Motion Of Core Research Articles

The Research on a Driving Device for Natural Gas Hydrate Pressure Core

Precise pressure core motion, including translation and rotation, is the basis and core part of the Analysis and Transfer System of Natural Gas Hydrate Pressure Core, which is crucial to nondestructive analyses, core cutting, and transfer. This paper mainly proposes a driving device, whereby a pressure core, up to 3 m long, can be transferred from pressure core drilling tools to proceed to nondestructive analyses and transferring the cores into other chambers. The lead screw is one of the most important components of this driving device. Therefore, the modal analyses of the lead screw are performed, which can help researchers to analyze the stability of this device. The analyzed data shows that the different positions of the slider have a great impact on the natural frequency of the lead screw. Furthermore, the lead screw with a support slider has a larger natural frequency than that without a support slider. According to data analysis, we can derive that the device with the support slider has a much larger rigidity, which can contribute to the stability of the device. To verify the feasibility of this device, the deformation of the lead screw was tested by the Micro-Electro-Mechanical Systems (MEMS) accelerometer array. Experimental results show that the deformation of the lead screw with the support slider is much less than that without the support slider.

Магнитно-резонансная силовая спектроскопия колебаний магнитного вихря

We present the results of micromagnetic modeling and experimental magnetic resonance force spectroscopy studies of forced magnetization oscillations in a circle NiFe disk in an external longitudinal magnetic field. The main attention is paid to the low-frequency resonance associated with the gyrotropic motion of the magnetic vortex core. It is shown that the applying external magnetic field in the plane of the sample leads to a significant shift in the resonance frequency of the gyrotropic mode. The influence of the inhomogeneous magnetic field of the probe on the peculiarities of the magnetization oscillations is discussed.

A study on the behavior of structures based on the rocking motion of rigid cores involving pre-compressed springs and viscous dampers

To create a partial rocking mode in a building structure during an earthquake, two or more rigid cores with joint connection to the foundation, and capable of moving in the two main directions of the building’s plan, can be used. A rigid core with a hinge connection to the foundation is essentially unstable. However, two rigid cores can be connected together by springs and dampers in certain floors to create a stable structure. At the same time, the structure shows a rocking behavior in which the building moves almost as a rigid body. In fact, the effects of all modes other than the fundamental one is almost eliminated. The use of yielding or friction dampers leads to permanent displacements in the structure in an earthquake. Therefore, in this study pre-compressed springs were employed, which do not create any permanent displacement. The pre-compressed springs were used to provide the structure with initial stiffness and prevent any displacement by small forces. Since an elastic spring does not have any damping, it was decided to control the structural displacements by viscous dampers in certain floors. Finally, the proposed structure underwent static and time-history analyses in plastic range, and the results suggested the desirable behavior of the proposed structure. In particular, there were no permanent displacements left in the structure after the earthquake.

Cut points of the Actigraph GT9X for moderate and vigorous intensity physical activity at four different wear locations

ABSTRACTAccelerometer cut points are an important consideration for distinguishing the intensity of activity into categories such as moderate and vigorous. It is well-established in the literature that these cut points depend on a variety of factors, including age group, device, and wear location. The Actigraph GT9X is a newer model accelerometer that is used for physical activity research, but existing cut points for this device are limited since it is a newer device. Furthermore, there is not existing data on cut points for the GT9X at the ankle or foot locations, which offers some potential benefit for activities that do not involve arm and/or core motion. A total of N = 44 adults completed a four-stage treadmill protocol while wearing Actigraph GT9X sensors at four different locations: foot, ankle, wrist, and hip. Metabolic Equivalent of Task (MET) levels assessed by indirect calorimetry along with Receiver Operating Characteristic (ROC) curves were used to establish cut points for moderate and vigorous intensity for each wear location of the GT9X. Area under the ROC curves indicated high discrimination accuracy for each case.

Unidirectional switching of magnetic vortex core confined in a cylindrical nanocavity

Ultrafast unidirectional reversal of magnetic vortex core confined in a cylindrical nanocavity is numerically investigated using micromagnetic simulations for the permalloy nanodisk. The excited modes (convergence/divergence) of the core motion are modulated differently by the cavity, depending on the dimension of the cavity, which is the main reason for the unidirectional vortex polarization switching. Assisted with the cavity, the core can be reversed well below 200 ps with less than 10 mT external magnetic field and over a wide range of field frequency. In particular, the core can be selectively switched by varying the dimension of the cylindrical cavity.

Vacancy-assisted core transformation and mobility modulation of a-type edge dislocations in wurtzite GaN

In this study, core structure dependent dislocation dynamics of a-type edge dislocation in three slip systems (basal, prismatic and pyramidal) of wurtzite GaN have been investigated using classical molecular dynamics simulations. All potential a-type edge dislocation cores in the shuffle and glide planes of the three slip systems have been identified, and the corresponding dislocation dynamics were examined. Our calculations reveal that for all of the three slip systems, all of the shuffle cores are planar glissile and mobile, while being non-planar sessile and immobile for all of the glide cores. We further show that vacancy can be used to activate the motion of glide cores via core transition from glide to shuffle, which is also valid for AlN and InN. The critical shear stresses for the motion of glide cores are also determined at various vacancy concentrations. Our study clarifies core structure dependent dislocation dynamics characteristics and provides ways in tuning dislocation motions in wurtzite crystals.

Development and Pilot Study of an iOS Smartphone Application for Perioperative Functional Capacity Assessment.

Functional capacity assessment plays a core role in the preoperative evaluation. The Duke Activity Status Index (DASI) and the 6-minute walk test (6MWT) are 2 methods that have demonstrated the ability to evaluate functional capacity and predict perioperative outcomes. Smartphones offer a novel method to facilitate functional capacity assessment as they can easily administer a survey and accelerometers can track patient activity during a 6MWT. We developed a smartphone application to administer a 6MWT and DASI survey and performed a pilot study to evaluate the accuracy of a smartphone-based functional capacity tool in our Anesthesia and Perioperative Medicine Clinic. Using the Apple ResearchKit software platform, we developed an application that administers a DASI survey and 6MWT on an iOS smartphone. The DASI was presented to the patient 1 question on the screen at a time and the application calculated the DASI score and estimated peak oxygen uptake (VO2). The 6MWT used the CMPedometer class from Apple's core motion facility to retrieve accelerometer data collected from the device's motion coprocessor to estimate steps walked. Smartphone estimated steps were compared to a research-grade pedometer using the intraclass correlation coefficient (ICC). Distance walked was directly measured during the 6MWT and we performed a multivariable linear regression with biometric variables to create a distance estimation algorithm to estimate distance walked from the number of steps recorded by the application. Seventy-eight patients were enrolled in the study and completed the protocol. Steps measured by the smartphone application as compared to the pedometer demonstrated moderate agreement with an ICC (95% CI) of 0.87 (0.79-0.92; P = .0001). The variables in the distance estimation algorithm included (β coefficient [slope], 95% CI) steps walked (0.43, 0.29-0.57; P < .001), stride length (0.38, 0.22-0.53; P < .001), age in years (-1.90, -3.06 to -0.75; P = .002), and body mass index (-2.59, -5.13 to -0.06; P = .045). The overall model fit was R = 0.72, which indicates a moderate level of goodness of fit and explains 72% of the variation of distance walked during a 6MWT. Our pilot study demonstrated that a smartphone-based functional capacity assessment is feasible using the DASI and 6MWT. The DASI was easily completed by patients and the application clearly presented the results of the DASI to providers. Our application measured steps walked during a 6MWT moderately well in a preoperative patient population; however, future studies are needed to improve the smartphone application's step-counting accuracy and distance estimation algorithm.

Analysis of effect of radial confluence flow on vortex core motion

The precessing vortex core (PVC) is evidently responsive to the escape of small particles. In this study, a computational fluid dynamics simulation was applied to the gas flow inside a cyclone separator to investigate the PVC phenomenon, particularly to observe the deviation of the vortex core away from the separator geometric center. The results reveal that the interaction between the gas and particles evidently contributes to the PVC unsteadiness. Consequently, a distinct deviation of the vortex core reappeared in the working cyclone with symmetric inlets, while it was too weak to be observed during the pure gas cyclone flow. However, an apex cone at the dust outlet evidently weakened the vortex core motion deviation and decelerated its rotation in the gas-particle flow within the working cyclone. Owing to the radial confluence flow from the outer to inner vortex over the separation space, the upward inner flow swung unsteadily. If >13% of mechanical energy within the downward gas flow was injected into the upward inner vortex with a radial confluence flow, the vortex core deviated from the separator geometric center, resulting in evident vortex core deviation.

Molecular orbitals of delocalized electron clouds in neuronal domains

We have further developed the two-brains hypothesis as a form of complementarity (or complementary relationship) of endogenously induced weak magnetic fields in the electromagnetic brain. The locally induced magnetic field between electron magnetic dipole moments of delocalized electron clouds in neuronal domains is complementary to the exogenous electromagnetic waves created by the oscillating molecular dipoles in the electro-ionic brain. In this paper, we mathematically model the operation of the electromagnetic grid, especially in regard to the functional role of atomic orbitals of dipole-bound delocalized electrons. A quantum molecular dynamic approach under quantum equilibrium conditions is taken to illustrate phase differences between quasi-free electrons tethered to an oscillating molecular core. We use a simplified version of the many-body problem to analytically solve the macro-quantum wave equation (equivalent to the Kohn-Sham equation). The resultant solution for the mechanical angular momentum can be used to approximate the molecular orbital of the dipole-bound delocalized electrons. In addition to non-adiabatic motion of the molecular core, ‘guidance waves’ may contribute to the delocalized macro-quantum wave functions in generating nonlocal phase correlations. The intrinsic magnetic properties of the origins of the endogenous electromagnetic field are considered to be a nested hierarchy of electromagnetic fields that may also include electromagnetic patterns in three-dimensional space. The coupling between the two-brains may involve an ‘anticipatory affect’ based on the conceptualization of anticipation as potentiality, arising either from the macro-quantum potential energy or from the electrostatic effects of residual charges in the quantum and classical subsystems of the two-brains that occurs through partitioning of the potential energy of the combined quantum molecular dynamic system.

Unprecedented Ultralow Detection Limit of Amines using a Thiadiazole-Functionalized Zr(IV)-Based Metal-Organic Framework.

A luminescent Zr(IV)-based metal-organic framework (MOF), with the underlying fcu topology, encompassing a π-conjugated organic ligand with a thiadiazole functionality, exhibits an unprecedented low detection limit of 66 nM for amines in aqueous solution. Markedly, this ultralow detection is driven by hydrogen-bonding interactions between the linker and the hosted amines. This observation is supported by density functional theory (DFT) calculations, which clearly corroborate the suppression of the twisting motion of thiadiazole core in the presence of amine, reducing significantly the nonradiative recombination pathways and subsequently enhancing the emission intensity. Credibly, nicotine regarded as a harmful chemical and bearing an amine pending group is also detected with high sensitivity, positioning this MOF as a potential sensor for practical environmental applications. This finding serves also as a benchmark to understand the sensing mechanism in MOFs.

Real-time process monitoring of core shifts during metal casting with wireless sensing and 3D sand printing

In this work, real-time in-process monitoring of core motion in metal castings is demonstrated through the use of two emerging technologies. 3D sand printing (3DSP) is a binder jetting additive manufacturing process that is quickly manifesting itself as a technological disrupter in the metal casting industry. Based on its direct digital manufacturing principle, 3DSP enables complex mold and core design freedom that has been previously unavailable to foundry engineers. In addition, the miniaturization and affordability of electronics and sensing equipment is rapidly accelerating. Here, these two shifting paradigms are leveraged together. An experimental casting and mold were designed in this research to demonstrate and evaluate wireless sensing of core shifts. With the use of 3D sand printing, precisely sized and located pockets were manufactured inside of cores. Miniature wireless Bluetooth sensors capable of measuring acceleration and rotation were then embedded inside the cores. From these, high fidelity data were captured wirelessly from the sensors during the casting process. With strategically designed core prints designed to allow varying levels of core motion, it is shown that core shifts can be measured and discriminated during casting in real time.

Chaotic dynamics in spin-vortex pairs

We report on spin-vortex pair dynamics measured at temperatures low enough to suppress stochastic core motion, thereby uncovering the highly non-linear intrinsic dynamics of the system. Our analysis shows that the decoupling of the two vortex cores is resonant and can be enhanced by dynamic chaos. We detail the regions of the relevant parameter space, in which the various mechanisms of the resonant core-core dynamics are activated. We show that the presence of chaos can reduce the thermally-induced spread in the switching time by up to two orders of magnitude.

Spin wave dynamics in elliptical dots

We investigate the ferromagnetic resonance modes of the magnetic vortex states on ${\mathrm{Ni}}_{81}{\mathrm{Fe}}_{19}$ ellipses using broadband ferromagnetic resonance measurements and micromagnetic simulations. Experiments show a rich structure of modes in the resonance absorption spectra, with absorption peak amplitudes dependent on the direction of the probing radio-frequency field. The evolution of the resonant modes is observed to be symmetric around zero field, due to the reversibility of the vortex core motion. The simulated absorption spectra reproduce the main features of the experimental results. A detailed analysis of the resonant modes at zero field shows that the observed absorption profiles result from the overlap of resonant modes which have an increasing complexity with the frequency. Besides, the simplest resonant modes are not those that exhibit the larger absorption amplitudes. Furthermore, the observed frequency splitting of some of the oscillation modes with the external field is correlated to the symmetry breaking during the vortex motion.

Структуры течений во вращающемся цилиндре с жидкостью и свободным цилиндрическим ядром при вибрациях

In the present work, the modes of steady time-average flows are studied experimentally, which are realized in a quasi-coaxial layer at circular inertial oscillations of a free cylindrical core and its simultaneous differential rotation. The outer cylinder is formed by the wall of a hermetically sealed rotating container. The inner cylinder (core) is hollow and made of polyester film. The volume between the cylinders is filled with a low-viscosity incompressible fluid (water), into which small heavy particles are added, which serve for visualization. The container is installed horizontally and rotates rapidly, so that the core occupies a stable position on the cavity axis. To measure the rotation rate of the core, synchronization with the flicker frequency of a stroboscope is used; to study the flow structure by the distribution of visualizer particles, photo-recording is used. To excite the core oscillations, translational vibrations are applied to the container directed perpendicular to the axis of rotation. In this case, an intensive leading rotation of the core is generated. Depending on the mode of the core motion, various distribution structures of the visualizers are observed. At relatively low rates of the core rotation, structures with a spatial period characteristic of inertial waves are observed. In the case of moderate rates, one observes a regular system of toroidal vortices. At high rates, the flow becomes irregular. The system of toroidal vortices is associated with the centrifugal instability. The threshold of its occurrence is noticeably lower than in the case of the classical Couette–Taylor flow. Analysis of the results shows that the system under study has essential prerequisites for the lowering of the onset threshold of Taylor vortex flow.

The Effect of Al and V Solutes on Dislocation Motion in Titanium Alloys: A First-Principles Study

The deformation mode of some titanium (Ti) alloys differs from that of pure Ti because of the presence of a secondary phase and alloying elements in the α-phase. Herein, we investigated the effect of Al and V solutes as typical additive elements on the dislocation motion in Ti alloys using density functional theory (DFT) calculations. Calculations of the stacking fault (SF) energy in all possible slip planes indicated that both Al and V solutes reduce the SF energy in the basal plane and the Al solute especially increases the SF energy in the prismatic plane, making the energy for slip motion in different planes more comparable. To clarify the energy differences between various dislocation core structures, we evaluated all possible core structures and motion in various slip planes. The energy difference between most stable pyramidal and prismatic cores is very small (22.8 meV/b), whereas that between the prismatic and basal cores is larger (127 meV/b), thereby preventing dislocation motion in the basal plane in pure Ti. However, the Peierls barrier for motion in the basal plane is not as high (15 meV/b) if the dislocation exists in the basal core. Direct calculations for the dislocation core around solutes revealed that both Al and V solutes facilitate dislocation motion in the basal plane by reducing the energy difference between the core structures while these solutes have a reverse trend for the interaction energy with the dislocation core.

Spin current induced dynamics and polarity switching of coupled magnetic vertices in three-layer nanopillars

Abstract We study dynamics of two magnetostatically coupled magnetic vortices excited by spin-polarized electrical current in a nanopillar consisting of permalloy magnetic layers with different thickness separated by a nonmagnetic spacer. We demonstrate three dynamical regimes of the vortices bound motion: damped oscillations, stationary oscillations and a regime of the polarity switching of one of the vortices; the critical currents for each dynamical phase are identified. The structure and trajectory of the vortex core motion in each magnetic layer are studied for the case of the vortex polarity switching in a thick layer. We show that the vortex polarity switching process has a dynamic nature and is associated with a vortex-antivortex pair formation.

First-principles calculations of interaction between solutes and dislocations in tungsten

Changes in mechanical properties due to transmutation products (Re and Os) in W alloys is a central issue for plasma-facing materials in fusion reactors. We conducted density functional theory calculations to investigate the effect of Re, Os, and other 5d solutes on core structure and motion of screw dislocations associated with plastic deformation. Ir, Pt, Au, and Hg solutes show strong attractive interactions with screw dislocations, causing solution strengthening by the pinning mechanism. On the other hand, Hf, Ta, and Re cause softening by facilitating dislocation motion around solutes. This prediction corresponds well with the experimental observation of softening behavior in W-Re alloys.

Simultaneous PIV/PLIF and Pulsed Shadowgraphy Measurement of Gas-Liquid Flows in a Swirling Separator

The gas-liquid separator is a key component in the gas removal system of the Thorium Molten Salt Reactor. Phase separation is driven by a swirling flow, and the fundamental principle is that dispersed bubbles are accumulated and coalesced into an air core to realize separation from the liquid phase. In this paper, simultaneous particle image velocimetry (PIV) and pulsed shadowgraphy techniques are applied to characterize the two-phase-flow patterns in the evolutionary process of the air core. The PIV technique utilizes fluorescent particles as tracers in the liquid flow field, and a charge coupled device (CCD) camera records the planar laser-induced fluorescence signal of the particles. Another camera simultaneously detects the shadow and motion of the air core via backlighting from an array of infrared light-emitting diodes. The signals originating from the different phases are separated by a beam splitter with a dichroic filter and optical filters, and only undisturbed signals from the shadow of the air core and fluorescence tracer particles of the fluid are effectively captured by the two CCD cameras, respectively. Experimental data are carried out for three Reynolds numbers Re for a range of outlet pressures Pout. The morphology of the air core tail periodically transforms from a linear type to a single-helix type to a double-helix type before reaching a stable state at the critical outlet pressures Pcout. The analysis of gas-liquid flow patterns indeed indicates that axial velocity has a strong influence on the air core evolution. The periodic fluctuation results from the magnitude and direction of axial velocity.

Parkinson's Disease Classification of mPower Walking Activity Participants.

Motion sensor data collected using Sage Bionetwork's mPower application on the Apple iPhone to record participant activities is analyzed to classify samples as positive or negative for Parkinson's Diagnosis. Pre-processing of the data showed differences in the time and frequency dimensions for features derived from Apple Core motion data. Several classic machine learning classification algorithms were trained on seventy-seven derived data points for best precision, recall, and F-1 score. Accuracy as high as ninety-two percent were achieved, with the best results attained from decision tree and multi-layered artificial neural network algorithms. This research shows that motion data produced on the Apple iPhone using the mPower application shows promise as an accessible platform to classify participants for presence of Parkinson's Disease signs.

ELECTROMECHANICAL TRANSIENT PROCESSES DURING SUPPLY VOLTAGE CHANGING IN THE SYSTEM OF POLYMER INSULATION COVERING OF THE CURRENT-CARRYING CORE OF ULTRA HIGH VOLTAGE CABLES

Aim. The article is devoted to the analysis of the electromechanical transient processes in a system of three frequency-controlled electric drives based on asynchronous motors that control current-carrying core motion, as well as to the study of the effect of such processes on the modes applying three-layer polymer insulation to the current-carrying core. Technique. The study was conducted based on the concepts of electromechanics, electromagnetic field theory, mathematical physics, mathematical modeling. Results. A mathematical model has been developed to analyze transients in an electromechanical system consisting of three frequency-controlled electric drives providing current-carrying core motion of ultra-high voltage cables in an inclined extrusion line. The coordination of the electromechanical parameters of the system drives has been carried out and the permissible changes in the supply voltage at the limiting mass while moving current-carrying core of ultra-high voltage cables with applied polymer insulation have been estimated. Scientific novelty. For the first time it is determined that with the limiting mass of the current-carrying core, the electromechanical system allows to stabilize the current-carrying core speed with the required accuracy at short-term decreases in the supply voltage by no more than 27 % of its amplitude value. It is also shown that this system is resistant to short-term increases in voltage by 32 % for 0.2 s. Practical significance. Using the developed model, it is possible to calculate the change in the configuration and speed of the slack current-carrying core when applying polymer insulation, depending on the specific mass of the current-carrying core per unit length, its tension at the bottom, the torque of the traction motor and the supply voltage to achieve stable operation of the system and accurate working of the set parameters.