Moment Of Inertia Research Articles

The retarding effect of glacier degradation on the Earth’s rotation

IntroductionThe massive loss of global glacier mass caused by climate problems has caused concern, while the Earth’s rotation as the most significant form of motion has also been subtly affected. However, the quantitative effects of massive glaciers losing mass on Earth’s rotation have not been revealed.MethodsHerein, the knowledge of moment of inertia and suitable rotational inertia models in classical mechanics is initially utilized to assess the effect of quantitative glaciers losing mass on Earth's rotation.ResultsAfter specific calculations, the putative 200 billion tons of glaciers losing mass bring on an increase of 1.4099×10-4s in Earth’s rotation time in 365 days.DiscussionThis work examines the connection between glaciers losing mass and Earth’s rotation from classical mechanics, thus providing the way for investigations of relationship between climate changes and Earth.

Geometry of the argon…imidazole complex revealed by the microwave spectra of four isotopologues

The rotational spectra of four isotopologues of an isolated complex formed between an argon atom and imidazole, Ar…imidazole, have been recorded in the 6–19 GHz region by Fourier transform microwave spectroscopy. Rotational transition frequencies have been fitted to Watson’s S-reduced Hamiltonian to yield rotational, centrifugal distortion and nuclear quadrupole coupling constants for the complex. Rotational constants determined for the parent and three 15N-containing isotopologues allow the three-dimensional structure of the complex to be described. The two angles, θ and ϕ, which define the orientation of the Ar atom relative to the imidazole ring have been determined for the first time in addition to the distance between Ar and the center of mass of the imidazole sub-unit, R. Fitting of structural parameters to the experimentally-determined moments of inertia yields a structure where Ar is positioned above the ring plane at a distance of 3.519 Å from the center of mass of the imidazole sub-unit. In the experimentally determined, average geometry, the intermolecular axis (drawn through Ar and the center of mass of the imidazole sub-unit) is oriented at 6° from the normal to the ring plane. The experimental results allow for four alternative possibilities for ϕ with 62.0(39)° being that which is most consistent with expectations for this parameter based on previous work. The experimentally-determined nuclear quadrupole coupling constants imply that the electric field gradient at each of the nitrogen nuclei of imidazole does not significantly change on formation of the complex with Ar.

Electromagnetic Field and Variable Inertia Analysis of a Dual Mass Flywheel Based on Electromagnetic Control

The moment of inertia of the primary flywheel and the secondary flywheel in a dual mass flywheel (DMF) directly affects the vibration damping performance in an automotive driveline. To enable better minimization of vibration and noise by changing the moment of inertia of the DMF to adjust the frequency characteristics of the automotive driveline, a new variable inertia DMF structure is proposed by introducing electromagnetic devices. The finite element simulation model of the electromagnetic field of an electromagnetic device is established, the electromagnetic field characteristics in the structure are analyzed, and the variation in the electromagnetic force under different air gaps and current conditions is obtained. The electromagnetic force test system of the electromagnetic device is constructed, and the validity of the finite element simulation analysis of the electromagnetic field of the electromagnetic device is verified. A mechanical model of the electromagnetic device is established to analyze the characteristics of the displacement of the moving mass in the structure as well as the variation in the moment of inertia of the DMF at different rotational speeds and currents. The maximum adjustable proportion of its moment of inertia can reach 15.07%. A torsional model of the automotive driveline is established to analyze the effect of variable inertia DMF on the resonance frequency of the system under different currents. The results show that the electromagnetic device introduced in the DMF can realize the active adjustment of the moment of inertia and enable the resonance frequency to decrease with increasing rotational speed, which expands the idea of optimizing the vibration damping performance of the DMF and provides a reference for better control of the torsional vibration of the automobile or other mechanical transmission systems.

The water bottle flipping experiment: a quantitative comparison between experiments and numerical simulations

Abstract The water bottle flip experiment is a recreational, non-conventional illustration of the conservation of angular momentum. When a bottle partially filled with water is thrown in a rotational motion, water redistributes throughout the bottle, resulting in an increase of moment of inertia and thus a decrease in angular velocity, which increases the probability of it falling upright on a table as compared with a bottle filled with ice. The investigation of this phenomenom is accessible to undergraduate students and should allow them to gain better understanding of combined translational and rotational motions in classical mechanics. We report a series of detailed experiments that are quantitatively compared with numerical calculations based on a simple theoretical framework in which the water volume is decomposed into thin slices of a rigid body that are subjected to fictitious forces in the non-inertial frame of the spinning bottle. This model also allows us to capture and predict other experimental configurations. Finally, we discuss additional counter-intuitive effects that contribute to bottle stabilization on landing.

Research on the change of the combined moment of inertia for two-link manipulator with angular coordinate system

The main of the problems of the development of two-link manipulators with an angular coordinate system is the lack of effective and universal control systems capable of implementing energy-intensive modes of movement. This is due to the design features of the pointer system of such manipulators and the methods of their use. During the operation of the manipulator, significant dynamic loads occur in its drive system, which create oscillations of the mechanical system and reduce the accuracy of work. The control system must also effectively compensate for such dynamic variations. Dynamic equations of motion used to build manipulator control controllers, which allow taking into account various features of using manipulators. These mathematical models necessarily contain one of the characteristics in the form of the combined moment of inertia of the mechanical system, which is important in the calculation of differential equations and the determination of kinematic parameters of motion. In this article, the combined moments of inertia of the boom system of a two-link manipulator with an angular coordinate system are determined. A study was carry out and it shown that the nature of the change in the combined moments of inertia influenced by the modes of movement of the boom system links. The results of the study showed that the combined moment of inertia of the boom system of the manipulator is not a constant value, which does not change uniformly under special operating conditions of the machine. To determine the combined moments of inertia, the method of bringing the kinetic energy of the moving system to the drive mechanism was apply. This is relevant, because in the future it will be necessary to adjust the unevenness of the movement of the manipulator links by the drive itself. The study was conduct for a typical linear motion mode and a motion mode with a change in speed along a parabolic trajectory.

Dynamic stability and response of morphing wing structure with time-varying stiffness

Abstract Morphing, adaptable or smart structures are being used in mechanical and aerospace applications in recent years. These structures often have the property of time-varying stiffness or inertial properties, which can cause parametric instability issues that are not well understood. This paper examines the dynamic stability and response of a morphing aircraft wing with periodically time-varying structural stiffness. The wing is modeled as a beam with coupled bending-torsion motion, and parametrically excited stiffness. Aerodynamic loads introduce aerodynamic damping and aerodynamic stiffness to the wing structure. The dynamic and aeroelastic equation of motion resembles a coupled, damped Mathieu-type equation but differs with asymmetric damping and stiffness matrices, and symmetric inertial matrix. Further, these equations are functions of airspeed, magnitude and frequency of parametric excitation. Initially, dynamic stability of the wing is analyzed using Floquet theory, and the instability regions are numerically quantified by stability charts. Subsequently, dynamic responses in the stable and unstable regions are investigated with a Floquet-based Harmonic balance method. The findings reveal that, at zero airspeed, the combination instabilities are eliminated by varying the bending and torsional stiffness with equal magnitudes and frequency. However, as airspeed increases, instability regions shift unevenly, leading to the emergence of new instabilities. Furthermore, the response analysis within stable regions uncovers several unfavorable zones for operating the variable stiffness, where response decay is slower. The results clearly show that parametric excitation can cause unusual phenomena that significantly impact the operation of morphing wings with variable stiffness, which needs to be thoroughly investigated for successful implementation.

Influence of Damping Plate Size on Pitch Motion Response of Floating Offshore Wind Turbine

For floating offshore wind turbines, a significant pitch and roll motion response of the platform can affect the acceleration and power generation of the nacelle. The damping plate is considered a type of attachment that can be used to reduce rotational motion, but research on its anti-rotational effect is limited. The objective of this work is to analyze the impact of installing damping plates and varying their sizes on the pitch motion response of semi-submersible platforms, while also proposing optimization strategies for damping plate design. Firstly, a comparison between numerical simulations and experimental measurements validates the accuracy of the CFD calculations. Subsequently, different sizes of damping plates are proposed for the platforms, followed by simulations under various conditions. Finally, comprehensive data analysis is conducted. The findings suggest that installing damping plates enhances both the platform’s added moment of inertia and damping coefficients while simultaneously amplifying its motion response in regular waves. Furthermore, increasing the size of damping plates leads to an increase in both the added moment of inertia and motion response for the platform, whereas the damping coefficient exhibits an initial increasing trend followed by a subsequent decrease. Ultimately, it is found that increasing the distance between damping plates and the free surface significantly reduces wave-induced loads on the platform.

Topology of Intermetallic Crystals: Classification, Uniformity, and Transitions.

We have analyzed the crystal structures of 7551 binary intermetallic compounds, which are deposited in the inorganic crystal structure database, using a combined geometrical-topological approach as implemented in our program package ToposPro. We represented each crystal structure with two models: (i) the topological model of periodic atomic net and (ii) the geometrical model of the Voronoi partition of crystal space. Within the former model, we have classified all intermetallics into 949 topological types, 20 of which cover 57% of the whole sample. Using our recently developed topological network model of reconstructive solid-state transformations, we have described possible mechanisms of displacive transitions between the most abundant topological types and revealed a key role of the body-centered lattice in these transitions. The Voronoi partition model enabled us to introduce the concept of uniformity of the overall structure and the environment of separate atoms; the uniformity is estimated by the second moment of inertia of atomic Voronoi polyhedra. We have shown that the structures with a low uniformity value either contain mistakes in the crystallographic data or have significantly directed interatomic bonds. The proposed uniformity criteria can serve for the estimation of the robustness of an intermetallic structure.

Ballast stiffness estimation based on measurements during dynamic track stabilization

Ballast compaction with the Dynamic Track Stabilizer (DTS) is known to improve the lateral track resistance by increasing the stiffness of the ballast. This paper presents two approaches for estimating the strain dependent ballast shear modulus G based on measurements during dynamic track stabilization. One approach uses the Hardin equation with its enhancement for coarse-grained soils to estimate the small strain shear modulus for a given grain size distribution curve. Since different shear strains are induced on an observed sleeper (with fixed location) by a bypassing DTS, the measurement of ballast shear strains with accelerometers on the top and the bottom edge of the ballast layer yield shear modulus degradation curves G/Gmax. It is shown for data from a regular maintenance operation, that these shear modulus degradation curves are in accordance with previous research. For the second approach, a SDOF model for the track-ballast interaction under harmonic loading (caused by the dynamic track stabilizer) is developed. Influence lines are used to estimate the mass, the mass moment of inertia and the geometry of an equivalent machine foundation (with spring and dashpot coefficients according to the Hall analog). An optimization algorithm is used to fit the model response to the measured data from field tests with the DTS. The resulting shear moduli show plausible values for loose and compacted ballast conditions, which proves the potential of the presented method as a basis for a future system for Intelligent Compaction (IC) with the DTS.

How Multifunctioning Joints Produce Highly Agile Limbs in Animals with Lessons for Robotics.

This paper reviews how multifunctioning joints produce highly agile limbs in animals with lessons for robotics. One of the key reasons why animals are so fast and agile is that they have multifunctioning joints in their limbs. The multifunctioning joints lead to a high degree of compactness which then leads to a host of benefits such as low mass, low moment of inertia and low drag. This paper presents three case studies of multifunctioning joints-the human wrist joint, knee joint and foot joints-in order to identify how multifunctioning is achieved and what lessons can be learned for robotics. It also reviews the multifunctioning nature of muscle which plays an important role in joint actuation. A key finding is that multifunctioning is achieved through various means: multiple degrees of freedom, multifunctioning parts, over-actuation and reconfiguration. In addition, multifunctioning is achieved through highly sophisticated layouts with high levels of integration and fine-tuning. Muscle also makes an important contribution to animal agility by performing multiple functions including providing shape, protection and heat. The paper reviews progress in achieving multifunctioning in robot joints particularly for the wrist, knee and foot. Whilst there has been some progress in creating multifunctioning robotic joints, there is still a large gap between the performance of animal and robotic joints. There is an opportunity to improve the agility of robots by using multifunctioning to reduce the size and mass of robotic joints.

The effect of salidroside on the bone and cartilage properties in broilers

Leg disorders frequently occur in fast-growing broiler chickens, constituting severe health and welfare problems. Although salidroside (SAL) promotes osteogenesis and inhibits apoptosis of chondrocytes in rats, it remains to be determined whether SAL can effectively improve bone growth in broilers. The present study was designed to investigate the effects of dietary SAL supplementation on bone and cartilage characteristics in broiler chickens. Ninety-six Arbor Acres broiler chickens were randomly divided into 4 groups: control, low-dose SAL, medium-dose SAL, and high-dose SAL groups. The broiler chickens were raised until 42 d of age, with samples of bone and cartilage collected for biomechanical testing and bone metabolism index detection. The results showed that SAL significantly increased the vertical external diameter, cross-sectional moment of inertia, and cross-sectional area of the femur and tibia. Additionally, SAL enhanced bone mineral density and strength, as evidenced by significant increases in stiffness, Young's modulus, ultimate load, and fracture work of the femur and tibia. Furthermore, SAL influenced the relative content of phosphate, carbonate, and amide I in cortical bone. Moreover, SAL upregulated the expression of osteogenic genes (Collagen-1, RUNX2, BMP2, and ALP) in a dose-dependent manner and maintained the homeostasis of the extracellular matrix (ECM) of chondrocytes. These results indicated that SAL promoted leg health in broilers by improving bone and cartilage quality and enhancing chondrocyte activity.

Neutron stars in f(R,T) theory: slow rotation approximation

In this paper, we study the slowly rotating neutron stars in f(R, T) gravity based on Hartle-Thorne formalism. We first consider the simplest matter-geometry coupled modified gravity, namely f(R, T) = R + 2χ T. We compute the mass, radius, moment of inertia, change in radius, and binding energy due to rotation, eccentricity, quadrupole moment, and the tidal love number. The quantities, which are of the second order in angular velocity, like change in radius and binding energy due to rotation, eccentricity, and quadrupole moment, deviate more from their corresponding general relativistic counterparts in lighter neutron stars than heavier ones. Whereas the moment of inertia, which is of the first order in angular velocity, in f(R, T) = R + 2χ T modified gravity, barely diverges from the general relativistic one. The Equation of state-independent I-Love-Q relation retains in this f(R, T) modified gravity, and it coincides with the general relativistic ones within less than one percent even for the maximum allowed coupling parameters. We also study the slowly rotating neutron star in f(R, T) = R + αR 2 + 2χT up to first order their angular velocity. We calculate the mass, radius, and moment of inertia of neutron stars in this modified gravity. The results show that the impact of the matter-geometric coupling parameter is greater on lighter neutron stars in both of these modified gravity models.

Dynamics of a falling plate at low Reynolds numbers

Free-falling of objects in fluids is universal in nature and engineering. The falling styles of the falling object are affected by the properties of both the object and the fluid. Based on the assumption that the final state of a free-falling object at low Reynolds numbers is stable and equivalent to that of a fixed object with incoming flow, we utilize the results for the fixed plate to interpolate and obtain the state of the falling plate. It is found that the plate would exhibit multiple stable falling solutions. The number of stable falling solutions is dependent on the location of the gravity center of the plate. The distribution of the multi-solution region is affected by both Archimedes number (Ar) and the density ratio (m*). The results of the actual fall of the plate do not always agree with those obtained by the static interpolation method due to the fact that the fall of the plate is a dynamic process. We simulate the falling behaviors of plates whose center of gravity is located in the multi-solution region for different initial release angles θ0. According to the falling behaviors of the plate, there are four regions that are observed and denoted in the multi-solution region: (1) single stable region; (2) bistable region; (3) single stable and fluttering region; and (4) bistable and fluttering region. The effects of Ar,m*, and the dimensionless moment of inertia I* of the plate on the distribution of the four regions are evaluated.

Design optimization of stiffening system for ocean thermal energy conversion (OTEC) cold water pipe (CWP)

Ocean thermal energy conversion (OTEC) uses heat from seawater to generate electrical energy by utilizing the temperature difference between the surface and deep ocean layer. Cold water pipe (CWP) attached to transport cold seawater over distances of up to 600 m to the plant is susceptible to failures caused by environmental loads. At this point, the CWP should be strengthened to prevent structural failure by inducing ring stiffeners along the pipe. To ensure its structural integrity, this study conducts a design optimization by investigating how the variation of ring stiffening system parameters such as height, thickness, distance between stiffeners, and shape of stiffeners influence the load-carrying capacity of the pipe using a Finite Element Analysis. Initially, the benchmarking procedure is done to ensure the reliability of the FEM modeling. After being verified, the modeling procedure is used for parametric study analyses. Results state that the higher and thicker stiffener ring increases the structural strength. In the case of the ring stiffener distance, as predicted, reducing the spacing between reinforcements is preferable to increasing the bending strength of CWP OTEC. Analyzing the variation of reinforcement height, thickness, and spacing, it was found that thickness had the most significant influence, followed by reinforcement height, and reinforcement spacing had the least. Additionally, changes in the shape of the reinforcement have minimal impact on the flexural strength of the structure when regions of identical moments of inertia exist.

Characteristics of deploying longitudinal folding wings with compound actuation

A mechanism has been developed to achieve rapid deployment of longitudinally folding wings by utilizing compound actuation from the firing powder and the compressive spring. A theoretical model based on rigid-body dynamics was first proposed to study the deployment characteristics of longitudinal folding wings under compound-driven effects. Subsequently, deployment experiments were conducted using a prototype to validate the theoretical model. It was observed that the folding wings are deployed in 11 ms. Further parametric analysis indicates that the mass of both the propellant and the locking rod has a positive effect on the deploying velocity. However, the angular moment of inertia of folding wings has a negative effect on the initial angular velocity. This work can be helpful for designing the folding wing structures of missiles and aircrafts.

Complex Pythagorean neutrosophic normal interval-valued set with an aggregation operators using score values

The complex Pythagorean neutrosophic normal interval-valued set approach solves the multiple-attribute decision-making problem. We introduce the new concepts such as complex Pythagorean neutrosophic normal interval-valued weighted averaging, complex Pythagorean neutrosophic normal interval-valued weighted geometric, complex generalized Pythagorean neutrosophic normal interval-valued weighted averaging and complex generalized Pythagorean neutrosophic normal interval-valued weighted geometric operator. We demonstrate that complex Pythagorean neutrosophic normal interval-valued set satisfy algebraic structures such as associative, idempotent, bounded, commutative and monotonic properties. Additionally, we develop algorithm and flowchart that solve problems using these operators. Examples of using enhanced score values and accuracy values in real-world environments are provided in this paper. Artificial intelligence refers to the simulation or approximation of human intelligence in machines. Its goals include computer enhanced learning, reasoning and perception. Artificial intelligence is being used today across different industries, from finance to healthcare. Agricultural robots have been described as being highly dependent on computer and machine tool technology. Four factors can be used to evaluate the quality of a robotics system: the controller’s sophistication, the software efficiency, the maximum moment of inertia, and the manufacturer’s reliability. The best alternative can be determined by comparing expert opinions to the criteria. Therefore, the parameter ∇ has a very significant impact on the results of the model. This comparison aims to prove that the models under consideration are valid and valuable by comparing them with the available and proposed models. In conclusion, the value of ∇ significantly impacts the model performance. Based on the comparison and sensitivity analysis, we conclude that the proposed aggregation operation is superior and more reliable than the existing one. The criteria were compared to the most appropriate options based on expert assessments.

Validation analysis of a method for determining the ship’s vertical centre of gravity and moment of inertia based on the model test

ABSTRACT Given the necessity for numerical validation, precisely determining the ship’s center of gravity and moment of inertia is crucial for validating simulations with motions. This paper performs three sections to illustrate the accuracy of the measurement method based on SolidWorks. Firstly, an analytical formulation on a shelled box is used to do the verification analysis. Secondly, the inclining test is used to validate the reliability of the measurement method in determining the ship's vertical center of gravity. By comparing the vertical center of gravity value in the test, SolidWorks yields only a 4.06% error. Thirdly, the flooding test of the damaged ship in still water is used to validate the reliability of the measurement method in determining the ship's moment of inertia. By comparing the test roll curve and its amplitude of 5.5 degrees, the tendency consistency and 3.6% amplitude error validate the moment of inertia input into CFD software.

Study On Operation Strategy Of CSP Peak-Regulating Power Station Based On Spot Trading Market In Gansu Province

On March 3, 2022, the National Development and Reform Commission of China and the National Energy Administration of China jointly published the Notice on Accelerating the Construction of the Electricity Spot Market. The notice indicated that the government would support the uninterrupted operation of the power spot pilot project with conditions and form a long-term and stable electricity spot market as soon as possible. These steps will help rapidly improve China's electricity spot market construction. Due to its large-scale energy storage capacity, the Concentrated Solar Power (CSP) station can be used as a peak-regulating power station to provide grid-friendly long-term peak regulating capacity and moment of inertia for the power system. When CSP stations participate in electricity spot market trading, they can optimize their operation strategy to generate more electricity during periods with higher electricity prices, thereby obtaining more profits. In this paper, a 100MW CSP Peak-Regulating Station with an 80.0hm2 reflecting area of Heliostats Field (HF) is designed in Gansu, China. In the Peak-Regulating operation strategy, the most suitable TES Capacity for this project is determined to be 15h. We take this CSP station as the research objective to optimize the operation strategy of the power station. The research results indicate that optimizing the operation strategy will increase the power station's annual electricity sales revenue by about 19.97% before the strategy was optimized when the power station participated in the real-time trading of the Gansu electricity spot market in 2022.

Measurement of tiny moment of inertia based on flexure hinge for automobile collision testing

Abstract The moment of inertia is a critical parameter for determining the motion state of an object and achieving precise control. At present, measurement techniques for the moment of inertia of large and heavy objects (greater than 0.5 kgm2) are very mature. However, it is still a challenge to achieve high precision for smaller objects (less than 0.5 kgm2). In this paper, a measuring device based on flexure hinges is proposed to achieve high-accuracy measurement of tiny moments of inertia, without additional friction. A theoretical model of measurement is developed and optimised to obtain the rotational inertia by measuring swing periods. The experimental results show that the maximum load of the device is 20 kg, and the resolution reaches 4 × 10−5 kgm2. For a 5 kg head model, the moment of inertia was measured to be 0.011 58 kgm2, with a combined standard uncertainty of 0.000 29 kgm2.

Vibration-rotational alternating-parity spectra of even–even nuclei with effective triaxiality

In the present work, a model combining vibration-rotational motion and effective triaxiality is developed for even–even nuclei with quadrupole and octupole deformations. The Davidson potential is used to solve the radial part of the vibration-rotational Schrödinger equation in the axial quadrupole and octupole variables. In an adiabatic approximation the contribution of the angular variable in the components of the moments of inertia is taken as a constant after which the triaxial-rotor energy is obtained. As a result the alternating-parity spectrum and wave functions of the nucleus with quadrupole-octupole degrees of freedom are obtained. The proposed model is used to describe the yrast and first-non-yrast alternating-parity bands of the even–even nuclei 150Nd, 154Sm, 154,160Gd, 156Dy, 162,164Er, 172Yb, 230,232Th, 230,232,234,236,238U and 238,240Pu. The relevance of the model for taking into account the collective quadrupole-octupole modes in a rather complete form is pointed out.