods, the proposed method has strong anti-interference ability and high calculation accuracy.