Non-circular Patterns Research Articles

Balanced clustering for student admission school zoning by parameter tuning of constrained k-means

The Indonesian government issued a regulation through the Ministry of Education and Culture, number 51 of 2018, which contains zoning rules to improve the quality of education in school educational institutions. This research aims to compare the performance of the k-means algorithm with the constrained k-means algorithm to model the zoning of each school area based on the shortest distance parameter between the school location and the domicile of prospective students. The study used data from 2248 prospective students and 22 public school locations. The results of testing the k-means algorithm in grouping showed the formation of non-circular patterns in the cluster membership with different numbers of centroid cluster members. In contrast, testing the constrained k-means algorithm showed balanced outcomes in cluster membership with a membership value of 103 for each school as the cluster center. The research findings state that the developed constrained k-means algorithm solves the problem of unbalanced data clustering and overlapping issues in the process of new student admissions. In other words, the constrained k-means algorithm can be a reference for the government in making decisions on new student admissions

Ritornell and Episodic Composition in Empedocles

Abstract Empedocles made use of two typical features of hexameter composition: Ritornellkomposition and episodic composition. By repeating lines in non-linear and non-circular patterns, Empedocles organized the episodes that made up his poem and invited his audience to reconstruct the relationship between them. Differences within repeated lines are not just variations but significant linguistic elements that determine the meaning: whereas the notion of repetition is misleading because it is vague and puts too much emphasis on similitude, a model that combines the notion of Ritornell with that of episodic composition allows us to apprehend more fully the meaning of the poetic organization of the material.

Bit-Parallel Approximate Matching of Circular Strings with k Mismatches

We consider approximate string matching of a circular pattern consisting of the rotations of a pattern of length m . From SBNDM and Tuned Shift-Add, we derive a sublinear-time algorithm for searching a noncircular pattern with k allowed mismatches, which is extended to the problem of approximate circular pattern matching with k mismatches. We prove that the presented algorithms are average-optimal for m ⋅⌈log 2 ( k +1)+1 ⌉ = O ( w ), where w is the size of the computer word in bits. Experiments conducted under the aforementioned condition show that the new k -mismatches algorithm for circular strings outperforms previous solutions in practice. In particular, our algorithm is the first nonfiltering method for approximate circular string matching in sublinear average time, which makes it more suitable than earlier filtering methods for high error levels k / m and small alphabets.

Dynamic performance analysis of a noncircular cylindrical floating ring bearing

The performance of a noncircular cylindrical floating ring bearing under the laminar flow condition has been analyzed. The noncircular cylindrical floating ring bearing is a modified version of the plain cylindrical floating ring bearing in which the outer bearing of the cylindrical floating ring bearing is changed in the form of lobed pattern. The noncircular patterns are known for its better stability and stiffness behavior according to the magnitude of applied loads. The finite element analysis has been used to solve the classical Navier–Stokes equations in the cylindrical coordinates of the modified form along with the continuity equation that represents the fluid flow field in the clearance space of the noncircular cylindrical floating ring bearing. The numerical data are for a proposed bearing with the length to diameter ratio of 1.0, and values of the ratio of film clearances of 0.70 and 1.30. Performance characteristics of a finite noncircular cylindrical floating ring bearing has been studied in terms of the inner and outer film eccentricity ratio, Sommerfeld number, attitude angle, stiffness and damping coefficients, equivalent support stiffness coefficient, whirl frequency ratio, and critical journal mass at various values of the outer film eccentricity ratios. The proposed analysis disseminates that the dynamic performance parameters of the noncircular cylindrical floating ring bearing are much better than the plain cylindrical floating ring bearing.

Polymer pattern transformation and inorganic polygonal networks driven by thermal degradation process

We describe a simple method to produce novel transformation of polymer pore patterns from circular to noncircular by annealing porous PVA films. These films were prepared by modified microcontact printing (μcp) technique of transferring colloidal crystals onto PVA-coated substrate. Two-dimensional ordered noncircular patterns, such as squares or hexagons depending on the lattice of colloidal templates, were fabricated. The pattern transformation from circular to noncircular is driven by thermal degradation of PVA. Furthermore, inorganic network structures were fabricated by mixing different decomposable inorganic precursors with PVA and using polymer matrix as structure-directing agent in the following pyrolysis process. The organic components of the hybrid film were removed by calcinations and finally inorganic polygonal networks were left on the substrate. These noncircular nanostructures may have unique size- and shape-dependent optical, electronic and magnetic properties.

Serial Pushing Model for the Self-Assembly in Dip-Pen Nanolithography

Based on the findings of molecular dynamics simulations, we propose a novel diffusion model for the self-assembly in dip-pen nanolithography. A central question in such modeling is how a nascent droplet created below an AFM tip spreads out to form a self-assembled monolayer (SAM) on a substrate later. In the present model, a molecule dropping from the tip pushes a molecule on the substrate out of its original position, and the molecule pushed out in turn pushes its own neighbor. A SAM grows through such a series of push-induced movements. The initial pushing propagates all the way to the periphery where there is no molecule to push out. By contrast, according to the previous hopping-down model, a molecule moves by stepping over molecules trapped on the substrate and occasionally hops down to the substrate. By implementing our model in random walk simulations, we study the structure and growth dynamics of the SAM generated by a fixed tip and the lines and characters created by a moving tip. We investigate how the SAM is influenced by the molecular dripping rate and tip scan speed. Compared to the hopping model, the present model gives a SAM growing faster and more fluctuating in its periphery. A salient feature of our model is its ability to generate various SAMs by changing the directional coherence length of the push-induced displacement. If we choose the coherence length to be zero, each push-induced displacement is random in direction to give a compact circular SAM. As the directional coherence length increases, the SAM becomes a noncircular pattern with distinct branches. In the limit of an infinite coherence length, the SAM becomes a long narrow cross due to the substrate anisotropy.

Common mechanism links spiral wave meandering and wave-front–obstacle separation

Spiral waves appear in many excitable chemical and biological media @1#. The spiral wave tip either rotates around a circular unexcited core or meanders, inscribing a noncircular pattern often similar to that of a multipetal flower. From numerical studies of FitzHugh-Nagumo-like models for a variety of medium parameters, Zykov @2# and Winfree @3# found a distinct boundary separating meandering from circular tip movement, suggesting that transitions between different modes of tip movement were dependent on certain medium parameter values. The transition from circular spiral tip motion to meandering is known to occur when the spiral tip approaches its refractory tail. The minimal distance between the spiral tip and refractory tail associated with the meandering transition and its relation to medium properties, though, is uncertain. Recently numerical studies of Karma @4# showed that meandering corresponds to the superposition of two rotating spiral wave solutions. He found that the reaction-diffusion field at points located on the wave front near the minimal core radius associated with the meandering transition ~determined numerically! displayed quasiperiodic variations originating from a supercritical Hopf bifurcation. Analytical investigations of spiral core stability by Kessler et al. @5# based on kinematic theory did not confirm this behavior, probably because their analysis was performed within a kinematic framework that differed significantly from the framework of Karma’s analysis @4#. Moreover, the kinematic approach is limited by the assumption that the wave radius of curvature is large compared with the wavelength, a condition that is not fulfilled at the spiral tip @6#. Barkley developed a phenomenological model that reproduced complex spiral tip movement @7#. However, based on the ordinary differential equation representation, this model did not describe the transition to meandering and did not provide a minimal core radius associated with a meandering transition boundary since it neglected generic diffusive properties of an excitable medium. In this paper, we show that the conditions associated with the meandering transition are equivalent to conditions associated with the transition between wave-front‐obstacle attachment and separation following a wave-obstacle interaction @Fig. 1~a!#. We found that the minimal distance that the spiral wave tip can approach its refractory tail without meandering is of the order of Lcrit , the wave-front thickness of a wave propagating with zero velocity. Following interaction with an unexcitable strip of thickness Lcrit , there are two possible outcomes. If the wave tip wraps itself around the end of this unexcitable strip, then it will meander if the strip is removed. Alternatively, if the wave tip separates from the end of the strip, then removal will result in circular spiral tip motion. Over a range of medium parameters, this transition can be accurately predicted by approximating the diffusive fluxes within the boundary layer at the wave tip @9,10#. Here we consider nonlinear reaction-diffusion equations of the FitzHugh-Nagumo class:

Modeling of a Liquid Phase Geothermal Doublet System at Regina, Saskatchewan, Canada

The paper describes a computer‐mathematical model used to analyze the nature of the subsurface temperature disturbance that results from extraction of hot liquid from a geothermal production well with concurrent injection of cooled tailings water in a nearby disposal well. The model was designed specifically to determine, at an early stage of development, an appropriate well spacing for the sedimentary‐basin geothermal project at Regina, Canada. Assumptions include an infinite horizontal confined aquifer with uniform thickness and a finely dispersed pore system. The mathematical model is based on an energy balance equation that combines Darcy's law, Fourier's law, and the change in heat content of an element within the active zone of the aquifer. The numerical model is developed by means of the integrated finite difference technique. Short computer run times are achieved through the use of symmetry, an expanding grid system, and the use of the Theis solution. Investigation of model sensitivity shows the model to be sensitive to such factors as interwell distance, pumping rates, porosity, and aquifer thickness, but quite insensitive to hydraulic conductivity and storativity. Sample results are given for Regin aquifers undergoing both continuous and seasonal pumping. Isotherm maps show that the temperature disturbance evolves with time from a cooled, circular area around the injection well to a strongly noncircular pattern with a protrusion of cooled water extending toward the production well. The model is used to predict time of thermal breakthrough for Regina aquifers using different pumping rates and interwell distances. Temperature histories for continuous pumping show that after thermal breakthrough, the produced water undergoes a slight decline of temperature over a considerable time span. For the withdrawal of equal volumes of fluid, the temperature disturbance around the disposal well is spread over a slightly larger area for the seasonal pumping case compared to continuous pumping. The thermal front is broader for the seasonal case because of the longer period of elapsed time during which thermal conduction occurs. For seasonal operations, thermal breakthrough will occur after less water has been pumped and there is a more gradual decline in the temperature of the production well after thermal breakthrough.

Retinal inhomogeneity. III. Circular-retina theory.

By introducing a local contrast-sensitivity function, defined as the Fourier transform of the local point-spread function, we have constructed a model of retinal inhomogeneity that predicts the contrast sensitivity for circular homogeneous or inhomogeneous sinusoidal targets up to 16 degrees in diameter. This model assumes that (1) contrast sensitivity is mediated by a standard, receptive-field-type filter function (one that fits our data somewhat better than available receptive-field models); (2) retinal inhomogeneity is circularly symmetric; i.e., receptive-field size varies only with eccentricity; (3) this size variation is governed by a linear scaling factor out to at least 8 degrees eccentricity; and (4) the local contrast sensitivities at different parts of the retina combine in accord with a fourth-power probability-summation rule. The parameters of the model were determined by fitting contrast-sensitivity data for a new class of stimulus patterns: locally sinusoidal, circularly symmetric targets with radially varying spatial frequency (but constant amplitude). The model also fits contrast thresholds for circular cosine disks and annuli of various sizes and eccentricities. (Predictions for noncircular patterns require a minor extension.) The results suggest that the uniform, homogeneous sinusoidal patterns used throughout the literature provide surprisingly little information about the form of receptive fields.

The relative luminosities of the disk and the invisible of M82 a rediscussion of the polarization pattern

AbstractThe origin of the noncircular pattern of the polarization vectors in the halo of scattered light around M82 is discussed anew. This pattern had been interpreted by SOLINGER and MARKERT (1975) to indicate a high contribution of the disk to the illumination of the halo, whereas the blue colour of the halo demands a significant contribution from a very blue illuminating source, the nucleus. The discussion of SOLINGER and MARKERT has been modified in two respects: 1. an extinction in the disk M82, distributed similar to the stars, is assumed; this strengthens the disk's ability to turn the polarization vectors parallel to itself, and 2. an original polarization of the nuclear light parallel to the galaxy's plane is assumed; this also causes a corresponding turning of the polarization vectors.The new estimate of the nuclear luminosity relative to the disk luminosity is LN/LD = 0.7 ± 0.3 compared to 0.05 by SOLINGER and MARKERT. This luminosity ratio enables the nucleus to determine the colour of the scattered light near the minor axis at low and medium distances from the centre.

Comparative ultrastructural study of spermiogenesis in monogeneans (flatworms): 3. Two species of Amphibdelloides (Monopisthocotylea, Amphibdellatidae)

Two species of the genus Amphibdelloides are described here. They exhibit essentially the same general sperm morphology. However, some minor differences exist. The spermatozoon is filiform and uniflagellate, and is comprised of several regions: (a) anterior extremity showing a single centriolar derivative made up of doublets and a cap-shaped centriolar adjunct; (b) a middle region containing parallel mitochondrion, nucleus, and a 9 + “1” axoneme; (c) a posterior region with only nucleus and axoneme, and (d) a posterior tip where the axoneme is simplified into singlets. In Amphibdelloides sp. 1, the axoneme is altered in the posterior region only: the nucleus is tightly pressed along the axoneme, causing the peripheral doublets to display a noncircular pattern. This spermatozoon is feebly motile. In Amphibdelloides sp. 2, the alteration extends along the whole length of the axoneme, and the spermatozoon is immotile. In Amphibdelloides sp. 1, two kinds of spermatozoa may be found, one with a straight nucleus and the other with a coiled nucleus; sperm polymorphism seems to exist within this species.

The Function of Eyespot Patterns in the Lepidoptera

1. Lepidoptera belonging to several different families bear eyespot patterns on their wings, often with a very strong resemblance to the vertebrate eye. These have been derived from different morphological structures in different groups, and their evolution is therefore convergent within the order. 2. A study of two individual hand-reared Yellow Buntings has shown that the pursuit of flying insect prey is fully released at the bird's first encounter with a flying butterfly, but that the orientation of the attack is modified by experience. 3. Eyespot patterns are associated with displays which exhibit them. In the case of a Nymphalid butterfly, Nymphalis io, an experiment has shown that the display releases escape responses from Yellow Buntings, and that the major part of this effect is due to the four ocelli on the upper surface of the fore- and hind wings. Experiments with other species of insects suggest that other factors contributing include the bright field of colour surrounding the eyespots, the rhythmic movements of the display, and the rustling noise which accompanies it. The bird's responses to this display waned rapidly in the majority of individuals, but some birds became conditioned to avoid the butterflies altogether. 4. Experiments with models showed that circular patterns presented suddenly to feeding birds (Chaffinches, Yellow Buntings and Great Tits) release escape responses more effectively than do non-circular patterns of the same area and perimeter. An increase in the perimeter of the models, achieved by the use of three concentric circles of the same area as the single circle, increased its releasing value. A flat, eye-like pattern which was so shaded and distorted as to appear three-dimensional was more effective than a similar flat pattern which was not shaded, and hence was more bright. Large models were more effective than similar small ones. Waning was again rapid. The differential responsiveness to circular and non-circular patterns is inborn in the case of Great Tits and Chaffinches. 5. An experiment with mealworms artifically ornamented with small eye-like spots at their extremities has shown that such markings, placed on a prey-object, tend to direct to themselves the attack of Yellow Buntings. The waning of the element of disturbed orientation in the responses is slow, and may not be significant. 6. The deflection and intimidation effects are discussed. The origin of the predator's responses to deflection marks is not known, but it is suggested that intimidating eyespots act by mimicking the eyes of the large avian predators preying on the small insectivorous passerines which are among their natural enemies. It has been shown that many small passerines possess inborn responses to their predators, and it is probable that these are parasitised by the eyespot patterns of insects. Eyespot patterns must be regarded as wholly distinct from pseudaposematic colouration. The effect of experience on small passerines, either of the predator-model or of an ocellated imitator, is most usually the reverse of that sustained by a predator encountering the model or mimic in a true case of Batesian or Mullerian mimicry, and the restrictions on the population size of a pseudaposematic insect relative to its model do not apply to insects utilising the inborn responses of their predators.