Circular Objects Research Articles

Evaluation of force term in lattice Boltzmann method with discrete external boundary force for flow over an immersed body

In this paper, lattice Boltzmann method is used for the simulation of two-dimensional flow over an immersed solid body using external boundary force. Fluid simulation is performed using the Eulerian grid for the entire computational domain, while the domain of solid body is discretized using a boundary-fitted Lagrangian grid, imposed on the uniform Eulerian grid. Fluid–solid interaction is modeled using external boundary force (EBF) technique. Two different methods of implementing boundary force are discussed including modification in (a) collision step of LBM and (b) both collision and computation of macroscopic velocity steps. Computations are performed for flow over a stationary circular object as well as particle sedimentation. Results of drag force and sedimentation velocity show good correspondence with previously published ones at Re =1.0 for both methods. No discrepancy in results was observed between two methods for higher Reynolds numbers. Results obtained for sedimentation of an elliptical object show that the type of implementation of boundary force has no significant effect on the predicted location and angular position of the elliptical object. Furthermore, it is observed that more accurate results are obtained by introducing a modification in EBF for which solutions were independent of the number of nodes on the surface boundary.

Collision Avoidance of Arbitrarily Shaped Deforming Objects Using Collision Cones

In this letter, the problem of collision avoidance of objects, which can deform by changing their shape as a function of time, is considered. There are several scenarios involving such deforming objects—examples include environments with shape-shifting robots, such as snake robots, boundaries of swarms of vehicles, and boundaries of oil spills. There is very limited work in the literature that considers dynamic environments comprising such shape changing entities. To develop conditions that predict the onset of collision for deformable objects, this letter uses the notion of collision cones in environments involving engagements between a point object and a deforming object, a circular object and a deforming object, and finally, an arbitrarily shaped object and a deforming object. The collision cone equations are subsequently embedded in a Lyapunov framework and used to develop nonlinear analytical guidance laws for collision avoidance in such environments. Simulations are performed to demonstrate the efficacy of the guidance laws.

End-of-waste life: Inventory of alternative end-of-use recirculation routes of bio-based plastics in the European Union context

The bio-based products market is currently limited resulting in relatively small quantities of waste streams, viewed as contaminants of conventional waste streams. The steady growth of bio-based products however, drives the need to investigate their End-of-Use (EoU)/End-of-Life (EoL) alternatives. A critical review of the inventory of targeted valorization options for bio-based plastic waste is presented with limitations and opportunities. Impacts on the conventional waste management routes and the environment are considered. The provisions of the circular economy package, the targets and objectives set by the relevant EU environmental legislation, are used as key drivers for developing the inventory of the alternative EoU/EoL routes. Optimal alternative EoU/EoL routes are defined for the bio-based products in such a way that they are turned into valuable resources for the circular economy. This is a prerequisite to promote recirculation of bio-based by-products and waste streams along the whole chain of their production and use. The expected impacts include reduction of public health and environmental pollution problems, preservation of natural resources, reduction of GHG emissions, avoidance of landscape deterioration and land and marine littering.

Rate and Collision Probability of Tethers and Sails Against Debris or Spacecraft

The work done on probability of collision between spherical objects in orbit is extended here to the case of one spherical object and one circular or rectangular object. The former is a model for spacecraft or debris, whereas the latter is a model for a sail or a tether. Two kinds of computations are done. The first kind is the computation of the collision rate when the flux of one object (typically debris) with respect to the other object is known. This information is important when planning a mission. The second kind is the computation of the collision probability for a particular pair of objects whose probability density functions of the positions are known. This information is necessary to decide whether an evasive maneuver will be performed or not.

DESIGN OF LEARNING MATERIALS ON CIRCLE BASED ON MATHEMATICAL COMMUNICATION

Mathematical communication skills is an important role in mathematics learning. However, the importance of mathematical communication skills has not been fully realized in learning, especially circle material. Design a learning material based on mathematical communication is one way to develop this ability. The preliminary study produced the findings of an epistemological learning obstacle so that students' mathematical communication skills were still in the low category. This study aimed to analyze learning obstacle and designing learning materials based on the material mathematical communication circle. This study is design research that contained two stages of Didactical Design Research (DDR), didactic situation and metapedadidactional stage. Research result obtained are students difficulties in relating the material defining elements of the circle with their own language, identifying circle elements that were known and explaining through pictures, calculating the circumference and distance of circular objects based on problems, calculating the surface area of circular objects based on the problems, and rearrange the formula which states the relationship of circle elements. To solve that learning obstacle, we recommend some learning trajectory in a circle that useful for teachers. This design of learning material is valid and practical to implement in the classroom.

Pose regulation of a constrained circular object using Echo State Networks

Pose regulation of a constrained circular object using Echo State Networks

A stimulus–response-based allocation method for the circle packing problem with equilibrium constraints

Based on the industrial background of packing objects inside the satellites, this paper addresses the circle packing problem with equilibrium constraints. From a new view of any solid material occupying certain space, a solution of the problem can be seen as different circular objects occupy different space in the container. Hence, the circle packing problem can be treated as a space allocation problem of allocating the container space reasonably to circular objects. Through the mapping between the task allocation in swarm intelligence labor division and the space allocation in circle packing problems, we propose a stimulus–response-based allocation (SRA) method. In this paper, we design four actions, viz., fix, shift, jump and swap, for circular objects to occupy the container space. The SRA method adopts the stimulus–response mechanism of labor division to regulate the actions performed on circular objects. With the characteristic of flexibility inherent in the stimulus–response mechanism, SRA could achieve an effective space allocation under dynamically changed packing environments. Three sets of 35 benchmark instances are used to test the performance of SRA, and SRA improves the best-known results on 28 instances, matches 4 and misses 3.

Spectra restoration and image reconstruction of a J0 amplitude transmittance object with circular symmetry.

It is known that image reconstruction (Talbot images) and spectra restoration (Talbot spectra) phenomena can be found for light diffraction of linear periodic structures. In this work the possibility of finding similar effects for a circular symmetric object, especially for one with amplitude transmittance J0(ρ) (zero-order Bessel function of the first kind) is discussed theoretically. The transfer function approach and the spatial-spectral correspondence relationship are used to investigate these effects, and conditions for image reconstruction and spectra restoration in the near field are obtained. The discussion of a more general form of amplitude transmittance is also included, and a comparison between the two types (linear periodic and circular symmetric structures) is made.

Precise pose and radius estimation of circular target based on binocular vision

A novel method of estimating circle pose and radius is proposed, based on binocular vision. This method uses the special vectors that are irrelevant to the unknown radius to calculate the normal vector of the circular plane, which is the foundation for calculating the vanishing line of the circular plane in the imaging plane. The projections of the circle center on the left and right image are calculated afterwards through the vanishing line. Then, the circle center is reconstructed by the triangulation technology of binocular stereo vision. Finally, the radius of the circular target is calculated through the relative positions of points in the same coordinate system. The estimates of normal vector, center position, and radius size are unique and definite, so there is no need for a subsequent screening process. When the radius is unknown, most of the conventional circle pose estimation methods are unusable. However, the proposed method has no prerequisites about the circular target in order to estimate the pose and radius of the circular target, which improves flexibility and extends the application field. Besides estimating the pose of a circular target of unknown radius, the proposed method can also be applied to the vision measurement of the radius of a circular object. Both actual measurement experiments and noise simulation experiments are performed. The results show that the proposed method is more precise and robust than conventional methods.

A Phenomenal Defense of Reflective Equilibrium

The method of reflective equilibrium starts with a set of initial judgments about some subject matter and refines that set to arrive at an improved philosophical worldview. However, the method faces two, trenchant objections. The Garbage-In, Garbage-Out Objection argues that reflective equilibrium fails because it has no principled reason to rely on some inputs to the method rather than others and putting garbage-in assures you of getting garbage-out. The Circularity Objection argues that reflective equilibrium fails because it has no principled, non-circular way of sorting whatever is put into the method. The moves required to avoid both objections are instructive. Reflective equilibrium requires a meta-justification, and we offer one that appeals to the epistemic goods that underwrite a view known as phenomenal conservatism. Reflective equilibrium calls on us to start with what seems most likely to be true and to alter that collection of judgments in the ways that seem most likely to get us to the truth. Proceeding in this way is epistemically defensible and unavoidable. Hence, reflective equilibrium is not just good, it’s phenomenal.

Binary monkey algorithm for approximate packing non-congruent circles in a rectangular container

A Packing problem consists in the best arrangement of several objects inside a bounded area named as the container. This arrangement must fulfill with technological constraints, for example, objects should not be overlapping. Some packing models for circular objects are typically formulated as non-convex optimization problems; where the continuous variables are the coordinates of the objects, so they are limited to not finding optimal solutions. Due to the combinatorial nature in the arrangement of such objects, heuristic methods are being used extensively which combine methods of global search and methods of local exhaustive search of local minima or their approximations. In this paper, we will address the packing problem for non-congruent (different size) circles with the binary version of the monkey algorithm which incorporates a cooperation process and a greedy strategy. We use a rectangular grid for covering the container. Every node in the grid represent potential positions for a circle. In this sense, binary monkey algorithm for the knapsack problem, can be used to solve de 0–1 approximate packing problem for non-congruet circles. The binary monkey problem uses two additional processes of the original monkey algorithm, these two processes are a greedy process and a cooperation processes.

Solution of the inverse problem of magnetic induction tomography based on Helmholtz coil

Magnetic induction tomography is a contactless technique that can measure conductivity distribution in biological tissues. This study proposed that Helmholtz coils as the excitation coils will generate a set of uniform excitation fields. The system model consists of a circular background area, a circular disturbance object, a set of Helmholtz coils, and eight magnetic detection coils. The diameter of the Helmholtz coil is 200 mm. The detection coil is a square, and its side length is 12 mm. The excitation current of the system is 30 mA, and the frequency is 10 MHz. This study discusses the reconstructed images of different locations, different volumes, different distances, and different electrical conductivities of perturbation bodies. The anti-noise ability of different noise signals is also analysed. Finally, the image differences are evaluated through structural similarity index (SSIM). The results show that the algorithm can distinguish the position and volume characteristics of the target object. However, when the volume of the target object is low, the position will be deviated. This algorithm can distinguish the position of the two, which is far away from each other.

Foreign Body Extraction Extravaganza! Approach to 25 Foreign Bodies, One Patient

Introduction: Specific characteristics of foreign bodies can present as challenges to successful endoscopic removal. Endoscopic removal is urgent in cases of sharp objects, esophageal obstruction, or battery ingestion. Case: A 45-year old Caucasian inmate with a history of bipolar disorder, self-injurious behavior (including self-mutilation creating enterocutaneous fistula), and ingestion of six AA batteries previously presented for repeat ingestion of multiple foreign bodies with diffuse abdominal pain, hemoptysis, and nausea. His vitals were stable with no significant lab abnormalities. Abdominal x-ray revealed 3 radio-opaque foreign bodies: An irregular circular object, a straightened paperclip, and a hexagonal/rectangular density. Cross-sectional imaging noted stable appearance straightened paperclip was interposed between stomach and transverse colon mesentery without perforation or inflammation. Neck and chest x-rays were negative for perforated viscus. Upper endoscopy was initially performed with moderate sedation, revealing multiple sharp razor blades in the stomach. The procedure was aborted to be performed with general anesthesia. Subsequent endoscopy resumed under general anesthesia. A blunt disc-shaped metallic object was removed with rat-toothed forceps and one AA battery was removed with a snare. A hood placed at the end of the endoscope for removal of sharp razorblades, however only partially opened at GE junction. A long esophageal overtube was placed. Subsequently, 21 razor blades were individually removed as an endoscopy technician held overtube in place to prevent migration and exposing GE junction/distal esophagus to sharp objects. Finally, two irregular circular objects, one of which became lodged into the overtube, were removed with both the snared lodged object and overtube taken out together from the mouth at the conclusion of the procedure. The patient tolerated the procedure well and was extubated without complication. Follow up abdominal x-ray did not reveal any remaining foreign bodies. The patient remained stable and discharged. Conclusions: Endotracheal intubation and general anesthesia should be considered for prolonged cases and safe endoscopic removal of multiple and/or sharp foreign bodies. A long esophageal overtube is preferred over hood for removal of sharp objects from the stomach. Future design improvements in endoscopic tools could aid in safer and more effective means of foreign body removal.1889_A Figure 1 No Caption available.1889_B Figure 2 No Caption available.1889_C Figure 3 No Caption available.

Investigation into Squeeze-Film Induced Levitation of Light Objects

The performance of a system consisting of a thin rectangular plate under plane stress due to the action of PZT actuators, thus subjected to the Poisson’s contraction effect, and a light circular object freely floating over it was studied both numerically and experimentally. The results show that performance of the system is influenced by a few factors, including the magnitude of elastic deformation of the plate and the electrostatic action of the PZTs attached to the plate, which combine to form oscillating dimples created by the Poisson’s effect to separate the object from the plate with a film of compressible fluid. The importance of operating frequency of PZTs, shape and size of the dimple, offset and amplitude voltage under which PZTs operate, and distribution of PZTs on the plate’s surface were all examined theoretically and verified experimentally. The plate was made of aluminium and stainless steel in order to find out the importance of the material’s energy absorption rate for the effectiveness of squeeze-film induced levitation. The agreement between theoretical models and experimental measurements proved to be quite satisfactory.

약속의무에 관한 확신견해는 순환성반론에 취약한가?

약속의무에 관한 확신견해는 순환성반론에 취약한가?

DEVELOPMENT OF AN INDIGENOUS ENVIRONMENTAL FRIENDLY REFUSE PICKER

Handling and removal of harmful waste from our environment is a collective responsibility that all must embrace to make the world a safe habitat. A low cost environmental friendly waste picker was devel-oped. Biometric force evaluation of the end user obtained averaged 469.73 N. The refuse picker was calibrated to obtain the spring constant of 3030.73 N/m. The tool was tested and found to perform well in picking objects of different weights and of regular and irregular shapes ranging from 0.12 g to 2.72 kg. Serrated jaw enhanced the picking performance of the unit whilst picking a circular object without slipping off. The maximum safe horizontal and vertical loading recommended for the tool at picking was 0.5 kg. The picker was used to pick the smallest item, a pin of diameter 0.70 mm and weight of 0.12 g successfully. This tool can be very handy in the hospital where harmful waste such as needles, syringes and other unhealthy substances and waste must be removed from the environment. The tool was made from low cost materials with 40% less than the existing ones.

Split Packing: Algorithms for Packing Circles with Optimal Worst-Case Density

In the classic, \(\mathsf {NP}\)-hard circle packing problem, one asks whether a given set of circles can be packed into a given container. In this paper, we present new sufficient conditions for packing circles into square and triangular containers, using only the sum of the circles’ areas: for square containers, it is possible to pack any set of circles with a combined area of up to \(\approx \!\,53.90\%\) of the square’s area. And when the container is a right or obtuse triangle, any set of circles whose combined area does not exceed the triangle’s incircle can be packed. These area conditions are tight: for any larger areas, there are sets of circles which cannot be packed. Similar results have long been known for squares, but to the best of our knowledge, we give the first results of this type for circular objects. Our proofs are constructive: we describe a versatile, divide-and-conquer-based algorithm for packing circles into various container shapes with optimal worst-case density, which employs an elegant, recursive subdivision scheme. We call this algorithm Split Packing. It can be used as a constant-factor approximation algorithm when looking for the smallest container in which a given set of circles can be packed, due to its polynomial runtime. A visualization can be found at https://morr.cc/split-packing/.

Multi-Scale Simulation of Well-Entangled Polymer Melt Flows in a Channel

In order to produce better polymeric goods, it is important to predict and to control a flow behavior of a polymeric fluid. To understand a flow behavior of a polymeric fluid, computational approach is quite effective. It is well-known that polymeric fluids exhibit complex flow behaviors owing to a strong correlation between the state of macroscopic flow and the microscopic state of polymer chains. The complex flow behaviors are originated from the stress tensor in the Cauchy momentum equation. When solving the equation, a constitutive equation is usually used to evaluate the stress tensor from the local deformation rate tensor and a set of parameters. By using a constitutive equation, however, it is difficult to reflect the microscopic state to the macroscopic flow. As one of the methods to overcome the difficulty, it has been proposed to use a multi-scale simulation (MSS) method where local microscopic states and the macroscopic flow are directly connecting each other. So far, the MSS method has succeeded in predicting the flow in simpler geometries such as a flow in between two parallel plates and polymer melt flows passing a circular object in a two-dimensional periodic system. To develop further the MSS method that can deal with more industrially oriented problems, it is necessarily to investigate the applicability of the method to a flow in complicated geometry of boundary. In this context, we have applied the multiscale simulation technique to flows of polymer melts in a channel with 4:1:4 contraction and expansion geometry. In the MSS method, we introduced Lagrangian particles which contain many chains to precisely maintain the microscopic states. As the microscopic polymer model, a slip-link model is used. Using the multiscale simulation method, we investigated the macroscopic spatial distribution of microscopic quantities, such as the spatial distribution of polymer chain orientation and the number of entanglements. We found that the number of entanglements strongly decreases around the middle of the polymer chains. This kind of information can be helpful when designing polymer melts with specific properties.

Enrichment Preferences of FIV-Infected and Uninfected Laboratory-Housed Cats

Environmental enrichment is critical for alleviating stress in laboratory felines. However, there is a paucity of information about suitable enrichment for cats. This study aimed to determine preferred enrichment options of individually-housed, castrated male domestic short hair cats (Felis catus) used in a longitudinal study of the effects of chronic feline immunodeficiency virus (FIV) infection, and to determine if the FIV status of the cats affected enrichment preferences. Preference testing was performed with two types of grooming brushes, three different interactive play options, including a laser, ball, and petting interaction with a familiar investigator, and two types of toenail conditioning objects. We found that cats elected to be brushed, preferred social interaction and play with the laser to the ball, and preferred to scratch on an inclined-box toenail conditioning object compared to a horizontal, circular toenail conditioning object. There were individual preferences for enrichment opportunities. There were no differences in preferences between FIV-infected and sham-infected cats. These enrichment preferences may be used to advise laboratory animal facilities and researchers about how to best accommodate the behavioral needs of laboratory cats.

Automated detection of parasitized Cadra cautella eggs by Trichogramma bourarachae using machine vision

Cadra (Ephestia) cautella (Walker) is a moth that attacks dates from ripening stages while on tree, throughout storage, and until consumption, causing enormous qualitative and quantitative damages, resulting in economic losses. Image-processing algorithms were developed for detecting and differentiating between three Cadra egg categories based on the success of Trichogramma bourarachae (Pintureau and Babaul) parasitization. These categories were parasitized (black and dark red), unparasitized fertile unhatched (yellow), and unparasitized hatched (white) eggs. Color, light intensity, and shape information was used to develop detection algorithms. Two image processing methods were developed based on three randomly selected images and were tested on a larger validation image set of 40 images: (i) segmentation and extractions of color and morphological features followed by Watershed delineation, and is referred to as Algorithm 1 (ALGO1), (ii) finding circular objects by Hough Transformation followed by convolution filtering, and is referred to as Algorithm 2 (ALGO2). ALGO1 and ALGO2 achieved correct classification rates (CCRs) for parasitized eggs of 92% and 96%, respectively. Their CCRs for unhatched eggs were 48% and 94%, and for hatched eggs were 42% and 73%, respectively. Regarding parasitized eggs, both methods performed satisfactorily, but, in general, ALGO2 outperformed ALGO1. These results ensure automatic evaluation of the efficiency of biological control of Cadra cautella by the egg parasitoid Trichogramma bourarachae by quantifying the rate of parasitization. The developed detection methods can be used by producers of biocontrol agents for online monitoring of Trichogramma and similar insect natural enemies during mass production and before release against crop pests. Moreover, with few adjustments these methods can be used in similar applications such as detecting plant diseases. Keywords: Trichogramma parasitization, Cadra eggs detection, machine vision, date fruit, image processing, objects recognition algorithms, biological control DOI: 10.25165/j.ijabe.20181103.2895 Citation: El-Faki M S, Song Y Q, Zhang N Q, El-Shafie H A, Xin P. Automated detection of parasitized Cadra cautella eggs by Trichogramma bourarachae using machine vision. Int J Agric & Biol Eng, 2018; 11(3): 94–101.