Large Eccentricity Research Articles

Pre- and post-punching performances of eccentrically loaded slab-column joints with in-plane restraints

In flat plate structures, interior slab-column joints are subjected to in-plane restraints and bending-shear actions, which can significantly impact their mechanical performance to resist progressive collapse. However, research in this area is still lacking. This paper presents experimental and numerical studies of pre- and post-punching performances of eccentrically loaded slab-column joints with in-plane restraints. Quasi-static tests were conducted on seven joint specimens, including one concentrically loaded (CL) joint and six eccentrically loaded (EL) ones. The effects of critical structural parameters (i.e., eccentricity, slab thickness and reinforcement ratio) on the pre- and post-punching performances were investigated by analysing the load–displacement relationships, failure modes and material strains. The experimental results indicated that larger eccentricity could lead to more reduction of the peak punching shear capacity by as much as 62%, whereas it has little effect on the post-punching capacity. In addition, the strain results of the through-column rebars showed that, with the well-restrained boundary conditions, the slab flexural reinforcement (FR) was found to resist the applied load to a large extent at small deformations and still able to contribute greatly during the post-punching stage. Numerical analysis was conducted to gain an in-depth understanding toward the effects of varied levels of in-plane restraints on both slab-column joints and actual flat plate structures. It was found that the lateral stiffnesses in the CL joint model with boundary beams and the substructure model were similar, which was around 400 N/mm. Finally, the interactions between the unbalanced moment and shear force were explored and compared with code predictions (ACI318-19 and EC2-04). Without considering the enhancement effects from in-plane restraints, the codes produced over-conservative predictions. Based on the FE analyses, the correlation between the dimensionless ratio e/d (eccentricity/effective thickness of slab) and punching shear strength was simplified by a combined straight line and a power curve.

Eccentric binary neutron star search prospects for Cosmic Explorer

We determine the ability of Cosmic Explorer, a proposed third-generation gravitational-wave observatory, to detect eccentric binary neutron stars and to measure their eccentricity. We find that for a matched-filter search, template banks constructed using binaries in quasi-circular orbits are effectual for eccentric neutron star binaries with $e_{7} \leq 0.004$ ($e_{7} \leq 0.003$) for CE1 (CE2), where $e_7$ is the binary's eccentricity at a gravitational-wave frequency of 7~Hz. We show that stochastic template placement can be used to construct a matched-filter search for binaries with larger eccentricities and construct an effectual template bank for binaries with $e_{7} \leq 0.05$. We show that the computational cost of both the search for binaries in quasi-circular orbits and eccentric orbits is not significantly larger for Cosmic Explorer than for Advanced LIGO and is accessible with present-day computational resources. We investigate Cosmic Explorer's ability to distinguish between circular and eccentric binaries. We estimate that for a binary with a signal-to-noise ratio of 8 (800), Cosmic Explorer can distinguish between a circular binary and a binary with eccentricity $e_7 \gtrsim 10^{-2}$ ($10^{-3}$) at 90% confidence.

Secular dynamics of a test particle perturbed by a Miyamoto–Nagai disc

ABSTRACT We study the secular behaviour of a test particle orbiting a dominant central body and perturbed by a Miyamoto–Nagai (MN) disc. We derive a quadrupole-level secular Hamiltonian of this system, which involves a dimensionless parameter η that is used to characterize the flattening of MN disc. (The smaller η, the flatter disc; and η = 0 gives the infinitely thin Kuzmin disc.) We find that, in the quadrupole approximation, the perturbation of the MN disc can give rise to the von Zeipel–Lidov–Kozai (ZLK)-like dynamics and depending on the value of η the dynamics has two different manifestations: (i) when η < 1/3, the test particle’s behaviour is similar to that described in the classical ZLK problem. In particular, as η increases from 0 to 1/3, the critical inclination for the large eccentricity oscillations decreases from $26{_{.}^{\circ}}56$ to 0°, ; (ii) when η > 1/3, the orbital evolution of the test particle and the phase-space morphology are opposite to the classical ZLK case. This leads to a striking result that the test particle cannot remain on a near-coplanar orbit if its eccentricity is sufficiently large. However, as η increases further the ZLK-like dynamics would be gradually suppressed by the spherical term in the Hamiltonian. We also survey the global secular dynamics numerically in which the quadrupole approximation is no longer valid.

Effective one-body model for extreme-mass-ratio spinning binaries on eccentric equatorial orbits: Testing radiation reaction and waveform

We provide a systematic analysis of the multipolar gravitational waveform, energy and angular momentum fluxes emitted by a nonspinning test particle orbiting a Kerr black hole along equatorial, eccentric orbits. These quantities are computed by numerically solving the Teukolsky equation in the time domain and are then used to test and improve the radiation reaction (and waveform) of an effective-one-body (EOB) model. Eccentricity is incorporated into EOB by replacing the quasi-circular Newtonian (or leading-order) prefactors in the EOB-factorized multipolar waveform (and fluxes) with their generic counterparts. The comparison between numerical and analytical quantities is carried out over a large portion of the parameter space, notably for orbits close to the separatrix and with high eccentricities. The analytical model agrees to $\sim 1\%$ with the numerical data for orbits with moderate eccentricities ($e\lesssim 0.3$) and moderate spins ($\hat{a}\lesssim 0.5$), although this increases up to $\sim 33\%$ for large, positive, black hole spins ($\sim 0.9$) and large eccentricities ($\sim 0.9$). For moderate eccentricities, the new EOB fluxes can be used to drive the dynamics through the nonadiabatic transition from eccentric inspiral to plunge, merger and ringdown, thus providing accurate an description of the merger. We also show that the same technique can be applied to hyperbolic encounters. In general, our approach to radiation reaction for eccentric inspirals should be seen as a first step toward EOB modelization of extreme-mass-ratio-inspirals waveforms for LISA.

Low cycle fracture behavior of steel members with circular hollow section subjected to eccentric load

This study aims to investigate the effect of eccentric load on the seismic and fracture behavior of Q235B steel members with circular hollow section (CHS). To this end, uniaxial tension and ultra-low cycle fatigue tests on both un-notched and notched Q235B steel coupon specimens were conducted first to evaluate the material’s micromechanical fracture behavior. Next, 7 full-scale Q235B CHS steel members with different global slenderness were tested under cyclic axial loads with varying eccentricities. It is observed that: (1) the increase of the eccentricity of the axial load negatively affects the seismic and fracture resistance of CHS steel members, resulting in the deterioration of the strength, stiffness, energy dissipation, and ductility; (2) Large eccentricities lead to the reduction in the fracture life of Q235B CHS steel members; and (3) High global slenderness results in the reduction in both compression bearing capacity and energy dissipation of CHS steel members. In addition to the experimental program, finite element analyses are performed to simulate the seismic and fracture behavior of CHS steel members. The results from the finite element analyses are in good agreement with those from the experiment.

Effect of Hollow Shape on the Behavior of Reinforced Self-Compacting Concrete Slender Column Under Eccentric Loading

Results of testing reinforced self-compacted concrete slender columns having longitudinal holes concealing PVC pipe in their cross sections under axial compression load and uniaxial bending are presented in this paper. The effect of hollow shape on the performance of slender columns having 200x200mm quadratic cross section and 1300mm long under concentric and eccentric loads was investigated. Three different shapes of central hole: circular, square, and lozenge pattern in addition to the different load eccentricity values were considered to investigate the axial loading resistance and cracking load, lateral and longitudinal deflections of the columns. Test results have showed that altering the hollow shape inside the area of column cross section does not show a great influence on the column behavior unless the hollow ratio changed. The effect of hole shape or the hollow ratio on loading capacity is insignificant but the existence of a hole embedded longitudinally in the column significantly decreases its ultimate capacity. The effect of hollow shape or hollow ratio on a slender columns behavior subjected to eccentric loading with small ratio of load eccentricity to total column thickness (e/h=.33) was more than that of large eccentricity (e/h=1.0). Accordingly, the decrease in loading column capacity of columns was (5.0%, 2.5%, and 6.6%) compared to (3.2%, 2.2%, and 4.7%) for the same hole shapes respectively.

Order in the chaos

Black hole (BH) triples represent one of the astrophysical pathways for BH mergers in the Universe detectable by LIGO and VIRGO. We study the formation of BH triples via binary–binary encounters in dense clusters, showing that up to two-thirds of the triples formed through this channel are hierarchical, whereas the remaining one-third are in a non-hierarchical, unstable configuration. We built a database of 32 000 N-body simulations to investigate the evolution of BH triples focusing on mildly hierarchical and non-hierarchical unstable configurations. Varying the mutual orbital inclination, the three BH masses and the inner and outer eccentricities, we show that retrograde, nearly planar configurations lead to a significant shrinkage of the inner binary. We find a universal trend of triple systems, namely that they tend to evolve toward prograde configurations and that the orbital flip, driven by the torque exerted on the inner BH binary (BHB) by the outer BH, leads in general to tighter inner orbits. In some cases, the resulting BHB undergoes coalescence within a Hubble time, releasing gravitational waves. A large fraction of merging BHBs with an initial separation of 1 AU enter the 10−3 − 10−1 Hz frequency band with large eccentricities, thus representing potential eccentric LISA sources. Mergers originating from an initially tighter BHB (a ∼ 0.01 AU), instead often have eccentricities above 0.7 in the 1 Hz band. We find that the mass distribution of the mergers in this astrophysical channel maps the original BH binary spectrum. This might have interesting consequences in light of the growing population of BH mergers detected by LIGO and VIRGO, namely that eccentric sources detected in high-frequency detectors are most likely connected with a high-velocity dispersion stellar environment, whereas eccentric sources detected in low-frequency detectors are likely to develop in low-density clusters.

Numerical analysis on the performance characteristics of a new gas journal bearing by using finite difference method

This paper proposes a novel gas journal bearing in which orifices are different in diameter and distribute unevenly. Finite Difference Method (FDM) combined with Linear Perturbation Method (LPM) is used to solve the unsteady-state Reynolds equation of the flow field in the bearing clearance. Moreover, four types of bearing structures are used to discuss the effects of orifices different in diameter and uneven distribution on the bearing performance. The results demonstrate that the new bearing has better static and dynamic performances compared with those of traditional bearing in which orifices are equal in diameter and distribute evenly. Moreover, thin gas film thickness, high supply pressure, and large eccentricity ratio are hopeful for improving load capacity of the new bearing. Furthermore, the stability of the novel bearing is improved if eccentricity ratio is 0.25–0.3.

Born extra-eccentric: A broad spectrum of primordial configurations of the gas giants that match their present-day orbits

In a recent paper we proposed that the giant planets’ primordial orbits may have been eccentric (eJ∼eS∼ 0.05), and used a suite of dynamical simulations to show outcomes of the giant planet instability that are consistent with their present-day orbits. In this follow-up investigation, we present more comprehensive simulations incorporating superior particle resolution, longer integration times, and eliminating our prior means of artificially forcing instabilities to occur at specified times by shifting a planets’ position in its orbit. While we find that the residual phase of planetary migration only minimally alters the planets’ ultimate eccentricities, our work uncovers several intriguing outcomes in realizations where Jupiter and Saturn are born with extremely large eccentricities (eJ≃ 0.10; eS≃ 0.25). In successful simulations, the planets’ orbits damp through interactions with the planetesimal disk prior to the instability, thus loosely replicating the initial conditions considered in our previous work. Our results therefore suggest an even wider range of plausible evolutionary pathways are capable of replicating Jupiter and Saturn’s modern orbital architecture.

Apsidal asymmetric-alignment of Jupiter Trojans

ABSTRACT The most distant Kuiper belt objects exhibit the clustering in their orbits, and this anomalous architecture could be caused by Planet 9 with large eccentricity and high inclination. We then suppose that the orbital clustering of minor planets may be observed somewhere else in the Solar system. In this paper, we consider the over 7000 Jupiter Trojans from the Minor Planet Center, and find that they are clustered in the longitude of perihelion ϖ, around the locations ϖJ + 60○ and ϖJ − 60○ (ϖJ is the longitude of perihelion of Jupiter) for the L4 and L5 swarms, respectively. Then we build a Hamiltonian system to describe the associated dynamical aspects for the co-orbital motion. The phase space displays the existence of the apsidally aligned islands of libration centred on Δϖ = ϖ − ϖJ ≈ ±60○, for the Trojan-like orbits with eccentricities e < 0.1. Through a detailed analysis, we have shown that the observed Jupiter Trojans with proper eccentricities ep < 0.1 spend most of their time in the range of |Δϖ| = 0°–120○, while the more eccentric ones with ep > 0.1 are too few to affect the orbital clustering within this Δϖ range for the entire Trojan population. Our numerical results further prove that, even starting from a uniform Δϖ distribution, the apsidal alignment of simulated Trojans similar to the observation can appear on the order of the age of the Solar system. We conclude that the apsidal asymmetric-alignment of Jupiter Trojans is robust, and this new finding can be helpful to design the survey strategy in the future.

A Pluto–Charon Concerto. II. Formation of a Circumbinary Disk of Debris after the Giant Impact

Abstract Using a suite of numerical calculations, we consider the long-term evolution of circumbinary debris from the Pluto–Charon giant impact. Initially, these solids have large eccentricity and pericenters near Charon’s orbit. On timescales of 100–1000 yr, dynamical interactions with Pluto and Charon lead to the ejection of most solids from the system. As the dynamics moves particles away from the barycenter, collisional damping reduces the orbital eccentricity of many particles. These solids populate a circumbinary disk in the Pluto–Charon orbital plane; a large fraction of this material lies within a “satellite zone” that encompasses the orbits of Styx, Nix, Kerberos, and Hydra. Compared to the narrow rings generated from the debris of a collision between a trans-Neptunian object and Charon, disks produced after the giant impact are much more extended and may be a less promising option for producing small circumbinary satellites.

The Space of Keplerian Orbits and a Family of Its Quotient Spaces

The distance functions on the set of Keplerian orbits play an important role in solving the problems of searching for the parent bodies of meteoroid streams. A special kind of function is the distances in the quotient spaces of orbits. Three metrics of this type were developed earlier. These metrics allow disregarding the longitude of the ascending node or the argument of pericenter, or both. Here, we introduce one more quotient space, where two orbits are considered to be identical if they differ only in their longitudes of nodes and arguments of pericenters, but have the same sum of these elements (the longitude of pericenter). Function $${{\varrho }_{6}}$$ is defined to calculate the distance between two equivalence classes of orbits. The algorithm for calculation of $${{\varrho }_{6}}$$ from given elements of the orbits is provided along with a reference to the corresponding program written in the C++ programming language. Unfortunately, function $${{\varrho }_{6}}$$ is not a full-fledged metric. We have proven that it satisfies the first two axioms of a metric space; however, it does not satisfy the third axiom: the triangle inequality does not hold, at least in the case of large eccentricities. However, there are two important cases when the triangle axiom is satisfied: one of three orbits is circular and the longitudes of pericenters of all three orbits coincide. Perhaps, the inequality holds for all elliptic orbits, but this is a matter of further research.

Eight new millisecond pulsars from the first MeerKAT globular cluster census

ABSTRACT We have used the central 44 antennas of the new 64-dish MeerKAT radio telescope array to conduct a deep search for new pulsars in the core of nine globular clusters (GCs). This has led to the discovery of eight new millisecond pulsars in six different clusters. Two new binaries, 47 Tuc ac and 47 Tuc ad, are eclipsing ‘spiders’, featuring compact orbits (≲0.32 d), very low mass companions, and regular occultations of their pulsed emission. The other three new binary pulsars (NGC 6624G, M62G, and Ter 5 an) are in wider (>0.7 d) orbits, with companions that are likely to be white dwarfs or neutron stars. NGC 6624G has a large eccentricity of e ≃ 0.38, which enabled us to detect the rate of advance of periastron. This suggests that the system is massive, with a total mass of Mtot = 2.65 ± 0.07 M⊙. Likewise, for Ter 5 an, with e ≃ 0.0066, we obtain Mtot = 2.97 ± 0.52 M⊙. The other three new discoveries (NGC 6522D, NGC 6624H, and NGC 6752F) are faint isolated pulsars. Finally, we have used the whole MeerKAT array and synthesized 288 beams, covering an area of ∼2 arcmin in radius around the centre of NGC 6624. This has allowed us to localize many of the pulsars in the cluster, demonstrating the beamforming capabilities of the TRAPUM software backend and paving the way for the upcoming MeerKAT GC pulsar survey.

A Comparative Study of Laminar-Turbulent Displacement in an Eccentric Annulus under Imposed Flow Rate and Imposed Pressure Drop Conditions

This paper presents a series of experiments focused on the displacement of viscoplastic fluids by various Newtonian and non-Newtonian fluids from a long horizontal, eccentric annulus. The flow regimes range from high Reynolds number laminar regimes through to fully turbulent. These experiments represent the primary cementing operation in a horizontal well. The main objective of our experiments is to gain insight into the role of the flow regime in the fluid-fluid displacement flows of relevance to primary cementing. We study strongly eccentric annuli and displaced fluids with a significant yield stress, i.e., those scenarios where a mud channel is most likely to persist. For fully eccentric annuli, the displacements are uniformly poor, regardless of regime. This improves for an eccentricity of 0.7. However, at these large eccentricities that are typical of horizontal well cementing, the displacement is generally poor and involves a rapid “breakthrough” advance along the wide upper side of the annulus followed only by a much slower removal of the residual fluids. This dynamic renders contact time estimates meaningless. We conclude that some of the simple statements/preferences widely employed in industry do not necessarily apply for all design scenarios. Instead, a detailed study of the fluids involved and the specification of the operational constraints is needed to yield improved displacement quality.

Effect of Torsion on Seismic Response of Single-Story Structures: an Energy-Based Design Approach (EBD)

Torsion of structural frames is one of the main causes of damage to structures during earthquakes. Accordingly, this study investigated the effects of torsion on frame structures with different asymmetries in stiffness when subjected to earthquakes with natural translational vibration period of less than 1.00 s. In this study, an idealized single-story lateral load resisting system was considered, and an energy-based design approach was used to analyze and investigate the effect of the resulting eccentric center of rigidity on the seismic response of frames. First, the stability of the energy spectrum due to torsional behavior was verified by conducting a nonlinear dynamic analysis. A series of nonlinear dynamic analyses was then used to investigate the responses of torsionally flexible systems with different eccentricity ratios in terms of total energy input, plastic strain energy distribution, cumulative plastic deformation ratio, and displacement ratio which found to be sensitive in different translational vibration of system. The results demonstrate that the energy input into asymmetric systems is less than that input into symmetric systems under the same accumulated plastic deformation ratio. Moreover, the vertical members that are located farthest to center of rigidity (flexible-edge member) were observed to suffer greater damage than other vertical members, particularly under large eccentricity ratios.

Analytical expressions for orbital perturbations due to Lorentz force

The selection of orbit propagation models strongly affects various space situational awareness applications like future object population prediction, collision avoidance maneuvers, object detection, object tracking, and catalog maintenance. Two key considerations in the selection of orbit propagation models are accuracy and computational cost. While one can use accurate numerical orbit propagation techniques for short propagation periods, it can be computationally taxing when the propagation period is long and/or when a large number of objects are to be propagated. This can be remedied by using analytical orbit propagation techniques, which not only facilitate fast orbit propagation but also permit meaningful theoretical insight into the structure of the perturbations. Most previous analytical object propagation in the near-Earth realm has been carried out in the presence of zonal and tesseral harmonics of Earth’s gravity, Sun and Moon gravities, atmospheric drag, and solar radiation pressure. However, for high-energy plasma weather and under eclipse where objects can get highly charged, Lorentz force should be included for better accuracy in orbital propagation. Lorentz force should also not be ignored for high-area-to-mass ratio objects. Among the work that has taken Lorentz force into consideration, most have made the simplifying assumption of non-tilted Earth magnetic dipole or have developed analytical formulas valid only for low Earth orbit region. In this paper, new analytical formulas for Lorentz perturbations are developed using a tilted dipole Earth magnetic field and a constant charge-to-mass ratio. The derived analytical formulas are valid for all near-Earth altitudes. Two sets of formulas are derived, one for small eccentricities and one for large eccentricities. The analytical results are validated using numerical simulations. A comparative study is also carried out using different charging levels and area-to-mass ratios for the low Earth orbit and geosynchronous Earth orbit regions.

Lateral-torsional seismic behaviour of plan unsymmetric buildings

Torsional response of buildings is attributed to poor structural configurations in plan, which arises due to two factors – torsional eccentricity and torsional flexibility. Usually, building codes address effects due to the former. This study examines both of these effects. Buildings with torsional eccentricity (e.g., those with large eccentricity) and with torsional flexibility (those with torsional mode as a fundamental mode) demand large deformations of vertical elements resisting lateral loads, especially those along the building perimeter in plan. Lateral-torsional responses are studied of unsymmetrical buildings through elastic and inelastic analyses using idealised single-storey building models (with two degrees of freedom). Displacement demands on vertical elements distributed in plan are non-uniform and sensitive to characteristics of both structure and earthquake ground motion. Limits are proposed to mitigate lateral-torsional effects, which guides in proportioning vertical elements and restricts amplification of lateral displacement in them and to avoid torsional mode as the first mode. Nonlinear static and dynamic analyses of multi-storey buildings are used to validate the limits proposed.

A semi-analytic model for the study of 1/1 resonant dynamics of the planar elliptic restricted co-orbital problem

Mean motion resonances (MMRs) are widespread in our Solar System. Moreover, resonant dynamics has always been an essential topic in planetary research. Recently, the research about exoplanets and the potential Planet Nine with large eccentricity has given rise to our interests in the secular dynamics inside MMRs in the elliptic model. In this paper, we study the fixed points of the averaged Hamiltonian and the long-term stable regions of the 1/1 resonance (or co-orbital motion) in the elliptic restricted three-body problem (ERTBP) systematically. Numerical integrations prove those test particles trapped in “apsidal co-rotation”, where both the resonant angle ϕ res and the secular angle ⧍ϖ (or apsidal longitude differences) librate simultaneously, always survive the long-term simulations. Furthermore, utilizing a semianalytical method based on the adiabatic approach, three families of long-term fixed points of the averaged Hamiltonian of the planar ERTBP inside the 1/1 resonance have been found. We call them QS-points, Hpoints, and T-points here, whose values of the (ϕ res, ⧍ϖ) are (0°, 180°), (180°, 0°), and (± 60°, ± 60°), respectively. All the fixed points of the averaged Hamiltonian of the co-orbital motion in the ERTBP are presented in the e-e′ plane (′ represents the elements of the planet in this paper). We find that QS-points and T-points always exist for the arbitrary eccentricity of a planet, while H-points only exist for the cases of low e′ and very high e. Furthermore, we measure the libration width in terms of eccentricity, ⧍e, around these stable equilibrium points in the e-⧍ϖ phase-space portraits. The “apsidal co-rotation” around all the stable equilibrium points is presented in the e-e′ plane. All these results are effectively confirmed by numerical experiments. The long-term stable zones around these periodic orbits in the e-e′ plane are significant for the research of the co-orbital motion in the ERTBP. Above all, these practical approaches that we proposed can also be used to study the secular dynamics of other MMRs.

Eccentric disks falling in water

The freely falling of solid bodies in viscous liquids is an interesting issue concerned with many hydrodynamics and engineering problems. The eccentricity of the solid bodies may lead to new dynamic behaviors and complex paths of falling. Eccentric annular disks with holes covered by transparent tapes are used to study the effect of eccentricity on the descent flight. This paper experimentally investigates the falling regimes of the eccentric disks in water with Reynolds number between 4000 and 21 000 and classifies the descent modes into three types, i.e., the fluttering, chaotic, and tumbling motions, the transition motion, and the new stable descending motion. Finally, we map out the three descent modes of eccentric disks in a two-dimensional phase space of eccentricity e and dimensionless moment of inertia I*. It is found that eccentricity is a significant parameter when describing the descent modes of eccentric disks. Enough large eccentricity stabilizes freely falling disks, while small eccentricity (e < 0.06) leads to the rotation of disk in an arc in the x-y plane accompanied by chaotic and tumbling motions or asymmetric zigzag motion. The descent modes are mainly dependent on e for I* higher than 0.02, and dependent on both e and I* for I* lower than 0.02.

Looking for Image Statistics: Active Vision With Avatars in a Naturalistic Virtual Environment.

The efficient coding hypothesis posits that sensory systems are tuned to the regularities of their natural input. The statistics of natural image databases have been the topic of many studies, which have revealed biases in the distribution of orientations that are related to neural representations as well as behavior in psychophysical tasks. However, commonly used natural image databases contain images taken with a camera with a planar image sensor and limited field of view. Thus, these images do not incorporate the physical properties of the visual system and its active use reflecting body and eye movements. Here, we investigate quantitatively, whether the active use of the visual system influences image statistics across the visual field by simulating visual behaviors in an avatar in a naturalistic virtual environment. Images with a field of view of 120° were generated during exploration of a virtual forest environment both for a human and cat avatar. The physical properties of the visual system were taken into account by projecting the images onto idealized retinas according to models of the eyes' geometrical optics. Crucially, different active gaze behaviors were simulated to obtain image ensembles that allow investigating the consequences of active visual behaviors on the statistics of the input to the visual system. In the central visual field, the statistics of the virtual images matched photographic images regarding their power spectra and a bias in edge orientations toward cardinal directions. At larger eccentricities, the cardinal bias was superimposed with a gradually increasing radial bias. The strength of this effect depends on the active visual behavior and the physical properties of the eye. There were also significant differences between the upper and lower visual field, which became stronger depending on how the environment was actively sampled. Taken together, the results show that quantitatively relating natural image statistics to neural representations and psychophysical behavior requires not only to take the structure of the environment into account, but also the physical properties of the visual system, and its active use in behavior.