Solid Circle Research Articles

Novel Octa-Structure Metamaterial Architecture for High Q-Factor and High Sensitivity in THz Impedance Spectroscopy.

Terahertz (THz) electric inductive-capacitive (ELC) resonant metamaterials (MMs) are well established tools that can be used to detect the presence of dielectric material (e.g., nanoparticles, bioparticles, etc.) spread on their surfaces within the gap of the capacitive plates of a nanoantenna array. In THz spectroscopy, the amount of the red shift in the resonance frequency (ΔF) plays an important role in the detection of nanoparticles and their concentration. We introduce a new LC resonant MM architecture in the ELC category that maximizes dielectric sensitivity. The newly proposed architecture has an octahedral structure with uniform capacitive gaps at each forty-five-degree interval, making the structure super-symmetric and polarization independent. The inductor core is condensed into a central solid circle connecting all the eight lobes of the octahedron, thereby completing the LC circuit. This ELC resonator has very large active areas (capacitor-gaps), with hotspots at the periphery of each unit cell. The MM structure is repeated in a clustered fashion, so that the peripheral hotspots are also utilized in dielectric sensing. This results in enhancing the quality factor of MM resonance, as well as in increasing ΔF. The research comprises a combination of rigorous system-level simulations along with THz impedance spectroscopy laboratory experiments. We achieved a highly sensitive MM sensor with sensitivity reaching 1600 GHz/RIU. This sensor is fully CMOS compatible and has promising potential applications in high-sensitivity bio-sensing, characterization of nanoparticles, and ultra-low-concentration dielectrics detection, as well as in sensing differential changes in the composition of substances deposited on the metasurface.

Real-time generation of circular patterns in electron beam lithography

Electron beam lithography (EBL) involves the transfer of a pattern onto the surface of a substrate by first scanning a thin layer of organic film (called resist) on the surface by a tightly focused and precisely controlled electron beam (exposure) and then selectively removing the exposed or nonexposed regions of the resist in a solvent (developing). It is widely used for fabrication of integrated circuits, mask manufacturing, photoelectric device processing, and other fields. The key to drawing circular patterns by EBL is the graphics production and control. In an EBL system, an embedded processor calculates and generates the trajectory coordinates for movement of the electron beam, and outputs the corresponding voltage signal through a digital-to-analog converter (DAC) to control a deflector that changes the position of the electron beam. Through this procedure, it is possible to guarantee the accuracy and real-time control of electron beam scanning deflection. Existing EBL systems mostly use the method of polygonal approximation to expose circles. A circle is divided into several polygons, and the smaller the segmentation, the higher is the precision of the splicing circle. However, owing to the need to generate and scan each polygon separately, an increase in the number of segments will lead to a decrease in the overall lithography speed. In this paper, based on Bresenham’s circle algorithm and exploiting the capabilities of a field-programmable gate array and DAC, an improved real-time circle-producing algorithm is designed for EBL. The algorithm can directly generate circular graphics coordinates such as those for a single circle, solid circle, solid ring, or concentric ring, and is able to effectively realizes deflection and scanning of the electron beam for circular graphics lithography. Compared with the polygonal approximation method, the improved algorithm exhibits improved precision and speed. At the same time, the point generation strategy is optimized to solve the blank pixel and pseudo-pixel problems that arise with Bresenham’s circle algorithm. A complete electron beam deflection system is established to carry out lithography experiments, the results of which show that the error between the exposure results and the preset patterns is at the nanometer level, indicating that the improved algorithm meets the requirements for real-time control and high precision of EBL.

Failure to post-dilate BeSmooth peripheral stents to adult vessel size diameters during benchside tests

Low-profile stent implantation remains a rescue treatment for aortic coarctation and branch pulmonary arteries stenosis in small children. Stent re-expansion to cope with vascular growth remains problematic. To evaluate ex vivo feasibility and mechanical behaviour of over-dilating BeSmooth peripheral stents (Bentley InnoMed, Germany). Three BeSmooth peripheral stents in diameters of 7, 8, and 10 mm were dilated to nominal pressure and then 13 atm. BeSmooth Ø7 × 23 mm was sequentially post-dilated using 12, 14, and 16 mm high-pressure balloons. BeSmooth Ø10 × 57 mm was post-dilated with a 14 mm balloon and then with a 48 mm bare-metal Optimus XXL stent hand-mounted on a 14 mm balloon (stent-in-stent). BeSmooth Ø8 × 57 mm was directly post-dilated with a 48 mm bare-metal Optimus XXL stent hand-mounted on a 16 mm balloon (stent-in-stent). The stents' diameter and length were measured. Digital inflation pressure was noted. Balloon rupture and stent fracture patterns were closely evaluated. At 20atm pressure, BeSmooth Ø7 × 23 mm shortened to 2 mm forming a 12 mm diameter solid ring circle and the woven balloon ruptured radially. At 10 atm pressure, BeSmooth Ø10 × 57 mm fractured longitudinally in various dispatched breaking points at a diameter of 13 mm without shortening and ruptured the balloon with multiple pinholes. At 10 atm pressure, BeSmooth Ø8 × 57 mm fractured centrally at three different points at a diameter of 11.5 mm without shortening and the balloon broke radially in half. In our benchmark tests, extreme shortening, severe balloon rupture, or unpredictable stent fracture patterns at small balloon diameters limits safe post-dilation of BeSmooth stents beyond 13 mm. BeSmooth stents are not ideal candidates for off-label stent interventions in smaller patients.

Sterilization mechanism of helium/helium–oxygen atmospheric-pressure pulsed dielectric barrier discharge on membrane surface

Pulsed dielectric barrier discharge (PDBD) exhibits several applications in different fields; however, the interaction of its components with substances remains a key issue. In this study, we employed experimental and numerical modeling to investigate the interactions between different PDBD components and substances in pure helium and a helium–oxygen mixture. A membrane comprising a Staphylococcus aureus strain was utilized as the treatment object to demonstrate the trace actions of the evolutions and distributions of certain components on the surface of the substance. The results revealed that the shapes and sizes of the discharging area and inhibition zone differed between groups. Under a pure helium condition, a discharge layer existed along the membrane surface, lying beside the main discharging channel within the electrode area. Further, an annulus inhibition zone was formed at the outer edge of the electrode in the pure helium group at 30 s and 1 min, and this zone extended to a solid circle at 2 min with a radius that was ∼50% larger than that of the electrode radius. Nevertheless, the discharging channel and inhibition zone in the helium–oxygen mixture were constrained inside the electrode area without forming any annulus. A 2D symmetrical model was developed with COMSOL to simulate the spatiotemporal distributions of different particles over the membrane surface, and the result demonstrated that the main components, which formed the annulus inhibition zone under the pure helium condition, contributed to the high concentration of the He+ annulus that was formed at the outer edge of the electrode. Moreover, O+ and were the main components that killed the bacteria under the helium–oxygen mixture conditions. These results reveal that the homogenization treatment on a material surface via PDBD is closely related to the treatment time and working gas.

Plasma-Assisted Dinitrogen Activation via Dual Platinum Cluster Catalysis: A Strategy for Ammonia Synthesis under Mild Conditions

Plasma-Assisted Dinitrogen Activation via Dual Platinum Cluster Catalysis: A Strategy for Ammonia Synthesis under Mild Conditions

Design of four rotor aircraft with obstacle avoidance

The system uses TM4C123G as the core of quadrotor autonomous vehicle control, which consists of flight control module, power supply module, motor speed control module, optical flow sensing module, and target tracking identification module. The flight control module includes angle sensor, gyroscope, and TLS1401-LF module. The flight control processes the collected data through the chip (TM4C123G), and processes the data with PID control algorithm, while solving the PWM increment and decrement needed for the corresponding motor, adjusting the motor in time and adjusting the flight attitude. The binocular camera identifies the color of the pole tower and measures the distance, so that the distance between the aircraft and the nearest point of the pole tower is kept within 50±10cm. After detecting the red (green) tower as the center, fly around the tower clockwise (counter) for one week (top view). Finally, the OV7725 camera is used to identify the solid black circle mark of the landing point and land smoothly and accurately in the target area, thus realizing an efficient robot around the barrier.

ANALYZING THE PERFORMANCE OF CIRCLE SEGMENT END MILL WITH PCD INSERTS WITH LASER-MACHINED INTEGRAL CHIPBREAKER WHEN DRY MILLING OF ADDITIVE MANUFACTURED TI-6AL-4V TITANIUM ALLOY

Components with generally shaped surfaces requiring higher surface quality and dimensional accuracy are, in most cases, machined. Specifically, milling technology is involved very often, which can be supplemented by finishing operations. Besides standard ball-nose end mills, circle segment end mills are modern type of cutter that has begun to be used with the development of advanced computer aided machining software, that allows to work with these shaped tools. In this research, comparing the performance of these two modern shaped end mills was investigated. One tool was a commercially available coated solid carbide circle segment end mill. A second prototype end mill with the same profile but different geometry was made with a PCD insert, that additionally had a chipbreaker produced by laser technology. Machining was carried out on the workpiece material the Ti-6Al-4V that was manufactured by additive manufacturing (AM) technology – selective laser melting (SLM). The titanium complex parts are generally used in the transport industries and medicine. Milling tests were performed under dry cutting conditions. The evaluation was based on the force load, the roughness of the machined surface and tool wear. The higher total forces were measured by the tool with a PCD insert, because a different tool geometry was used, despite the use of integral chipbreaker, which allows a partial change of the cutting geometry of the insert. The geometry of end mills with brazed insert is limited by the production process.

MO614A PRACTICAL SOLUTION TO SCREEN COGNITIVE FRAILTY AMONG HEMODIALYSIS PATIENTS USING A GAME-BASED INTRADIALYTIC EXERCISE WITH WEARABLE SENSORS

Abstract Background and Aims Assessing and monitoring cognitive frailty (CF; coexistence of physical frailty and cognitive impairment) are critical for hemodialysis patients. For administering physical frailty and cognitive assessments, however, clinical settings need to address challenges (e.g., cost, human and technical resources, patient’s fatigue, etc.). This study aims to investigate the feasibility and accuracy of a novel intradialytic cognitive-demanding exercise program based on wearables, called, intradialytic-exergame for screening CF in hemodialysis patients. Method Individuals diagnosed with diabetes and end-stage renal disease requiring hemodialysis (n=28, age: 61.36 ± 6.85 years, 54% female) participated. All participants were assessed for physical frailty using the Fried frailty phenotype method and cognitive impairment using the Mini-Mental State Examination (MMSE). The Fried frailty phenotype method assesses physical frailty, which ranges between 0 and 5 based on five criteria (unintentional weight loss, weakness, slowness, exhaustion, and low physical activity). CF was determined with a frailty phenotype greater than or equal to 1 and a MMSE score less than or equal to 24. The intradialytic-exergame system consists of an inertial wearable sensor and an interactive software installed on a standard laptop. A clinician attaches one wearable sensor to each foot after the participant sits or lies down on a bed (Figure A). While undergoing hemodialysis treatment, the participant performs 15 non-weight-bearing cognitively-demanding dorsiflexion and plantarflexion exercises for each foot. For each exercise, the laptop’s screen displays a target (solid yellow circle) and a cursor (solid red square), which the participant points down for a dorsiflexion motion or up for a plantarflexion motion (Figure B). When the participant successfully puts the cursor in the target, the target disappears, and a new target appears in a different location on the screen (dashed yellow circle shown in Figure B). If the participant moves the cursor to a target in less than 2s, the custom software provides both visual (the target explodes) and auditory (positive sound) feedback as a reward (success). The three outcome measures (Exergame-slowness, frailty, and cognitive performance) were analyzed. Exergame-slowness was computed as an average of the ranges of ankle angular velocity measured by wearable sensors. Linear regression analysis was conducted for the three outcome measures to examine correlations between each outcome measure. Binary logistic regression model was conducted, and its area-under-curve (AUC) was calculated to determine the ability of Exergame-slowness to identify CF. An independent t-test was conducted to compare the differences of Exergame-slowness for CF and non-CF conditions. Significance was defined at the 2-sided p < 0.05 level. Results Five out of 28 participants were identified with CF. Significant correlations were observed between Exergame-slowness and frailty (p = 0.004, R = -0.531), Exergame-slowness and cognitive performance (p = 0.023, R = 0.437), and frailty and cognitive performance (p = 0.015, R = -0.463). The model was significantly reliable (p = 0.012) and its AUC was 0.90. Results indicated that Exergame-slowness was significantly higher (lower velocity) for participants with CF than for those with non-CF (CF: 27.41 ± 3.58 degree/s, non-CF: 34.25 ± 5.24 degree/s, p = 0.010). Conclusion To our knowledge, this is the first study to investigate the feasibility and accuracy of intradialytic-exergame with wearable sensors, as a practical tool for routine screening CF assessment in hemodialysis patients. The results of this study indicate that speed of ankle rotation, measurable using a wearable sensor during a simple intradialytic cognitive-demanding exercise, can be used as a practical digital biomarker for screening CF in hemodialysis patients.

An algorithm to measure shape of intravascular ultrasound image using image processing techniques

In diagnosing coronary artery disease, measurement of the cross-sectional area of the lumen, maximum and minimum diameter is very important. Mainly, it will be used to confirm the diagnosing, to predict the stenosis if any and to ensure the size of the stent to be used. However, the measurement only offers by the existing software and some of the software needs human interaction to complete the process. The purpose of this paper is to present the algorithm to measure the region of interest on intravascular ultrasound modality that is lumen and media adventitia area and diameter using an image processing technique. The methodology starts with the image acquisition process followed by image segmentation. After that, border for each region was detected and the algorithm was applied to calculate the corresponding region. The result shows that the measurement is accurate and could be used not only for intravascular ultrasound image but applicable to solid circle and irregular circle shape.

An algorithm to measure unsymmetrical circle shape of intravascular ultrasound image using image processing techniques

In diagnosing coronary artery disease, measurement of the cross-sectional area of the lumen, maximum and minimum diameter is very important. Mainly, it will be used to confirm the diagnosing, to predict the stenosis if any and to ensure the size of the stent to be used. However, the measurement only offers by the existing software and some of the software needs human interaction to complete the process. The purpose of this paper is to present the algorithm to measure the region of interest (ROI) on intravascular ultrasound (IVUS) using an image processing technique. The methodology starts with image acquisition process followed by image segmentation. After that, border detection for each ROI was detected and the algorithm was applied to calculate the corresponding region. The result shows that the measurement is accurate and could be used not only for IVUS but applicable to solid circle and unsymmetrical circle shape.

Visualization of Exact Invariant Solutions Associated with Atmospheric Waves in a Thin Circular Layer

The purpose of the research was to investigate the exact solutions of nonlinear shallow water equations associated with planetary equatorial waves corresponding to the Cauchy-Poisson free boundary problem describing the nonstationary motion of an incompressible perfect fluid propagating around a solid circle. We consider water waves for which the ratio of the depth of fluid above the circular bottom to the radius of the circle is small (shallow water).

Comparison of spatial distribution of active substances and sterilization range generated by array of printed-circuit-board plasma jets

By copper deposited in the holes of two perforated printed circuit boards to form copper rings with a radius and width of 1.5 mm as electrodes, a 4 × 4 plasma-jet-array device equipped with ring-ring electrode structure can realize stable and synchronous discharge of each unit. On the other hand, the transposition of the active substances on the agar plate produced by atmospheric-pressure plasma-jet array was visualized using a KI-starch reagent. It showed that the shape of the distribution of active substances can change from a ring to a solid circle when the gas-flow rate was reduced below 8 slm. In particular, the inactivation range of Escherichia coli at 90 s and inactivation range of Staphylococcus aureus at 180 s using this device were both close to twice the array area when the gas-flow rate was 5 slm. • A two-dimensional 4 × 4 array atmospheric pressure plasma jet device was manufactured by using PCB technology. • The transposition of the active substances on the agar plate was visualized using a KI-starch reagent. • The distribution shape of active substances can change from ring to solid circle when the gas flow rate was reduced. • The spatial distribution of active substances and sterilization range are good fit.

Effects of rotation on planetary inertial gravity waves initiated by the stratospheric polar vortex

We examine stability of the polar vortex that initiates planetary-scale westerly (west to east) atmospheric flow that encircles the pole in middle or high latitude of a planet. In our studies, the polar vortex is modeled as an annular flow (zonal flow) extending radially from a rigid inner boundary to a free outer boundary on a Ek− plane, which is parallel to the equatorial plane but generally displaced in latitude. The vortex is associated with a particular class of exact solution of a nonlinear two-dimensional free boundary problem on the nonstationary motion of a perfect fluid propagating around a solid circle with a sufficiently large radius with included Coriolis effect. The intensity of the polar vortex is parametrized by means of the “average” (in vertical) zonal flow that can be associated with atmospheric flow patterns that are parallel or nearly parallel to the lines of latitude. Perturbations are allowed in the zonal and nominally vertical (inward–outward) direction. A linear stability analysis purportedly suggests that increasing latitude decreases the maximum strength of the vortex that is permitted for stability. Three essential parameters that control stability of the vortex are identified.

Steady-state visual evoked potential and its applications in studying visual selective attention

Steady-state visual evoked potentials (SSVEP), an evoked brain potential, possesses the same frequency as periodic visual stimuli evoking potentials. It is extensively utilized in Brain-Computer Interface and human cognitive research. Moreover, the amplitude of SSVEP is sensitive to resources allocation of visual selective attention, and therefore can always serve as a corresponding electrophysiological indicator. In comparison with event-related potentials (ERPs) presented by P300 and N2pc, SSVEP index can be flexibly applied to a variety of paradigms and avoid errors caused by the brain lateralization as different items can be present in the center or in the same region of the view. Furthermore, SSVEP can reflect attention variation because of its continuity and sensibility to attention fluctuation. Besides, ERPs and SSVEP may reflect diverse attentive stages, and certain evidence suggests the attentive stage that SSVEP reflects is earlier compared with ERPs. Specifically, SSVEP may reflect the regulation that brain regions in charge of advanced cognitive function act on the visual cortex or the earlier stage of visual attention. Nevertheless, ERPs might reveal a later stage accomplished by brain regions responsible for higher-order cognitive processes such as the parietal lobe. In the study of visual selective attention, the frequency tagging is primarily employed to induce SSVEP. Visual stimuli are presented periodically at various frequencies to evoke SSVEP so that the stimuli are frequency tagged. We are able to figure out the allocation of attentive resources in those conditions by means of comparing SSVEP amplitude that the same stimulus evokes in a wide range of conditions. The frequency tagging is particularly appropriate to visual selective attention, especially feature-based and space-based attention. Benefiting from its accurate and sensitive reflection of attentive spatial distribution, SSVEP-based frequency tagging is widely adopted in space-based attention and directly proves the attention focus is shape-flexible and dividable but not always a solid circle. On the other hand, researchers developed the random dot kinematograms (RDK) paradigm for feature-based attention, which prolongs instantaneous feature-based attention process so that SSVEP can detect it. With RDK paradigm, researchers find strong evidence that feature-based attention does exist and has a global attentive activation. However, the other kind of visual selective attention, object-based attention, cannot be explored by frequency tagging because periodic flicker will be a highlighted feature so that participants will consider it as an object recognition marker and further destroy the integrity of the object. In the future, researchers can attempt to add emotion, reward and punishment, and working memory representations as research variables, or to build connections between feature-based attention and spatial-based attention in the process of using SSVEP to explore visual selective attention. In addition, the results of BCI algorithms for SSVEP have a potential for being a new visual selective attention index.

A calibration method for stereovision system based on solid circle target

All kinds of calibration methods have many optimal variables and complicated computation. How to calibrate stereovision system rapidly and precisely is always a pressing problem in the field of visual measurement. Therefore, a calibration method for stereovision system based on solid circle target is proposed in the present paper. A solid circle calibration pattern is adopted to calibrate the stereovision system. The centers of solid circles on calibration pattern are extracted by Canny-Zernike combination algorithm and sorted based on a triangle mark on calibration pattern. According to the pinhole camera model, the intrinsic and extrinsic parameters of left and right cameras are firstly obtained. Then, the distortion model including four parameters is adopted, Levenberg-Marquardt algorithm is used to separately optimize the image coordinates of projection of 3D point on the imaging plane of left and right cameras, the intrinsic parameters including distortion coefficients and extrinsic parameters of stereovision system are acquired in this step. In the last step, the distance between two centers on diagonal direction of calibration pattern is regarded as the constraint to further optimize the extrinsic parameters of stereovision system. Furthermore, a calibration software for stereovision system based on solid circle target is compiled with MATLAB, and the comparison test of two calibration methods and two calibration patterns are performed in lab. Results show that the proposed method has a higher precision, can automatically proceed calibration and can be widely used in engineering.

Erratum: “A Novel Method for the Development of Environmental Public Health Indicators and Benchmark Dose Estimation Using a Health-Based Endpoint for Chlorpyrifos”

Vol. 126, No. 9 ErratumOpen AccessErratum: “A Novel Method for the Development of Environmental Public Health Indicators and Benchmark Dose Estimation Using a Health-Based Endpoint for Chlorpyrifos”is correction ofA Novel Method for the Development of Environmental Public Health Indicators and Benchmark Dose Estimation Using a Health-Based End Point for Chlorpyrifos Todd J. Zurlinden and Brad Reisfeld Todd J. Zurlinden Search for more papers by this author and Brad Reisfeld Search for more papers by this author Published:6 September 2018CID: 099001https://doi.org/10.1289/EHP4279AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit The estimated exposure thresholds for RBC acetylcholinesterase (AChE) inhibition and plasma butyrylcholinesterase (BuChE) inhibition were listed incorrectly in the Results as “99% available RBC AChE, and 90% available plasma BuChE.” The correct values are 99.98% for available RBC AChE and 96.25% for available plasma BuChE.In addition, the RBC AChE level associated with a 15% cognitive deficit, based on data from Farahat et al. (2003), was derived incorrectly as BM sub RBC – AchE equals open parenthesis 100 minus 80 close parenthesis divided by 100 equals 0.20BMRBC–AChE=(100−80)/100=0.20. The correct value is BM sub RBC – AchE equals open parenthesis 100 minus 80 close parenthesis divided by 80 equals 0.25BMRBC–AChE=(100−80)/80=0.25. The estimate shown in the original Figure 5 for the level of BM sub AChEBMAChE associated with a 15% cognitive deficit in Farahat et al. (2003) also was incorrect. The corrected figure is included in this erratum.Figure 5. Predictions of human-specific cognitive deficits from measurable biomarkers of exposure. BM sub CPF, BM sub AChEBMCPF,BMAChE, and BM sub BuChEBMBuChE, are the independent biomarker of exposure variables for Equation 2 and correspond to peak plasma chlorpyrifos (CPF) concentration, minimum blood acetylcholinesterase (AChE) inhibition and minimum blood butyrylcholinesterase (BuChE) inhibition, respectively. Dashed lines represent 95% prediction intervals, and the solid circle (•) represents measured fractional cognitive deficit data from Farahat et al. (2003) using the differences in performance of the Benton Visual Retention Test between the exposed and unexposed groups and fractional plasma AChE activity from the reported plasma AChE activity.The authors confirm that these changes do not affect the study conclusions.The authors regret these errors.ReferenceFarahat TM, Abdelrasoul GM, Amr MM, Shebl MM, Farahat FM, Anger WK. 2003. Neurobehavioural effects among workers occupationally exposed to organophosphorous pesticides. Occup Environ Med 60(4):279–286, PMID: 12660376, 10.1136/oem.60.4.279. Crossref, Medline, Google ScholarFiguresReferencesRelatedDetailsRelated articlesA Novel Method for the Development of Environmental Public Health Indicators and Benchmark Dose Estimation Using a Health-Based End Point for Chlorpyrifos20 April 2018Environmental Health Perspectives Vol. 126, No. 9 September 2018Metrics About Article Metrics Publication History Manuscript received1 August 2018Manuscript accepted1 August 2018Originally published6 September 2018 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.

Simulation of Gas Solid Flow in Quasi Two Dimensional Fluidized Bed by Immersed Boundary Method

Gas solid two phase flow occurs in multiple fields of industry. Therefore, a study researching the phenomena of this type of systems is highly adequate. In the present work subsonic, compressible flow equation in conservative Euler form is solved numerically on PC by a two step finite difference method, which is validated by the analytical solution of Sod’s shock tube problem. Fluid solid interaction is described by Immersed Boundary Method, where body force is calculated by direct forcing algorithm. Two dimensional simulation of a single solid circle shaped particle motion in the gas flow is calculated and compared to the trajectory of a particle recorded by a high speed camera measurement system in a laboratory scale quasi two dimensional fluidized bed. Image processing algorithms are implemented to track the motion of a chosen single. Comparison of experimental measurement and simulation resulted in the same magnitude of particle velocities. The possible reasons of differences and opportunities of improving the results are discussed in the study. The results are promising, and the presented preliminary simulator can be a useful tool in supporting industrial design and operation after further developments.

The Truth from Another Angle

The purpose of this paper is to prove that the truth we know might be just a relative term which changes by looking from a different angle. To this end we will provide a model of 3D Universe, and invite a two- dimensional being to live in. Here this being lives in the inner curved (lateral) surface of the cone on the circumference of a circle. Because the curvature or the third dimension is infinitesimal, the two-dimensional being thinks that he lives on a circumference of a solid circle in a 2D Universe. In fact he will not understand the real truth of his universe. Or let’s say in other words, he will describe the truth of his universe as he observes it. This paper will prove how the understanding of the sun, the concept of day and night and even the whole universe changes by changing the angle we are looking from. Thereafter we will explain how science and new discoveries make the two-dimensional being believe in new truth. All the theories, thoughts and ideas included in this paper will be explained mathematically and scientifically, and illustrated through (9) figures.

Asymptotic stability of a polar vortex perturbed by harmonic waves describing atmospheric gravity waves circulating in an equatorial plane of a spherical planet

We examine stability of the vortex that represents one particular class of exact solution of a a nonlinear shallow water model describing atmospheric gravity waves circulating in an equatorial plane of a spherical planet. The mathematical model is represented by a two-dimensional free boundary Cauchy–Poisson problem on the nonstationary motion of a perfect uid around a solid circle with a sufficiently large radius so that the gravity is directed to the center of the circle. It is shown that the model admits two functionally independent nonlinear systems of shallow water equations. Two essential parameters that control stability of the vortex for both systems are identified. The order of their importance is analyzed and it is shown that one of the systems is more resistant to small perturbations and remains stable for larger range of these two parameters.

Invariant solutions and shock atmospheric waves in a thin circular layer

The objective of this paper is to investigate the nonlinear mathematical model describing equatorial waves from Lie group analysis point of view in order to understand the nature of shallow water model theory, which is associated to planetary equatorial waves. Such waves correspond to the Cauchy–Poisson free boundary problem on the nonstationary motion of a perfect incompressible fluid circulating around a solid circle of a large radius.