Variations In Inclination Research Articles

Orbital Dynamics with the Gravitational Perturbation due to a Disk

Abstract The secular behavior of an orbit under gravitational perturbation due to a two-dimensional uniform disk is studied in this paper, through analytical and numerical approaches. We develop the secular approximation of this problem and obtain the averaged Hamiltonian for this system first. We find that when the ratio of the semimajor axes of the inner orbit and the disk radius takes a very small value (≪1), and if the inclination between the inner orbit and the disk is greater than the critical value of 30°, the inner orbit will undergo the (classical) Lidov–Kozai resonance in which variations of eccentricity and inclination are usually very large and the system has two equilibrium points at ω = π/2, 3π/2 (ω is the argument of perihelion). The critical value will slightly drop to about 27° as the ratio increases to 0.4. However, the secular resonances will not occur for the outer orbit and the variations of the eccentricity and inclination are small. When the ratio of the orbit and the disk radius is nearly 1, there are many more complicated Lidov–Kozai resonance types which lead to orbital behaviors that are different from the classical Lidov–Kozai case. In these resonances, the system has more equilibrium points which could appear at ω = 0, π/2, π, 3π/2, and even other values of ω. The variations of eccentricity and inclination become relatively moderate, moreover, and in some cases the orbit can be maintained at a highly inclined state. In addition, an analysis shows that a Kuzmin disk can also lead to the (classical) Lidov–Kozai resonance, and the critical inclination is also 30°.

Research on thermal response of pool fire of oil tank based on PyroSim

This paper presents a numerical investigation aimed at studying the thermal response of adjacent tank caused by different fire conditions. The analysis involves two-step procedure:(1) PyroSim model to obtain the temperature and the inclination variation of the large pool-fire flame, to determine the ultimate temperature distributions of the target tank, and to compare the ultimate temperature and the fuel ignition temperature, thus to determine the target tank is safety or not,(2) There are three kinds of semi-empirical models for describing the radiation e.g.(i) point source,(ii) Shokri-Beyler and (iii) Mudan models, to determine thermal radiation flux of the target tank. The analysis considered the influence of two parameters: (i) seven kinds of wind, (ii) five kinds of distances between the tanks. The paper compares three kinds of semi-empirical models and PyroSim model, so PyroSim model is more fit for relationships between thermal radiation flux. The simulation results show that the maximum temperature of the target tank is the connection between the wall and the top of the tank; the target tanks have failure risk within 0.3D and 0.6D tank distances and the tank spacing greater than or equal to 0.9D have no failure risk.

The Potential Impacts of the Erratic Motion of Dip Equator and Magnetic Poles

AbstractThis paper examined the secular displacement of the dip equator and the geomagnetic poles as well as the variations of the global magnetic inclination and declination angles using magnetometer measurements onboard different low‐Earth orbit (LEO) satellite. The secular variation of the dip equator and geomagnetic poles has different impacts on different applications—from affecting the long‐term characterization of the low‐latitude ionosphere to degrading the precision of geomagnetic navigation. The strong displacement of the dip equator can result in a systematic error in the determination of the long‐term equatorial electric field variations and hence in the characterization of ionospheric density structure, especially in the region, where the displacement of dip equator is large enough (more than 20 km or 0.2°/year) within the time scale of a solar cycle or less. Similarly, the slowly moving locations of magnetic poles, estimated from magnetometer observations onboard LEO satellite, exemplify noticeable discrepancy with that of world magnetic model (WMM) and International Geomagnetic Reference Field (IGRF) values, indicating inevitable possible impact on the precise geomagnetic navigation for commercial and military applications. Thus, accurately estimated locations of the dip equator and magnetic poles, as well as declination angles, are critically important.

PERFORMANCE OF HELICAL METERING MECHANISMS IN THE APPLICATION OF MICROGRANULAR FERTILIZER

ABSTRACT The use of microgranular fertilizers is currently increasing, with low application rates as an obstacle in the mechanization. This study aimed to verify the performance of helical metering mechanisms using microgranular fertilizer. Four different fertilizer-metering mechanisms were tested at two pre-established dose rates (35 and 50 kg ha−1) and seven longitudinal angles (−15°, −10°, −5°, 0°, +5°, +10°, and +15°). The experiment was carried out according to Brazilian standards. The results showed that the longitudinal inclination affects the actual fertilizer dose in all tested metering systems. Metering mechanisms with a helicoid with longitudinal and lateral overflow presented a similar dose, according to the variation of the longitudinal inclination. The metering mechanism with two helicoids showed the highest dose variation, while the metering mechanism with a helical thread and longitudinal overflow, filled between the shaft and the helicoid, had the best performance.

A study of the moderate altitude frozen orbits around the Moon

Lunar frozen orbits, characterized by fixed eccentricity and argument of perigee on average, have been previously studied using different dynamical models. In this work, frozen orbits about the Moon are investigated on the basis of an averaged Hamiltonian. The gravitational field of the Moon is considered up to the seven zonal harmonic plus the third body perturbation (Earth). The third body is assumed to move in an elliptic inclined orbit. The averaging procedure is performed through Lie transformation method. We used the eccentricity-inclination diagrams to obtain a deep insight about the evolution of frozen orbits. For the reduced system, we found two frozen solutions which correspond to argument of perigee ω=π2,3π2. Moreover, we studied the evolution of the eccentricity and inclination as a function of time. The results showed that, for moderate altitude orbits, the eccentricity oscillates with small amplitudes around its initial value, while the inclination almost remains constant. In higher altitudes case, we observed that variations in eccentricity and inclination are larger than the moderate ones. The present dynamical model gives acceptable results for low initial eccentricity and inclination.

Study on anisotropic characteristics of dynamic deformation parameters of phyllite

The acoustic wave test was carried out by selecting the joints of the joint surface and the horizontal plane at 0°, 30°, 45°, 60°, 75°, and 90° phyllite samples. According to the corresponding waveform diagram, the starting point is selected, and the dynamic deformation parameters of thousands of rock samples under various angles are calculated. The results show that: The anisotropy characteristics of the dynamic deformation parameters are obvious, and the influence of the variation of the joint surface inclination on the dynamic deformation parameters is achieved by affecting the wave impedance. P-wave impedance and S-wave impedance have different effects on rock dynamic deformation parameters. Generally, P-wave and S-wave impedance should be considered comprehensively for the dynamic deformation parameters of rock samples. Acoustic waves are in the elastic deformation law of the rock sample caused by the propagation in the rock sample is similar to the elastic deformation law caused by the external load acting on the rock sample.

Preoperative glenoid considerations for shoulder arthroplasty: a review.

Preoperative assessment of the glenoid in the setting of shoulder arthroplasty is critical to account for variations in glenoid morphology, wear, version, inclination, and glenohumeral subluxation.Three-dimensional computed tomography (3D CT) scan assessment of the morphology of glenoid erosion allows for a more accurate surgical decision-making process to correct deformity and restore the joint line.Newer technology has brought forth computer-assisted software for glenoid planning in shoulder arthroplasty and patient-specific instrumentation.There have been promising early findings, although further evaluation is needed to determine how this technology impacts implant survivorship, function, and patient-reported outcomes.Cite this article: EFORT Open Rev 2020;5:126-137. DOI: 10.1302/2058-5241.5.190011

Geochemistry and Magnetism of Peat Deposits in the Khor–Kiya Interfluve, Sikhote–Alin (Preliminary Results)

This paper presents geochemical, microprobe, paleomagnetic, and rock magnetic data from peat accumulated over the past 10 000 years in the area between the Khor and Kiya rivers (Khabarovsk krai). A horizon ranging in thickness between 75 and 100 cm with elevated concentrations of Ni, Zn, Bi, and Se is identified as a result of comprehensive studies. Magnetite and carbon spherules, as well as native iron found at the bottom of the horizon suggest an impact event that occurred about 5500 years ago. For the first time, peat deposits are a target of paleomagnetic research. Distinct inclination variations of the remanent magnetization vector are established in the horizon at a depth of 50 to 75 cm, which corresponds in time to the “Etrussia” geomagnetic excursion (2500 years ago).

Thinking outside the glenohumeral box: Hierarchical shape variation of the periarticular anatomy of the scapula using statistical shape modeling.

Variation in the shape of the glenoid and periarticular anatomy of the scapula has been associated with shoulder pathology. The goal of this study was to identify the modes of shape variation of periarticular scapular anatomy in relation to the glenoid in nonpathologic shoulders. Computed tomography scans of 31 cadaveric scapulae, verified to be free of pathology, were three-dimensionally reconstructed. Statistical shape modeling and principal component analysis identified the modes of shape variation across the population. Corresponding linear and angular measurements quantified the morphometric variance identified by the modes. Linear measures were normalized to the radius of the inferior glenoid to account for differences in the scaling of the bones. Five modes captured 89.7% of total shape variation of the glenoid and periarticular anatomy. Apart from size differences (mode 1: 33.0%), acromial anatomy accounted for the largest variation (mode 2: 32.0%). Further modes described variation in glenoid inclination (mode 3: 11.8%), coracoid orientation and size (mode 4: 9.0%), and variation in coracoacromial (CA) morphology (mode 5: 3.1%). The average scapula had a mean acromial tilt of 49 ± 7°, scapular spine angle of 61 ± 6°, the glenoid inclination of 84 ± 4°, coracoid deviation angle of 26 ± 4°, coracoid length of 3.7 ± 0.3 glenoid radii, and a CA base length of 5.6 ± 0.5 radii. In this study, the identified shape modes explain almost all of the variance in scapular anatomy. The acromion exhibited the highest variance of all periarticular anatomic structures of the scapula in relation to the glenoid, which may play a role in many shoulder pathologies.

Discrepancy between radiographic and true cup position after total hip arthroplasty : Are we interpreting our radiographic quality indicators correctly? Video article

After total hip arthroplasty (THA), objective postoperative quality control is done via X‑rays by as component position assessment. The cup position is defined by its version and inclination. However, there is adiscrepancy between radiographically measured and true (anatomic) cup position, which may lead to misinterpretation. To visualize the discrepancy between true and radiographically measured cup position, in this video, acup holder was used to set the angular cup version and inclination. Hereby, the cup position (anteversion and inclination) can be characterized in its radiographic and anatomic definition in greater detail. The viewer of this video should receive an impression as to when radiographically measured cup angles must be considered with caution. In asimultaneous X‑ray and image sequence, this video shows decreased radiographic inclination measurement with increasing anterior rotation of the cup exceeding 20° of anteversion, yet with unchanged true inclination on the cup holder. Isolated consideration of the radiographic angles of anteversion and inclination may cause misinterpretation of true cup position. In pectoral illustration we show that variations in cup version and inclination may remain undetected when considering isolated the radiographic cup parameters. True cup position in its anatomical definition can be calculated from the radiographically measured position. For this purpose, both cup parameters (radiographic anteversion and radiographic inclination) have to be taken into account.

Surface inclination effects on muscle and joint contact force during walking: A systematic review

Outdoor surfaces are generally uneven as the surface topography diverges in terms of its inclination. Due to variation of inclination, there are risks of injury caused by muscle response and force reaction during gait. The objective of this review is to characterize the effects of incline surface on muscle and forces during walking that contribute to injury. The search strategy was carried out from Worldcat.org database. Majority of the previous studies agree on the fact that muscle response and force significantly change according to the changes of surface inclination. Future studies involving ligament force should be performed in order to obtain a valid result on muscle response and force reaction during inclined gait.

The Lidov-Kozai resonance at different scales

AbstractThe Lidov-Kozai (LK) resonance is one of the most widely discussed topics since the discovery of exoplanets in eccentric orbits. It constitutes a secular protection mechanism for systems with high mutual inclinations, although large variations in eccentricity and inclination are observed. This review aims to illustrate how the LK resonance influences the dynamics of the three-body problem at different scales, namely i) for two-planet extrasolar systems where the orbital variations occur in a coherent way such that the system remains stable, ii) for inclined planets in protoplanetary discs where the LK cycles are produced by the gravitational force exerted by the disc on the planet, iii) for migrating planets in binary star systems, whose dynamical evolution is strongly affected by the LK resonance even without experiencing a resonance capture, and iv) for triple-star systems for which the migration through LK cycles combined with tidal friction is a possible explanation for the short-period pile-up observed in the distribution of multiple stars.

Side Variations of Anterior Cruciate Ligament Coronal Angles: Implications for ACL Reconstruction.

Current literature has shown a biomechanical advantage of recreating the native coronal obliquity of the anterior cruciate ligament (ACL) during grating procedures; however, the majority of studies on ACL morphological variation have been performed unilaterally. This cadaveric study aimed to evaluate sided ACL coronal angle of inclination variation including trend analysis with sex, age, height, and femoral condyle width. The ACLs of 57 embalmed cadaveric specimens were evaluated bilaterally for a total of 114 ACLs. The knees were flexed to 110°. A 0.70-mm wire measured coronal angulation through the lateral tibial plateau and the medial ACL border. An image taken of the wire allowed digital measurement with the ImageJ software. IBM SPSS was utilized for statistical analysis. Bilateral measurements demonstrated a difference in an individual's sided ACL angulation (P < 0.001). Right-sided angulation was greater in 61.4% (35/57). In cadavers with greater right-side angulation, right ACLs averaged 66.2° versus left ACLs averaged 60.9° (P < 0.001). Cadavers with greater left-sided ACL angles demonstrated average left ACLs measuring 65.5° versus right ACLs measuring 60.6° (P < 0.001). Right-sided angles were greater in 69.7% of females. Understanding the anatomy of the ACL's native coronal angle and variations between a patient's knees is imperative during reconstruction surgery to aid in anatomic tunnel placement for improved knee motion and rotational knee kinematics following surgery. A statistically significant difference exists between an individual's right and left ACL coronal angles of inclination. Clin. Anat. 32:1102-1106, 2019. © 2019 Wiley Periodicals, Inc.

Comments on “The Influence of Equatorial Scintillation on L-Band SAR Image Quality and Phase”

As was indicated in the mentioned paper, the ionospheric stripes, in general, aligned well with the orientation of the projected ambient geomagnetic field vector. However, it is shown in our study that the calculated striping heading is not only dependent upon the orientation of the projected ambient geomagnetic field vector, namely, the geomagnetic heading but also the geomagnetic inclination, the system incident, and squint angle. It also confirms that the changing direction of the visible stripes in the mentioned Phased Array-type L-band Synthetic Aperture Radar (PALSAR) data is mainly due to the variation of the geomagnetic inclination, while the geomagnetic heading is nearly constant along the orbit. Therefore, the denotation and presentation in that research that the projected geomagnetic field vector elongates in the direction of the stripe orientation might not be feasible.

Reestablishing Odd–Even Effects in Anthracene-Derived Monolayers by Introduction of a Pseudo-C2v Symmetry

A series of anthracene[2,3-d]oxazolyl-2-alkylthioacetates (AOxCnSAc) with n = 2–6 methylene groups in the alkyl chain were designed and synthesized to investigate the influence of the substitution along the long axis of the molecule on the structural behavior of the respective self-assembled monolayers (SAMs) on Au(111). While in previous work anthracene-terminated alkanethiols, in which the alkyl group was attached to the off-axis 2-position of the acene, showed an exceptionally small influence of the number of methylene groups (n) in the aliphatic linker, the new system exhibits a strong dependence of almost all monolayer properties on the length of the aliphatic linker, with the parity of n being the decisive parameter. These so-called odd–even effects are a result of the bond angle at the anchoring S atom as well as the all-trans conformation of the alkyl linkers, which in particular affect the packing density and the orientation of the aromatic part. Thus, using a variety of complementary experimental techniques, distinct odd–even variation of molecular inclination (by 10–11°) and the packing density (by 20%) were found, with the packing density of the odd-numbered systems being even as high as the ones of the well-established alkanethiolate systems. The high quality and well-defined character of these SAMs, along with a low band gap of only 3.0 eV, make them relevant for application in organic and molecular electronics.

Inclination of Blumensaat's line influences on the accuracy of the quadrant method in evaluation for anterior cruciate ligament reconstruction.

The quadrant method is used to evaluate the bone tunnel position with the grid based on the Blumensaat's line in anterior cruciate ligament (ACL) reconstruction. This study aimed to clarify the influence of variation in the Blumensaat's line on the accuracy of the quadrant method measurements. A retrospective review of the radiological records of patients aged 18-30years who underwent computed tomography (CT) scanning of the knee joint was conducted. The Blumensaat's line inclination angle (BIA), along with the most posterior point of the posterior condyle (point P) position using the quadrant method and morphology of the Blumensaat's line were measured on true lateral transparent three-dimensional CT images of the distal femoral condyle in 147 patients. Statistical analysis was conducted to determine associations among these measurements. BIA was 37.5° (standard deviation 4.2°; range 27°-48°). The point P position was significantly correlated with BIA in the high/low (R2 = 0.590, P < 0.0001) and deep/shallow (R2 = 0.461, P < 0.0001) directions. The morphology of the Blumensaat's line was straight in 35 knees (23.8%); whereas, the remaining 112 knees (76.2%) were not straight but had some hill on the Blumensaat's line. No significant difference among the morphological variation of the Blumensaat's line was observed in BIA and the point P position. There was a strong correlation between BIA and the point P measured using the quadrant method, suggesting the influence of the Blumensaat's line on the accuracy of the quadrant method measurements in ACL reconstruction. As for the clinical relevance, surgeons should be careful in application of the quadrant method for ACL reconstruction, because the variation of the Blumensaat's line inclination influences the accuracy of this method.

Pengaruh Kemiringan Saluran Terhadap Fenomena Flooding Dengan Gangguan Pada Aliran Udara–Air Dan Udara–Minyak Tanah

Some equipments which are used in petroleum industries, chemical industries, steam power-plants and nuclear reactors must avoid the flooding phenomena in order to work at optimal condition. The purpose of this research is to investigate the effects of inclination and obstacle on flooding onset at counter-current air-water and air-kerosene flows with porous inlet and sharp outlet. The model of obstacle was conformed to industrial application i.e .pipe joining or pipe scaling. Experimen&#x0D; ts were conducted in a plexyglass pipe of 25.4 mm diameter and 2500 mm length of test section at annular flow pattern. The variation of inclination of ducts are 90o, 80o and 60o. The geometry of the obstacle is a ring with rectangular cross sectional which is installed with a distance 600 mm or 1200 mm from the inlet. The result of the research indicated that the effects of inclination and obstacle of ducts are significant toward flooding onset. Flooding phenomena was indicated with drastic increase of pressure gradient above the liquid inlet. Flooding phenomena happened earlier of larger inclination of the ducts and nearer obstacle of the inlet. This phenomena also early happened at kerosene which have higher viscosity and lower surface tension than water

Application of Impulsive Aero-Gravity Assisted Maneuvers in Venus and Mars to Change the Orbital Inclination of a Spacecraft

Thse powered aero-gravity-assist is an orbital maneuver that combines three basic components: a gravity-assist with a passage by the atmosphere of the planet during the close approach and the application of an impulse during this passage. The mathematical model used to simulate the trajectories is the Restricted Three-Body Problem including the terms coming from the aerodynamic forces. The present paper uses this type of maneuver considering that the trajectory of the spacecraft is in the ecliptic plane and the presence of the atmospheric Drag and Lift forces. The maneuver in the ecliptic plane can be done due to technologies that provides spacecraft with high values for the Lift to Drag ratio. The main advantage is that this maneuver allows the modification of the semi-major axis of the orbit of the spacecraft using the gravity of the planet and, at the same time, to change the inclination, using the high Lift that is perpendicular to the ecliptic plane. So, it is a combined maneuver that changes two important orbital parameters at the same time. The Lift is applied orthogonal to the initial orbital plane to generate an inclination change in the trajectory of the spacecraft, which is a very expensive maneuvers when made using propulsion systems. The Lift to Drag ratio used in the present paper goes up to 9.0, because there are vehicles, like waveriders, designed to have these values. When the spacecraft is passing by the periapsis of its orbit, an instantaneous impulse is applied to increase or decrease the variation of energy given by the aero-gravity-assist maneuver. The planets Venus and Mars are selected to be the bodies for the maneuver, due to their atmospheric density and strategic location in the Solar System to provide possible uses for future missions. Results coming from numerical simulations show the maximum changes in the inclination obtained by the maneuvers, as a function of the approach angle and direction of the impulse; the Lift to Drag ratio and the ballistic coefficient. In the case of Mars, inclination changes can be larger than 13°, and for Venus larger than 21°. The energy and inclination variations are shown for several selected orbits. The powered aero-gravity-assist maneuver generates inclination changes that are higher than the ones obtained from the powered maneuver and/or the aero-gravity maneuver.

Solar-photon sail hovering orbits about single and binary asteroids

Solar-photon sails can be useful for missions towards and about asteroids. Indeed, for the interplanetary transfer phase, missions to asteroids often require a large variation in inclination and solar-photon sails perform very well for such high energy missions. In the same way, solar-photon sails are also expected to perform well in the phase about the asteroid. This paper studies single and binary asteroids’ hovering regions by using a sailcraft. In order to consider a sailcraft with its own mass and shape, the mutual polyhedral method (usually used to study asteroid dynamics) is used; therefore, the sailcraft is designed by means of tetrahedra. The procedure to obtain the hovering regions about a single asteroid is presented and an accurate analysis of the control variables is carried out. Moreover, control torques required to maintain hovering orbits are obtained by considering the gravitational torques acting on the sailcraft due to the asteroid. In the end, the theory for hovering orbits is extended to binary-asteroid systems and applied to the binary system 1999 KW4.

Influence of Variations in Seat Surface Inclination on Trunk Muscle Recruitment and Reaching Ability in Children with Spastic Cerebral Palsy: Systematic Review

Influence of Variations in Seat Surface Inclination on Trunk Muscle Recruitment and Reaching Ability in Children with Spastic Cerebral Palsy: Systematic Review