The calculation of the structural parameters for the pyrochlore family of structures. The stability regions of the pyrochlore type structure

ABSTRACTAt present, crystalline ceramic based on titanate pyrochlore, (Ca,Gd,Hf,Pu,U)2Ti2O7, is considered as the US candidate waste form for the immobilization of weapons grade plutonium. Naturally occuring U-bearing minerals with pyrochlore-type structure: hatchettolite, betafite, and ellsworthite, were studied in orders to understand long-term radiation damage effects in Pu ceramic waste forms. Chemical shifts (δ) of U(Lδ1)– and U(Lβ1) – X-ray emission lines were measured by X-ray spectrometry. Calculations were performed on the basis of a two-dimensional δLá1- and δLδ1- correlation diagram. It was shown that 100% of uranium in hatchettolite and, probably, 95-100% of uranium in betafite are in the form of (UO2)2+. formal calculation shows that in ellsworthite only 20% of uranium is in the form of U4+ and 80% of the rest is in the forms of U5+ and U6+. The conversion of the initial U4+ ion originally occurring in the pyrochlore structure of natural minerals to (UO2)2+ due to metamict decay causes a significant increase in uranium mobility.

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The effect of process and structural parameters on the stability, thermo-mechanical and thermal degradation of polymers with hydrocarbon skeleton containing PE, PP, PS, PVC, NR, PBR and SBR

Journal of Thermal Analysis and Calorimetry ◽

10.1007/s10973-020-09344-0 ◽

2020 ◽

Cited By ~ 5

Author(s):

Mehrdad Seifali Abbas-Abadi

Keyword(s):

Thermal Degradation ◽

Structural Parameters ◽

The Stability

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Numerical and Experimental Approaches to Investigate the Stability of a Motorcycle Vehicle

Volume 2: Automotive Systems, Bioengineering and Biomedical Technology, Fluids Engineering, Maintenance Engineering and Non-Destructive Evaluation, and Nanotechnology ◽

10.1115/esda2006-95311 ◽

2006 ◽

Cited By ~ 1

Author(s):

Federico Cheli ◽

Marco Bocciolone ◽

Marco Pezzola ◽

Elisabetta Leo

Keyword(s):

Degrees Of Freedom ◽

Structural Parameters ◽

Experimental Tests ◽

Roll Angle ◽

Longitudinal Motion ◽

Reference Trajectory ◽

Steering Angle ◽

Steady State Condition ◽

The Stability ◽

Linearized Model

The study of motorcycle’s stability is an important task for the passenger’s safety. The range of frequencies involved for the handling stability is lower than 10 Hz. A numerical model was developed to access the stability of a motorcycle vehicle in this frequency range. The stability is analysed using a linearized model around the straight steady state condition. In this condition, the vehicle’s vertical and longitudinal motion are decoupled, hence the model has only four degrees of freedom (steering angle, yaw angle, roll angle and lateral translation), while longitudinal motion is imposed. The stability was studied increasing the longitudinal speed. The input of the model can be either a driver input manoeuvre (roll angle) or a transversal component of road input able to excite the vibration modes. The driver is introduced in the model as a steering torque that allows the vehicle to follow a reference trajectory. To validate the model, experimental tests were done. To excite the vehicle modes, the driver input was not taken into account considering both the danger for the driver and the repeatability of the manoeuvre. Two different vehicle configurations were tested: vehicle 1 is a motorcycle [7] and vehicle 2 is a scooter. Through the use of the validated model, a sensitivity analysis was done changing structural (for example normal trail, steering angle, mass) and non structural parameters (for example longitudinal speed).

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A Quasiperiodic Mathieu Equation

Volume 3A: 15th Biennial Conference on Mechanical Vibration and Noise — Vibration of Nonlinear, Random, and Time-Varying Systems ◽

10.1115/detc1995-0315 ◽

1995 ◽

Author(s):

Richard Rand ◽

Rachel Hastings

Keyword(s):

Numerical Integration ◽

Mathieu Equation ◽

Stability Regions ◽

Regions Of Stability ◽

Extensive Computation ◽

The Stability ◽

Direct Numerical Integration

Abstract In this work we investigate the following quasiperiodic Mathieu equation: x ¨ + ( δ + ϵ cos ⁡ t + ϵ cos ⁡ ω t ) x = 0 We use numerical integration to determine regions of stability in the δ–ω plane for fixed ϵ. Graphs of these stability regions are presented, based on extensive computation. In addition, we use perturbations to obtain approximations for the stability regions near δ=14 for small ω, and we compare the results with those of direct numerical integration.

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The assessment of the stability of the corneal structure after LASIK correction of myopia by different optical zone diameters

Vojnosanitetski pregled ◽

10.2298/vsp140627029m ◽

2016 ◽

Vol 73 (6) ◽

pp. 572-576 ◽

Cited By ~ 1

Author(s):

Milorad Milivojevic ◽

Vladimir Petrovic ◽

Miroslav Vukosavljevic ◽

Ivan Marjanovic ◽

Mirko Resan

Keyword(s):

Structural Parameters ◽

Preoperative Assessment ◽

Laser In Situ Keratomileusis ◽

Group I ◽

Significant Difference ◽

Optical Zone ◽

Corneal Structure ◽

The Stability ◽

Corneal Thinning

Background/Aim. Enlargement of optical zone (OZ) diameter during laser in situ keratomileusis (LASIK) correction of myopia postoperatively improves the optical outcome, however, it also leads to the increased stroma tissue consumption - progressive corneal thinning. The aim of this investigation was to present the possibility of safe OZ enlargement without impairing the structural stability of the cornea, while obtaining an improved optical outcome with LASIK treatment of shortsightedness. Methods. Preoperative assessment of the cornea structure and prediction of the ablated stroma tissue consumption was conducted in 37 patients (74 eyes) treated for shortsightedness by means of the LASIK method. With the eyes that, according to their cornea structure, had the capacity for OZ diameter enlargement of 0.5 mm, LASIK treatment was performed within the wider OZ diameter of 7.0 mm compared to the standard 6.5 mm. The following two groups were formed, depending on the diameter of the utilized OZ: the group I (the eyes treated with the OZ 6.5 mm, n = 37) and the group II (the eyes treated with the OZ 7.0 mm, n = 37). Results. No significant difference in the observed structural parameters of the cornea was detected between the groups of patients treated with different OZ diameters. The values of all the parameters were significantly bellow the threshold values for the development of postoperative ectasia. Conclusion. Diameter enlargement of the treated OZ, if there is a preoperative cornea capacity for such enlargement, will not impair the postoperative stability of the cornea structure, and will significantly improve the optical outcome.

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Metal-insulator Crossover in Pb-Ru Based Oxides with Pyrochlore-type Structure

Journal of the Japan Society of Powder and Powder Metallurgy ◽

10.2497/jjspm.65.249 ◽

2018 ◽

Vol 65 (5) ◽

pp. 249-254

Author(s):

Masaki KATO ◽

Kazuya IWAMOTO ◽

Yuki IWAKURA ◽

Ken HIROTA ◽

Angel AREVALO-LOPEZ ◽

...

Keyword(s):

Type Structure ◽

Metal Insulator ◽

Pyrochlore Type

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LOCATION AND STABILITY OF THE TRIANGULAR POINTS IN THE TRIAXIAL ELLIPTIC RESTRICTED THREE-BODY PROBLEM

Revista Mexicana de Astronomía y Astrofísica ◽

10.22201/ia.01851101p.2021.57.02.05 ◽

2021 ◽

Vol 57 (2) ◽

pp. 311-319

Author(s):

M. Radwan ◽

Nihad S. Abd El Motelp

Keyword(s):

Linear Stability ◽

Periodic Orbits ◽

Body Problem ◽

Restricted Three Body Problem ◽

Three Body Problem ◽

Stability Regions ◽

Triangular Points ◽

Problem Frame ◽

The Stability ◽

Three Body

The main goal of the present paper is to evaluate the perturbed locations and investigate the linear stability of the triangular points. We studied the problem in the elliptic restricted three body problem frame of work. The problem is generalized in the sense that the two primaries are considered as triaxial bodies. It was found that the locations of these points are affected by the triaxiality coefficients of the primaries and the eccentricity of orbits. Also, the stability regions depend on the involved perturbations. We also studied the periodic orbits in the vicinity of the triangular points.

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