Circular Path Research Articles

Vortex evolution in a rotating tank with an off-axis drain

Fluid entering the periphery of a steadily rotating cylindrical tank exits through an off-axis drain hole, located in the tank's base at the half-radius. Experiments show that, though a concentrated vortex forms over the drain, it soon advects around the tank in what is at first a circular path. Though inviscid vortex dynamics predicts continued motion, our experiments show that the vortex moves inwards from the predicted circular path, finally coming to rest at approximately $50^{\circ }$ from the drain. In this final state, the vorticity is concentrated in a thin shear layer bounding an irrotational core, which passes over the drain. The broadening of the vortex structure and eventual steady-state formation are believed to be due to the growing boundary layer on the outer wall.

Deformation simulations of sand under Bi-directional shear loading

A well-developed sand plasticity model is further revised and validated based on bi-directional simple shear test data on medium to high relative density sands, which includes circular, oval and figure-8 type stress paths at different cyclic stress ratio (CSR) levels. The sand properties revealed from non-proportional loading tests, such as extended contractive behavior for medium to dense sands, flow rule dependency on plastic strain increment direction, stress increment direction dependency of plastic moduli, as well as the so-called non-coaxial property are incorporated into the new model development. Specifically, the recently proposed strain increment direction dependent flow rule is formulated and validated using bi-directional simple shear test results; and the relatively simple plastic moduli revised for the non-proportional loading are validated.After the model parameters are calibrated using a circular stress path, predictions are made for oval and figure-8 type stress paths at two cyclic stress levels. The modeling results show that the computed deformations up to a large strain state (i.e., 6% double amplitude strain) match fairly well with the test results; and the predicted pore-water pressure generation (or the effective stress change) followed the trend of test measurements including the repeating contractive and dilative cycles near the failure surface. A fabric dilatancy concept-based stiffness reduction approach is adopted that is active for the simulations of oval and figure-8 type stress paths.By comparing with test results, the model predictions demonstrate the capability of the present model in simulating the complex deformation magnitudes and patterns for sands under bi-directional loadings.

Bolero Film e Grand Hotel

The essay focuses on one of the fundamental points of Enzo Moscato’s literature (poetics of transsexualism) investigated through the creative process that generates the staging. In particular, the work of the director Francesco Saponaro about Ragazze sole con qualche esperienza (written by Moscato in 1985) is analyzed with special attention in observing the main characters as declinations of gender identity. A circular path that – starting from characters such as Bolero Film and Grand Hotel as staging by Saponaro in 2017 – analyzes the directorial / dramaturgical vision that conveys and mutates into a ‘scenic key’ the intrinsic paradigms of Enzo Moscato’s dramaturgy.

ЭНЕРГЕТИКА ИЗЛУЧЕНИЯ ЭЛЕКТРИЧЕСКОГО ЗАРЯДА И ЕЕ СЛЕДСТВИЯ

It is believed that an electric charge moving along a circular path, i.e. with centripetal acceleration, it is necessary to emit electromagnetic waves. This applies, inter alia, to cyclotron radiation. The purpose of the work is to establish the conditions for the radiation of an electric charge, based on the significant differences between its tangential and centripetal accelerations. The relevance of the work is determined by the widespread use of devices that generate electromagnetic radiation due to the acceleration of electric charges, including X-ray units and magnetrons. The starting point is a credible statement. A number of mathematically correct transformations are performed with it. Therefore, the result is necessarily reliable. Sad experience shows that this logic is not available for many specialists. In the event that such a necessary reliable result contradicts the existing paradigm, preference is almost always given to the paradigm, regardless of the persuasiveness of the evidence. This circumstance is an almost insurmountable obstacle to obtaining new knowledge. After all, if it does not contradict the paradigm, then it is not new and does not represent any value. Electromagnetic radiation carries away energy. It follows from this that the energy of the radiating system changes during radiation. Associated with this is the well-known rule: the change in energy is equal to the perfect work. Four theorems are proved. Theorem 1. A tangentially accelerated charge emits electromagnetic waves. Theorem 2. A normally accelerated charge does not emit electromagnetic waves. Theorem 2 formalizes a circumstance well-known in mechanics that the centripetal force does not perform work (since the scalar product of orthogonal vectors must be zero). Theorem 3. Electric charge satisfies Newton's second law. When a hydrogen-like atom passes from one stationary state to another, the orbital angular momentum changes. The difference is attributed to a photon and is called the photon's spin. Theorem 4. The spin of a photon is zero. The defect in the angular momentum of an atom during radiation can easily be attributed to the nucleus of an atom and even to an electron.

Lateral inhibition between banks of orientation selective channels predicts shape context effects: A tilt-illusion field

The perceived shapes of almost circular paths are modified by concentrically placed context paths. These induced changes have previously been attributed to curvature masking. This paper shows that, instead, they can be explained by the impacts of local tilt illusions. First, the tilt-illusion was measured over the full range of orientation differences between short test and context lines and it was shown that the resulting function can be predicted by a model based on a vectorial population response of a bank of orientation selective channels, provided lateral inhibition between channels with the same orientation selectivity and adjacent receptive fields was postulated. Subsequently, it was demonstrated that, if the perceived shape of a test path were modified to accommodate the predicted local tilt-illusion, then this could account for previously reported changes in the detectability of a path sinusoidally modulated in radius. Further, we measured points of subjective vertical in test lines and points of subjective circularity in test paths when surrounded by modulated context paths. The tilt required to null the tilt-illusion approximated the maximum orientation difference from circular measured in the modulated paths at their point of subjective circularity, supporting the proposal that the illusory shape change is due to local changes in the position of the path arising from a response to local tilt illusions induced by the orientation context. An important corollary to this result is that such effects will generalize to all paths which are adjacent.

Stability control of a fixed full-wing layout UAV under manipulation constraints

The fixed full-wing layout unmanned aerial vehicle (UAV) has simple structure and high aerodynamic efficiency, but the special configuration and manipulation characteristics bring challenges to the controller design, which has little related research work. Aiming at the aileronless and rudderless manipulation mode, considering the disturbance and uncertainty, this paper proposes a comprehensive stability controller for the fixed full-wing layout UAV under manipulation constraints. First, adaptive neural network dynamic surface control schemes based on the asymmetric barrier Lyapunov function and auxiliary system are designed for pitch and yaw attitude control. Then, this paper combines the adaptive super-twisting observer, terminal sliding mode control, and double power reaching law to design the airspeed controller and the altitude controller, and further introduces the pitch angle command constraint in the altitude controller. In addition, an improved vector field-based lateral-directional path following control method is designed to realize straight-line and circular orbit path following control. In this paper, the approximation and compensation effects of the radial basis function neural network and robust compensator are fully verified. The design of the pitch angle command constraint specifically considers the characteristics of weak pitch manipulation ability, small available trim airspeed range, and low longitudinal moment of inertia. The developed path following control approach effectively prevents the nonlinear tracking differentiator from generating unreasonable yaw angle commands. Simulation results also show that the proposed controller can enable the fixed full-wing layout UAV to achieve the typical three-dimensional mission flight with high robustness and high precision, and make the fixed full-wing layout UAV remain stable even after suffering stall and manipulation saturation under the action of the gust wind field.

Whispering-gallery-mode sensors for biological and physical sensing

The term whispering gallery mode (WGM) was first introduced to describe the curvilinear propagation of sound waves under a cathedral dome. The physical concept has now been generalized to include light waves that are continuously reflected along the closed concave surface of an optical cavity such as a glass microsphere. The circular path of the internally reflected light results in constructive interference and optical resonance, a morphology-dependent resonance that is suitable for interferometric sensing. WGM resonators are miniature micro-interferometers that use the multiple-cavity passes of light for very sensitive measurements at the microscale and nanoscale, including single-molecule and ion measurements. This Primer introduces various WGM sensors based on glass microspheres, microtoroids, microcapillaries and silicon microrings. We describe the sensing mechanisms, including mode splitting and resonance shift, exceptional-point-enhanced sensing and optomechanical and optoplasmonic signal transductions. Applications and experimental results cover in vivo and single-molecule sensing, gyroscopes and microcavity quantum electrodynamics. We also discuss data analysis methods and the limitations of WGM techniques. Finally, we provide an outlook for molecule, in vivo and quantum sensing.

Propeller Clock using Arduino Nano Micro-controller

Abstract: Once John Lubbock rightfully propounded, “What we see depends mainly on what we look for”. Perfection is a just a illusion whereas Perception is the real vision. This “illusion” is based on inertia of human eye. Propeller clock is a special kind of circular LED display. It is making use of POV, a scientific phenomena termed as ‘Persistence of Vision’, which means that if something appears in the same spot consistently, at least 50-60 times per second, our brains think that it’s permanently there when it is not. The term ‘Persistence of Vision display’ or ‘POV display’ has been used for LED display devices that compose images by displaying one spatial portion at a time in rapid succession (for example, one column of pixels every few milliseconds). A two-dimensional POV display is often accomplished by means of rapidly moving a single row of LEDs along a linear or circular path. The effect is that the image is perceived as a whole by the viewer as long as the entire path is completed during the visual persistence time of the human eye. A further effect is often to give the illusion of the image floating in mid-air. This implementation will be a coordination of electrical, electronics and mechanical engineering. Keywords: Persistence of Vision, Arduino Nano, Micro-controller, Led’s, Propeller, POV

A conceptual model of vulnerability to care delay among women at risk for endometrial cancer

ObjectiveCare delay may allow for cancer progression prior to treatment initiation. However, in endometrial cancer, quantitative data to support this hypothesis is mixed. Factors that cuase delay prior to clinical presentation are present among Black women, however the whether and how they present among White women, and thus how they may drive racial disparity is unknown. MethodsIn this qualitative study, from June 2019 to March 2020, we conducted in-depth semi-structured interviews among 17 White women with EC (34–73 years), living in the Northwest (11), West (2), Midwest (1), Southwest (1), and Northeast (2) U.S. regions, including six with high-risk and/or advanced stage endometrial cancer. An exploratory and descriptive content analysis was performed using iterative rounds of inductive coding, case summaries, and additional interviews to confirm emergent themes, followed by synthetic analysis of themes from a prior qualitative study conducted among Black women, which we analyzed for overlap and distinctions. ResultsThere were critical points of overlap and distinction between Black and White women in four delay factors identified: menopause and endometrial cancer knowledge, prior negative healthcare experiences, prior/concurrent reproductive conditions, and healthcare provider response. Conceptualizing the care journey as a circular path demonstrates the potential for accumulation of delay that is dependent on underlying risk. ConclusionWe have identified four areas of vulnerability that are often unrecognized and difficult to assess in quantitative investigations of overall quality and co-occurring disparities in endometrial cancer care. With the addition of epidemiologic risk, we present a unified model of vulnerability to care delay in endometrial cancer that can be applied to future quantitative studies and ongoing clinical care.

Flight Stability of Rigid Wing Airborne Wind Energy Systems

The flight mechanics of rigid wing Airborne Wind Energy Systems (AWESs) is fundamentally different from the one of conventional aircrafts. The presence of the tether largely impacts the system dynamics, making the flying craft to experience forces which can be an order of magnitude larger than those experienced by conventional aircrafts. Moreover, an AWES needs to deal with a sustained yet unpredictable wind, and the ensuing requirements for flight maneuvers in order to achieve prescribed control and power production goals. A way to maximize energy capture while facing disturbances without requiring an excessive contribution from active control is that of suitably designing the AWES craft to feature good flight dynamics characteristics. In this study, a baseline circular flight path is considered, and a steady state condition is defined by modeling all fluctuating dynamic terms over the flight loop as disturbances. In-flight stability is studied by linearizing the equations of motion on this baseline trajectory. In populating a linearized dynamic model, analytical derivatives of external forces are computed by applying well-known aerodynamic theories, allowing for a fast formulation of the linearized problem and for a quantitative understanding of how design parameters influence stability. A complete eigenanalysis of an example tethered system is carried out, showing that a stable-by-design AWES can be obtained and how. With the help of the example, it is shown how conventional aircraft eigenmodes are modified for an AWES and new eigenmodes, typical of AWESs, are introduced and explained. The modeling approach presented in the paper sets the basis for a holistic design of AWES that will follow this work.

Breathing in Birds and Crocodiles: What’s Different, What’s the Same, and Why Does It Matter?

At first glance, crocodiles and birds appear to be two very different groups of animals. Crocodiles tend to inhabit marshes and wetlands, while most birds tend to nest on dry land or in trees. Not only do they look very different, but while crocodiles walk on all fours and are excellent swimmers, most birds fly. Interestingly, researchers have found remarkable similarities in the way crocodiles and birds breathe! Different from how humans breathe, both birds and crocodiles have one-way air flow through their airways, meaning that air moves in a circular path into the lungs and back out. This article compares the structures of the respiratory systems in birds and crocodiles. We also examine how their respiratory systems are specialized for their unique environments and activities.

JOANNE: Joint dropsonde Observations of the Atmosphere in tropical North atlaNtic meso-scale Environments

Abstract. As part of the EUREC4A field campaign which took place over the tropical North Atlantic during January–February 2020, 1215 dropsondes from the HALO and WP-3D aircraft were deployed through 26 flights to characterize the thermodynamic and dynamic environment of clouds in the trade-wind regions. We present JOANNE (Joint dropsonde Observations of the Atmosphere in tropical North atlaNtic meso-scale Environments), the dataset that contains these dropsonde measurements and the products derived from them. Along with the raw measurement profiles and basic post-processing of pressure, temperature, relative humidity and horizontal winds, the dataset also includes a homogenized and gridded dataset with 10 m vertical spacing. The gridded data are used as a basis for deriving diagnostics of the area-averaged mesoscale circulation properties such as divergence, vorticity, vertical velocity and gradient terms, making use of sondes dropped at regular intervals along a circular flight path. A total of 85 such circles, ∼ 222 km in diameter, were flown during EUREC4A. We describe the sampling strategy for dropsonde measurements during EUREC4A, the quality control for the data, the methods of estimation of additional products from the measurements and the different post-processed levels of the dataset. The dataset is publicly available (https://doi.org/10.25326/246, George et al., 2021b) as is the software used to create it (https://doi.org/10.5281/zenodo.4746312, George, 2021).

Multiaxial low cycle fatigue behavior and life prediction method of 316LN stainless steel at 550 °C

This work studied the uniaxial, torsional and multiaxial low cycle fatigue behavior of 316LN stainless steel at 550 °C. Results show that the normalized kernel average misorientation value can be used to describe the loading path non-proportionality quantitatively. The formation of equiaxed and small-sized dislocation cells leads to the occurrence of continuously cyclic hardening under circular loading path. The crack initiation and early crack growth is dominated by intergranular mode in uniaxial test, whereas the transgranular cracking is observed in multiaxial test. Moreover, a weighting factor, evaluating the contribution of shear fatigue damage to the total multiaxial damage is proposed to modify the damage parameter of Chen-Xu-Huang (CXH) life prediction model, which enables all life data falling into the scatter band of 1.5.

Orientation Detection of Unequally Spaced Complexed Grounding Grids using Transient Electromagnetic Method

Configuration of Grounding Grid is required for all currently proposed Fault Diagnosing methods of Grounding Grid if the configuration is unknown then Grounding Grid Configuration detection techniques are applied and all of these latest techniques further requires the oriented angle at which the grid is laid and if the orientation of the grid is unknown or incorrect then the calculated configuration will be misleading and incorrect and we will fail to diagnose the Grounding Grid Fault. In this paper Transient Electromagnetic Method approach is used for orientation detection of Unequally Spaced Grounding Grids which are categorized as complexed grids further classified as Unequally spaced grounding grids with a diagonal element at larger mesh, smaller mesh, or in both of these meshes. In TEM method Equivalent Resistivities and Magnetic Field Intensities are found at eight different points in a circular path of constant radius r to determine the size of meshes and the presence of conductors whether diagonal or not diagonal. Model Designing and Simulations are performed using COMSOL Multiphysics 5.4 software, values of Magnetic Field Intensities and EMF are derived from COMSOL Multiphysics 5.4 software and the EMF values are further called in a MATLAB code to run through a number of mathematical formulations and Equivalent Resistivity is obtained for all desired points. Obtained values of Equivalent Resistivity and Magnetic Field Intensities verifies the effectiveness of the proposed approach for orientation detection of complexed grounding grid.

A Hollow Cylinder Torsional Shear Device to Explore Behavior of Soils Subjected to Complex Rotation of Principal Stresses

Abstract A hollow cylinder torsional shear device that is modified to simulate more generalized earthquake loading, involving simultaneous compression and shear wave loading in situ, is presented. The nature and degree of stress rotation due to coupled action of compression waves and shear waves are discussed, and illustrative experiments conducted to simulate different loading scenarios in the laboratory are presented. The stress rotation due to this coupled loading is significantly influenced by the initial consolidation stress state and shearing parameters such as the ratio between shear stress and normal stress increments (ΔS/ΔN) and the phase shift (ϕ) between the waves. The representative (ΔS/ΔN) ratios were obtained from the numerical simulations and used in hollow cylinder torsional shear apparatus to investigate the cyclic response of Fraser River sand under the simultaneous action of normal and shear stresses. Typical cyclic test results demonstrating the capability of a hollow cylinder torsional shear apparatus commissioned at Carleton University in following complicated cyclic loading paths are presented in this paper. It is noted that loading under such nonconventional stress paths, such as elliptical and circular paths, could be initiated along different pathways. Cyclic test results along these pathways demonstrate that soil response is dependent on the overall path including the initial stress state. Test results also highlighted the significance of stress rotation and cyclic stress paths in affecting the liquefaction susceptibility of sands.

Leader–follower formation with reduction of the off-tracking and velocity estimation under visibility constraints

This article addresses the time-varying leader–follower formation control problem for nonholonomic mobile robots, under communication and visibility constraints. Although the leader–follower formation control under visibility constraints has been studied, the elimination of the off-tracking effect has not been widely addressed yet. In this work, a new method to eliminate the off-tracking effect, considering the time-invariant formation as a tractor–trailer system, for unknown and circular tractor paths, taking into account the visibility constraints, is proposed. For a time-varying formation with not circular tractor’s path, the proposed method significantly reduces the off-tracking. Only the relative position and the relative orientation, provided by the on board monocular camera, are required. Thus, both the leader robot’s absolute position and the leader robot’s velocities are not needed. Furthermore, to avoid explicit communication among the robots, an extended state observer is implemented to estimate both the translational and the rotational leader’s velocity. In this way, the desired tasks are executed and achieved in a decentralized manner. For a time-varying formation, with constant leader robot’s velocities, the proposed control strategy, based on the kinematic model, guarantees that the formation errors asymptotically converge to the origin. Based on the Lyapunov theory, the stability proof of the formation errors dynamics is shown. Simulation results, considering time-varying leader robot’s velocities, show the efficiency of the proposed scheme.

Model-based motion simulation of delta parallel robot

For a parallel configuration of a robot manipulator, the solution of Forward Kinematics (FK) is tough compared to Inverse Kinematics (IK). This paper presents the model-based motion planning of a delta parallel robot in Simulink’s SimScape environment. A model was developed and simulated for motion study. The developed model has been simulated to solve the FK of the parallel manipulator and to check its efficacy. First, a helix curve has been planned within the reachable workspace. Then IK was solved to extract angular positions of the biceps. Obtained angular positions then fed to SimScape model to run a simulation. The path taken by the end effector of the system calculated by simulation is in good approximation to the planned helix path. Further, visual simulation and motion analysis of delta parallel robot can be performed by Model-based simulation and solves mechanical design as well control system design problems. Experimental study also shows that the circular path designed for experiment is well followed in real time simulation.

Cyclic changes to the negative coordinating conjunction from Latin to Modern French

AbstractThe evolution of the negative coordinating conjunction (‘neither’/‘nor’) from Latin to Modern French instantiates a type of cyclic development that is previously undocumented as such at the level of morphosyntax, viz. a ‘semasiological’ cycle. In effect, the conjunction appears to have taken an almost perfectly circular path. Thus, in Classical Latin, as is consonant with the typological status of that language as a Double Negation language,neque/necwas exclusively used in negative contexts. Medieval French being a Negative Concord language, on the other hand, its negative coordinating conjunction,ne, a direct descendant ofneque/nec, was able to develop a full range of weak negative polarity uses. In a range of contexts,newas thus semantically equivalent to either the additive conjunctionet(‘and’) or the disjunctionou(‘or’). By the end of the Classical French period, however, the conjunction (which by then takes the formny/ni) has lost all of its weak negative polarity uses again, and it is used only in strong negatively polar environments in Modern Standard French. Based on data from the electronic corporaFrantextandBase de Français Médiéval, I analyze the three stages of this evolution. I show that, together with other developments in the French negative system, it falsifies predictions made in the literature and has consequences for the reconstruction of negative systems in less well-documented languages.

The dislocation-based fatigue deformation mechanism of a RAFM steel under multi-axial loadings

Reduced Activation Ferritic/Martensitic (RAFM) steel is a candidate blanket material for a fusion reactor, which should have outstanding performance under extreme environments containing complex thermal and stress damage during operation. To date, the properties under a single-axial loading type of tensile, creep and fatigue have been extensively reported, while the multi-axial loadings were rarely studied. Here, the multi-axial fatigue behaviors of a RAFM steel were investigated in an axial-torsional cyclic tester with controlled strain and different loading paths. The results show that the fatigue behavior of the RAFM is strongly determined by the shear-stress condition, where the lifetime under the pure torsional loading is only 16% of the uniaxial cyclic loading one. The fatigue life of the specimens under multi-axial loadings with a phase angle of 0° or 180° are comparable to that of uniaxial tension-compression one. However, it was decreased by ∼28% as the loading angle changed to 90° with a circular path. Besides, we found the fatigue softening under the proportional multi-axial loading while additional hardening in the non-proportionally multi-axial cyclic loading related to the dislocation activities during loadings. Under the proportional-multiaxial loading and uniaxial tension-compression loading and torsion loading, the high density of dislocation was rearranged and annihilated by the cyclic shear stress, while the tempered martensite lath structure was mainly retained. However, under the non-proportional multi-axial loading, dislocations transform the lath structure into a finer cell structure, improving the resistance upon fatigue deformation.

Accuracy measurement of HoloLens2 IMUs in medical environments

Abstract As augmented reality devices become more available, collaborative work in the augmented space is expected to increase. Knowing the position of participants allows for realistic interaction rather than passive participation. The HoloLens 2’s camera and IMUs fuse data to locate the device. In this paper, accuracy and repeatability of the HoloLens2 position finding was analysed to provide a quantitative measure of pose repeatability and deviation from a path while in motion. Deviation from a circular path was found to be below 5 mm per 628 mm travelled.