Path Of Rotation Research Articles

AIE mechanism of 2-(2-hydroxyphenyl) benzothiazole derivatives: CASPT2 and spin-flip study

Wang et al. synthesized phenylacetylene modified HBT derivative (HBT-s-Ph) and diphenylacetylene modified HBT derivative (HBT-d-Ph) with aggregation-induced emission (AIE) phenomenon. In this work, we have theoretically compared the photochemical and photophysical processes of HBT-s-Ph and HBT-d-Ph in the gas phase, toluene and solid phase using several theoretical methods. The ground-state, excited-state equilibrium structures, the potential energy curves and the excited-state properties were comparatively calculated for a better understanding of the AIE mechanism. The excited-state intramolecular proton transfer (ESIPT) process within HBT derivatives is very fast in both gas phase, toluene, and solid phase due to the small energy barrier, inducing the formation of Keto tautomer which is responsible for emission peaks observed in experiment in both gas phase, toluene and solid phase. But, the reaction paths are very different from there. In toluene, the non-radiative path via HBT intramolecular rotation along the C–C bond is favorable to occur, leading to low Φf of HBT-s-Ph and HBT-d-Ph in toluene. In contrast, the non-radiative path of HBT intramolecular rotation is strongly suppressed in solid phase due to the high energy barriers, which is responsible for high Φf of HBT-s-Ph and HBT-d-Ph in solid phase. The substitution effect on AIE and the large difference of Φf in HBT-s-Ph and HBT-d-Ph in solid phase have been revealed. The presents results contribute to a better understanding of the different photophysical properties of HBT derivatives in toluene and solid phase, and unveil the AIE mechanism in HBT derivatives, which provides deep insight into molecular design of organic photoelectric materials with high Φf.

Conical spin arrangement and spin reorientation process in Er2-xHoxFe14B observed with Mössbauer spectroscopy

The series of Er2-xHoxFe14B (x = 0.5, 1.0, 1.5, 2.0) intermetallic compounds was studied in order to investigate different types of spin arrangements expected in this series. The variety of processes connected with spin reorientation, especially transition through conical spin arrangements was of special interest. The compounds have been measured with 57Fe Mössbauer spectroscopy over the temperature range 5.2–320 K. Each compound was studied with precise Mössbauer scanning in the vicinity of the transition. A special fitting procedure of Mössbauer spectra, enabling to analyze up to ten spectra simultaneously, was developed to determine the arrangement of spins. The path of spin rotation was proposed. The results were verified and compared by applying computer simulations based on the Yamada-Kato model. The spin arrangement diagram was constructed. Obtained results are convincing enough to conclude that Mössbauer spectroscopy can be very helpful in studies of tilt angle in conical spin arrangements in the studied type compounds.

ON THE PERFORMANCE OF VERTICAL AXIS WIND TURBINES IN STEADY WIND UNDER VARIOUS BLADE CAMBER LEVELS

Vertical axis wind turbine (VAWT) has been shown to be more suited to small scale power production in the urban environment due to distinct advantages over its horizontal counterpart. Over the last few years, continuous improvement on its aerodynamic performance, either through experimental or numerical analysis, have been carried out by numerous researchers. VAWT performance was investigated using Computational Fluid Dynamics modeling. The influence of camber on steady wind performance was analyzed and the most efficient of all levels of blade camber studied for VAWT application was determined. Various levels of camber were imposed on to a NACA XX25 blade profile, namely: 0.5%; 1.5% (cambered close to the path of rotation); and 2%. Results revealed positive effect of incorporating a positive level of blade camber to VAWT design. The most favorable configuration for the VAWT under study was determined to be the camber level that causes the camber line to coincide with the path of the rotor rotation. The paper presents an in-depth discussion of the flow physics and wake dynamics, for the two wind cases of VAWTs, through flow visualizations and blade force analysis.

A description of neck motor performance, neck pain, fatigue, and mental effort while driving in a sample with chronic whiplash-associated disorders.

Individuals with chronic whiplash-associated disorders (WADs) often note driving as a difficult task. This study's aims were to (1) compare, while driving, neck motor performance, mental effort, and fatigue in individuals with chronic WAD against healthy controls and (2) investigate the relationships of these variables and neck pain to self-reported driving difficulty in the WAD group. This study involved 14 participants in each group (WAD and control). Measures included self-reported driving difficulty and measures of neck pain intensity, overall fatigue, mental effort, and neck motor performance (head rotation and upper trapezius activity) while driving a simulator. The WAD group had greater absolute path of head rotation in a simulated city area and used greater mental effort (P = 0.04), but there were no differences in other measures while driving compared with the controls (all P ≥ 0.05). Self-reported driving difficulty correlated moderately with neck pain intensity, fatigue level, and maximum velocity of head rotation while driving in the WAD group (all P < 0.05). Individuals with chronic WAD do not seem to have impaired neck motor performance while driving yet use greater mental effort. Neck pain, fatigue, and maximum head rotation velocity could be potential contributors to self-reported driving difficulty in this group.

Altered Spinal Motion in Low Back Pain Associated with Lumbar Strain and Spondylosis

Study Design We present a patient-specific computer model created to translate two-dimensional (2D) fluoroscopic motion data into three-dimensional (3D) in vivo biomechanical motion data.Objective The aim of this study is to determine the in vivo biomechanical differences in patients with and without acute low back pain. Current dynamic imaging of the lumbar spine consists of flexion–extension static radiographs, which lack sensitivity to out-of-plane motion and provide incomplete information on the overall spinal motion. Using a novel technique, in-plane and coupled out-of-plane rotational motions are quantified in the lumbar spine.Methods A total of 30 participants—10 healthy asymptomatic subjects, 10 patients with low back pain without spondylosis radiologically, and 10 patients with low back pain with radiological spondylosis—underwent dynamic fluoroscopy with a 3D-to-2D image registration technique to create a 3D, patient-specific bone model to analyze in vivo kinematics using the maximal absolute rotational magnitude and the path of rotation.Results Average overall in-plane rotations (L1–L5) in patients with low back pain were less than those asymptomatic, with the dominant loss of motion during extension. Those with low back pain also had significantly greater out-of-plane rotations, with 5.5 degrees (without spondylosis) and 7.1 degrees (with spondylosis) more out-of-plane rotational motion per level compared with asymptomatic subjects.Conclusions Subjects with low back pain exhibited greater out-of-plane intersegmental motion in their lumbar spine than healthy asymptomatic subjects. Conventional flexion–extension radiographs are inadequate for evaluating motion patterns of lumbar strain, and assessment of 3D in vivo spinal motion may elucidate the association of abnormal vertebral motions and clinically significant low back pain.

Quantum chemical studies of photochromic properties of benzoxazine compound

Molecular electronic structure of ground and excited states of a photochromic indolo[2,1-b][1,3]benzoxazine compound incorporating closed-ring system, which opens upon UV light excitation, was studied using various quantum chemical methods. Three local minima of the ground electronic state potential energy surface and related transition states were identified along the path of rotation of 4-nitrophenol group. Additionally, three local minima of the excited electronic states were located. The evaluated transition energy barriers between local ground-state minima nearest to the initial structure of the investigated molecule are less than 2 kBT, making open structures likely to revert to the initial structure by thermalization. Results obtained using ab initio GMC–QDPT method were explored and compared to the widely used TD-DFT and semi-empiric ZINDO methods.

Effect of Roll Diameter and Modes of Rolling on Evolution of Texture in High Purity Aluminum

Present work describes the development of texture in high purity aluminum under different modes of deformation by rolling using two different roll diameters, namely 300 and 610 mm. It has been observed that the change in both the roll diameter as well as the modes of rolling has a marked influence on the evolution of texture as well as the characteristics of a- and β-fibres. The results are discussed in terms of the effects of roll gap geometry and the relevant stress conditions that affect the strain path of crystallite rotation.

Magnetic anomalies across Bastar craton and Pranhita-Godavari basin in south of central India

Aeromagnetic anomalies over Bastar craton and Pranhita-Godavari (P-G) basin in the south of central India could be attributed to NW-SE striking mafic intrusives in both the areas at variable depths. Such intrusions can be explained considering the collision of the Bastar and Dharwar cratons by the end of the Archaean and the development of tensile regimes that followed in the Paleoproterozoic, facilitating intrusions of mafic dykes into the continental crust. The P-G basin area, being a zone of crustal weakness along the contact of the Bastar and Dharwar cratons, also experienced extensional tectonics. The inferred remanent magnetization of these dykes dips upwards and it is such that the dykes are oriented towards the east of the magnetic north at the time of their formation compared to their present NW-SE strike. Assuming that there was no imprint of magnetization of a later date, it is concluded that the Indian plate was located in the southern hemisphere, either independently or as part of a supercontinent, for some span of time during Paleoproterozoic and was involved in complex path of movement and rotation subsequently. The paper presents a case study of the utility of aeromagnetic anomalies in qualitatively deducing the palaeopositions of the landmasses from the interpreted remanent magnetism of buried intrusive bodies.

Polar and chemical order in relation with morphotropic phase boundaries and relaxor behaviour in bulk and nanostructured PSN–PT

We have recently evidenced the existence of a complex path of polarisation rotation via two monoclinic phases in the giant-piezoelectric materials PSN–PT that is similar to the PMN–PT system. In this article we have presented the state of knowledge on the PSN–PT system and have given new results showing the close connection between the local inhomogeneous chemical order of Sc/Nb/Ti cations and the stability of different ferroelectric phases. The notion of morphotropic phase boundaries is discussed in relation with the gradual appearance of long-range polar order with increasing Ti content in PSN–PT. Comparison with the films and nanopowders/ceramics has also been made.

Electronic Structure of Sulfimides: A Theoretical Study

Abstract The electronic structure of sulfimides has been studied using the model system HN=SH2, 1, by performing ab initio calculations. There are two minima on the path of rotation across the S–N bond in 1. G2 calculations showed that the S–N rotational barrier in 1 is 8.50 kcal/mol. The inversion around S in 1 goes through a high-energy barrier of 26.85 kcal/mol at the same level. Substituent effects on the electronic structure were studied using Me, Cl, and F as substituents. Charge analysis using the NPA method has been performed to understand the electronic factors responsible for the observed trends in the S–N interactions. The NBO method was employed to quantitatively estimate the second-order interactions, which indicate that the S–N partial double-bond character in sulfimides is mainly attributable to negative hyperconjugative interactions, rather than pπ–pπ interactions.

Para-CORDIC: Parallel CORDIC Rotation Algorithm

In this paper, the parallel COrdinate Rotation DIgital Computer (CORDIC) rotation algorithm in circular and hyperbolic coordinate is proposed. The most critical path of the conventional CORDIC rotation lies in the determination of rotation directions, which depends on the sign of the remaining angle after each iteration. Using the binary-to-bipolar recoding (BBR) and microrotation angle recoding techniques, the rotation directions can be predicted directly from the binary value of the initial input angle. The original sequential CORDIC rotations can be divided into two phases where the rotations in each phase can be executed in parallel. Our proposed architectures have a more regular and simpler prediction scheme compared to previous approaches. The critical path delay is reduced since the concurrently predicted rotations can be combined using multioperand carry-save addition structures.

Numerical Computation of Apex Angle Effects on Taylor Vortices in Rotating Conical Cylinders Systems.

The occurrence of Taylor vortices between two conical cylinders of the inner one rotating and the outer one at rest is numerically simulated by the integration of time-dependent Navier-Stokes equations of the primitive variables. The motion is initiated by a progressive acceleration following a linear path of the inner conical cylinder rotation from the state of rest until its final rotation speed. In the integrated equations, the use of a coordinate transformation permitted to point out the apex angle α in the circular coordinates system and then to study the effects of α on the transient development of the Taylor-vortex structures, the steady states and the flow field characteristics. The numerical calculations have been achieved by the use of the SMAC method applied to a finite difference scheme for the case of a finite length. As a result, the symmetry of the Taylor vortices formed with regard to the mid plane for α = 0 does not exist anymore when the apex angle α becomes greater. The study of the flow field details showed that the contribution of the centrifugal forces becomes more important for increasing α due to the increase of the azimuthal component.

Measurement of relative tool displacement to the workpiece for the assessment of influences of machining errors on surface profiles

The paper presents a model being disturbed by transverse surface profile machined by displacement of tool relative to the workpiece. Measuring system consisting of radial and axial tool displacement in relation to the workpiece to determine the interaction of the machining system on shaping the geometrical structure of the surface machined has been presented. The system has two analog measuring paths of relative displacements with contactless gauges and a/d data processing, and a digital measuring path of the workpiece rotation with its marker and the interface with the computer. The displacement signals have been measured and their amplitude-frequency characteristics have been presented. The filtration of tool displacements at every turn of the workpiece has been done and their synthesis with the tool profile for generating of transverse surface profile. The amplitude spectra of surfaces profiles disturbed by the tool displacements have been calculated and significant frequency components affected by the displacements have been analysed.

On machining dynamics of flexible parts

Solid modellers are now well established for computer aided design of mechanical parts. Machining applications, however, remain limited to geometric tool path planning. The physical aspects of the process are largely ignored. Success in actual machining, however, depends on consideration of cutting forces, torques, part and tool deflection, chatter, tool breakage and wear. This paper reports research progress towards a comprehensive simulation of the physical machining process of thin flexible parts. The system is based on extensions to a commercially available solid modeller. Cutting tool location data (CL-DATA) files along with an initial solid model of the workpiece are inputs. Each tool motion is segmented into short steps along the path and angular increments of spindle rotation. At each simulation step, immersion of the cutting tool teeth with the part is calculated. This information is then used by a machining process model to calculate cutting forces and tool/workpiece deflection. Up to five-axis motion is supported using a sweep representation of the tool swept volume. Flexible tools are modelled as cantilevers; flexible parts are created as solid models, are meshed and are dynamically solved using finite element analysis. The mesh is updated as material is machined away from the part.

Se–N interactions in selenohydroxylamine: a theoretical study

The potential energy surfaces of thiohydroxylamine HS–NH2, 1, and selenohydroxylamine HSe–NH2, 2, have been searched, using ab initio and density functional methods, to study the conformational preferences. There are two minima on the path of rotation around the Se–N bond in 2. High accuracy G2MP2 calculations showed that the Se–N rotational barrier in 2 is 5.41 kcal mol−1, which is 1.16 kcal mol−1 less than the S–N rotational barrier in 1. The inversion around N in 1 and 2 goes through low energy barriers of 1.79 and 2.44 kcal mol−1 at the same level respectively. Charge analysis using the natural population analysis (NPA) method has been performed to understand the electronic factors responsible for the observed trends in the Se–N interactions. The strength of the negative hyperconjugation in 2 has been estimated using natural bond orbital (NBO) analysis and by studying the substituent effect.

Theoretical investigation on the conformational preferences of sulfinimines

The potential energy surfaces of sulfinimine, H2CNS(O)H, 1, and methylsulfinimine, MeHCNS(O)H, 2, have been searched, using the ab initio MO and Density Functional Methods, to study the conformational preferences. Complete optimizations at HF/6-31G*, HF/6-31+G*, MP2/6-31+G* and B3LYP/6-31+G* levels on 1 showed that there are three minima on the path of rotation around N–S bond in 1. A conformer with synperiplanar arrangement, with the C–N–S–O torsional angle close to 13°, has been found to be the most preferred. Repulsions between the lone pairs of electrons present on N, S and O atoms are responsible for the observed conformational preferences of 1. The N–S bond rotational barrier in 1 is 9.16 kcal mol−1 at the B3LYP/6-31+G*(+ZPE) level. This high energy barrier can be attributed to the nN → σ*SO negative hyperconjugation and to the repulsive interactions between the lone pairs of electrons. The planar N-inversion barrier in 2Z is 18.72 kcal mol−1 at the B3LYP/6-31+G* (+ZPE) level, comparable to experimental values.

Interaction in Immersive Virtual Environments: Rotating Objects with an Instrumented Prop

An instrumented prop was used to rotate a virtual object in an immersive virtual environment. For each experimental trial, two virtual objects were displayed adjacent to each other. With an emphasis placed on speed and accuracy, participants rotated one object until its orientation matched the orientation of the other object. Participants used an efficient path of rotation more often when the axes of the object, the participant, and the shortest path of rotation were aligned. In relative terms, these paths were more efficient when there was a large angular difference between the objects' orientations. The rate at which participants rotated the virtual object increased substantially with the magnitude of the initial angular difference between the two orientations. By contrast, in most mental rotation studies the rate of rotation remained constant for variations in angular disparity.

Conformations and conformational changes of 3-isobutyl- and 3-neopentyl-rhodanines. A case of steric attraction studied by X-ray crystallography, NOE effects and force-field calculations

An X-ray crystallographic study of 3-neopentyl-5-phenylrhodanine [3-neopentyl-5-phenyl-2-thioxo-2,3dihydro-1,3-thiazol-4(5H)-one 4] shows that the crystal is composed of the syn form, previously supposed to be less stable than the anti form. MM2(91) calculations also predict the syn form to be the most stable one due to an attractive steric effect, mainly between two methyl groups of the tert-butyl group and the nearest carbon and hydrogen atoms in the benzene ring. MM2 calculations of the barriers to rotation the 3-isobutylrhodanines 1 and 3 and on the 3-neopentyl analogues 2 and 4 reproduce the experimental barriers quite well and indicate that the preferred path of rotation of the 3-substituent is with the isopropyl or tert-butyl group passing the carbonyl rather than passing the thiocarbonyl group.A substantial NOE enhancement was observed between tert-butyl and phenyl protons, but this was not strong enough to exclude the possibility that it was caused by a minor form present in ca. 30%.

Path and Extent of Cross-Bridge Rotation during Muscle Contraction

The angular distribution of myosin cross-bridges in muscle fibers was investigated in four physiological states using a multiple probe analysis of varied extrinsic probes of the cross-bridge [Burghardt & Ajtai (1994) Biochemistry (preceding paper in this issue)]. The analysis combines data of complementary techniques from different probes giving the highest possible angular resolution. Four extrinsic probes of the fast reactive sulfhydryl (SH1) on myosin subfragment 1 (S1) were employed. Electron paramagnetic resonance (EPR) spectra from paramagnetic probes, deuterium- and 15N-substituted for greater sensitivity to orientation, on S1 were measured when the protein was freely tumbling in solution and when it was decorating muscle fibers. The EPR spectra from labeled S1 tumbling in solution were measured at X- and Q-band microwave frequencies to uniquely specify the orientation of the probe relative to the S1 principal hydrodynamic frame. The EPR spectra from labeled S1 decorating muscle fibers in rigor and in the presence of MgADP were measured at X-band and used in the multiple probe analysis of cross-bridge orientation. The time-resolved fluorescence anisotropy decay (TRFAD) of fluorescent probes on S1 was measured when the protein was freely tumbling in solution, and fluorescence polarization (FP) intensities from fluorescent probes modifying SH1 in intact muscle fibers were measured for fibers in rigor, in the presence of MgADP, in isometric contraction, and in relaxation at low ionic strength. The TRFAD measurements limit the range of possible orientations of the probe relative to the S1 principal hydrodynamic frame. The FP intensity measurements were used in the multiple probe analysis of cross-bridge orientation. The combination of the EPR and FP data determined a highly resolved cross-bridge angular distribution in rigor, in the presence of MgADP, in isometric contraction, and in relaxation at low ionic strength. These findings confirm earlier observations of a rigid body rotation of the SH1 region in the myosin head group upon physiological state changes and indicate the path and extent of cross-bridge rotation during contraction. The rotation of the cross-bridge is visualized with computer-generated space-filling models of actomysin in six states of the contraction cycle.

Postural Stabilization and Motion Control of the Rope-Hopping Robot

In addition to the industrial robots for production, a large number of robots for nonindustrial use have been developed recently. These include emergency rescue and fire-fighting robots, as well as robots for amusement, educational use and security. The authors have no doubt that the robots for amusement and educational purposes hold great promise for future applications. Thus, we developed a rope-hopping amusement Although rope-hopping is an easy exercise even for young children, there are several difficulties to overcome if it is to be executed by a The developed robot is composed essentially of one leg, one main body attached by a pivoting joint to the top end of the leg, and a double arm holding a rope. As the main body swings forward and backward, postural stability of the robot in the vertical plane is maintained using feedback control based on compound center of gravity of the robot. The rope-hopping motion of the robot is realized by cooperative use of the leg, the main body and the arms which rotate the rope according to the proposed path. Experimental results show that the control methods developed to achieve the postural stability and jumping of the robot coordinated with the path of rotation of the rope have useful applications in other areas.