Simple Rotation Research Articles

Effect of multi-frequency parametric excitations on the dynamics of on-board rotor-bearing systems

In the transportation domain such as automotive turbochargers and aircraft turbines, the vibrations of on-board rotors are induced not only by the mass unbalance excitation but also by various movements of their support. The dynamics of an on-board rotor mounted on hydrodynamic finite-length bearings is investigated in the presence of support motions which create multi-frequency parametric excitations. The developed on-board rotor model is based on the gyroscopic Timoshenko beam finite element with two nodes and six degrees of freedom per node for 3D motions (transverse and axial displacements as well as rotations due to the bending and to the torsion). The equations of motion highlight time-varying parametric terms due to the mass unbalance, the support rotations, the coupling between both phenomena and the combination of mass unbalance and support translations. These parametric terms can yield a dynamic instability because they contribute as generators of internal excitation. In the presented applications, single-frequency and multi-frequency parametric excitations are used. Namely, the rotor is excited either by simple and combined sinusoidal support rotations or by a rotating mass unbalance combined with sinusoidal support translations to examine the stability of the static equilibrium point through the Floquet theory.

A new fast double-chaotic based Image encryption scheme

In this paper, a new scheme for image encryption based on a double chaotic pseudo random generator (DCPG), simple XOR and shift rotations operations is proposed. The DCPG is a combination of both Tent and Chebyshev chaotic and so it needs three values of control parameters which are used as shared secret keys. The encryption consists of two rounds. In the first round, the hash value of the input image is computed using SHA-512. This value also is used as a forth shared secret key and from which, 4 amounts of the shift rotations are extracted. A pseudorandom sequence is generated using the proposed DCPG with the same size of the input image. This sequence and also the input image are divided into blocks of size 1 × 8. Each block of input image is processed with the corresponding block of the pseudorandom sequence using simple shift rotation and XOR operation. To extend the effect of the original image one pixel change to all the pixels of the cipher image, a second round of XOR operation is added. The proposed scheme has many advantages. It is highly secure due to two reasons. Firstly, it uses four secret keys for encryption which provides a large key space to overcome all types of brute force attacks. Secondly, the amounts of shift rotation used are input image dependent which achieves a strong resistance against chosen plaintext attacks. Also, it is more efficient compared to other recently existing schemes as it consists only of two rounds of simple operations. Security analysis of scheme has been provided. Based on the results, our scheme is highly secure with a reduced encryption time and so it can be used for many applications which require real time secure image communications.

A Comparison of Simple Structure Rotation Criteria in Temporal Exploratory Factor Analysis for Event-Related Potential Data

Abstract. It is challenging to apply exploratory factor analysis (EFA) to event-related potential (ERP) data because such data are characterized by substantial temporal overlap (i.e., large cross-loadings) between the factors, and, because researchers are typically interested in the results of subsequent analyses (e.g., experimental condition effects on the level of the factor scores). In this context, relatively small deviations in the estimated factor solution from the unknown ground truth may result in substantially biased estimates of condition effects (rotation bias). Thus, in order to apply EFA to ERP data researchers need rotation methods that are able to both recover perfect simple structure where it exists and to tolerate substantial cross-loadings between the factors where appropriate. We had two aims in the present paper. First, to extend previous research, we wanted to better understand the behavior of the rotation bias for typical ERP data. To this end, we compared the performance of a variety of factor rotation methods under conditions of varying amounts of temporal overlap between the factors. Second, we wanted to investigate whether the recently proposed component loss rotation is better able to decrease the bias than traditional simple structure rotation. The results showed that no single rotation method was generally superior across all conditions. Component loss rotation showed the best all-round performance across the investigated conditions. We conclude that Component loss rotation is a suitable alternative to simple structure rotation. We discuss this result in the light of recently proposed sparse factor analysis approaches.

Easy-to-build Wollaston-like polarization splitter with adjustable beam deviation and tunable chromatic dispersion.

In this paper, we show that it is possible to build a polarization splitter from a pair of commercially available geometrical phase lenses. This optical component splits an incoming beam into two circularly polarized beams, with a separation angle that can be varied by a simple translation or rotation adjustment. Our experiments show that excellent polarization separation is obtained with separation angles ranging from nearly zero up to 120mrad, and for wavelengths ranging from 532nm up to 780nm. The measured properties of this new component are well described by a simple analytical model. However, unlike conventional Wollaston prisms, this component exhibits a very large dispersion with wavelength. It can also be described as a polarization grating with adjustable dispersion.

Rotating Arm Internally Can Change the Arthroscopic Diagnosis of a Partial-thickness Tear of the Subscapularis.

BackgroundThe aims of this study were (1) to examine the footprint of the subscapularis tendon using the traditional posterior portal and 30° arthroscope by simple internal rotation of the arm during surgery, and (2) to classify the pattern of a subscapularis partial-thickness tear.MethodsThis study analyzed a total of 231 patients with a partial-thickness subscapularis tear from 550 consecutive patients undergoing an arthroscopic operation who had a visualization of the subscapularis tendon footprint by internal rotation of the arm. First, the patients were classified into four categories according to the tear pattern: (1) stable lamination, (2) unstable lamination, (3) avulsion, and (4) laminated avulsion. Randomized arthroscopic videos were reviewed blindly by two independent orthopedic surgeons. The pattern of the tear of the subscapularis at the neutral position and after internal rotating the arm were assessed and compared with the treatment decision (level IV case series).ResultsStable lamination, unstable lamination, avulsion, and laminated avulsion were observed in 9.1% (n=21), 20.8% (n=48), 41.1% (n=95), and 29.0% (n=67) of cases, respectively. In 145 out of 231 cases (62.8%), the decision was changed after inspecting the footprint after internal rotation of the arm, and the treatment method was changed in 116 (50.2%) cases.ConclusionsIn a subscapularis tendon partial-thickness tear, inspecting the footprint of the subscapularis tendon is essential to diagnosing and deciding on the appropriate treatment. In addition, simply internal rotating the arm during surgery when using the traditional posterior portal and 30° arthroscope can be a valuable method.

Regenerating Agricultural Landscapes with Perennial Groundcover for Intensive Crop Production

The Midwestern U.S. landscape is one of the most highly altered and intensively managed ecosystems in the country. The predominant crops grown are maize (Zea mays L.) and soybean [Glycine max (L.) Merr]. They are typically grown as monocrops in a simple yearly rotation or with multiple years of maize (2 to 3) followed by a single year of soybean. This system is highly productive because the crops and management systems have been well adapted to the regional growing conditions through substantial public and private investment. Furthermore, markets and supporting infrastructure are highly developed for both crops. As maize and soybean production have intensified, a number of concerns have arisen due to the unintended environmental impacts on the ecosystem. Many areas across the Midwest are experiencing negative impacts on water quality, soil degradation, and increased flood risk due to changes in regional hydrology. The water quality impacts extend even further downstream. We propose the development of an innovative system for growing maize and soybean with perennial groundcover to recover ecosystem services historically provided naturally by predominantly perennial native plant communities. Reincorporating perennial plants into annual cropping systems has the potential of restoring ecosystem services without negatively impacting grain crop production and offers the prospect of increasing grain crop productivity through improving the biological functioning of the system.

Rotations and mixtures of soil‐applied herbicides delay resistance

Weed resistance to foliar herbicides has dramatically increased worldwide in the last two decades. As a consequence, current practices of weed management have changed, with an increased adoption of soil-applied herbicides to restore control of herbicide-resistant weeds. We foresee metabolism-based resistance and cross-resistance to soil-applied herbicides as a potential global consequence to the increased and widespread adoption of new and old soil-applied herbicides. Thus, the aim of this study is to use computer simulation modelling to quantify and rank the risk of weeds evolving resistance to soil-applied herbicides under different usage strategies (single herbicide use, rotations and mixtures) and population genetic hypotheses. Simulations indicate that without rotation it takes twice as long to select for resistance to a particular soil-applied herbicide - trifluralin - than to any other herbicide option considered. Relative to trifluralin-only use, simple herbicide rotation patterns have no effect in delaying resistance, whereas more complex rotation patterns can delay resistance two- or three-fold. Herbicide mixtures further delay resistance up to six-fold in comparison to single use or simple herbicide rotations. By computer modelling simulations we demonstrate that mixtures maximize herbicide effectiveness and the selection heterogeneity of soil-applied herbicides, and delay herbicide resistance evolution in weedy plants. Our study is consistent with previous state-of-art scientific evidence (i.e. epidemiological and modelling studies across different systems and pests) and extension efforts (i.e. 'rotate herbicide mixtures') to provide insight to manage the selection and evolution of weed resistance. © 2019 Society of Chemical Industry.

Does diversifying crop rotations suppress weeds? A meta-analysis

Over the past half-century, crop rotations have become increasingly simplified, with whole regions producing only one or two crops in succession. Simplification is problematic from a weed management perspective, because it results in weeds’ repeated exposure to the same set of ecological and agronomic conditions. This can exacerbate weed infestations and promote the evolution of herbicide resistance. Diversifying crop rotations through addition of crop species and their associated managements may suppress weeds and reduce selection pressure for herbicide resistance by altering stress and mortality factors affecting weed dynamics. Here we report the results of a meta-analysis using 298 paired observations from 54 studies across six continents to compare weed responses due to simple and more diverse crop rotations. We found diversifying from simple rotations reduced weed density (49%), but did not have a significant effect on weed biomass. We investigated the effect of management practices, environmental factors, and rotation design on this effect. Diversification that increased the variance around crop planting dates was more effective in suppressing weeds than increasing crop species richness alone. Increasing rotational diversity reduced weed density more under zero-tillage conditions (65%) than tilled conditions (41%), and did so regardless of environmental context and auxiliary herbicide use. Our findings highlight the value of diversifying crop rotations to control weed populations, and support its efficacy under varied environmental conditions and management scenarios.

Torticaput versus Torticollis: Clinical Effects with Modified Classification and Muscle Selection.

BackgroundSeveral different subtypes are distinguished in cervical dystonia, depending on their different levels of movement. In simple rotation, classified as torticollis spasmodicus, we now differentiate between torticollis and torticaput dependent on whether only the head or the neck is turned. The new classification system permits for different injection schemes.Case reportsIn a retrospective study of 22 patients, we examined whether modifying the injected muscles leads to improvement in the results as evaluated in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). The results showed that both injection schemes do in fact lead to improvements while differentiating between caput and collum has significantly better effects.DiscussionDue to our results we recommend the classification differentiating between torticollis and torticaput type.

Torticaput versus Torticollis: Clinical Effects with Modified Classification and Muscle Selection

<strong>Background:</strong> Several different subtypes are distinguished in cervical dystonia, depending on their different levels of movement. In simple rotation, classified as torticollis spasmodicus, we now differentiate between torticollis and torticaput dependent on whether only the head or the neck is turned. The new classification system permits for different injection schemes. <strong>Case reports:</strong> In a retrospective study of 22 patients, we examined whether modifying the injected muscles leads to improvement in the results as evaluated in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). The results showed that both injection schemes do in fact lead to improvements while differentiating between caput and collum has significantly better effects. <strong>Discussion:</strong> Due to our results we recommend the classification differentiating between torticollis and torticaput type.

Dynamic Morphology and Swimming Properties of Rotating Miniature Swimmers With Soft Tails

Helical microswimmers are suitable for propelling at low Reynolds numbers. To date, artificial microswimmers with rigid helical tails have been significantly developed. However, swimmers made of soft materials, which are more adaptive in confined or complex environments, are still lack of adequate investigation. In our previous studies, we demonstrated that a magnetically actuated swimmer with a plate soft tail could form a helical structure in a rotating magnetic field to propel itself at low Reynolds numbers. In this paper, we report the different dynamic morphologies formed by the soft tail of the swimmers during a simple rotation. We prove that the pitch length of the formed helical structure dynamically decreases with the rotation frequency. The formed helical structure collapses down to a cylindricallike structure, when the pitch gap of the soft tail decreases to zero. The corresponding rotation frequency is defined as a morphological step-out frequency, which is different from the magnetic step-out frequency in previous works. At the morphological step-out frequency, the swimmers performs a pure rotation without a forward propulsion, which is defined as a “dynamic stop.” The pitch length and the morphological step-out frequency increase with the rigidity of the tail. More interestingly, we found that if the rotation frequency keeps increasing, the swimmer may achieve a reverse propulsion without changing any other input parameters. The dynamic stop and reverse swimming cannot be observed if the soft tails are too long. We expect that the dynamic swimming phenomena found in the swimmers with soft tails can be used for agile and delicate motion control of soft miniature swimmers, which will be the base of numerous biomedical applications.

Zooming X-rays with a single rotation in X-ray prism zoom lenses (XPZL).

Prism arrays arranged to form a slightly open alligator mouth were found to focus incident X-rays, as with increasing distance from the object symmetry axis these rays hit an increasing number of refracting prism tips. Such an object is then formally a refractive lens. Due to the strong energy dependence of the refractive index of material for X-rays a refractive X-ray lens is chromatically focusing. The attractive feature of the alligator lens is the inherent zoomability possible as the mouth can easily be opened or closed. However, the required tolerances for the jaw rotations and the jaw positioning are so stringent, that the routine use of such systems has not been reported yet. This study will show that the related technical problems can be overcome by proper object fabrication. In fact the here presented objects can already be aligned in the production stage. Then the assembly can be made with simple tools. And the zooming is achieved by just a simple rotation. The transmission through the devices was found to be as expected, and thus performance-wise these objects can directly compete with other refractive X-ray focusing systems.

A Configurable Virtual Impedance Method for Grid-Connected Virtual Synchronous Generator to Improve the Quality of Output Current

There are two significant problems for the virtual synchronous generator (VSG) under the nonideal grid, including power coupling and current distortion. Although the virtual impedance (VI) is often used to decouple the control of active power and reactive power, it can neither suppress current harmonics nor solve current imbalance caused by the nonideal grid. Therefore, this paper proposes the configurable virtual impedance (CVI) approach to improve both the power coupling and the output current quality. The proposed methodology could aid the independent design of the virtual sequence impedance (VSI) for any harmonics, of which the virtual fundamental positive sequence impedance can be used to realize power decoupling, and the other VSI is designed to mitigate current aberration. Due to the requirements of VSI, the novel harmonic extraction algorithm (NHEA) based on the state space model is presented to separate the positive-sequence component (PSC), negative-sequence component (NSC), and zero-sequence component (ZSC) in the fundamental and harmonic current. Then, under this harmonic extractor, 90° phase lead for each SC can be easily achieved by means of simple vector rotation. Excellent extraction performance of the NHEA and remarkable ability of current quality control and power decoupling regarding CVI are demonstrated by simulations and experiments.

Governance of electoral preferences, consensus and voting intention

The political system in which it is possible to observe the similarities and differences between groups for and against presidential candidates based on processes of negotiation, mediation, conciliation and arbitration around the management and administration of Information Technologies and Communication is known as governance. This is a growing phenomenon as local or federal elections approach and digital networks are exacerbated as instruments for the promotion or dissuasion of a candidate. In this sense, the objective of the study was to optimize the Governance instrument of the Cyber Political Culture of Carreón (2016) in order to pay the reliability and validity of it; explore the relationship between preferences and expectations regarding voting intentions in a non-probabilistic sample of students using digital networks. From a structural model it was found that the consensus expectation factor determined the intentions to vote. The scope and limits of the exploratory factor analysis of main axes with a simple and oblique promax rotation regarding the confirmation of an orthogonal structure are discussed. DOI: https://doi.org/10.54167/tch.v12i2.147

Magnetic field at a jet base: extreme Faraday rotation in 3C 273 revealed by ALMA

Aims. We studied the polarization behavior of the quasar 3C 273 over the 1 mm wavelength band at ALMA with a total bandwidth of 7.5 GHz across 223–243 GHz at 0.8′′ resolution, corresponding to 2.1 kpc at the distance of 3C 273. With these observations we were able to probe the optically thin polarized emission close to the jet base, and constrain the magnetic field structure. Methods. We computed the Faraday rotation measure using simple linear fitting and Faraday rotation measure synthesis. In addition, we modeled the broadband behavior of the fractional Stokes Q and U parameters (qu-fitting). The systematic uncertainties in the polarization observations at ALMA were assessed through Monte Carlo simulations. Results. We find the unresolved core of 3C 273 to be 1.8% linearly polarized. We detect a very high rotation measure (RM) of (5.0 ± 0.3) × 105 rad m−2 over the 1 mm band when assuming a single polarized component and an external RM screen. This results in a rotation of &gt;40° of the intrinsic electric vector position angle, which is significantly higher than typically assumed for millimeter wavelengths. The polarization fraction increases as a function of wavelength, which according to our qu-fitting could be due to multiple polarized components of different Faraday depth within our beam or to internal Faraday rotation. With our limited wavelength coverage we cannot distinguish between the cases, and additional multifrequency and high angular resolution observations are needed to determine the location and structure of the magnetic field of the Faraday active region. Comparing our RM estimate with values obtained at lower frequencies, the RM increases as a function of observing frequency, following a power law with an index of 2.0 ± 0.2, consistent with a sheath surrounding a conically expanding jet. We also detect ~0.2% circular polarization, although further observations are needed to confirm this result.

Instanton rate constant calculations using interpolated potential energy surfaces in nonredundant, rotationally and translationally invariant coordinates.

A trivial flaw in the utilization of artificial neural networks in interpolating chemical potential energy surfaces (PES) whose descriptors are Cartesian coordinates is their dependence on simple translations and rotations of the molecule under consideration. A different set of descriptors can be chosen to circumvent this problem, internuclear distances, inverse internuclear distances or z-matrix coordinates are three such descriptors. The objective is to use an interpolated PES in instanton rate constant calculations, hence information on the energy, gradient, and Hessian is required at coordinates in the vicinity of the tunneling path. Instanton theory relies on smoothly fitted Hessians, therefore we use energy, gradients, and Hessians in the training procedure. A major challenge is presented in the proper back-transformation of the output gradients and Hessians from internal coordinates to Cartesian coordinates. We perform comparisons between our method, a previous approach and on-the-fly rate constant calcuations on the hydrogen abstraction from methanol and on the hydrogen addition to isocyanic acid. © 2018Wiley Periodicals, Inc.

The real-time determination of d- and l-lactate based on optical weak measurement

A simple transmission optical rotation (OR) configuration based on weak measurement was developed for the real-time determination of d- and l-lactate.

Researches into Structure and Motion of Plants from Mechanical View Point

In the past two or three decades, I have studied a number of topics concerning plant biomechanics or plant biomimetics, such as structure of folding paper observed in leaves and flowers of plants, folding storage and unfolding manner observed in Sensitive Plant, mechanical functions of sepals and petals observed in lily flower bud, vein structure and mechanical properties of a leaf of Santa Cruz Water Lily, mechanical behavior of tendrils with spiral structure supporting cucumber body, adherence in the column of Stylidium caesupitosum and high speed rotation ... etc. From these researches, several interesting ideas or mechanisms adopted by plants have been clarified. For examples, the unfolding vein angle of regularly corrugated simple leaves is chosen as satisfying smooth and earlier unfolding with relatively small energy, the thick main veins of giant water lily have the cross-section with a tear drop shape including many voids to accomplish simultaneously a large bending rigidity and a body as light as possible, very complicated closing motion of a sensitive plant (Mimosa pudica) leaflet can be carried out by a simple rotation of a small pulvinus and a combination of a few installation angles of leaflet on the mid rib, or the incredibly rapid rotation of Stylidium flower column may be performed by the quick release of strain energy stored in a bending part of column. A number of interesting topics are shown here.

Covalency and magnetic anisotropy in lanthanide single molecule magnets: the DyDOTA archetype.

Lanthanide ions when complexed by polyamino-polycarboxylate chelators form a class of compounds of paramount importance in several research and technological areas, particularly in the fields of magnetic resonance and molecular magnetism. Indeed, the gadolinium derivative is one of the most employed contrast agents for magnetic resonance imaging while the dysprosium one belongs to a new generation of contrast agents for T2-weighted MRI. In molecular magnetism, Single Molecule Magnets (SMMs) containing lanthanide ions have become readily popular in the chemistry and physics communities since record energy barriers to the reversal of magnetization were reported. The success of lanthanide complexes lies in their large anisotropy due to the contribution of the unquenched orbital angular momentum. However, only a few efforts have been made so far to understand how the f-orbitals can be influenced by the surrounding ligands. The outcomes have been rationalized using mere electrostatic perturbation models. In the archetype compound [Na{Dy(DOTA) (H2O)}]·4H2O (Na{DyDOTA}·4H2O) an unexpected easy axis of magnetization perpendicular to the pseudo-tetragonal axis of the molecule was found. Interestingly, a dependency of the orientation of the principal magnetization axis on the simple rotation of the coordinating apical water molecule (AWM) - highly relevant for MRI contrast - around the Dy-OAWM bond was predicted by ab initio calculations, too. However, such a behaviour has been contested in a subsequent paper justifying their conclusions on pure electrostatic assumptions. In this paper, we want to shed some light on the nature of the subtle effects induced by the water molecule on the magnetic properties of the DyDOTA archetype complex. Therefore, we have critically reviewed the structural models already published in the literature along with new ones, showing how the easy axis orientation can dangerously depend on the chosen model. The different computed behaviors of the orientation of the easy axis of magnetization have been rationalized as a function of the energy gap between the ground and the first excited doublet. Magneto-structural correlations together with a mapping of the electrostatic potential generated by the ligands around the Dy(iii) ion through a multipolar expansion have also been used to evidence and quantify the covalent contribution of the AWM orbitals.

Electromagnetic-wave beam-scanning antenna using near-field rotatable graded-dielectric plates

The paper proposes an electromagnetic-wave beam-scanning antenna system using a simple rotation of a pair of near-field graded-dielectric plates (GDPs). The antenna system requires an electromagnetic (EM) illuminator, with nearly symmetric aperture field distribution, as the base antenna and two types of GDPs: one radially graded dielectric (RGD) and two linearly graded dielectric (LGD) plates. The RGD first focuses the beam of the base antenna in the broadside direction, and the LGD then tilts the focused beam at an offset angle. For some types of base antennas, having fairly uniform aperture phase distributions, an RGD may not be required and only a pair of LGDs are sufficient. Irrespective of the antenna configuration, using a simple rotation of the two LGDs, the beam can be scanned to any position within a large conical region. The antenna system presented as a proof of concept has a resonant-cavity antenna as the base antenna and three graded-dielectric plates. The aperture length of the antenna system is 6λ0 and its height is 2.2λ0. The results predicted by numerical simulations indicate that the antenna system has highest peak directivity of 21 dBi. The beam can be scanned to any direction within a cone having an apex angle of 20°.