Angular Parameters Research Articles

The Phenomenon of Bistable Phase Difference Intervals in the Times-Frequency Vibration Synchronization System Driven by Two Homodromy Exciters

A vibration system with two homodromy exciters operated in different rotational speed is established to investigate whether the phenomenon of bistable phase difference intervals exists in the times-frequency vibration synchronization system. Some constructive conclusions are proposed. (1) By introducing an average angular velocity perturbation parameter ε0 and two sets of phase difference perturbation parameters and ε2, the frequency capture criterion and the necessary criteria for realizing the times-frequency vibration synchronization are derived. The corresponding stability analysis is carried out. (2) By the theoretical analysis and experiments, it is verified that the times-frequency vibration synchronization system exists the phenomena of bistable phase difference interval. That is, the phase differences between the two homodromy exciters are stable around 180 degrees when they are located at a short distance; the antiphase synchronization phenomenon appears. On the contrary, they are stable around 0 degrees at the in-phase synchronization state. (3) Because of the two homodromy exciters operating in the different rotational speed, the vibration system obtains relatively complex compound motion trajectories; the corresponding application is investigated by adding a feeding material chamber. The times-frequency vibration synchronization system can be used to design the vibration mill for reducing its low-energy zone and developing chaotic mixing equipment for obtaining a better mixing effect.

Effect of custom-made and prefabricated foot orthoses on kinematic parameters during an intense prolonged run.

Foot orthoses are one of the most used strategies by healthy runners in injury prevention and performance improvement. However, their effect on running kinematics throughout an intense prolonged run in this population is unknown. Moreover, there is some controversy regarding the use of custom-made versus prefabricated foot orthoses. This study analysed the effect of different foot orthoses (custom-made, prefabricated and a control condition) on spatio-temporal and angular (knee flexion and foot eversion) kinematic parameters and their behaviour during an intense prolonged run. Twenty-four recreational runners performed three similar tests that consisted of running 20 min on a treadmill at 80% of their maximal aerobic speed, each one with a different foot orthosis condition. Contact and flight time, and stride length and stride rate were measured every 5 min by an optical measurement photoelectric cell system. Knee flexion and foot eversion kinematic parameters were measured by two high-speed cameras. No significant differences were found between the different foot orthoses in any of the time points studied and between the interaction of foot orthosis and behaviour over time, in any of the variables studied (P > 0.05). The use of custom-made and prefabricated foot orthoses during an intense prolonged run does not produce changes in spatio-temporal and kinematic parameters in healthy runners. These results suggest that a healthy runner maintains its ideal movement pattern throughout a 20 minute prolonged run, regardless the type of foot orthosis used.

Efficient tensor decomposition method for noncircular source in colocated coprime MIMO radar**Project supported by the National Natural Science Foundation of China (Grant Nos. 61701507, 61890542, and 61890540).

An effective method via tensor decomposition is proposed to deal with the joint direction-of-departure (DOD) and direction-of-arrival (DOA) estimation of noncircular sources in colocated coprime MIMO radar. By decomposing the transmitter and receiver into two sparse subarrays, noncircular property of source can be used to construct new extended received signal model for two sparse subarrays. The new received model can double the virtual array aperture due to the elliptic covariance of imping sources is nonzero. To further exploit the multidimensional structure of the noncircular received model, we stack the subarray output and its conjugation according to mode-1 unfolding and mode-2 unfolding of a third-order tensor, respectively. Thus, the corresponding extended tensor model consisted of noncircular information for DOA and DOD can be obtained. Then, the higher-order singular value decomposition technique is utilized to estimate the accurate signal subspace and angular parameter can be automatically paired via the rotational invariance relationship. Specifically, the ambiguous angle can be eliminated and the true targets can be achieved with the aid of the coprime property. Furthermore, a closed-form expression for the deterministic CRB under the NC sources scenario is also derived. Simulation results verify the superiority of the proposed estimator.

Self-accelerated optical activity in free space induced by the Gouy phase

Optical activity (OA) is the rotation of the polarization orientation of the linearly polarized light as it travels through certain materials that are of mirror asymmetry, including gases or solutions of chiral molecules such as sugars and proteins, as well as metamaterials. The necessary condition for achieving OA is the birefringence of two circular polarizations in material. Here, we propose a new kind of self-accelerated OA in free space, based on the intrinsic Gouy phase induced mode birefringence of two kinds of quasi-non-diffracting beams. We provide a detailed insight into this kind of self-accelerated OA by analyzing angular parameters, including angular direction, velocity, acceleration, and even the polarization transformation trajectory. As the Gouy phase exists for any wave, this kind of self-accelerated OA can be implemented in other waves beyond optics, from acoustic and elastic waves to matter waves.

Quasinormal modes of charged black holes in Einstein-Maxwell-Weyl gravity * * Supported by Natural Science Foundation of China (11605152, 11675139, 51802247)

We study quasinormal modes (QNMs) of charged black holes in the Einstein-Maxwell-Weyl (EMW) gravity by adopting the test scalar field perturbation. We find that the imaginary part of QNM frequencies is consistently negative for different angular parameters l, indicating that these modes always decay and are therefore stable. We do not observe a linear relationship between the QNM frequency ω and parameter p for these black holes, as their charge Q causes a nonlinear effect. We evaluate the massive scalar field perturbation in charged black holes and find that random long lived modes (i.e., quasiresonances) could exist in this spectrum.

Sagittal alignment of the cervical spine: do we know enough for successful surgery?

Over the past decade, there has been growing interest in the sagittal alignment of the cervical spine and its correlation to clinical outcomes. It is now known that cervical lordosis is not universally physiological and should not be pursued in all patients undergoing surgery. Rather, it is increasingly understood that it is how these angular parameters (lordosis or kyphosis) interact with translational parameters that is reflective of overall cervical spine and whole spine balance, which in turn impacts patient outcomes. This review synthesises currently available evidence relating to the sagittal alignment of the cervical spine. Radiographic assessment of the cervical spine including horizontal gaze is discussed and alignment in physiological and pathological states analysed. The interdependence of spinal segments is reviewed, with cervical alignment correction influencing the adjacent thoracic spine, and similarly lumbar lordosis (LL) and global balance correction changing cervical spine alignment. Cervical kyphosis with associated cervical sagittal imbalance is known to lead to poorer post-operative outcomes, and this dichotomy in outcomes has not been shown to improve even with alignment correction. Further work is required to uncover the extent to which cervical spine alignment correction should be attempted toward improved patient outcomes, in order to plan and deliver patient-specific surgical realignment targets.

Photographic Assessment of Cephalometric Measurements in Different Malocclusions in Raichur Population-An in Vivo Study

The present study is to assess the coherence of facial photographs as a viable means for analysis of the soft tissues in orthodontic patients. Aim: To assess the repeatability and creditability of measurements obtained from lateral cephalograms and facial photographs. Methods and Material: The study was done on standardized lateral cephalograms and facial photographs obtained from a total of 120 patients. An observational collation of linear and angular measurements was formulated between lateral cephalometric radiographs and homologous measurements procured from facial photographs. With patient in ortho position and adhesive dots set on the anatomical landmarks, right profile photographs were captured in NHP. With protractor connecting the tip of the nose and the soft tissue pogonion, a plumb line recorded the NHP angle. Likewise, digital lateral skull radiographs were taken with a PLANMECA and it was analyzed if the same position achieved during photographic record had also been acquired on the radiographic record. Both digital photographic and radiographic records were uploaded into nemoceph 10.4.2 software program for windows and were scrutinized by a single examiner. A total of 19 parameters were analyzed. Results: All angular and linear parameter showed statistically insignificant differences. The parameters which showed the mean difference between cephalometric measurements and photogrammetric measurements which is greater than one degree in angular parameters and one mm in linear parameters. Conclusion: The phogrammetric analysis can be used as a screening or adjunctive aid in clinical diagnosis.

Modeling of One-Dimensional Thermoelastic Dual-Phase-Lag Skin Tissue Subjected to Different Types of Thermal Loading

This work introduces a mathematical model of thermoelastic skin tissue in the context of the dual-phase-lag heat conduction law. One-dimensional skin tissue has been considered with a small thickness and its outer surface traction free. The bounding plane of the skin tissue is subjected to three different types of thermal loading; thermal shock, ramp type heating, and harmonic heating. The inner surface has no temperature increment and traction free. Laplace transform techniques have been used, and its inversions have been calculated by using the Tzuo method. The numerical results have been represented in figures. The thermal shock time parameter, the ramp-type heat parameter, and the angular thermal parameter have significant effects on the temperature increment, the strain, the displacement, and the stress distributions, and they play vital roles in the speed propagation of the thermomechanical waves through the skin tissue.

Studies of the spectral and angular distributions of transition radiation using a silicon pixel sensor on a Timepix3 chip

X-ray transition radiation detectors (TRDs) are used for particle identification in both high energy physics and astroparticle physics. In most of the detectors, emission of the X-ray transition radiation (TR) starts at Lorentz factors above γ∼500 and reaches saturation at γ∼2÷3⋅103. However, many experiments require particle identification up to γ∼105, which is very difficult to achieve with conventional detectors. Semiconductor pixel detectors offer a unique opportunity for precise simultaneous measurements of spectral and angular parameters of TR photons. Test beam studies of the energy and the angular distributions of TR photons emitted by electrons and muons of different momenta crossing several types of radiators were performed at the CERN SPS with a 480 μm thick silicon detector bonded to a Timepix3 chip. High resolution images of the energy−angle phase space of the TR produced by different radiators were obtained and compared with MC simulations. The characteristic interference patterns are in agreement with the theoretical models with an unprecedented level of details. The studies presented in this paper also show that simultaneous measurements of both the energy and the emission angles of the TR X-rays could be used to enhance the particle identification performances of TRDs.

Rotating regular black holes in conformal massive gravity

In this paper, we use a suitable conformal rescaling to construct static and rotating regular black holes in conformal massive gravity. The new metric is characterized by the mass $M$, the "scalar charge" $Q$, the angular momentum parameter $a$, the "hair parameter" $\lambda$, and the conformal scale factor encoded in the parameter $L$. We explore the shadow images and the deflection angles of relativistic massive particles in the spacetime geometry of a rotating regular black hole. For $\lambda \neq 0$ and $Q > 0$, the shadow is larger than the shadow of a Kerr black hole. In particular, if $\lambda < 0$, the shadow radius increases considerably. For $\lambda \neq 0$ and $Q < 0$, the shadow is smaller than the shadow of a Kerr black hole. Additionally we put observational constraints on the parameter $ Q $ using the latest Event Horizon Telescope (EHT) observation of the supermassive black hole M87*. Lastly, using the Gauss-Bonnet theorem, we show that the deflection angle of massive particles is strongly affected by the parameter $L$. The deflection angle might be used to distinguish rotating regular black holes from rotating singular black holes.

Quasinormal modes of generalized black holes: δ-Kerr spacetime

The nonlinear superposition of the -metric and the Kerr metric results in a -Kerr metric that represents a deformed Kerr black hole with , where q > 0 is proportional to the nonrelativistic quadrupole moment of the collapsed configuration. We study this spacetime and determine q+ such that for q, 0 < q < q+ , the outer spacetime singularity remains a null hypersurface. In this case, -Kerr spacetime represents a generalized black hole, namely, an asymptotically flat, stationary and axisymmetric vacuum solution of general relativity for which the outer singularity is a closed null hypersurface. For an approximate variant of -Kerr spacetime characterized by mass M, quadrupole parameter q and angular momentum parameter a, where the latter two parameters are treated to first and second orders of approximation, respectively, we analytically determine the quasinormal mode (QNM) frequencies in the ray approach using the light-ring method as well as in the complementary wave approach for massless scalar field perturbations in the a = 0 limit. The QNM frequencies of -Kerr spacetime turn out to be nearly the same as those of the rotating Hartle–Thorne spacetime.

Negative volume thermal expansion of monoclinic Cu2-2xZn2xV2O7 in the temperature range from 93 to 673 ​K

Negative volume thermal expansion was found for the monoclinic structure of the solid solution β-Cu2-2xZn2xV2O7 in a wide temperature range from 93 to 673 ​K: αV· ​= ​−31.4(2) · 10−6 ​K−1 for β-Cu1.6Zn0.4V2O7, αV· ​= ​−12.6(4) · 10−6 ​K−1 for β-Cu0.8Zn1.2V2O7. Precision X-ray studies of β-Cu2-2xZn2xV2O7in situ made it possible to detail the changes in the linear and angular parameters of the structure upon heating. The obtained data set revealed the defining role of changes the symmetry-nonfixed angle of rotation of the vanadium-oxygen tetrahedra in the [V2O7] orthogroups at the initiation of the hinged deformations, leading to the compression of the structure.

Measurement of J/ψ→Ξ(1530)−Ξ¯+ and evidence for the radiative decay Ξ(1530)−→γΞ−

The SU(3)-flavor violating decay $J/\psi\to\Xi(1530)^{-}\bar\Xi^{+}+c.c.$ is studied using $(1310.6\pm7.0)\times 10^{6} ~J/\psi$ events collected with the BESIII detector at BEPCII and the branching fraction is measured to be ${\cal{B}}(J/\psi\to\Xi(1530)^{-}\bar\Xi^{+}+c.c.)=(3.17\pm0.02_{\rm stat.}\pm0.08_{\rm syst.})\times10^{-4}$. This is consistent with previous measurements with an improved precision. The angular parameter for this decay is measured for the first time and is found to be $\alpha=-0.21\pm0.04_{\rm stat.}\pm0.06_{\rm syst.}$. In addition, we report evidence for the radiative decay $\Xi(1530)^{-}\to\gamma\Xi^- $ with a significance of 3.9$\sigma$, including the systematic uncertainties. The 90\% confidence level upper limit on the branching fraction is determined to be $\mathcal{B}(\Xi(1530)^{-}\to\gamma\Xi^- )\leq3.7$\%.

Modelling and compensation of temperature errors for articulated arm coordinate measuring machines

The temperature variation is an important factor affecting the accuracy of the articulated arm coordinate measuring machine (AACMM). This paper addresses the modelling and compensation of temperature errors in AACMMs. Firstly, a temperature field model of AACMMs is established by finite element analysis, based on which the influence of temperature change on single-point repeatability accuracy and spatial distance measuring accuracy for AACMMs are analysed. The results of the analysis show that non-zero linear parameters of AACMMs are influenced by temperature variation greatly, while the angular parameters are almost unchanged. Then, a temperature scaling method is proposed to improve the distance measuring accuracy of AACMMs, and a linear regression temperature error compensation model is established under the simulation environment. Experimental results show that in the presence of temperature scaling method, the average absolute value of distance measuring accuracy is improved by 65.24%.

Radiographic parameters of the digit in a cohort population of Amiata donkeys.

Background:The most common musculoskeletal conditions reported in donkeys are related to the foot. Radiographic examinations are clinically important in the diagnosis of foot abnormalities and are commonly used. However, few studies have been conducted to establish the normal radiographic appearance of a donkey’s foot.Aim:To determine the radiographic features of the front digit in healthy Amiata donkeys.Methods:Radiographic examinations were performed on 56 forefeet of 28 Amiata donkeys. Three radiographic views of each front foot were taken: lateromedial, dorsopalmar and dorso-65°proximal/palmarodistal oblique. Seventeen angular and linear radiographic parameters and the crena solearis were evaluated in all forefeet, and 18 morphometric parameters were evaluated in 16 out of 56 forefeet. Statistical analysis was carried out on all the measures assessed.Results:The radiographic appearance of the forefoot was ascertained, and data were reported as median ± standard error, minimum and maximum values. No statistical differences were obtained between the right and left forefeet.Conclusion:The normal baseline parameters of the forefeet of Amiata donkeys were recorded and described and compared with other donkey breeds and horses. The findings highlighted that the donkey breed affects the radiographic parameters of the digit.

Position of the hyoid bone and its correlation with airway dimensions in different classes of skeletal malocclusion using cone-beam computed tomography.

PurposeThis study investigated the position of the hyoid bone and its relationship with airway dimensions in different skeletal malocclusion classes using cone-beam computed tomography (CBCT).Materials and MethodsCBCT scans of 180 participants were categorized based on the A point-nasion-B point angle into class I, class II, and class III malocclusions. Eight linear and 2 angular hyoid parameters (H-C3, H-EB, H-PNS, H-Me, H-X, H-Y, H-[C3-Me], C3-Me, H-S-Ba, and H-N-S) were measured. A 3-dimensional airway model was designed to measure the minimum cross-sectional area, volume, and total and upper airway length. The mean cross-sectional area, morphology, and location of the airway were also evaluated. Data were analyzed using analysis of variance and the Pearson correlation test, with P values <0.05 indicating statistical significance.ResultsThe mean airway volume differed significantly among the malocclusion classes (P<0.05). The smallest and largest volumes were noted in class II (2107.8±844.7 mm3) and class III (2826.6±2505.3 mm3), respectively. The means of most hyoid parameters (C3-Me, C3-H, H-Eb, H-Me, H-S-Ba, H-N-S, and H-PNS) differed significantly among the malocclusion classes. In all classes, H-Eb was correlated with the minimum cross-sectional area and airway morphology, and H-PNS was correlated with total airway length. A significant correlation was also noted between H-Y and total airway length in class II and III malocclusions and between H-Y and upper airway length in class I malocclusions.ConclusionThe position of the hyoid bone was associated with airway dimensions and should be considered during orthognathic surgery due to the risk of airway obstruction.

Моды бегущих электромагнитных волн в цилиндрах

An algorithm is proposed for numerical calculation of traveling electromagnetic wave modes for solid and hollow solid state cylinders. Complex eigenvalues are defined for angular parameters characterizing emissive modes and whispering gallery modes (WG-mode). The polar component imaginary parts of the wave vectors are found for all modes, including WG modes. The calculation is carried out for the fixed cylinder sizes. The field distributions are calculated inside the cylinders. The dependence of the mode parameters on the extinction coefficients of the cylinder material was studied. The ratio of the density of energy fluxes for the radial and polar directions shows a sharp change when passage from the emissive modes to WG modes.

Kinematic analysis of the kick start from OSB12

Introduction: Start performance in swimming plays a major role in determining the final standings, especially in sprint races. The purpose of the study was to determine kinematic parameters underlying the kick start from OSB12 in terms of the kick plate position and shoulder positioning at the start. Material and methods: The sample included 8 non-randomly recruited performance-level swimmers whose average age, body height, and body weight was 17.4 ± 1.8 years, 182.2 ± 3.4 cm and 81.00 ± 3.9 kg, respectively. To measure the kinematic parameters, we used the SwimPro camera system. The parameter rs measured included angular parameters and kinematic parameters for each of the start phases: block phase, flight phase, and water phase. We processed the collected biomechanical data using the Statistica 12.0 software. To determine significant differences between the kick plate positions in three types of start, we applied the Mann-Whitney U test. Results: We found significant differences (p&lt;0.05) in the selected kinematic parameters in all phases, which depended on the OSB12 kick plate position and basic starting position (front-, neutral-, and rear-weighted). The greatest differences in the parameters measured were found between the front-weighted start and rear-weighted start. We may conclude that performance-level swimmers should adjust the rear kick plate to positions 3 and 4 and assume the following starting position: front knee angle between 131° and 133°, rear knee angle around 80°, and trunk angle between 40° and 41°. This starting position affects the flight phase, namely takeoff angle (40⁰-41⁰), head position at takeoff (1.33-1.38 m), flight time and distance (0.346-0.368 s; 2.74-2.79 m), entry angle (38⁰). The starting position also affects the glide phase, namely the glide time and distance (0.532-0.536 s; 2.22-2.26 m) and maximum depth (-0.91-0.92 m). Conclusions: The results of the study show that swimmers produced shorter times to 5 meters and higher velocity at 5 meters compared with other starting positions and OSB12 kick plate positions.

Investigation of subsidence process angular parameters during secondary underworking in the conditions of Western Donbas

Investigation of subsidence process angular parameters during secondary underworking in the conditions of Western Donbas

SCIENTIFIC JUSTIFICATION OF THE USE OF CONE-BEAM COMPUTERIZED TOMOGRAPHY (CBCT) FOR CEPHALOMETRIC ANALYSIS IN THE «AUDAXCEPH» PROGRAMM

This article is concerned with peculiarities of points’ placement in orthodontics and study of cephalometric parameters on 3D reconstructions.&#x0D; The aim of the investigation is to develop out the algorithm of distribution of main cephalometric points on 3D reconstructions, received from CBCT and compare characteristics of measurements done on classic teleroentgenogram (TRG) and 3D reconstructions.&#x0D; Materials and methods. The main angular (SNA, SNB, ANB, SN-Ba) skeletal saggital parameters, vertical (ML-NSL, NL-ML, Facial axis, &lt;G), and dental were taken (+1/NL, -1/ML, +1/-1). The analysis of dental radiographs was done for cephalometry «AudaxCeph». Teleroentgenogram and 3 D reconstructions of 20 patients were investigated.&#x0D; Comparing all indices of TRG and 3D reconstructions statistically significant difference was not revealed (р&gt; 0,05). The most significant indices was established during the study of incisive indices - +1/NL, 110±2,72 и 110,2±5,02 correspondingly inter-incisal angle +1/-1 - 133,8±2,21 and 138±5,79.