Variable Inertia Research Articles

714 慣性負荷変動を考慮したベルト駆動二慣性系のロバスト制御(GS28-1機械力学・計測制御)

714 慣性負荷変動を考慮したベルト駆動二慣性系のロバスト制御(GS28-1機械力学・計測制御)

Energy-recovering Workover Rig with Variable Inertia Flywheel

ABSTRACT An energy-recovering workover rig with variable inertia flywheel is investigated, and its basic structure and working theory are introduced. The variable inertia flywheel is composed of three identically sized flywheels with a mass of 458 kg each. It stores the energy of an idle motor as the tubing string is raised, as well as the potential energy released by the tubing string when it is lowered. The power of this rig decreases remarkably as compared to that of a conventional rig, and it can also recover and reuse the potential energy of the tubing string. The energy recovered by the flywheels is about 3.9×105 kJ when a 2500 m-long tubing string is lowered. The mathematical model for when the workover rig raises the tubing string is deduced, and simulation analyses are conducted. Through simulation, the curves of the rising velocity of the tubing string and displacement with time are obtained, and the following conclusions are reached: the heavier the tubing string, the lower the velocity of the ...

Modeling of chaotic motion of gyrostats in resistant environment on the base of dynamical systems with strange attractors

A chaotic motion of gyrostats in resistant environment is considered with the help of well known dynamical systems with strange attractors: Lorenz, Rössler, Newton–Leipnik and Sprott systems. Links between mathematical models of gyrostats and dynamical systems with strange attractors are established. Power spectrum of fast Fourier transformation, gyrostat longitudinal axis vector hodograph and Lyapunov exponents are find. These numerical techniques show chaotic behavior of motion corresponding to strange attractor in angular velocities phase space. Cases for perturbed gyrostat motion with variable periodical inertia moments and with periodical internal rotor relative angular moment are considered; for some cases Poincaré sections areobtained.

Design and Analysis of Hybrid Power Systems with Variable Inertia Flywheel

The purpose of this study is to analyze and to design for the hybrid power systems with variable inertia flywheel while the hybrid power system consists of 1 power plant, 1 variable inertia flywheel which is used as the energy storage device, a planetary gear set, and a set of actuators. First, the kinematic and kinetic equations of the hybrid power system are developed in order to establish the relationships of the speed and torque of all elements, and the specific speed and torque of the output needed for the vehicle can be found by using the software “ADVISOR” in various operation modes. Then, with the prescribed mechanical brake energy recovery system model and a control model, a comprehensive analysis can be achieved. Finally, various driving modes, such as ECE, ECE+EUDC and New York Bus driving mode are investigated in order to demonstrate the characteristics of the hybrid power system. The numerical results show and conclude the effectiveness of the variable inertia flywheel, and the improvement on the efficiency of hybrid power systems. Copyright Form of EVS25.

Fission as diffusion of a Brownian particle with variable inertia

An expression for stationary fission width is obtained for systems with steep shape-dependent nuclear collective inertia by extending the work of Kramers, which was originally derived for a fixed value of the inertia. The domain of validity of the present expression is examined by comparing its predictions with widths obtained from the corresponding Langevin equations.

Vibration control of two degrees of freedom system using variable inertia vibration absorbers: Modeling and simulation

Variable inertia vibration absorbers (VIVA) are previously used for the vibration control of single degree of freedom (dof) primary systems. The performance of such absorbers is studied in many investigations. This paper presents the dynamic modeling and simulation of a proposed modified design of such VIVA’s for the vibration control of two dof primary systems. Lagrange formulation is used to obtain its dynamic model in an analytical form. This model, which is highly nonlinear, is used to develop a computational algorithm to study the absorber performance characteristics. This algorithm is programmed and simulated in Matlab. The obtained results are numerically verified using SAMS2000 software. The effect of mass and stiffness of the proposed VIVA on its performance and tuning is discussed. An optimization algorithm is developed to select the best absorber parameters for vibration suppression of a specific primary system. The obtained results show a good agreement with those obtained using similar techniques. In addition, a linearized model of VIVA dynamics is developed, tested and simulated for the same data used in its nonlinear model. The relative deviation between results of the linear and nonlinear models is less than 1%, which confirms the realistic use of this linearized model. The experimental testing and verification of the simulation results of the proposed VIVA is the subject of another paper.

From the Inertia Variations

From the Inertia Variations

Key Factors Effect on Vehicle Braking Performance Based on Nonlinear 3DOF Vehicle Dynamic Model

3DOF nonlinear braking dynamic model considering tire-road adhesion characteristics was established, and non-dimensional equations were gained from the above mathematic models by using braking torque coefficient, front and rear axle equivalent inertia coefficients and braking force distribution coefficient. Based on the numerical calculation in Matlab-Simulink software, the effect of key factors, (including vehicle mass and vehicle gravity center position variation, frontal and rear braking force distribution coefficient, and frontal and rear axle inertial variation caused by driven mode) on vehicle braking performance, such as braking distance and wheel lockup status, was investigated and summarized. Several 3D visualizations of the simulation results show that variation of vehicle center of gravity, vehicle mass, braking moment distribution, wheel equivalent inertia due to driveline, can cause quite complex effect. It can be assumed that the gained results in this study can help to improve vehicle braking performance and enhance braking stability.

Experiment of H<sub>∞</sub> Driving Control System for Electric Vehicle

This paper discusses different drive control methods of electric vehicle (EV), presents the design of H∞ robust controller for driving control, with the consideration of protecting the battery. Research work is done under different conditions namely variable battery voltage and variable load rotational inertia separately. Experiments show that the H∞ robust controller has better performance than the PID controller in both steady-state tracking error and response speed. Moreover, the H∞ robust controller can improve the drive range of electric vehicle.

Surface-compositional properties of the Malea Planum region of the Circum-Hellas Volcanic Province, Mars

We used Thermal Emission Spectrometer (TES), Thermal Emission Imaging System (THEMIS), High-Resolution Stereo Camera (HRSC), and Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA) data to assess the physical and compositional properties of the Malea Planum portion of the Circum-Hellas Volcanic Province (CHVP). Our analysis of surface materials shows that the thermal inertia decreases from north to south, and that there is greater dust cover on the flanks of the CHVP volcanoes than in their putative calderas. Local variations in thermal inertia in Malea Planum are likely due to variations in surface material caused by aeolian and periglacial/permafrost processes, whereas regional variations are likely due to seasonal deposition and sublimation of ice at higher latitudes. Spectral analysis of OMEGA data indicates the widespread presence of pyroxenes and/or olivine, particularly in the rims of craters that likely excavated volcanic materials. Dark materials occur throughout the CHVP, but are concentrated in topographic lows such as crater and caldera floors. Derivation of modal mineralogies from OMEGA data show a variation in composition of dark materials across Malea Planum: eastern dark deposits have higher olivine and low-calcium pyroxene contents, lower high-calcium pyroxene contents, and higher ratios of low-calcium to total pyroxene, relative to western dark deposits. Correlation with cratering-model age estimates suggests that the western deposits are associated with older features (3.8 Ga) than the eastern deposits (3.6 Ga), but these age differences are within uncertainties. Nevertheless, these results suggest a potential change in composition of volcanic materials in the Malea Planum portion of the CHVP with space, and possibly time.

Spindle position regulation for wind power generators

The three-time-scale plant model of a wind power generator, including a wind turbine, a flexible vertical shaft, a variable inertia flywheel (VIF) module, an active magnetic bearing (AMB) unit and the applied wind sequence, is constructed. In order to make the wind power generator be still able to operate as the spindle speed exceeds its rated speed, the VIF is equipped so that the spindle speed can be appropriately slowed down once any stronger wind field is exerted. Currently, most of wind energy input is, as a matter of fact, a waste since the commercially available wind power generators only operate for fairly mild or low-speed wind field. To prevent any potential damage due to collision by shaft against conventional bearings, the AMB unit is proposed to replace the traditional bearings and regulate the shaft position deviation. By singular perturbation order-reduction technique, a lower-order plant model can be established for the synthesis of feedback controller. It is found that two major system parameter uncertainties, an additive uncertainty and a multiplicative uncertainty, are constituted by the wind turbine and the VIF, respectively. The upper bounds of system parameters variation can be therefore estimated and the frequency shaping sliding mode control (FSSMC) loop is proposed to account for these uncertainties and suppress the unmodeled higher-order plant dynamics. At last, the efficacy of the FSSMC is verified by intensive computer and experimental simulations for regulation on position deviation of the shaft and counter-balance of unpredictable wind disturbance.

A contribution to the interpretation of polymer viscoelasticity in DMTA testing

Some ideas relevant to the prevailing viscoelasticity interpretations of dynamic mechanical thermal analysis (DMTA) experiments are presented. The main aspect is the inclusion of kinetic energy and inertia as variables, seeing the relaxing mass constantly increasing during strain, assigning inertial variation and not viscosity to energy dissipation. The equations developed make it possible to obtain the values of important viscoelastic properties, under in any experimental condition, with the data taken from previous experiments.

Intraseasonal Latent Heat Flux Based on Satellite Observations

Abstract Weekly average satellite-based estimates of latent heat flux (LHTFL) are used to characterize spatial patterns and temporal variability in the intraseasonal band (periods shorter than 3 months). As expected, the major portion of intraseasonal variability of LHTFL is due to winds, but spatial variability of humidity and SST are also important. The strongest intraseasonal variability of LHTFL is observed at the midlatitudes. It weakens toward the equator, reflecting weak variance of intraseasonal winds at low latitudes. It also decreases at high latitudes, reflecting the effect of decreased SST and the related decrease of time-mean humidity difference between heights z = 10 m and z = 0 m. Within the midlatitude belts the intraseasonal variability of LHTFL is locally stronger (up to 50 W m−2) in regions of major SST fronts (like the Gulf Stream and Agulhas). Here it is forced by passing storms and is locally amplified by unstable air over warm SSTs. Although weaker in amplitude (but still significant), intraseasonal variability of LHTFL is observed in the tropical Indian and Pacific Oceans due to wind and humidity perturbations produced by the Madden–Julian oscillations. In this tropical region intraseasonal LHTFL and incoming solar radiation vary out of phase so that evaporation increases just below the convective clusters. Over much of the interior ocean where the surface heat flux dominates the ocean mixed layer heat budget, intraseasonal SST cools in response to anomalously strong upward intraseasonal LHTFL. This response varies geographically, in part because of geographic variations of mixed layer depth and the resulting variations in thermal inertia. In contrast, in the eastern tropical Pacific and Atlantic cold tongue regions intraseasonal SST and LHTFL are positively correlated. This surprising result occurs because in these equatorial upwelling areas SST is controlled by advection rather than by surface fluxes. Here LHTFL responds to rather than drives SST.

Adaptive Speed Control for Permanent-Magnet Synchronous Motor System With Variations of Load Inertia

Considering the variations of inertia in real applications, an adaptive control scheme for the permanent-magnet synchronous motor speed-regulation system is proposed in this paper. First, a composite control method, i.e., the extended-state-observer (ESO)-based control method, is employed to ensure the performance of the closed-loop system. The ESO can estimate both the states and the disturbances simultaneously so that the composite speed controller can have a corresponding part to compensate for the disturbances. Then, considering the case of variations of load inertia, an adaptive control scheme is developed by analyzing the control performance relationship between the feedforward compensation gain and the system inertia. By using inertia identification techniques, a fuzzy-inferencer-based supervisor is designed to automatically tune the feedforward compensation gain according to the identified inertia. Simulation and experimental results both show that the proposed method achieves a better speed response in the presence of inertia variations.

THEMIS high‐resolution digital terrain: Topographic and thermophysical mapping of Gusev Crater, Mars

We discuss a new technique to generate high‐resolution digital terrain models (DTMs) and to quantitatively derive and map slope‐corrected thermophysical properties such as albedo, thermal inertia, and surface temperatures. This investigation is a continuation of work started by Kirk et al. (2005), who empirically deconvolved Thermal Emission Imaging System (THEMIS) visible and thermal infrared data of this area, isolating topographic information that produced an accurate DTM. Surface temperatures change as a function of many variables such as slope, albedo, thermal inertia, time, season, and atmospheric opacity. We constrain each of these variables to construct a DTM and maps of slope‐corrected albedo, slope‐ and albedo‐corrected thermal inertia, and surface temperatures across the scene for any time of day or year and at any atmospheric opacity. DTMs greatly facilitate analyses of the Martian surface, and the MOLA global data set is not finely scaled enough (128 pixels per degree, ∼0.5 km per pixel near the equator) to be combined with newer data sets (e.g., High Resolution Imaging Science Experiment, Context Camera, and Compact Reconnaissance Imaging Spectrometer for Mars at ∼0.25, ∼6, and ∼20 m per pixel, respectively), so new techniques to derive high‐resolution DTMs are always being explored. This paper discusses our technique of combining a set of THEMIS visible and thermal infrared observations such that albedo and thermal inertia variations within the scene are eliminated and only topographic variations remain. This enables us to produce a high‐resolution DTM via photoclinometry techniques that are largely free of albedo‐induced errors. With this DTM, THEMIS observations, and a subsurface thermal diffusion model, we generate slope‐corrected maps of albedo, thermal inertia, and surface temperatures. In addition to greater accuracy, these products allow thermophysical properties to be directly compared with topography.

Critical comparison of Kramers’ fission width with the stationary width from the Langevin equation

It is shown that Kramers' fission width, originally derived for a system with constant inertia, can be extended to systems with a deformation-dependent collective inertia, which is the case for nuclear fission. The predictions of Kramers' width for systems with variable inertia are found to be in very good agreement with the stationary fission widths obtained by solving the corresponding Langevin equations.

Analysis of piston secondary motion considering the variation in the system inertia

The secondary motion of a piston has a significant impact on the performance and reliability of an internal combustion engine. However, the variation in the system inertia, namely the variable inertia of the piston—connecting-rod—crankshaft mechanism due to the change in their positions relative to the crankshaft axis, has been neglected in most studies on piston secondary motion. A novel mathematical model is developed for piston—connecting-rod—crankshaft dynamics by taking the variation in the system inertia into consideration. Then a coupling model of the piston secondary dynamics and the fluid dynamic lubrication is built. The simulations show that the variation in the system inertia influences the piston secondary motion and piston side force, and that the piston side force plays an important role in determining the piston lateral motion. Results also show that the engine speed and the centre-of-mass (COM) positions of the connecting rod have considerable effect on the piston secondary motion. The analysis of the COM positions can be employed to optimize the design of the connecting rod.

Estimation and mapping of wintertime increase in water ice content of the Martian surface soil based on seasonal Thermal Emission Spectrometer thermal inertia variations

Results of the Mars Global Surveyor Thermal Emission Spectrometer (TES) thermal inertia seasonal variations analysis show significant increase of the thermal inertia during autumn‐winter periods in the middle latitudes. This observed increase occurred with regular repetition during each of the three Mars years of the TES observations. Two climatic factors (atmospheric dust loading and water ice (frost) formation in the soil) might lead to the real and/or apparent seasonal increase in thermal inertia. We compare maps of summertime and wintertime thermal inertia at similarly low atmospheric dust opacity within the latitude belt ±50°, outside of the seasonal CO2 ice cover. On the basis of the results of such comparison we developed a new method for estimating and mapping the wintertime increase of the water ice within the surface soil layer corresponding to the daily thermal skin depth of 2–10 cm. We use both the nomograms of relation between the thermal inertia for dry and icy soil compiled for different water ice content and an analytical approach. Comparison of the mapped wintertime TES thermal inertia values with computed values of the parameter for icy soil at different ice amounts shows that the wintertime thermal inertia values in the latitude ranges 40°–50°N and 40°–50°S are consistent with the presence of the water ice amount in the soil from 4 up to 17 vol % (locally), whereas at lower latitudes the ice amount is mainly less than 1 vol %. Mapping results show that the zone with a soil water ice amount of >3 vol % is much more in the northern hemisphere than in the southern one.

Dynamic task scheduling with load balancing using parallel orthogonal particle swarm optimisation

This paper presents a novel approach for dynamic task scheduling using particle swarm optimisation. Particle swarm optimisation (PSO) is a population-based meta-heuristic method which can be used to solve np-hard problems. The algorithm has been developed to dynamically schedule heterogeneous tasks on to heterogeneous processors in a distributed setup. Load balancing which is a major issue in task scheduling is also considered. The nature of the tasks are independent and non pre-emptive. Different approaches using PSO has been tried namely PSO with fixed inertia, PSO with variable inertia, PSO with elitism, MPSO, parallel PSO, hybrid PSO, orthogonal PSO and parallel orthogonal PSO. The performance of PSO and its variants is also compared with the genetic algorithm concept. The objective of the algorithms is to minimise the make-span of the entire schedule. Benchmark problems have been taken and validated. The result depicts that the dynamic task scheduling implemented using parallel orthogonal particle swarm optimisation technique is cost-effective in nature when compared to the other algorithms tested.

Influencia de los Parámetros de Carga en la Estabilidad Direccional de un Vehículo Combinado

This work is about the directional stability of truck-semitrailer vehicle, commonly used in Brazil, as a function of load parameters. For different positions of centre of gravity of semi-trailer, the curves that represent the characteristic movements and the ratio of damping for these movements during curved and straight trajectories are obtained. The influence of load and moment inertia variations for different adopted positions of the centre of gravity of semi-trailer was calculated. The results show significant changes on dynamic response of vehicle with the variations of load parameters. Thus, the operating conditions with less safety margins were determined, so they can be avoided by users. The study allows concluding that there are load conditions that although being accepted by the present legislation, must be avoided.