Central Orbit Research Articles

An Analysis of the Gear Meshing Characteristics of the Main Planetary Gear Trains of Helicopters Undergoing Shafting Position Changes

The complex three-shaft three-reducer structural designs of helicopter transmission systems are prone to changes in the relative positions of shafting under the conditions of main rotor and tail rotor loads. These changes will affect the transmission characteristics of the entire transmission system. In this study, the planetary gear trains of helicopters were examined. Due to the fact that these structures are considered to be the most representative structures of the main reducers of helicopters, they were selected as the study objects for the purpose of examining the meshing characteristics of planetary gear trains when the relative positions of the shafting changed due to the position changes of the main rotor shafts under variable load conditions. It was found that by embedding the comprehensive time-varying meshing stiffness values of the main rotor shafts at different positions, a dynamic model of the relative position changes of the planetary gear trains could be established. Then, combined with the multibody dynamics software, the meshing characteristics of the sun gears, and the planetary gears, the planetary gears and the inner ring gears were simulated and analyzed under different inclinations and offsets of the shafting. The results obtained in this study revealed the following: (1) the average meshing force of the gears increased with the increases in the angle inclinations, and the meshing force between the sun gears and the planetary gears increased faster than the meshing force between the planetary gears and the inner ring gears. It was observed that during the changes in the shafting tilt positions, obvious side frequency signals had appeared around the peak of the meshing frequency in the spectrum. Then, with the continuous increases in the tilt position, the peak was gradually submerged; (2) the average meshing force of the gears increased with the increases in the offset, and the increasing trend of the meshing force between the sun gears and the planetary gears was similar to that observed between the planetary gears and the inner ring gears. It was found that when the shafting offset position changed, there were obvious first and second frequency doubling in the spectrum; (3) the mass center orbit radii of the sun gears increased with the increases in the shafting position changes, and the changes in the angular tilt position were found to have greater influencing effects on the mass center orbit radii of the sun gears than the changes in the offset positions. This study’s research findings will provide a theoretical basis for future operational status monitoring of the main transmission systems of helicopters and are of major significance for improvements in the operational stability of helicopter transmission systems, which will potentially ensure safe and efficient operations.

Hybrid Atomic Orbital Basis from First Principles: Bottom-Up Mapping of Self-Energy Correction to Large Covalent Systems.

Construction of hybrid atomic orbitals is proposed as the approximate common eigenstates of finite first moment matrices. Their hybridization and orientation can be a priori tuned as per their anticipated neighborhood. Their Wannier function counterparts constructed from the Kohn-Sham (KS) single particle states constitute an orthonormal multiorbital tight binding (TB) basis resembling hybrid atomic orbitals locked to their immediate atomic neighborhood, while spanning the subspace of KS states. The proposed basis thus renders predominantly single TB parameters from first principles for each nearest neighbor bond involving no more than two orbitals irrespective of their orientation and also facilitates an easy route for the transfer of such TB parameters across isostructural systems exclusively through mapping of neighborhoods and projection of orbital charge centers. With hybridized 2s, 2p and 3s, 3p valence electrons, the spatial extent of the self-energy correction (SEC) to TB parameters in the proposed basis is found to be localized mostly within the third nearest neighborhood, thus allowing effective transfer of self-energy-corrected TB parameters from smaller reference systems to much larger target systems, with nominal additional computational cost beyond that required for explicit computation of SEC in the reference systems. The proposed approach promises inexpensive estimation of the quasi-particle structures of large covalent systems with workable accuracy.

Uncertainty Assessments of Load Deformation from Different GPS Time Series Products, GRACE Estimates and Model Predictions: A Case Study over Europe

A good understanding of the accuracy of the Global Positioning System (GPS) surface displacements provided by different processing centers plays an important role in load deformation analysis. We estimate the noise level in both vertical and horizontal directions for four representative GPS time series products, and compare GPS results with load deformation derived from the Gravity Recovery and Climate Experiment (GRACE) gravity measurements and climate models in Europe. For the extracted linear trend signals, the differences among different GPS series are small in all the three (east, north, and up) directions, while for the annual signals the differences are large. The mean standard deviations of annual amplitudes retrieved from the four GPS series are 3.54 mm in the vertical component (69% of the signal itself) and ~ 0.3 mm in the horizontal component (30% of the signal itself). The Scripps Orbit and Permanent Array Center (SOPAC) and MEaSUREs series have the lowest noise level in vertical and horizontal directions, respectively. Through consistency/discrepancy analysis among GPS, GRACE, and model vertical series, we find that the Jet Propulsion Laboratory (JPL) and Nevada Geodetic Laboratory (NGL) series show good consistency, the SOPAC series show good agreements in annual signal with the GRACE and model, and the MEaSUREs series show substantially large annual amplitude. We discuss the possible reasons for the notable differences among GPS time series products.

Quasi circular orbits around prolate bodies

ABSTRACT Recent observations of stellar occultations have revealed rings of particles around non-planetary bodies of the Solar system. These bodies are irregular and can be modelled by ellipsoids. In the context of numerical integrations for the study of studying the region close to these ellipsoidal bodies, it is known that the use of geometric initial conditions is necessary when the central object is significantly oblatened. In this paper, we show that for elongated bodies there is also a need for the adaptation of the initial velocity ($\nu _{C_{22}}$) so that equatorial periodic orbits of the first kind around this body have smaller radial variations since the circular Keplerian velocity produces a high oscillating eccentricity and radial variation. We describe an empirical method to obtain the velocity $\nu _{C_{22}}$ of a set of simulations where we vary the physical parameters of the central body. With the obtained data, developed empirical equations that allow the calculation of the orbital eccentricity, the initial velocity and an adapted Kepler’s Third Law as a function of the ellipticity coefficient and the semimajor axis. In addition, we identify an important change in the location of the primary body in relation to the elliptical orbit. In the cases of the orbits with minimal radial variation found in our study, the body starts to occupy the centre of the elliptical orbit. Finally, we include the rotation of the central body in the studied systems and analyse its implications for the dynamics of these orbits of low radial variation.

Tethered aerobraking design for repeatable maneuvers

An aerobraking maneuver performed with a tethered system has the benefit of increasing the drag for a given center of mass orbit by dropping the lower subsatellite into the denser atmosphere. While this concept has received significant attention in the literature, the exact means of controlling the attitude prior to the aerobraking fly-through has not been adequately treated. In particular, a scheme for repeated passes in elliptical orbits has not been developed, which would be required, for example, in a debris elimination system. This work uses tether reeling during the exoatmospheric flight in order to control the tether libration to target a desired state prior to the aerobraking trajectory. The design of the control law requires numerical solution of nonlinear equations, but newly developed analytics provide an estimate that reduces computational time and increases the robustness of the algorithm. The results show that the nearly periodic state that is required for successive passes can be achieved for practical tether lengths and power requirements.

Analysis Method for the Mass Center of Low Earth Orbit Remote Sensing in Orbit

A real-time method for estimating the mass center of low earth orbit (LEO) remote sensing satellite in orbit is introduced in this paper. LEO remote sensing satellite requires highly on calculating the position of its mass center, due to the need of precise orbit determination and attitude control. This article offers an analysis method for the factors that play a leading role in the change of the centroid of satellite in orbit, which are the consuming of satellite fuel, the circulation of satellite-to-ground data transmission antenna and rotation of solar arrays. The parameters for calculating the centroid of LEO remote sensing satellite are defined, and a formula for computing the position of the satellite mass center in orbit is proposed.

Guiding center and gyrokinetic orbit theory for large electric field gradients and strong shear flows

The guiding center and gyrokinetic theory of magnetized particle motion is extended to the regime of large electric field gradients perpendicular to the magnetic field. A gradient in the electric field directly modifies the oscillation frequency and causes the Larmor orbits to deform from circular to elliptical trajectories. In order to retain a good adiabatic invariant, there can only be strong dependence on a single coordinate at lowest order, so that resonances do not generate chaotic motion that destroys the invariant. When the gradient across magnetic flux surfaces is dominant, the guiding center drift velocity becomes anisotropic in response to external forces and additional curvature drifts must be included. The electric polarization density remains gyrotropic, but both the polarization and magnetization are modified by the change in gyrofrequency. The theory can be applied to shear flows that are even stronger than those observed in the edge transport barrier of a high-performance tokamak (H-mode) pedestal, even if the toroidal field is as small as or even smaller than the poloidal field. Yet, the theory retains a mathematical form that is similar to the standard case and can readily be implemented within existing simulation tools.

Theoretical and experimental investigation on the effect of supply pressure on the nonlinear behaviors of the aerostatic bearing-rotor system

With low friction, high rotational speed and low motion error, the aerostatic bearings have been widely applied to the high speed rotating and high precision machines. However, comparison with liquid-lubricated bearings, the gas lubrication is compressible and has low viscosity and then the aerostatic bearings tend to generate self-excited vibration phenomenon which results in the instability and then limits future improving of the precision and rotational speed. So, it is necessary to study the nonlinear behaviors of the aerostatic bearing-rotor system. In this paper, based on the bifurcation diagram, orbit of rotor center, frequency spectrum diagram, Poincaré map and speed waterfall diagram, the effects of supply pressure and rotational speed on the nonlinear behaviors of the aerostatic bearing-rotor system are studied theoretically and experimentally. The results show that there exists complex nonlinear behaviors and the nonlinear behaviors are delayed to generate by improving supply pressure. According to the results, a simple and convenient method based on adjustment of supply pressure is proposed to restrain and even eliminate the subsynchronous vibration and the experimental results verify the correctness and feasibility of the method.

Effect of temperature on the nonlinear dynamic behavior of two-lobe non-circular gas-lubricated micro-bearings

In this paper, the molecular gas lubrication model was used to analyze the nonlinear dynamic behavior of two-lobe non-circular gas-lubricated micro-bearings. The effects of temperature rise are taken into account. At high temperatures, in addition to gas rarefaction, its viscosity and friction will also change, and slip across boundaries will occur. The rarefaction of the lubricating gas film caused by the microscale effect at high temperatures was considered. The effects of temperature and rotation speed (with and without rarefaction effect) on the dynamic behavior of the non-circular micro gas bearing were studied. The nonlinear equation governing the gas behavior is discretized using the finite-element method and then solved simultaneously with the dynamic equations of rotor motion using the fourth-order Runge–Kutta method. Center orbit diagrams, phase portraits, Poincare maps, power spectrum, and bifurcation diagrams are used to investigate the dynamic behavior of two-lobe non-circular gas-lubricated micro-bearings. Some results show that with increasing temperature, the rotor behavior changes from T-periodic to quasi-periodic. It was also observed that at high temperatures, with increasing rotational speed, the behavior of the system changes from T-periodic to quasi-periodic, but if the gas is rarefied, this change occurs at a slower speed.

Total Body Irradiation for Hematopoietic Stem Cell Transplantation: What Can We Agree on?

Total body irradiation (TBI), used as part of the conditioning regimen prior to allogeneic and autologous hematopoietic cell transplantation, is the delivery of a relatively homogeneous dose of radiation to the entire body. TBI has a dual role, being cytotoxic and immunosuppressive. This allows it to eliminate disease and create “space” in the marrow while also impairing the immune system from rejecting the foreign donor cells being transplanted. Advantages that TBI may have over chemotherapy alone are that it may achieve greater tumour cytotoxicity and better tissue penetration than chemotherapy as its delivery is independent of vascular supply and physiologic barriers such as renal and hepatic function. Therefore, the so-called “sanctuary” sites such as the central nervous system (CNS), testes, and orbits or other sites with limited blood supply are not off-limits to radiation. Nevertheless, TBI is hampered by challenging logistics of administration, coordination between hematology and radiation oncology departments, increased rates of acute treatment-related morbidity and mortality along with late toxicity to other tissues. Newer technologies and a better understanding of the biology and physics of TBI has allowed the field to develop novel delivery systems which may help to deliver radiation more safely while maintaining its efficacy. However, continued research and collaboration are needed to determine the best approaches for the use of TBI in the future.

Local structural investigations of Fe-doped TiO2 amorphous thin films

The present study deals with the local structure of amorphous TiO2 and Fe-doped TiO2 thin films deposited on Si substrate using magnetron sputtering. The absence of long range order is confirmed by grazing incidence x-ray diffraction and the short range order is studied using x-ray absorption near edge structure (XANES) measurements at Ti, Fe and O K-edges and Fe and Ti L3-edge. The XANES provides understanding about the electronic transition induced from the short range ordering and dependence of electronic hybridization of the central Ti-p orbitals with the Ti-d orbitals. The XANES measurements also show that maximum Fe doping concentration allowed to replace Ti is 2 at.% and after that separate phase starts appearing, which is consistent with simulation by ab-initio multiple scattering theory based code FEFF9. Ellipsometry measurements show gradual decrease in band-gap energy upto 2 at.% Fe doping from pristine TiO2, however a drastic decrease in band-gap energy is observed at 4 at.% or higher doping concentration due to formation of other phases.

Analysis of motor control strategy for frontal and sagittal planes of circular tracking movements using visual feedback noise from velocity change and depth information.

We aim to investigate a control strategy for the circular tracking movement in a three-dimensional (3D) space based on the accuracy of the visual information. After setting the circular orbits for the frontal and sagittal planes in the 3D virtual space, the subjects track a target moving at a constant velocity. The analysis is applied to two parameters of the polar coordinates, namely, ΔR (the difference in the distance from the center of a circular orbit) and Δω (the difference in the angular velocity). The movement in the sagittal plane provides different depth information depending on the position of the target in orbit, unlike the task of the frontal plane. Therefore, the circular orbit is divided into four quadrants for a statistical analysis of ΔR. In the sagittal plane, the error was two to three times larger in quadrants 1 and 4 than in quadrants 2 and 3 close to the subject. Here, Δω is estimated using a frequency analysis; the lower the accuracy of the visual information, the greater the periodicity. When comparing two different planes, the periodicity in the sagittal plane was approximately 1.7 to 2 times larger than that of the frontal plane. In addition, the average angular velocity of the target and tracer was within 0.6% during a single cycle. We found that if the amount of visual information is reduced, an optimal feedback control strategy can be used to reduce the positional error within a specific area.

Quantizing viscous transport in bilayer graphene

The momentum transport in ultraclean bilayer graphene is characterized by the viscous transport. In quantizing magnetic field the momentum current passes through the guiding center of the cyclotron orbit. In this study we derive the formula of the quantized Hall viscosity for bilayer graphene. This can be detected in the non-local magnetoresistivity measurements that varies with the quantized step. For weak magnetic field the Landau levels start overlapping and lead to the Shubnikov–de-Haas oscillations, superimposed on the classical formulae, reference Steinberg (1958 Phys. Rev. 109 1486). These oscillations are present in the longitudinal and Hall viscosities.

Recent advances in screening two-dimensional materials for high-performance energy storage and conversion devices based on electronic structure theory

With the ever-growing global energy demands and environmental pollution issues, developing high-performance energy storage and conversion materials has become a hot topic in the material science community. In this regard, substantial progress has been made in theoretically predicting new materials for energy-related fields, experimentally synthesizing these materials, and further improving their properties for high performance in energy storage and conversion devices. In particular, two-dimensional (2D) materials have shown great potential in the field of energy storage and conversion. However, it remains challenging to explore 2D materials that render high efficiency of energy storage and conversion while guarantee long-term stability and safety. Over the past decades, theoretical calculations based on density functional theory (DFT) have become a practical toolkit to address this issue by revealing the reaction mechanism at an atomic scale and screening high-performance energy storage and conversion materials on a large scale. In particular, DFT calculations enable us to establish the relationships between the intrinsic properties of materials and their performance for energy storage and conversion, and provide theoretical guidance for screening and experimentally synthesizing the promising materials. In this review, we summarize the DFT calculations’ applications in recent studies of developing high-performance and reliable energy-related 2D materials for Li-ion battery (LIB), water splitting, fuel cells, and electrochemical carbon dioxide reduction (CRR). First, we introduce the reaction mechanism of LIB, hydrogen evolution reaction (HER), oxygen evolution reaction/oxygen reduction reaction (OER/ORR), and CRR in detail and the application of 2D material in these fields. Then, we highlight the role of DFT calculations in unveiling the intrinsic relationships between the electronic structure and the performance of 2D materials by comprehensively discussing the descriptors in predicting the performance of 2D materials. For example, the occupancy of d orbital and energy required to fill empty states serve as descriptors to predict the electrochemical performance of the electrode in ion intercalation battery. The d orbital center, lowest unoccupied states, and oxygen vacancy formation energy serve as descriptors to predict the catalytic performance of electrode in HER. The energy difference between the lowest valance electron orbital center and Fermi level, occupancy of p z orbital, and the energy difference between p z and p x /p y orbital center serve as descriptors to predict the catalytic performance of electrode in ORR. Even though these descriptors can help to further understand the relationships between the electronic structure and the performance of the electrochemical electrode, they are only reliable to specific materials and inapplicable to the electrode with a complex structure or complex reaction path, such as the electrode in CRR. Newly developed machine learning methods may bring a breakthrough to the exploration of a universal descriptor, which is a key factor in the large-scale screening of potential electrode materials with excellent performance and the dependable guidance to experimental synthesis. Finally, we summarize the disadvantage of DFT calculation, such as the underestimation of bandgap and incorrect description of van der Waals interaction, and give a perspective of DFT calculations in the study of new energy-related materials. The method to simulate the ambient environment of the electrode (including the electrolyte, external electric field, and non-cooperative transfer of proton and electron) based on DFT calculation is needed to be developed, which is vital to reflect the actual working condition of the electrode. The universal descriptor applicable to the electrode with a complex structure is also needed to explore to overcome the poor versatility of single intrinsic property of the material in predicting the performance of the electrochemical electrode.

Solar driven CO2 hydrogenation on transition metal doped Zn12O12 cluster.

Photocatalytic hydrogenation of carbon dioxide (CO2) to produce value-added chemicals and fuel products is a critical routine to solve environmental issues. However, developing photocatalysts composed of earth-abundant, economic, and environmental-friendly elements is desired and challenging. Metal oxide clusters of subnanometer size have prominent advantages for photocatalysis due to their natural resistance to oxidation as well as tunable electronic and optical properties. Here, we exploit 3d transition metal substitutionally doped Zn12O12 clusters for CO2 hydrogenation under ultraviolet light. By comprehensive ab initio calculations, the effect of the dopant element on the catalytic behavior of Zn12O12 clusters is clearly revealed. The high activity for CO2 hydrogenation originates from the distinct electronic states and charge transfer from transition metal dopants. The key parameters governing the activity and selectivity, including the d orbital center of TM dopants and the energy level of the highest occupied molecular orbital for the doped Zn12O12 clusters, are thoroughly analyzed to establish an explicit electronic structure-activity relationship. These results provide valuable guidelines not only for tailoring the catalytic performance of subnanometer metal oxide clusters at atomic precision but also for rationally designing non-precious metal photocatalysts for CO2 hydrogenation.

Tuning Criteria of Nonlinear Flexible Rotor Mounted on Squeeze Film Damper Using Analytical Approach

A close form solution was developed in this paper to find the nonlinear tuning parameters of symmetric/asymmetric rotor—Squeeze film damper system. Initially, close form solution was developed to find the optimum tuning criteria using linear models. Later, it has been extended to nonlinear unbalanced rotor damper system using circular centre orbit condition. Analytical modeling of Squeeze film damper forces is carried out considering viscous, inertial and temporal contributions under laminar and turbulent conditions. Modified Reynolds equation with short damper approximation is used to derive the SFD forces for 2π-film. The solution of the system of equations helped to predict optimum tuning parameters, such as cross-over frequency and maximum possible amplitudes. Contributions of various governing parameters are discussed. Mass ratio of damper-to-rotor mass and nonlinear radial/tangential damper forces play an important role in finding the tuning parameters of symmetric system. Additional shaft parameter, fp, plays an important role in getting the optimum tuning parameters of asymmetric system as compared to symmetric system.

Higher-Order Corrections for Frozen Terminator Orbit Design

Suitable orbit options around asteroids are limited due to strong perturbations caused by solar radiation pressure (SRP), a target’s irregular gravity field, and third-body acceleration. One potential option for mission operations is a frozen terminator orbit, a near-circular polar orbit that has been extensively studied for the SRP dominant case. This paper addresses modification of the conventional initial condition for the terminator orbit to account for two distinctive features: an irregular gravity field and offset of the orbit center. When orbit size is small, the asteroid’s higher-order gravity field becomes nonnegligible, and this paper specifically focuses on the effects that and have on new frozen orbit conditions. When the orbit is large, a point mass assumption becomes valid, but strong SRP pushes the spacecraft away from the sun, resulting in a geometric offset between orbit and mass centers. The offset causes large short-period variation of orbital elements, and the resulting orbit is not frozen if initial elements are defined simply as the desired mean elements. This paper proposes an approach to define orbital elements around an offset shifted along the sun–asteroid line. Finally, a unified correction valid for a wide range of semimajor axes is discussed.

Orbitadekompression bei endokriner Orbitopathie – Erfahrungen und Ergebnisse

HintergrundDie endokrine Orbitopathie ist die häufigste extrathyreoidale Manifestation des Morbus Basedow und tritt bei schätzungsweise 25–50 % der betroffenen Patienten auf. Krankheitsbedingt kommt es zu einer entzündlichen Schwellung der Orbitaweichteile. Die Behandlung erfolgt meist konservativ. Bei schweren Fällen mit beeinträchtigendem Exophthalmus oder akuter, steroidrefraktärer Visusbedrohung kann eine chirurgische Orbitadekompression die Beschwerden der Patienten lindern oder das Sehvermögen erhalten. Ein wesentlicher Aspekt der Versorgungsqualität besteht in der Vermeidung postoperativer Doppelbilder.Ziel der ArbeitErfahrungs- und Ergebnisbericht von 100 chirurgischen Orbitadekompressionen bei 62 Patienten an einem interdisziplinären Orbitazentrum. Patienten mit Kompression der Orbitaspitze wurden mittels pterionaler Dekompression behandelt. Patienten ohne Hinweise auf Orbitaspitzenbeteiligung wurden mittels tiefer lateraler Wandresektion oder pterionaler Dekompression behandelt.MethodikRetrospektive Datenanalyse.ErgebnisseDie mittlere Exophthalmusreduktion betrug 2,9 mm. Augen mit visusbedrohendem Schweregrad gewannen im Mittel 2,2 Zeilen an Sehschärfe, der Visus bei rehabilitativer Indikation blieb stabil. Die Komplikationsrate betrug 4 %. Neue Doppelbilder wurden nach 2 Eingriffen beobachtet. Bei einem Patienten kam es zu einer Visusminderung von 0,8 auf 0,1. In 9 Fällen führte die Operation zu einem vollständigen Rückgang zuvor beklagter Doppelbilder.DiskussionVisusgewinn, Exophthalmusreduktion und Komplikationsrate sind in diesem Kollektiv vergleichbar mit zuvor publizierten Arbeiten. Diese Studie bestätigt die Rolle der Orbitadekompression bei visusbedrohender und schwer beeinträchtigender endokriner Orbitopathie.

Predictive Factors for Changes in Quality of Life after Steroid Treatment for Active Moderate-to-Severe Graves’ Orbitopathy: A Prospective Trial

Objectives: To investigate the predictive factors for changes in the quality of life (GO-QoL) of patients with Graves’ orbitopathy (GO) prior to and after specific treatment. Methods: A prospective follow-up study was conducted at an academic tertiary referral orbital center with a joint thyroid-eye clinic on 100 consecutive patients with GO. Before and after the standard 12-week course of weekly intravenous methylprednisolone (cumulative dose 4.5 g), the GO-QoL questionnaire provided by the European Group on Graves’ Orbitopathy (EUGOGO) was completed. Endocrine and ophthalmic assessments were performed at each visit. Results: All patients were biochemically euthyroid and untreated for GO at baseline and presented with active and moderate-to-severe disease. Both GO-QoL subscales (visual functioning [VF] and appearance [AP]) significantly increased after immunosuppressive therapy and showed a sustained improvement for 6 months. At baseline, demographic variables (sex, age, and smoking) influenced QoL in the stepwise linear regression (p < 0.01, adjusted R² = 0.24 for VF and p < 0.01, adjusted R² = 0.21 for AP). In contrast, 6 months after treatment, the improved QoL was now exclusively associated with ophthalmic parameters (p < 0.01, adjusted R² = 0.47 for VF; p < 0.01, adjusted R² = 0.23 for AP). Conclusions: Predictive factors for GO-QoL differed not only between the 2 subscales but also before and after the first treatment of GO.

Chaotic motion due to lateral Casimir forces during nonlinear actuation dynamics.

We investigated here the influence of the lateral Casimir force on the dynamical actuation of devices with interacting materials covering a broad range of optical properties ranging from poor to good conductors, such as, for example, nitrogen doped SiC and Au, respectively. The conservative actuating system shows a central heteroclinic orbit surrounded by a finite number of homoclinic orbits, because at higher periods, an increased lateral Casimir force will be necessary to counterbalance the restoring force. As a result, the conservative system reaches stable operation sooner for the higher conductivity materials (Au-Au), indicating the significant impact of the material optical properties on the lateral Casimir force. Furthermore, for the non-conservative driven systems, the decrement of the Melnikov parameter α leads to a faster disappearance of the satellite homoclinic orbits in the Poincaré portraits, followed by a strong shrinkage of the central heteroclinic orbit toward unstable chaotic motion. The latter is more pronounced for the lower conductivity materials since comparison shows the Au-Au system to be significantly more stable than the SiC-SiC system. Therefore, in actuating systems where the lateral Casimir force could play a significant role, the higher conductivity materials appear to be a better choice to ensure stable operation against a chaotic motion.