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The direct problem in gravimetry is one of the few areas of applied geophysics where complete, general and fully valid solutions are available. The common issue in the gravimetric direct problem is that there are several different solutions for even simple shaped bodies available throughout the literature. While the direct problem is single-valued, the general solutions (if possible to find analytically) are desired. The aim of the present paper is to bring clarity into the “information noise” which occurs in the literature for the case of the spherical shell/layer. We collected several different solutions and proved their equality (as special cases of the general solution). The differences between these solutions are caused by the symbolism used, but mostly by the different area of validity of each formula. The formulae are discussed and scored on several criteria. The general solutions for the gravitational potential and attraction on the rotational axis of the spherical shell are presented, as well as the solution for the biaxial ellipsoidal layer for comparison.

Design and development of a domino cyclative approach for the synthesis of new polycyclic γ-butenolides from β-aryl-Z-enoate propargylic alcohols, through the interception of an intermediate of the Z-enoate-assisted Meyer-Schuster rearrangement, has been reported. A systematic NMR analysis of various derivatives of this class revealed and supported the potential atropisomerism associated with them. These molecules represent first examples of butenolide ring-based atropisomeric compounds in organic chemistry. The synthetic process involves a synchronous construction of both rings with concurrent creation of the potential stereogenic rotational axis.

Tibiofemoral synchronization technique matches the rotational alignment of the tibial component to the femoral component during the total knee arthroplasty (TKA). The rotational axis of the proximal tibia can be changed by this technique, which affects tibial torsion postoperatively. The purpose of this study was to investigate whether the tibiofemoral synchronization technique affect the tibial torsion, and the lower limb rotation after primary TKA. It was hypothesised that the tibial torsion would change after primary TKA. Ninety-three posterior stabilised TKAs from 89 patients were included from January 2017 to December 2018. Mechanical hip–knee–ankle axis (mHKA), in plain radiographs, femoral anteversion, tibial torsion, femoral neck-malleolar angle (FNMA), and rotational alignment of the femoral and the tibial components in pre- and postoperative CT scans were measured by two blinded observers. The primary outcome was a postoperative change in femoral anteversion, tibial torsion and FNMA. Clinical outcomes were evaluated using the American Knee Society Knee Score (AKSKS)/Function Score (AKSFS), and Oxford Knee Score (OKS) preoperatively and at 1 year after TKA. Patients’ perception of changes in the foot progression angle after TKA was investigated. Statistical significance was set at p

A submerged oscillating heave plate is utilized as a mechanism in some marine structures for vibration reduction. Quantifying the hydrodynamic properties in axial (heave) oscillations has ...

The ability to verify the geometrical quality of a machined workpiece on the machine tool itself can be a crucial advantage in ultra-precision diamond turning. This paper presents a new positioning procedure for optical one-dimensional (1D) probes integrated on diamond turning machines with two horizontal linear axes and one rotational axis. A tilted flat, mounted onto the spindle, is used to determine the offsets between the probe and the spindle axis in order to minimize measurement deviations referred to probe alignment errors. An estimation of the positioning uncertainty, which can be specified to be less than 0.3 µm, is given.

“Grinding Mechanism having Advanced Secondary Rotational Axis” is one of the newer plane surface grinding methods that has an uncommon abrasion mechanism. Unlike conventional methods, in Grinding Mechanism having Advanced Secondary Rotational Axis, there are two rotations of a wheel. The first rotation is the same as the conventional grinding methods, which is the circumferential rotation. The other rotation is the newly developed axial rotation, where the wheel rotates around itself perpendicular to its radial axis. In the grinding process, the grinding force, energy, power, and temperature are directly related to the material removal rate. In this article, the chip model in Grinding Mechanism having Advanced Secondary Rotational Axis was addressed and material removal rate was reformulated. The new chip ratio formula was adapted to the grinding force, energy, power, and temperature in the conventional plane surface grinding method. The chip formed in the conventional plane surface grinding method consists of two-dimensional xy plane. In Grinding Mechanism having Advanced Secondary Rotational Axis, on the other hand, the chips consist of three-dimensional xyz plane. The reason behind this is the second rotation obtained in Grinding Mechanism having Advanced Secondary Rotational Axis (axial rotational motion). The chip model was obtained from the combination of two rotations in Grinding Mechanism having Advanced Secondary Rotational Axis. As a result, the resulting chip model increased the material removal rate only slightly and this increase was negligible. Accordingly, an increase in grinding force, energy, power, and temperature was observed at negligible rates.

In the present study, the physical meaning of vorticity is revisited based on the Liutex-Shear (RS) decomposition proposed by Liu et al. in the framework of Liutex (previously called Rortex), a vortex vector field with information of both rotation axis and swirling strength (Liu et al. 2018). It is demonstrated that the vorticity in the direction of rotational axis is twice the spatial mean angular velocity in the small neighborhood around the considered point while the imaginary part of the complex eigenvalue (λci) of the velocity gradient tensor (if exist) is the pseudo-time average angular velocity of a trajectory moving circularly or spirally around the axis. In addition, an explicit expression of the Liutex vector in terms of the eigenvalues and eigenvectors of velocity gradient is obtained for the first time from above understanding, which can further, though mildly, accelerate the calculation and give more physical comprehension of the Liutex vector.

We aimed to evaluate whether there is a consensus among bi- (2D) and three-dimensional (3D) evaluations of mandible condyle position and its rotation center. Also, if this data can be replicated in orthognathic surgery planning. The survey was carried out on the major databases (PubMed, SCOPUS, Embase, Cochrane). Human or human bio models evaluations in 2D or 3D of mandibular condylar position concerning its fossa and rotational axis for orthognathic surgery planning were eligible. The heterogeneity of the studies and uncertainties in methodological biases did not allow us to identify the superiority of 2D or 3D methodology in determination of the condylar rotational axis. There is a lot of divergences in the definition of occlusal relationships among dental specialties. Although there was no consensus regarding condylar position in relation to the fossa, the most reported axis of rotation was positioned posterior-inferior. Weak scientific evidence and divergences in dental vocabulary shows the need for clinical studies with more accurate and transparent methodological design to standardize concepts. Despite we cannot affirm, we can suggest that the centric relation (CR) is not the condylar position when clinically manipulated in the posterior superior direction. This condylar position is the retruded contact position (RCt) while CR is the functional position of the condyle. In this way, the orthognathic surgery has two occlusal relationships during planning and execution. The ideal axis of rotation for orthognathic surgery planning must be fixed, permit individualization for each condyle and be reproducible. The 2D planning is obsolete as cannot provide all the necessary tools for an accurate planning.

Here we report two new multicomponent supramolecular rotors (1 and 2) based on 2,7-diphenyl-9H-carbazole stators and two rotators brought together by a non-innocent C-H…O interaction. This hydrogen bond serves a dual function: it constitutes the rotational axis for THF and acts as a ‘brake’ for the motion of DABCO. Dynamic characterization of 1 by VT 2H NMR experiments supports that DABCO rotates about its supramolecular axis with jumps of 120º (3-fold) and a krot >10 MHz at 300 K, but interestingly, this motion is reduced to 5 MHz at 150 K. Concurrently, the THF experiences an atypical motion on an axis that is perpendicular to that of DABCO, experiencing 180º jumps in the fast regime even at 175 K. 1H(T1) relaxometry studies show that DABCO has an Ea=3.5 kcal/mol, while for THF, an Ea=2.3 kcal/mol was computed by periodic DFT. Fast and organized mobility of two constituents within crystals is extremely infrequent and could have strong implications for future applications of multicomponent solids with regulated dynamics.

In recent machining processes, 5-axis controlled machine tool is widely used for machining complicated workpiece shape with curved surface. In such process, to achieve high productivity, planning method of cutting conditions to satisfy both following the commanded tool feed rate in machining process and realization of good surface roughness are required. In conventional study, it is known that lead angle of tool posture against local machined surface influence the surface roughness. Then, common commercial CAM systems have already functioned to avoid interference and control the lead angle in each cutter location. However, in the generated cutter locations by the conventional algorithms, when the tool posture changes rapidly, there is a problem that actual feed rate does not reach the command value and machining time becomes longer than expected. In this paper, we propose the new tool posture correction algorithm. In the proposed method, first, the rotational axis that causes the feed speed rate decline is specified by preliminary experiments. And, the jerk value that is the threshold for the feed speed decline is investigated. After that, for the NC program, the command value of the target axis is modified within a range where interference of cutting tool does not occur, thereby preventing a decline in the actual feed rate. This paper describes an outline of the proposed modification method and the effect of the modification of the target axis positions on the lead angle and the actual feed rate.

In the field of modern manufacturing, probes have been playing a more and more crucial role. However, contact probes are unfit for measuring objects with soft surfaces or very tiny cavities and require radius compensation of stylus. In comparison, noncontact probes such as optical probes do not have to consider these problems and are well-performed in measurement. However, existing optical probes (triangulation) may fail to detect objects with rich spatial structures (due to the occlusion effect) and highly reflective curved surfaces (due to existence of highlight spots). Considering the problems, an optical probe based on discrete rotational symmetric triangulation is proposed in this paper. The emitting laser beam of the probe is the rotational axis and the five receiving optical paths (lenses and mirrors) are rotationally symmetrically distributed around the laser axis and are coimaged on a CMOS camera. Results of simulations and experiments show that the new-established prototype is designed with good robustness under various conditions such as different surface characteristics and different inclination degrees. The probe enables conducting real-time on-machine measurement without directional dependency with a resolution of 39 μm and repeatability accuracy of 0.72 μm.

Left ventricular rotational motion is a feature of normal and diseased cardiac function. However, classical torsion and twist measures rely on the definition of a rotational axis which may not exist. This paper reviews global and local rotation descriptors of myocardial motion and introduces new curl-based (vortical) features built from tensorial magnitudes, intended to provide better comprehension about fibrotic tissue characteristics mechanical properties. Fifty-six cardiomyopathy patients and twenty-two healthy volunteers have been studied using tagged magnetic resonance by means of harmonic phase analysis. Rotation descriptors are built, with no assumption about a regular geometrical model, from different approaches. The extracted vortical features have been tested by means of a sequential cardiomyopathy classification procedure; they have proven useful for the regional characterization of the left ventricular function by showing great separability not only between pathologic and healthy patients but also, and specifically, between heterogeneous phenotypes within cardiomyopathies.

PURPOSE The aim of this cross-sectional study was to assess maximum restraining lip force (MLF), maximum voluntary bite force (MBF), and patient-related parameters to evaluate their influence on masticatory function in four groups of participants with different dental states. METHODS Participants were recruited and assigned to one of four different groups depending on dental status: complete removable dental prostheses (CRDP group); edentulous with two-implant overdentures (IOD group); Kennedy Class I partial removable dental prostheses (PRDP group); or fully dentate (control group). A dental examination was performed and history taken. MLF was measured as the maximum withstood pulling force with three sizes of oral screens, MBF was evaluated using a digital force gauge, and masticatory performance was assessed using a two-color mixing ability test. Linear regression was used to determine the predictive effects of covariates on masticatory performance. Global and pairwise comparisons were also carried out. RESULTS A total of 68 participants with an average age of 69.3 ± 7.7 years were recruited. MLF depended on the screen size (P = .0004; Kruskal-Wallis) and increased with CRDP use, especially in challenging tasks, such as restraining the smallest screen. The highest MBF was found in dentate participants (P < .0001; Mann-Whitney). Analysis of variance (ANOVA) showed a global significant difference in masticatory performance between groups, with PRDP patients chewing better than CRDP patients. Dental state, time lapse since last tooth loss, and MBF predicted masticatory function. CONCLUSION Tooth loss significantly affects MBF and masticatory performance. Free-end saddles with a rotational axis in two-implant IODs and Kennedy Class I PRDPs may limit MBF and consequently masticatory performance. CRDP design should facilitate perioral muscular function.

The main purpose of the present study is to prove the usability of a mechanism with a common rotational axis during twisting manipulation using a multi-fingered robotic hand where two fingers and two other fingers can independently rotate in inner and outer circles with a dual turning mechanism. Although various types of conventional multi-fingered hands have potential capability to achieve twisting manipulations such as opening a bottle cap from within a hand, it is well-known that such tasks are difficult to execute quickly due to limited working space of the fingers and complexity of control. The proposed hand with a common rotational axis is effective in rotational manipulation around a particular axis, where each joint role assignment is completely decoupled into internal force control for grasping an object and velocity control around the axis for rotating the object. We prove the usability of this mechanism with a common rotational axis through the use of a control scheme, and show experimental results involving manipulation tasks where twisting manipulation is dominant.

It has been demonstrated that the torsional patterns of the metatarsal heads are associated with the presence or absence of the medial longitudinal arch in hominoid feet. The relatively untwisted second metatarsal is unique in humans, but that of the African apes is much more inverted, suggesting that the torsion of the second metatarsal might represent the overall shape and flatness of the foot. Some clinical studies have recently argued that the onset of foot pathologies such as hallux valgus might be related to the torsional pattern of the metatarsals. However, to date, no studies have systematically investigated the morphological variations of the torsional patterns of human metatarsals. In this study, therefore, the aim was to clarify the age- and sex-associated variations in the torsional patterns of human metatarsals using three-dimensional computed tomography. The torsion angles of the five metatarsals were calculated by defining the dorsopalmar vector of the metatarsal base and the vector corresponding to the rotational axis of the metatarsal head. The present result demonstrated that the second metatarsals of females were significantly more inverted with increasing age. Flat foot is known to be most common in elderly women. Whether there is a cause-effect relationship between second metatarsal torsion and flattening of the medial longitudinal arch has yet to be answered, but this study suggested that torsion of the second metatarsal might possibly be used as an indicator for the early diagnosis of flat foot and associated foot pathologies. Clin. Anat. 30:1058-1063, 2017. © 2017 Wiley Periodicals, Inc.

Inner-and-outer steel flange has gained many attentions in China. This type flange has both inner and outer rings, as well as bolts. To gain insight into the intrinsic characteristics of the flange, an experimental study is conducted, taking into account that the tension and bending loads are imposed simultaneously. The varying of relative displacement between two adjacent flange planes with external loading is surveyed. It is indicated that the deformation is almost linearly increased with the external loads, if there is no yielded bolt. Strain gauges are employed to capture the strain distribution in the ribs as well as the tube. The internal tension force of bolt is also measured in the test. It is revealed that the failure mode of the flange is the breaking of the outer bolts. Moreover, the existence of the tension load would reduce the bending bearing capacity of the flange, and prying force could be ignored. It is concluded that the plane-section assumption holds approximately. Accordingly, formulas are given to compute the bearing capacity of the flange. It is found that the computing method is quite conservative if the position of rotation axis takes a value of 0.8 times of the diameter of the steel tube.

Parallel mechanisms (PMs) having three translational (T) and one rotational (R) movement capability draw continuous attention from academia and industry. The existing 3T1R PMs can only generate Schoenflies motion and bifurcation of Schoenflies motion. This paper proposes a new 3T1R motion that features one rotation about a varying axis plus three pure translations. Drawing mainly on finite screw theory, a hierarchical approach for type synthesis of limb structures of the PMs having 3T1R motion with variable rotational axis is presented by developing the basic limb bonds first and then their equivalent substitutions using the properties of screw triangle product. The assembly conditions for the PMs of this kind are discussed. Consequently, numerous novel PMs consisting of four identical limbs are synthesized using this technique.

Simultaneous 5-axis control machining is used to machine components in complex, deep grooved shapes. In order to maintain actual feed rates in this kind of machining, it is vitally important to secure continuity in the movement of the rotational axis. When the tool reverses its direction of travel, however, its axis of rotation is liable to make sudden movements. In this study, therefore, we first derive candidate tool postures that can meet the conditions for relative postures to machined surfaces while avoiding tool interferences. We then develop a method for automatically planning continuous changes in the command values of the rotating axial angles in the machine coordinate space.

Surgeon-dependent factors such as optimal implant alignment of the tibial component are thought to play a significant role in the outcome following primary total knee arthroplasty (TKA). In addition, tibial component malrotation is associated with pain, stiffness, and altered patellofemoral kinematics in TKA. However, measuring tibial component rotation after TKA is difficult. Therefore, the purpose of this study was to find a reliable method for positioning the tibial component in TKA. To investigate the morphology of the tibial plateau, 977 patients' knees (829 females and 148 males) were evaluated using MRI. The relationships between the femoral transepicondylar axis (TEA), Akagi line, posterior tibial margin (PTM), medial third of the tibial tubercle (MTT), and anatomical tibial axis (ATS) were investigated in this study. In addition, gender difference in tibial rotational alignment were evaluated. Relative to the TEA, the MTT and ATS were externally rotated by 0.5° ± 4.4° and 0.5° ± 5.4°, respectively, while Akagi line and PTM were internally rotated by 3.7° ± 4.5° and 9.9° ± 6.1°, respectively. Gender differences were found in MTT, Akagi line and ATS (P

We systematically examine light curves from a single hot spot on a slowly rotating neutron star with very high compactness, where the so-called invisible zone does not exist. In particular, we adopt three different shapes of hot spot and take into account the finite size effect of hot spot on the light curves. Then, we find that the brightening of flux occurs when the hot spot with small area crosses the opposite side to the observer, where the brightening becomes stronger as the area of hot spot decreases. Since this brightening happens only when a part of hot spot crosses the opposite side to the observer, one may constrain the neutron star geometry, i.e., the combination of an inclination angle, angle between the rotational axis and normal vector at the center of hot spot, and the opening angle of hot spot, if the brightening would be observed. In addition, by counting such a brightening in the light curves, one may know how many narrow bands of hot spot and/or spots with small area cross the opposite side to the observer., Comment: accepted for publication in PRD

The existence of quintessential dark energy around a black hole has considerable consequences on its spacetime geometry. Hence, in this article, we explore its effect on horizons and the silhouette generated by a Kerr-Newman black hole in quintessential dark energy. Moreover, to analyze the deflection angle of light, we utilize the Gauss-Bonnet theorem. The obtained result demonstrates that, due to the dragging effect, the black hole spin elongates its shadow in the direction of the rotational axis, while increases the deflection angle. On the other hand, the black hole charge diminishing its shadow, as well as the angle of lights deflection. Besides, both spin and charge significantly increase the distortion effect in the black hole's shadow. The quintessence parameter \gamma, increases the shadow radius, while decreases the distortion effect at higher values of charge and spin parameters., Comment: 11 Pages, 7 figures, Matches published version

The New Horizons spacecraft's flyby of Kuiper Belt Object (KBO) (486958) Arrokoth revealed a bilobed shape with highly flattened lobes both aligned to its equatorial plane, and a rotational axis almost aligned to the orbital plane (obliquity ~99 deg). Arrokoth belongs to the Cold Classical Kuiper Belt Object population that occupies dynamically undisturbed orbits around the Sun, and as such, is a primitive object that formed in situ. Therefore, whether its shape is primordial or evolutionary carries important implications for understanding the evolution of both KBOs and potentially their dynamically derived objects, Centaurs and Jupiter Family Comets (JFC). Applying our mass loss driven shape evolution model (MONET), here we suggest that the current shape of Arrokoth could be of evolutionary origin due to volatile outgassing in a timescale of about 1 to 100 Myr, while its spin state would not significantly affected. We further argue that such a process may be ubiquitous in the evolution of the shape of KBOs shortly after their formation. This shape changing process could also be reactivated when KBOs dynamically evolve to become Centaurs and then JFCs and receive dramatically increased solar heating., Comment: 20 pages, 10 figures, a revised version is published in Nature Astronomy (2020)

Successful implementation of a catheter-based imaging system relies on the integration of high-performance miniaturized distal end optics. Typically, compensation of chromatic dispersion, as well as astigmatism introduced by the device’s sheath, can be addressed only by combining multiple optical elements, adversely impacting size and manufacturability. Here, we present a 300 × 300 × 800 μm(3) monolithic optic that provides high optical performances over an extended wavelength range (near UV-visible-IR) with minimal chromatic aberrations. The design of the optic, fully optimized using standard optical simulation tools, provides the ability to freely determine aperture and working distance. Manufacturing is cost effective and suited for prototyping and production alike. The experimental characterization of the optic demonstrates a good match with simulation results and performances well suited to both optical coherence tomography and fluorescence imaging, thus paving the way for high-performance multimodal endoscopy systems.

Tibial tubercle-trochlear groove (TT-TG) distance is associated with a greater risk of recurrent patellar dislocation in young, active patients. However, the effect of TT-TG distance after total knee arthroplasty (TKA) has not been investigated. The purpose is to analyze the effect of TT-TG distance and component rotation on patellar tilt and patellar shift after TKA.After TKA, axial computed tomography scans and axial radiograph were taken in 115 consecutive knees. TT-TG distance was measured between the most anterior point of the tibial tuberosity and the deepest point of the femoral component relative to a line connecting the anterior condyles. Femoral and tibial component rotation was measured relative to the femoral and tibial rotational axis, respectively. Pearson correlation coefficients were calculated.TT-TG distance had a significant correlation with patellar tilt in extension (R = 0.220, P = .018), patellar tilt in flexion (R = 0.438, P.001), and patellar shift (R = 0.330, P.001). Tibial component rotation had a significant correlation with patellar tilt in flexion (R = -0.251, P = .007) and patellar shift (R = -0.360, P.001). Femoral component rotation had no significant correlations. Tibial component rotation had a significant correlation with TT-TG distance (R = -0.573, P.001), whereas femoral component rotation had no correlation (P = .192).TT-TG distance had a significant correlation with patellar tilt and patellar shift. Surgeons need to understand the factors affecting TT-TG distance and to pay attention to avoiding excessive TT-TG distance after TKA.

This paper introduces the development of the seating posture holding assist chair and proposes the variable compliance control method. The children with cerebral palsy (CP) cannot control the seating posture themselves. In order to support their life, a wheelchair for holding the seating posture is used. However, the seating posture is holding forcibly. As a result, they get stressed and press their back to wheelchair. From the backgrounds, the seating posture holding assist chair is developed in our research. This chair has three-degrees rotational axis in reclining, twist of hip, and neck. Furthermore, the variable compliance control for holding seating posture is proposed. By experiment of reclining control, the proposed control method is verified.

Given the design of the Helical TomoTherapy device, the patient's central axis is routinely aligned with the machine's rotational axis to prevent the patient's body from colliding with the machine walls. However, for treatment of tumors located away from the patient's central axis, this position may not be optimal as the adequate radiation dose may not reach the affected site. Our study aimed to investigate the influence of tumor location on dose quality and delivery efficiency of tomotherapy plans. A phantom and 15 patients were selected for this study. Two plans, A and B, were implemented for each case. In plan A, the patient's central axis was aligned with the machine's rotational axis, whereas in plan B, the center of the planning target volume (PTV) was aligned with the machine's rotational axis. Both plans were optimized with the same planning parameters, and the dose quality of the plans was evaluated using dosimetrics. The delivery efficiency was determined from delivery time and monitor units (MUs). A paired t-test or nonparametric Wilcoxon signed-rank test was performed for statistical comparison. In the phantom study, the median delivery times were 358 and 336 seconds for plans A and B, respectively, and this difference was significant ( p = 0.005). In the patient study, the median delivery times were 348 and 317 seconds for plans A and B, respectively, and this difference was also significant ( p = 0.001). The dose qualities of both plans for each patient were nearly identical. No significant differences were found in the conformal index, heterogeneity index, and mean dose delivered to normal tissue between the plans. Both phantom and patient studies showed that for normal-sized patients, the delivery time reduced as the distance between the PTV and the patient's central axis increased when the PTV center was aligned with the machine axis. In conclusion, aligning the PTV center with the machine's rotational axis by shifting the patient during tomotherapy reduces the delivery time without compromising the dose quality of intensity-modulated radiation therapy.

Background: The origin of femoral maltorsion is often unknown. However, defining the origin of the rotation of the femoral maltorsion can be useful for establishing the most suitable point to do an external derotational osteotomy. Previous studies have not considered the femoral diaphysis in their investigations of the origin of the deformity. The study of the whole morphology of the femur with 3D volumetric tools, including the femoral diaphysis can contribute to a better understanding of the behavior of femoral maltorsion. Methods: An atypical case of unilateral femoral anteversion was selected. Both femurs were used to obtain 3D bio-models. The mirror image of the asymptomatic side was obtained and overlapped with the symptomatic femur. The Hausdorff&ndash, Besicovitch method was used to evaluate the morphologic discrepancies (in mm) between the two femurs in three zones: (1) the femoral neck, (2) the proximal diaphysis, and (3) the distal diaphysis. The differences between the two femurs were analyzed and its correlation was statistically defined using a lineal regression model. Results: The deformity in the distal diaphysis increased from the supracondylar area until the apex of the antecurvatum angle (R2 = 0.91) and then decreased until the base of the femoral neck (R2 = (&minus, 0.83)), to finally increase significantly in the femoral neck area (R2 = 0.87). All of the correlations were statistically significant (p-value ˂ 0.001). Conclusion: The femoral maltorsion originates in the supracondylar area and its rotational axis is the longitudinal axis of the femoral diaphysis. Even though the deformity affects the femoral diaphysis, its clinical relevance is much higher in the femoral neck since the rotational axis passes through its base. Thus, the osteotomy can be conducted along all of the femoral diaphysis as long as it is done perpendicular to it.

The Runout of a shaft is defined as the deviation of the measured surface from an ideal circle rotating around its rotational axis. The total runout can be split into two main components: the mechanical and the electrical runout. The electrical runout depends on the metallurgical state of the shaft which can only be altered to a certain degree after the forging and heat treatment processes are finished. Especially large shafts for electric motors are prone for high electrical runout, because material imperfections are moved to the center of the shaft by the forging process. As there is an unfavorable ratio between bearing diameter and the largest diameter of the shaft, these imperfections will be in the area of the new shaft surface after machining. Statistics have proven that material inhomogeneity generating an electrical runout occurs in almost all kinds of steel. This paper will provide some information about how to eliminate uncertain material properties causing the electrical runout. One measure will be presented in detail including test results.

This paper proposes a novel roller burnishing method that achieves simultaneously rolling and sliding effects on the burnishing point to accomplish a finish with superior surface integrity using a commercially available roller burnishing tool. The circumferential surface of the workpiece, which is rotated by the main spindle of the lathe, was targeted. The sliding effect was obtained by changing the rotational axis of the burnishing roller with respect to the workpiece. The principle of this method was examined theoretically, and the generation of rolling and sliding effects was confirmed experimentally. The processing characteristics of the method with an aluminum-based alloy workpiece were evaluated to compare with the conventional method. The influence of the burnishing conditions, such as the burnishing speed, thrust force, and feed rate, was also investigated. The thrust force and feed rate had a large influence on the burnished surface integrity, whereas the influence of the burnishing speed was minimal. The applicability of the proposed method for burnishing a carbon steel workpiece material was also examined.

A simple cyclic elastoplastic constitutive model for sand is proposed based on the UH model for overconsolidated clay. The proposed model has the following features. First, in order to describe the stress-induced anisotropy in sand, a rotational hardening rule is introduced for the evolution of the yield surface axis with development of plastic deviatoric strain in the principal stress space. Second, the relationship between the rotational axis and stress-induced anisotropy is modeled by introducing the slope of rotational axis into the yield function. The flatness of the yield surface can be determined by the slope of rotational axis. Finally, a revised unified hardening parameter is proposed to incorporate the stress-induced anisotropy. The model capability in describing the cyclic response of sand is verified by comparing the simulations with available test results.

O presente artigo descreve uma atividade pratica para determinar o ângulo de inclinacao do eixo de rotacao da Terra como um recurso didatico com potencial para promover a aprendizagem significativa em temas relacionados a astronomia e a Terra. Sao discutidos alguns topicos de interesse para a realizacao da atividade como o movimento aparente do Sol, o ângulo de incidencia dos raios solares ao longo do ano e as estacoes do ano. Apresenta-se os procedimentos e materiais utilizados na medicao do comprimento da sombra de um gnomon e, com os dados coletados, a determinacao do ângulo de inclinacao do eixo de rotacao. O artigo e finalizado com uma reflexao acerca da implementacao desta atividade no contexto do ensino fundamental e medio. http://dx.doi.org/10.18226/23185279.v3iss1p36

The relationship between the surgical epicondylar axis (SEA) and the rotational axis of the distal femur remains unclear. We investigated the relationship between the SEA and the distal femur and whether the SEA can be used as the rotational axis of the knee. Angular and linear measurements of 70 femora at 0°, 30°, 60°, 90°, and 120° of flexion were recorded. Results showed that the SEA was a logical and appropriate parameter as a principal axis for knee flexion at least between 0° and 60° of flexion. The study has important implications for the design and positioning of femoral components in total knee arthroplasty.

The intraband electromagnetic transitions in the framework of collective Hamiltonian for chiral and wobbling modes are calculated. By going beyond the mean field approximation on the orientations of rotational axis, the collective Hamiltonian provides the descriptions on both yrast band and collective excitation bands. For a system with one $h_{11/2}$ proton particle and one $h_{11/2}$ neutron hole coupled to a triaxial rotor ($\gamma=-30^\circ$), the intraband electromagnetic transitions given by the one-dimensional and two-dimensional collective Hamiltonian are compared to the results by the tilted axis cranking approach and particle rotor model. Compared with the tilted axis cranking approach, the electromagnetic transitions given by the collective Hamiltonian have a better agreement with those by the particle rotor model, due to the consideration of the quantum fluctuations., Comment: 17 pages, 4 figures

Dynamics of waves generated by scopes in gas centrifuges (GC) for isotope separation is considered. The centrifugal acceleration in the GC reaches values of the order of 10 6 g. The centrifugal and Coriolis forces modify essentially the conventional sound waves. Three families of the waves with different polarization and dispersion exist in these conditions. Dynamics of the flow in the model GC Iguasu is investigated numerically. Comparison of the results of the numerical modeling of the wave dynamics with the analytical predictions is performed. New phenomena of the resonances in the GC is found. The resonances occur for the waves polarized along the rotational axis having the smallest dumping due to the viscosity.

Mental-rotation tasks usually induce large gender differences in favor of males. The influence of task features and stereotype activation on the mental-rotation performance of elementary-school children has rarely been investigated. This study examined the performance of 272 fourth-grade boys and girls in a psychometric mental-rotation task varying implicit gender-stereotype activation (threatening vs. non-threatening task framing) and rotational axis (picture-plane vs. in-depth rotations). Children's gender stereotypes were assessed by a questionnaire. Both genders showed a male stereotype for mental rotation. Implicit gender stereotype activation influenced the gender difference only in picture-plane mental-rotation tasks. Boys outperformed girls in the threatening condition, but not in the non-threatening condition, here. However, in-depth rotation tasks induced a significant male advantage in both the threatening and the non-threatening conditions. Findings suggest that a task framing relating mental rotation to arts induces a stereotype-lift effect and that the rotational axis moderates the effect of implicit gender-stereotype activation.

This paper presents a new error measurement method, a Dual Optical Path Measurement Method (DOPMM), to identify error parameters of the rotational axis of a machine tool along its error sensitive directions. The method development was carried out on a motorized rotary stage equipped with a Doppler laser instrument. An error measurement experiment and a machining experiment were conducted on a five-axis machining center with a titling rotary table. It was found that the DOPMM can identify all of the six volumetric error parameters with the simple algebraic operations. Compared with the existing ball bar tests, which need a mathematical error modeling of machine tools to separate the error parameters, the identified process of DOPMM is more simple and easier to understand. And the operation of machine tools during the measurement is much easier than that of the existing ball bar tests. The experimental results showed that the part precision can have a significant improvement of 68% when the identified error parameters are used for error compensation. Hence, the measurement method established in this study is sensible and efficient, and could be used for the error compensation on a wide range of machine tools to improve their machining precision.

Background In clinical practice, clubfeet feel stiffer compared to healthy feet. Furthermore, the clinical impression is that stiffer clubfeet have a higher tendency to relapse. Until now, no objective measure has been available to determine the stiffness of clubfeet. The goal of the current project was to objectively quantify ankle and subtalar joint stiffness in clubfeet patients and to compare this stiffness between clubfeet patients and healthy controls using a newly developed measurement device. Methods The newly developed Torque-Displacement-Handpiece in combination with an adjusted Abduction Dorsiflexion Mechanism clubfoot-brace, made it possible to move a foot over two rotational axis, while continuously capturing the applied torque and the achieved angulation. Based on this information, stiffness of the ankle and subtalar joint were assessed for 11 clubfoot patients with 17 clubfeet and 11 healthy subjects with 22 healthy feet. Findings With the Torque-Displacement-Handpiece measuring device it was possible to measure torque, angulation and stiffness in a reliable and precise manner. Clubfoot patients showed less angulation and a higher stiffness for measurements over the ADM subtalar axis compared to controls. After adjusting for shoe size, the stiffness for measurements over the ADM tibiotalar axis was also significantly higher in clubfeet than controls. Interpretation Overall, these results indicate that clubfoot patients have a higher ankle and subtalar joint stiffness in the affected joint compared to healthy controls. In the future, the Torque-Displacement-Handpiece could be used to monitor stiffness of clubfeet during treatment, and as such, play a potential role in the early detection of relapsing clubfeet.

Purpose Ear position contributes significantly to facial appearance. However, while objective measurements remain the foundation for esthetic evaluations, little is known about how an ear should ideally be positioned regarding its rotational axis. This study aimed to further evaluate whether there exists a universally applicable ideal ear axis, and how sociodemographic factors impact such preferences. Materials and methods An interactive online survey was designed, enabling participants to change the axis of a female model's ear in terms of its forward and backward rotation. The questionnaire was sent out internationally to plastic surgeons and the general public. Demographic data were collected and analysis of variance was used to investigate respective preferences. Results A total of 1016 responses from 35 different countries (response rate: 18.5%) were gathered. Overall, 60% of survey takers chose the minus 10 or 5° angles to be most attractive. Significant differences were found regarding sex, ethnicity, country of residence, profession and respective ear axis preferences. Conclusion Across multiple countries and ethnicities, an ear position in slight reclination of minus 5–10° is considered most pleasing in Caucasian females. However, sociodemographic factors significantly impact individual ear axis preferences and should be taken into consideration when performing reconstructive ear surgery.

The bearings for rotary mirror scanners must be capable of establishing an extremely accurate rotational axis. This chapter outlines an appreciation of the advantages and limitations of the various types of spin axis bearings available. Gas bearings are particularly suited to low-noise, high-speed, high-accuracy bearing applications, which makes them attractive for many rotary mirror scanners. Gas bearings were a fairly natural derivative of the early work on hydrodynamic fluid film bearings, when it was realized that air could carry loads like any other fluid. A gas bearing is surrounded by its lubricant, the atmosphere. In self-acting gas bearings, stiffness will change with speed and will not necessarily be linear with deflection. Pressurized bearings should have long life in spin axis applications, as, because the bearings are pressurized to separate the surfaces prior to running, no wear should occur. However, it is still desirable to have wear resistant surfaces to withstand accidental turning when unpressurized, or overload touchdown.

“Origami” is an art of paper-folding. Recently, origami has been applied to the design of foldable robot structure. There are various folding techniques including the one we studied — Miura-ori. We designed a Miura-ori of non-zero thickness that 1) was made from rigid materials (rigid origami), and 2) contained self-similar units (modular origami). Our design has a maximum thickness of 6 mm, but can be folded up to 180° (complete fold)—equivalent to a zero-thickness origami. In this paper, we presented a novel design of rigid, foldable, modular origami, as well as derived constraints of joint design that enable a complete fold. Moreover, neodymium magnets were placed in the cores of each rotational axis in certain patterns. This not only allows for the structure to have characteristics of self-folding or self-unfolding, but also gives us the ability to control this robot structure using a current-induced magnetic field. When the magnetic field is on, the robot can switch from an unfolding position to a folding position. Such feature presents a potential for this structure to be used as a dynamic “spring” with an adjustable stiffness. This adjustability could be achieved by varying the input current applied to generate the magnetic field. Another application of this mechanism includes reducing shocks, and vibrations that are perpendicular to the structure.

A numerical study of flow structure and lift generation on a simplified rotating wing model caused by increasing the distance from the rotational axis is presented. Deterioration in characteristic leading-edge vortex structure and lift force reduction occur as this distance increases.