Inertia Models 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.

Position sensorless extended and unscented Kalman filters with permanent magnet flux linkage and load torque estimation for surface-mounted PMSM

In this paper, novel position sensorless state estimators with improved robustness to permanent magnet (PM) flux linkage variations in permanent magnet synchronous machines (PMSMs) are presented. Unlike state estimators using conventional infinite inertia or electromechanical models, the estimators presented here can also estimate the PM flux linkage, so they are not sensitive to its uncertainty. For each models used for state estimation, a detailed observability study is presented. Due to the nonlinear models, extended and unscented Kalman filter algorithms are used for the implementation. To compare the sensitivity of conventional and proposed state estimators to uncertainty in electrical parameters, numerical simulations are carried out. In addition, the computational burden of the estimators is compared by real-time execution.

Investigating Tailless UAV Flight Dynamics through Modeling, Simulation, and Flight Testing

Tailless Unmanned Aerial Vehicles (UAVs) offer several advantages over their conventional counterparts, including enhanced maneuverability, higher durability, and better stealth. However, they are challenging in their stability and control due to the absence of stabilizing and control surfaces that typically exist in conventional empennage. A crucial process for analyzing the tailless UAVs’ stability/performance characteristics and determining/validating their flight control parameters is done via the modeling and simulation of flight dynamics. This paper presents a comprehensive and systematic procedure for investigating the flight dynamics of a tailless UAV, including modeling, simulation, analytical verification, and flight testing, while also explaining the interconnections among these elements. It also addresses the common challenge of limited accessibility of UAV essential data through using diverse analytical, empirical, and experimental methods. First, a rapid and effective first-principles modeling approach is introduced to simulate the nonlinear six-degree-of-freedom flight dynamics of a small tailless UAV case study. The modeling process follows a modular framework where well-defined experiments and commercial of-the-shelf software, tools, and sensors are employed to build the necessary sub-models, including geometric, mass–inertia, aerodynamic, propulsion, and actuator models. Then, all sub-models are integrated into a simulation environment to allow the prediction of the UAV dynamic response obtained from the given control inputs. The developed flight dynamic model is subjected to a thorough verification process to ensure its integrity and proper functionality by comparing the simulated trim and natural flight modes with the calculated analytical results. Finally, a set of specific flight tests are performed to validate the developed simulation model and verify relevant performance characteristics for the case-study UAV. The results show that the proposed approach provides a systematic and straightforward method for examining the flight dynamics of small tailless UAVs with reasonable accuracy.

Thermal Properties of the Leading Hemisphere of Callisto Inferred from ALMA Observations

We present a thermal observation of Callisto's leading hemisphere obtained using the Atacama Large Millimeter/submillimeter Array at 0.87 mm (343 GHz). The angular resolution achieved for this observation was ∼0.″16, which for Callisto at the time of this observation (D ∼ 1.″05) was equivalent to ∼six elements across the surface. Our disk-integrated brightness temperature of 116 ± 5 K (8.03 ± 0.40 Jy) is consistent with prior disk-integrated observations. Global surface properties were derived from the observation using a thermophysical model constrained by spacecraft data. We find that models parameterized by two thermal inertia components more accurately fit the data than single thermal inertia models. Our best-fit global parameters adopt a lower thermal inertia of 15–50 J m−2 K−1 s−1/2 and a higher thermal inertia component of 1200–2000 J m−2 K−1 s−1/2, with retrieved millimeter emissivities of 0.89–0.91. We identify several thermally anomalous regions, including spots ∼3 K colder than model predictions colocated with the Valhalla impact basin and a complex of craters in the southern hemisphere; this indicates the presence of materials possessing either a higher thermal inertia or a lower emissivity. A warm region confined to the midlatitudes in these leading hemisphere data may be indicative of regolith property changes due to exogenic sculpting.

Describe of Nuclear Structure for Germanium (_32^66)Ge_34) Nucleus under frame (IBM-1, GVMI and VMI) Models

In this paper, the interacting bosons model-1 (IBM-1), a variable moment of inertia (VMI) and generalized moment of inertia (GVMI) models were used to calculate the energy levels of the positive parity and its gamma transitions as a function of the angular momentum of even-even (_32^66Ge_34) nucleus. To determine the dynamic symmetry of this nucleus, the ratios of the energy levels (E_4^+)⁄(E_2^+ ), (E_6^+)⁄(E_2^+), and (E_8^+)⁄(E_2^+) were evaluated and compared with experimental energy values and the ideal scheme of the three dynamic symmetries SU(5), SU(3), and O(6). The current study showed that the dynamic symmetry of this nucleus is determined to be O(6) - SU(5). The intersection of the energy band and the phenomenon of back bending were also studied using the (VMI) and (GVMI) models. These consequences were compared with the experimental results, and the results obtained have been in good agreement.

OBJECTIVE FUNCTION OF PARAMETRIC OPTIMIZATION OF THE SPEED OF A CLOSED PLANETARY MECHANISM FORMED BY TWO SIMPLE JAMES PLANETARY MECHANISMS

The results of building а mathematical model of estimation the speed of the designed construction of the closed planetary mechanism formed from two simple planetary mechanisms of James are presented. The speed of the designed construction of the mechanism is estimated by the value of the equivalent moment of inertia of the mechanism links reduced to its input shaft. A model is a dimensionless function (analogue the equivalent moment of inertia) of two variables - transmission relations of simple planetary mechanisms, and set of numerical parameters. The parameters take into account the values of the coefficients that characterize the mass inertia models of gears and planet carriers, the design and strength limitations of external gears of simple planetary mechanisms of James, as well as the structure of these mechanisms. Set of values of parameters and range of varying of possible values of transmission relations of simple planetary mechanisms influence on position of a minimum of the analogue the equivalent moment of inertia. The influence of the number of planetary gears of simple planetary mechanisms and the moment of inertia of the planet carrier of the differential mechanism on the positions of the minima of the analogues of the reduced moment of inertia of a closed planetary gear was analyzed in calculations for contact strength and bending strength. Based on the function of the analogue of the equivalent moment of inertia, the objective function of parametric optimization of the project fast-acting of the design of a closed planetary mechanism is built. Keywords: simple James planetary mechanism (mechanisms type ); closed planetary mechanism; moment of inertia of gear-wheel; moment of inertia of the planet carrier; moment of inertia of the planetary mechanism; contact strength of the gearing; bending strength of the gearing; parametric optimization; parametric optimization of the equivalent moment of inertia of the planetary mechanism

Study on the Optimal Cross-Sectional Shapes of the PEMFC Endplates by Using a Moment of Inertia and 3D FEM Models

The deflection of the endplate under the clamping force has a vital effect on fuel cell performance. An optimal cross-sectional shape with a high moment of inertia of the endplate is significant to maximize the bending stiffness of the fuel cell stack. Five cross-sectional shapes (rectangular, round, parabolic, rectangular + round, and rectangular + parabolic) of the typical endplates are proposed. An analytical study on the moments of inertia of the endplates is introduced and analyzed. The maximum moments of inertia of the cross-sections are obtained and displayed in a matrix in thickness and length. The statistical results show that the “rectangular + parabolic” cross-section has the advantage of wide dimensional size while maintaining a high moment of inertia. Finally, the analytical studies are validated by a finite element method (FEM) and the corresponding trends are highly agreed upon. The maximum moment of inertia of the parabolic endplate is 85.71% higher than the rectangular endplate with a thickness of 80 mm, and the corresponding contact pressure variance is 6.15% less than the rectangular endplate. The presented analytical study is significant and effective to optimize the cross-sectional shape of the endplate and provide an endplate design direction for a large fuel cell stack.

Multi-objective optimization of turbocharger turbines for low carbon vehicles using meanline and neural network models

• Optimization framework for engine-turbocharger match and turbine design is described. • Framework couples engine cycle, turbine meanline, and neural network inertia models. • Aerodynamic and inertia changes reflect in steady and transient engine performance. • Turbine is optimized for the Worldwide harmonized Light vehicles Test Procedure. • We estimate resulting global CO2 saving of millions of tonnes over vehicle lifetimes. Due to slow turnover of the global vehicle parc internal combustion engines will remain a primary means of motive power for decades, so the automotive industry must continue to improve engine thermal efficiency to reduce CO 2 emissions, since savings will be compounded over the long lifetime of millions of vehicles. Turbochargers are a proven efficiency technology (most new vehicles are turbocharged) but are not optimally designed for real-world driving. The aim of this study was to develop a framework to optimize turbocharger turbine design for competing customer objectives: minimizing fuel consumption (and thus CO 2 emissions) over a representative drive cycle, while minimizing transient response time. This is achieved by coupling engine cycle, turbine meanline, and neural network inertia models within a genetic algorithm-based optimizer, allowing aerodynamic and inertia changes to be accurately reflected in drive cycle fuel consumption and transient performance. Exercising the framework for the average new passenger car across a drive cycle representing the Worldwide harmonized Light vehicles Test Procedure reveals the trade-off between competing objectives and a turbine design that maintains transient response while minimizing fuel consumption due to a 3 percentage-point improvement in turbine peak efficiency, validated by experiment. This optimization framework is fast to execute, requiring only eight turbine geometric parameters, making it a commercially viable procedure that can refine existing or optimize tailor-made turbines for any turbocharged application (whether gasoline, diesel, or alternatively fuelled), but if applied to turbocharged gasoline cars in the EU would lead to lifetime CO 2 savings of > 290,000 tonnes per production year, and millions of tonnes if deployed worldwide.

Experimental validation of fluid inertia models for a cylinder settling in a quiescent flow

This work studies experimentally the angular and translational dynamics of elongated cylindrical particles settling in a quiescent fluid at low Reynolds numbers. The measured force and torque are compared with expressions accounting for the effect of fluid inertia, obtained either in the slender-rod limit or in the case of spheroids.

A method for discriminating between dark matter models and MOND modified inertia via galactic rotation curves

ABSTRACT Dark matter (DM) and modified Newtonian dynamics (MOND) models of rotationally supported galaxies lead to curves with different geometries in (gN, gtot)-space (g2-space). Here, gtot is the total acceleration and gN is the acceleration as obtained from the baryonic matter via Newtonian dynamics. In MOND modified inertia (MI) models, the curves in g2-space are closed with zero area and so curve segments at radii r ≥ rN (large radii) and r < rN (small radii) coincide, where rN is the radius where gN is greatest. In DM models with cored density profiles where gtot is also zero at the Galactic Centre, the curves are again closed, but the area of the closed curves are in general non-zero because the curve segments at radii r ≥ rN and r < rN do not coincide. Finally in DM models with cuspy density profiles such as the NFW profile where gtot is formally non-zero at the galactic origin the curves are open, and again the curve segments at radii r ≥ rN and r < rN do not coincide. We develop a test of whether data at small and large radii coincide and investigate rotation curves from the SPARC data base in order to discriminate between the above geometries. Due to loosely quantified systematic uncertainties, we do not underline the result of the test, but instead conclude that the test illustrates the relevance of this type of analysis and demonstrate the ability to discriminate between the considered DM and MI models in this way.

Risk-Based Underground Cable Circuit Ratings for Flexible Wind Power Integration

Cable circuit rating methods, used by utilities for connecting wind farms into the grid, neglect the stochastic intermittent nature of wind output and the thermal inertia of the cable. This paper proposes new risk-based rating approaches for windfarm underground cables and suggests a method to evaluate their effectiveness. The novelty stems from integrating cable system thermal inertia and aging models to determine the benefits and risks of time-dependent flexible ratings. These risk-based ratings are compared against standard static cable rating and dynamic rating practices with an aim to identify the value of simple cable operating strategies that minimize wind curtailment, but they could introduce higher aging risks. A wind farm cable tie in Scotland is used to assess the different rating approaches considering wind curtailment and cable aging costs in a multi-year cost-benefit analysis. This case study indicated a 21% increase in wind integration on the existing tie with the proposed Flexible Cable Rating when compared to the Static Rating and with aging equivalent to that of the Dynamic Cable Rating. Thus, the proposed rating approaches and methodology can facilitate risk-based planning and operation practices to increase flexibility at different, operator pre-defined, risk levels.

Theoretical Dynamic Modeling and Validation of Braided Pneumatic Artificial Muscles

Abstract The high force-to-weight ratios of braided fluidic artificial muscles (AMs) are ideal for human scale and mobile robot applications. Prior modeling efforts focus on the theoretical static characteristics or empirical dynamic models of these actuators when pressurized. This paper develops a comprehensive high fidelity theoretical dynamic model based on first principles for braided pneumatic AMs and presents experimental validation. A novel theoretical model for the nonlinear stiffness is derived to describe the pressure–displacement behavior. The stiffness model, together with friction, damping, and inertia models, forms an equation of motion (EOM) for braided pneumatic AMs. The EOM is coupled with first-order servopneumatic pressure dynamics, resulting in a third-order system model. System model simulations are compared to experimental results of prototypes with nine different geometries. On average, the system model is able to predict the quasi-static displacement within 7% and the dynamic response within 11%. The theoretical model is also benchmarked against a high fidelity curve fit method, with the empirical method showing a 2% improvement in only quasi-static scenarios. The model promises to be useful for mechanical system and model-based control designs.

Dynamic Collapse Mechanism of Global Hull Girder of Container Ships Subjected to Hogging Moment

The purpose of the present study is to investigate dynamic ultimate strength of global hull girder of container ships using large-scale nonlinear finite element analysis (FEA). A series of time domain nonlinear finite element (FE)-simulation is carried out using large-scale FE models of a 8000 twenty-foot equivalent unit (TEU) container ship where a hogging moment is applied to the midship section. Five types of finite element models (three full models, a half hold model, a one transverse model) are used. These models adopt elastoplastic material model, which includes strain rate effect. The hogging moment, which is modeled by sinusoidal impulse, is applied to these models, and collapse mechanism as well as dynamic hull girder ultimate strength is investigated by varying the load time duration. Moreover, effects of load time duration, mass inertia, strain rate, and analysis models are investigated in detail. It is found from the present study that ultimate strength as well as collapse mode is significantly dependent on load time duration of hogging moment.

Assessing the Performance of Thermal Inertia and Hydrus Models to Estimate Surface Soil Water Content

The knowledge of soil water content (SWC) dynamics in the upper soil layer is important for several hydrological processes. Due to the difficulty of assessing the spatial and temporal SWC dynamics in the field, some model-based approaches have been proposed during the last decade. The main objective of this work was to assess the performance of two approaches to estimate SWC in the upper soil layer under field conditions: the physically-based thermal inertia and the Hydrus model. Their validity was firstly assessed under controlled laboratory conditions. Thermal inertia was firstly validated in laboratory conditions using the transient line heat source (TLHS) method. Then, it was applied in situ to analyze the dynamics of soil thermal properties under two extreme conditions of soil-water status (well-watered and air-dry), using proximity remote-sensed data. The model performance was assessed using sensor-based measurements of soil water content acquired through frequency (FDR) and time domain reflectometry (TDR). During the laboratory experiment, the Root Mean Square Error (RMSE) was 0.02 m3 m−3 for the Hydrus model and 0.05 m3 m−3 for the TLHS model approach. On the other hand, during the in situ experiment, the temporal variability of SWCs simulated by the Hydrus model and the corresponding values measured by the TDR method evidenced good agreement (RMSE ranging between 0.01 and 0.005 m3 m−3). Similarly, the average of the SWCs derived from the thermal diffusion model was fairly close to those estimated by Hydrus (spatially averaged RMSE ranging between 0.03 and 0.02 m3 m−3).

Analysis the Inertia Modeling and Stability of Brushless Doubly-Fed Induction Generator of Wind Power Grid

Brushless doubly-fed induction generator (BDFIG) leave out the slip ring and brush as the dual-stator structure, which can improve the reliability, reduce maintenance costs and expect to be widely used in wind power system. The current converter is installed in the one of the dual stator winding: control winding (CW), then the motor rotor is linked together with the wind turbines. The mechanical and electric inertia have different with the doubly-fed induction generator (DFIG) because of the special structure and these features directly affect the stability of power system. On the establishment and qualitative analysis of the inertia models of single and group motors of BDFIG, the vector control (VC) of the small signal model is established to solve the eigenvalue for quantitative analysis of the stability of the wind power system connected to the grid, and compared with squirrel-cage asynchronous induction generator (SCAIG), DFIG and permanent magnet synchronous generator (PMSG) to analyze the different effects on the stability of the power system. The simulation results prove the correctness of the model.

SOCIO-ECONOMIC DEVELOPMENT OF THE ARCTIC: THE RELEVANCE OF COORDINATION OF CONTROL PROCESSES

The aim of the study is to justify the need of coordination of processes of socio-economic development of the Russian Arctic territories. To achieve this goal required the following tasks: • to describe the existing economic model of development of the Arctic; • to structure information about the target units of the participants of the investment processes in the region; • identify problematic situations, related to the divergent goals of the participants within the framework of self-organization of financial and investment processes; • to justify the need for structural and logical coordination of activities and investment projects. Research methods. The study applied the methods of generalization, system analysis, comparisons. The results of the study During the study, the following results were obtained. • Determined that the national interests of the Russian Federation are inextricably linked to economic development prospects of the Arctic. • It is proved that powerful resource potential of the Russian Arctic largely determines the model behaviour of the leading players in the global market. • Found that the Russian Arctic territory, an area of direct Federal presence due to the concentration of key national interests. • Peculiarities and weaknesses actively promoted models of development of the Russian Arctic. • Established the concept of integrated development of the Arctic should be based on maintaining balance of the elements that determine effective inclusion in the economic turnover of the Arctic territories. • It is proved that the complex development of the Russian Arctic requires careful definition of the goals of effective program planning, management and synchronization of activities and investment projects. • It is established that the coordination mechanism of management of development of the Arctic territories should be innovative and be based on large-scale intelligent systems. Conclusion Due to the fact that the Arctic is now gaining exceptional political and economic importance, the Russian Arctic territories is provided by the interaction of authorities, scientific communities, and numerous businesses. This gives rise to the creation of complex of information flows, requires the formation of multi-level control system, determines the relevance of ensuring proper coordination in control systems. Coordination mechanisms should be innovative and operate on the basis of large-scale intelligent systems. Scientific novelty Scientific novelty of research consists in the following: • Formulated arguments in favor of inertia and innovative models of development of the Arctic, identified weaknesses of the innovation model. • Identified the key cause of the ineffective implementation of the existing inertia model – the lack of clear coordination of the activities developed in the framework of the strategic management processes of the Arctic territories. • As a system of measures capable of ensuring sustainable development of the Arctic, the procedure of program planning, control and synchronization of activities and investment projects with the use of conceptual models, cognitive and mind maps.

A Novel Backstepping Approach for the Attenuation of Torsional Oscillations in Drill Strings

A common problem in the petroleum drilling process is the torsional oscillation generated by the friction present during the cutting process. Torsional oscillations in drill string are particularly difficult to control because the drill string is an underactuated system, it has a very small diameter to length ratio and it is driven at top end with the cutting process at the other end. These factors make the drill string prone to self-excited torsional vibrations caused by the stick-slip of the cutting bit. The system is modeled as a torsional pendulum with two degrees of freedom, where the upper inertia models the top drive and also part of the drilling pipes. The bottom inertia models the bottom hole assembly (BHA). The drill is considered to be a massless torsional spring-damper. The drill string is subjected to friction, which is formulated using a dry friction model. The friction model takes into account Coulomb friction, stiction and Stribeck effect. The latter friction component is the main nonlinear phenomenon that introduces negative damping at the bit; it leads to self-enforcing stick-slip torsional oscillations.In the approach of this work, for the attenuation of these self-excited oscillations a recursive backstepping control strategy is used and it is carried out in continuous time. The main contribution of this work, which is different from the backstepping approaches reported in the literature, is to use a nonlinear/artificial damping as virtual control input. The stability of the system has been proven in the sense of Lyapunov. The goal of the proposed algorithm is to deal the underactuation of the system and to provide a good response for different operating points. The effectiveness and robustness of the controller has been tested in simulations.

A simple and efficient unstructured finite volume scheme for solving the shallow water equations in overland flow applications

AbstractThis paper presents the decoupled hydrological discretization (DHD) scheme for solving the shallow water equations in hydrological applications involving surface runoff in rural and urban basins. The name of the scheme is motivated by the fact that the three equations which form the two‐dimensional shallow water system are discretized independently from each other and thus, the numerical scheme is decoupled in a mathematical sense. Its main advantages compared to other classic finite volume schemes for the shallow water equations are its simplicity to code and the lower computational cost per time step. The validation of the scheme is presented in five test cases involving overland flow and rainfall‐runoff transformation over topographies of different complexity. The scheme is compared to the finite volume scheme of Roe (1986), to the simple inertia formulation, and to the diffusive wave model. The test cases show that the DHD scheme is able to compute subcritical and supercritical flows in rural and urban environments, and that in overland flow applications it gives similar results to the second‐order scheme of Roe with a lower computational cost. The results obtained with the simple inertia and diffusive wave models are very similar to those obtained with the DHD scheme in rural basins in which the bed friction and topography dominate the flow hydrodynamics but they deteriorate in typical urban configurations in which the presence of supercritical flow conditions and small‐scale patterns boost the relevance of the inertial terms in the momentum equations.

Simulation of open- and closed-end border irrigation systems using SIRMOD

In many regions in the world, more than 90% of areas equipped for irrigation apply surface methods. The major problem of the surface irrigation system is low performance due to poor design, operation, and maintenance. Use of the mathematical models for simulation of surface irrigation is necessary for reducing costs and decrease of time in analysis of indexes including application efficiency and distribution uniformity. This study aims to simulate border irrigation systems using the SIRMOD (surface irrigation simulation, evaluation and design, developed by Utah State University, Logan, UT, USA) software package under open- and closed-end conditions. For this purpose, 22 sets of data including four no-cultivated open-end borders, nine no-cultivated closed-end borders, and nine cultivated closed-end borders were used. The results showed that the models predicted open-end conditions better than closed-end for recession time. In addition, the hydrodynamic (HD) and the zero inertia (ZI) models estimated volume of infiltrated water, equal or less than volume of observed water in all the borders. Although the HD model uses the Saint-Venant equations without simplification, during numerical solution of them by the software, uncertainty is raised due to further calculations than the ZI and kinematic wave models. This leads to further error of the HD model than the other models in some cases.

Descriptive New features of high angular momentum rotational states in some rear-earth nuclei

The results from the variable moment of inertia (VMI) and cubic polynomial (CP) models with the available experimental information on transition energies for the yrast band levels in all studied nuclei. These models has been generalized so as to be applicable to transitional and vibrational nuclei by requiring that the extended models reduce at low angular momentum, to the polynomial dependence which gives excellent fits to the experimental spectra in the spherical, transitional and deformed regions. The level structure indicate a transition from collective to few-particle characteristics at high spin, possibly suggesting a change shape from prolate through triaxial to oblate. The loss of collectivity occurs at much lower angular momentum than predicted by calculations. The calculated Qt-value of the yrast band of the nucleus with N = 90.