Moment Of Inertia Values Research Articles

Simultaneous design of morphing hexarotor and autopilot system by using deep neural network and SPSA

Purpose The purpose of this paper is to optimize the simultaneous flight performance of a hexarotor unmanned aerial vehicle (UAV) by using simultaneous perturbation stochastic approximation (i.e. SPSA), deep neural network and proportional integral derivative (i.e. PID) according to varying arm length (i.e. morphing). Design/methodology/approach In this paper, proper PID gain coefficients and morphing ratio were obtained using the stochastic optimization method, also known as SPSA to maximize flight efficiency. Because it is difficult to establish an analytical connection between the morphing ratio and hexarotor moments of inertia, the deep neural network was used to obtain the moments of inertia according to the morphing ratio. By using SPSA and deep neural network, the best performance indexes were obtained and both longitudinal and lateral flight simulations were performed with the obtained data. Findings With SPSA, the best PID coefficients and morphing ratio are obtained for both longitudinal and lateral flight. Because the hexarotor solid body model changes according to the morphing ratio, the moment of inertia values used in the simulations also change. According to the morphing ratio, the moment of inertia values was obtained with the deep neural network over a created data set. Research limitations/implications It takes a long time to obtain the morphing ratio suitable for the hexarotor model and the PID gain coefficients suitable for this morphing ratio. However, this situation can be overcome with the proposed SPSA. In addition, it takes a long time to obtain the appropriate moments of inertia according to the morphing ratio. However, in this case, it was overcome using the deep neural network. Practical implications Determining the morphing ratio and PID gain coefficients using the optimization method, as well as determining the moments of inertia using the deep neural network, is very useful as it can increase the efficiency of hexarotor flight and flight efficiently with different arm lengths. With the proposed method, the hexarotor design performance criteria (i.e. rise time, settling time and overshoot) values were significantly improved compared to similar studies. Social implications Determining the hexarotor flight parameters using SPSA and deep neural network provides advantages in terms of time, cost and applicability. Originality/value The hexarotor flight efficiency is improved with the proposed SPSA and deep neural network approaches. In addition, the desired flight parameters can be obtained more quickly and reliably with the proposed approaches. The design performance criteria were also improved, enabling the hexarotor UAV to follow the given trajectory in the best way and providing convenience for end users. SPSA was preferred because it converged faster than other methods. While other methods perform 2n operations per iteration, SPSA only performs two operations. To obtain the moment of inertia, many physical parameter values of the UAV are required in the existing methods. In the proposed method, by creating a date set, only arm length and moment of inertia were estimated without the need to obtain physical parameters with the deep neural network structure.

Possible Chemical Composition And Interior Structure Models Of Venus Inferred From Numerical Modelling

Abstract Venus’ mass and radius are similar to those of Earth. However, dissimilarities in atmospheric properties, geophysical activity, and magnetic field generation could hint toward significant differences in the chemical composition and interior evolution of the two planets. Although various explanations for the differences between Venus and Earth have been proposed, the currently available data are insufficient to discriminate among the different solutions. Here we investigate the possible range of models for Venus’ structure. We assume that core segregation happened as a single-stage event. The mantle composition is inferred from the core composition using a prescription for metal-silicate partitioning. We consider three different cases for the composition of Venus defined via the bulk Si and Mg content, and the core’s S content. Permissible ranges for the core size, mantle, and core composition as well as the normalized moment of inertia (MoI) are presented for these compositions. A solid inner core could exist for all compositions. We estimate that Venus’ MoI is 0.317–0.351 and its core size 2930–4350 km for all assumed compositions. Higher MoI values correspond to more oxidizing conditions during core segregation. A determination of the abundance of FeO in Venus’ mantle by future missions could further constrain its composition and internal structure. This can reveal important information on Venus’ formation and evolution, and, possibly, the reasons for the differences between Venus and our home planet.

Indirect determination of moisture using biospeckle technique

The classification and selection of agricultural products is very important to assure post harvest quality processes. However, most of physical and chemical analyses are destructive. It means those products turn useless after these analyses. Moisture is one of the most important parameter to assure the storage quality and as well to facilitate product processing. This research offers an alternative method to determine that parameter through an indirect and non-destructive way, using the image analysis based on the Biospeckle phenomenon. This method consists in get a 10 seconds video of a laser focused on the object. This video is divided in frames, using a computational routine in Matlab and, then, the sequence of images is processed using the computational program named ImageJ . The results are expressed in terms of modified correlation matrix and Moment of Inertia (MI). At the same time, a moisture analysis is carried out using the traditional methodology employing conventional heater equipment set at 130 oC. By correlating MI and moisture values, it was possible to determine the moisture content by means of an indirect method. To this research, it was employed grains of Moringa oleifera .

Reprodutibilidade e aplicabilidade de um método para avaliação do momento de inércia para testes de esforço em um dinamômetro para cadeiras de rodas

In order to test of a method for evaluating the moment of inertia in a wheelchair dynamometer, with 24h of difference, two evaluators performed the calibration procedure with known mass increments on both sides (right and left) of the prototype. Then, 6 healthy male subjects (weight: average= 67.14 ± standard deviation=4.41kg; height: average=1.73 ± standard deviation=4.41m), performed sprint protocol at maximum speed for 20s. The moment of inertia values determined by the experimental model were compared with the MI calculated by the theoretical model. In addition, the power values determined using the experimental model were compared with those calculated by the theoretical model. The results of the Bland-Altman plot and the intraclass correlation coefficient showed excellent intra-reproducibility results (r = 0.94, evaluator A; and 0.92, evaluator B; p

Determination of inertial parameters using a dynamometer.

In this study, a simple method based on the dynamic equation of motion was introduced to determine the moment of inertia using a commercial dynamometer, and an optimization technique was utilized to estimate inertial parameters with the determined moment of inertia. To evaluate the feasibility of the developed method, three different passive speeds (i.e. 240, 270 and 300°/s) were chosen to confirm whether the moment of inertia values are the same irrespective of angular speeds. Moreover, the estimated inertial parameters (i.e., the mass, center of mass and moment of inertia) of the elbow attachment and the disk-like 3 kg-weight were compared with solutions of uniform square cube and solid disk, respectively. As a result, the values of moments of inertia of the elbow attachment were 0.216 ± 0.017, 0.215 ± 0.016 and 0.216 ± 0.017 kg · m(2) at angular speeds of 240, 270 and 300°/s, respectively. The values of the moment of inertia of both the attachment and weight were 0.821 ± 0.054, 0.823 ± 0.058 and 0.824 ± 0.053 kg · m(2) at angular speeds of 240, 270 and 300°/s, respectively. There were no significant differences among the speeds. The estimated inertial parameters of the attachment or the weight were very similar to the theoretical values. Therefore, it is expected that the developed method has the potential to estimate inertial parameters of a human body segment and to improve the accuracy and reliability of the studies on human dynamics.

Attunement to haptic information helps skilled performers select implements for striking a ball in cricket

This study examined the perceptual attunement of relatively skilled individuals to the physical properties of striking implements in the sport of cricket. We also sought to assess whether utilizing bats with different physical properties would influence performance of a specific striking action: the front foot straight drive. Eleven skilled male cricketers (mean age = 16.6 ± 0.3years) from an elite school cricket development program consented to participate in the study. While blindfolded, participants wielded six bats exhibiting different mass and moment of inertia (MOI) characteristics and were asked to identify the three bats they preferred the most for hitting a ball to a maximum distance by performing a front foot straight drive (a common shot in cricket). Next, participants actually attempted to hit balls projected from a ball machine using each of the six bat configurations to enable kinematic analysis of front foot straight drive performance with each implement. Results revealed that, on first choice, the two bats with the smallest mass and MOI values (1 and 2) were most preferred by almost two thirds (63.7%) of the participants. Kinematic analysis of movement patterns revealed that bat velocity, step length, and bat-ball contact position measures significantly differed between bats. Data revealed how skilled youth cricketers were attuned to the different bat characteristics and harnessed movement system degeneracy to perform this complex interceptive action.

A Novel Passive Movement Method for Parameter Estimation of a Musculoskeletal Arm Model Incorporating a Modified Hill Muscle Model

In this paper we present a method of parameterising a two muscle arm model incorporating a structurally identifiable modified Hill muscle model. Length and moment of inertia values were obtained by direct measurement and calculation. Spring and damping parameters in the model were determined by parameter estimation from experiments using passive flexion and extension movements. The results showed good agreement between measured and simulated data with consistent parameter values across subjects. Adding a hand load improved the agreement by reducing errors resulting from body segment geometry assumptions.

Temperature-dependent particle-number projected moment of inertia

Expressions of the parallel and perpendicular temperature-dependent particle-number projected nuclear moment of inertia have been established by means of a discrete projection method. They generalize that of the FTBCS method and are well adapted to numerical computation. The effects of particle-number fluctuations have been numerically studied for some even-even actinide nuclei by using the single-particle energies and eigenstates of a deformed Woods-Saxon mean field. It has been shown that the parallel moment of inertia is practically not modified by the use of the projection method. In contrast, the discrepancy between the projected and FTBCS perpendicular moment of inertia values may reach 5%. Moreover, the particle-number fluctuation effects vary not only as a function of the temperature but also as a function of the deformation for a given temperature. This is not the case for the system energy.

Comparison of Molecular Simulation and Pseudo-Rigid-Body Model Predictions for a Carbon Nanotube–Based Compliant Parallel-Guiding Mechanism

We report on the accuracy of the pseudo-rigid-body model (PRBM) in predicting the behavior of a nanoscale parallel-guiding mechanism (nPGM) that uses two single-walled (5,5) carbon nanotubes (CNTs) as the flexural guiding elements. The nPGM has two regions of behavior: region 1 is governed by the bulk deformation of the nanotubes, and region 2 is characterized by hingelike flexing of four “kinks” that occur due to buckling of the nanotube walls. PRBM parameters for (5,5) CNTs are proposed. Molecular simulation results of region 1 behavior match PRBM predictions of (1) kinematic behavior with less than 7.3% error and (2) elastomechanic behavior with less than 5.7% error. Although region 1 is of more interest because of its well-defined and stable nature, region 2 motion is also investigated. We show that the PRBM parameters are dependent on the selection of the effective tube thickness and moment of inertia, the lesson being that designers must take care to consider the thickness and moment of inertia values when deriving PRBM constants.

Backpack Moment of Inertia Affects Oxygen Consumption During Walking

Prior research on the metabolic energy cost of carrying backpack loads has focused primarily on the effects of weight carried on the rate of oxygen consumption during walking. However, less research has been done on the effects of manipulating backpack mass center location or moment of inertia (MOI) on oxygen consumption. PURPOSE: The purpose of this study was to examine the effects of manipulating the MOI (distribution of mass about an axis of rotation) of a backpack load on the rate of oxygen consumption during walking. We hypothesized that varying the relationships among MOI values for the principal axes would differentially affect oxygen consumption. METHODS: Fourteen male volunteers participated in the study. Steel weights (26 kg total mass) were positioned in each of three military backpacks to produce different MO Is, but with the same mass (35 kg, inclusive of the backpack) and mass center locations (0.3 m posterior to the pack frame and 0.3 m superior to the bottom of the pack). The three packs differed in that each had the MOI of a unique principal axis (Ixx, Iyy, Izz) set at a small value (< 1.0 kg.m2), while the other two principal axes had large moments of inertia (> 2.0 kg.m2). Relative to the load carrier's body, Ixx, Iyy, and Izz defined the MOI about the anterior-posterior axis, the medial-lateral axis, and the vertical axis, respectively. The volunteers walked on a level treadmill at 4.8 km/h for 10 min carrying each of the packs. The rate of oxygen consumption (VO2) was recorded (COSMED K4b2, COSMED, Rome, Italy) during the last 90 sec of the walking period and was scaled to body plus load mass. A repeated measures ANO VA with three levels of MOI and follow-up comparisons were used to assess differences in the mean mass specific VO2. RESULTS: A significant difference (p < .05) in mean mass specific VO2 was found between the small Ixx value pack (15.04 ml/kg/min (SD 1.96)) and the small Iyy value pack (16.27 ml/kg/min (SD 2.09)). Mean differences approached statistical significance (p = .061) between the small Ixx pack and the small Izz pack (16.15 ml/kg/min (SD 2.23)). The small Iyy value and small Izz value packs did not statistically differ. CONCLUSION: The mean mass specific rate of oxygen consumption was 7.6% lower when Ixx was minimized relative to Iyy. Therefore, the metabolic energy cost of carrying backpack loads is not solely dependent on the amount of mass carried. The manner in which items are stowed in the backpack also affects metabolic energy expenditure and thus the physical endurance of the load carrier.

Effects of grape seed proanthocyanidins extract on Rat mandibular condyle

We investigated the effects of grape seed proanthocyanidins extract (GSPE) on bone formation by examining total and cortical bone mass, density, architecture, and strength non-invasively using mandibular condyles of Ca-restricted rats. Forty Wistar male rats, each 5 weeks old, were divided into control (C), low-Ca diet (LCaD), low-Ca diet-standard diet (LcaD x SD), and low-Ca diet x Estandard diet with supplementary GSPE (LcaD x SD+GSPE) groups. In LCaD x SD group, after the bone debility was induced by low-Ca diet, a standard diet therapy was given. In LCaD x SD+GSPE group, after the bone debility was induced by low-Ca diet, a standard diet therapy with supplementary GSPE was given. Each mandibular condyle was examined using peripheral quantitative computed tomography (pQCT). There were no significant inter-group differences in body weight seen throughout the experimental period. In LcaD x SD+GSPE, cortical bone cross-sectional area and mineral content were not significantly different from C, while bone mineral content was significantly higher in LcaD x SD+GSPE than in LcaD x SD. Cortical bone density of LcaD x SD+GSPE was not significantly different from that of C, however, that value in LCaD and LcaD x SD was significantly lower than that. The cross-sectional (bending) moment of inertia values in LcaD x SD+GSPE were the highest among all groups, though they did not differ significantly from those in C. Further, the cross-sectional (bending) Stress/Strain Index (SSI) values in LcaD x SD+GSPE were statistically similar to those in C, however, not significant higher than in LcaD x SD. These results suggest that GSPE treatment would increase both bone mass and bone strength on the rat mandibular condyles.

Effects of Lifetime Volleyball Exercise on Bone Mineral Densities in Lumbar Spine, Calcaneus and Tibia for Pre-, Peri- and Postmenopausal Women

To clarify the effects of habitual volleyball exercise on bone in women during the menopausal periods, we measured bone mineral densities (BMDs) of the lumbar spine, calcaneus and tibia every 12 months for 2 years and estimated factors related to the baseline values and annual loss rates. Forty Japanese female volleyball players 42-62 years of age, who had belonged to the district non-professional club for more than 10 years on average, were recruited. Twenty women had regular menstruation at the start, but 7 underwent menopause during the study. Fifty-nine healthy women who did not participate in habitual exercise, but were otherwise comparable with the players, were recruited as the controls. The lumbar and calcaneus BMDs were measured by dual-energy X-ray absorptiometry (DXA), and both the volumetric BMDs and cross-sectional geometry at the diaphysis of the tibia were measured by peripheral quantitative computed tomography. The baseline BMDs of all measured sites and the values of the cortical area and moment of inertia of the tibia in the players were significantly higher than the values in the control women. In the peri- and postmenopausal players, the baseline values of the lumbar and calcaneus BMDs related to total years of participating in regular exercises during adulthood including volleyball (TYE), body mass index (BMI) and years since menopause (YSM). Tibia cortical area and moment of inertia values related to TYE. Annual bone loss rates in the tibia and calcaneus of players were significantly smaller than those values in the controls. However, the bone loss rates in the lumbar spine did not differ significantly between the groups. The bone loss rate in the calcaneus was significantly related to the current number of training hours per week and YSM. The rate of bone loss in the tibia was related to BMI. These data indicated that the total number of years participating in exercise activity during adulthood have positive effects on lumbar and calcaneus BMDs and the cortical structure of the tibia. Habitual volleyball exercise apparently did not alleviate the menopause-related bone loss in the lumbar spine.

πg9/2structures in odd-odd130Prand alignment processes in superdeformed praseodymium nuclei

Two strongly coupled bands with large dynamic moment of inertia values have been observed for the first time in the neutron-deficient odd-odd nucleus ${}^{130}$Pr using Gammasphere and the Microball charged-particle detector array. These bands involve the important ${g}_{9/2}$[404]9/2 proton orbital. This new information on ${}^{130}$Pr coupled with Projected Shell Model calculations provide valuable insight on rotational alignment processes taking place in this mass region, the size of the $N$=72 deformed shell gap, and the position of the ${i}_{13/2}$[660]1/2 neutron intruder orbital at the boundary of the $A$=135 superdeformed region.

Accuracy of Human Limb Moment of Inertia Estimations and Their influence on Resultant Joint Moments

Segmental moment of inertia values, which are often required to perform mechanical analyses of human movement, are commonly computed using statistical models based on cadaver data. Two sets of equations for estimating human limb moments of inertia were evaluated: linear multivariable equations and nonlinear equations. Equation coefficients for both sets of equations were determined using the cadaver data of Chandler et al. (1975). A cross-validation procedure was used to circumvent the problem of model evaluation when there is limited data with which to develop and evaluate the model. Moment of inertia values for the longitudinal axes were predicted with similar degrees of accuracy with either set of equations, while for the transverse axes the nonlinear equations were superior. An evaluation of the influence of the accuracy of moment of inertia estimates on resultant joint moments for three activities showed that the influence of these errors was generally small.

Cross-sectional geometrical properties and bone mineral contents of the human radius and ulna

The mechanical strength of the human radius and ulna depends on their geometrical and material properties. This study quantifies the cortical bone cross-sectional properties of the adult radius and ulna (cross-sectional area, thickness, centroids, area moments of inertia and section moduli) using computerized tomographic (CT) scanning coupled with image processing along the lengths of eight human cadaveric forearms. Bone mineral mass and apparent ash density were also quantified at serial locations. Sites of significant variation of selected geometric and mineral properties along the length of each forearm bone were determined. Our results show that interpolation of CT measurements made at 10 and 30% of the radial length in the radius and 30 and 90% of the radial length in the ulna can provide approximate geometric values over the 10–90% region. This information can be used to develop a protocol using the fewest sites to clinically assess changes in forearm bone geometry. Regression analyses did not show significant linear relationships between geometric properties and apparent cortical ash density. Thus, CT derived geometric properties are not helpful in estimating the extent of changes in bone density. Area moment of inertia results suggest that the junction of the middle and distal third of the radius, and the ulnar shaft region may have increased vulnerability to fractures. The former is likely due to the change in moment of inertia values, whereas the latter is due to the relatively small magnitude of cross-sectional moments along the ulnar shaft as compared to the proximal or distal ends. This is consistent with fracture patterns observed clinically when a single forearm bone is fractured: Galeazzi fracture of the radius and nightstick fracture of the ulna.

Estimating segment inertial properties: Comparison of magnetic resonance imaging with existing methods

To explore magnetic resonance imaging (MRI) as the basis of a technique for estimating body segment inertial properties directly on subjects, MRI-based estimates were compared with those generated with more traditional methods. The sensitivity of mass, center of mass location, and moment of inertia estimates to the estimation methods and the distribution of muscle, bone, and fat tissues in the lower leg were also evaluated. A series of transverse plane images spaced 2.5 cm apart on the right lower leg of 12 adult males were taken, using MRI. Cross-sectional area data determined from the images served as the basis of the inertial calculations. MRI-based estimates for mass, center of mass location, and moment of inertia about a transverse axis through the center of mass all fell within the range of values obtained with other methods. While the center of mass position was similar for all estimation methods, MRI-based estimates of lower leg mass and moment of inertia showed considerable variability among methods. In addition, MRI mass and moment of inertia values were higher than those from most of the other prediction methods. It is suggested that the higher MRI-based estimates for these descriptors may be reasonable when age and structural differences between young adult runners and cadaver specimens for the comparison studies are considered. These results provide further support for MRI as a means of generating valid inertial property estimates.

Spectroscopic studies of phase transitions in some organic crystals: C 2H 2, CHBr 3 and CH 3CN

Raman and infrared spectra of crystalline acetylene, bromoform and acetonitrile have been obtained. These three crystals and their fully deuterated analogues exhibit solid state phase transitions. Particular attention is given to the low frequency region (< 350 cm −1) where lattice vibrations and low-lying intramolecular fundamentals are observed. Such properties as frequency shifts on deuteration, relative intensities and moment of inertia values are used to aid in assignments. Changes in the observed spectra for crystals below and above the transition temperature are related to the types of transition involved, and, where possible, comparisons are made with inorganic crystals having similar structures.

Segmental Moment of Inertia Scaling Procedures

Abstract The segmental moment of inertia values obtained from 7 of the 8 cadavers reported by Dempster were scaled to a common height and weight. The scaled values for each segment for the 7 cadavers were averaged. An equation is given for rescaling the Dempster average values for use with any individual in proportion to their height and weight.

Centrifugal pump and compressor characteristics

This article presents, in general terms, the typical moment of inertia values and speed-torque characteristics of centrifugal pumps and compressors which occur during normal starting periods and immediately following momentary voltage failures to the driving motors.