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Analysis of the Circular Restricted N-Body Problem (CRNBP) in the Sun-Venus System
No full textThird-body dynamical approximations such as the Circular Restricted 3-Body Problem (CR3BP) have become ubiquitous in orbital mechanics in determining useful trajectories in systems with two massive bodies and a spacecraft. These models provide a better estimation of real-world trajectories than the simple 2-Body Problem (2BP), but the addition of a greater number of massive celestial bodies to gain insights into the effect of additional gravitational perturbations would enable the design of more accurate trajectories without reliance on a higher-fidelity ephemerides n-body model. As this extension to the CR3BP, the Circular Restricted N-body Problem (CRNBP) was first presented in 2022 by Negri and Prado [1]. Using that CRNBP model, initial conditions from the Sun-Venus CR3BP are propagated numerically in CRNBP for multiple orbit types to include the gravitational effects of Mercury and Earth. The resulting trajectories are compared between the two models, demonstrating that significant perturbing effects and a reliance on the initial phase angles of the tertiary and quaternary bodies exist. Some trajectories and initial phase angle cases are identified to be less perturbed over the time period of propagation, which may aid in the selection of more stable trajectories or the selection of an initial epoch at which to enter certain orbits. This analysis demonstrates the main benefit of the CRNBP model. Additionally, the application of Poincaré mapping to this problem and the challenges with this approach are examined
Mechanical Response of Cylindrically Mapped Triply Periodic Minimal Surface Structures Under Combined Loading
No full textThis work explored combined tensile and torsional loads applied to additively manufactured Inconel 718 specimens employing Triply Periodic Minimal Surface (TPMS) structures. The gyroid TPMS unit cell was selected with two variations of cylindrical cell maps by varying arc count. The 4-arc and 8-arc structures were tested in an axial-torsion test frame at room temperature using equal parts of vertical and angular displacement control until failure. The data from the tests were compared to finite element analysis models to visualize when yielding was predicted. Finally, the fracture surfaces were investigated with a scanning electron microscope to characterize the primarily ductile fracture
Simultaneous Observations of Irregular Sporadic E Structures using the LWA and a DPS4D
Get PDFMulti-instrument studies have recently shed new light on the morphology of sporadic E, especially intense sporadic E. Here we present simultaneous observations of dense sporadic E (Es) structures using the Long Wavelength Array (LWA) radio telescopes and a Digisonde Portable Sounder 4D (DPS4D). Our coordinated observations show that the LWA radio telescopes in central New Mexico can reliably locate regions of dense Es structures as they pass over a Digisonde located over 500 km away in Texas. The LWA appears to be most sensitive to the densest Es structures, which also appear to contain irregularities with vertical structure, possibly indicating turbulence. These irregularities cause off-zenith backscatter, as observed by the DPS4D, and are observed to move at speeds of a few tens of m/s. The irregularities also appear to act as a phase screen, producing short-lived daytime spread F and E conditions. We hypothesize that turbulent structures driven by the Kelvin–Helmholtz (KH) instability may be responsible for the observations
Performance Evaluation of Utilizing Rust for PCAP Analysis in Satellite Cybersecurity
No full textPreviously, launched satellites were not designed with the necessary resource capacity or safety protocols to integrate essential Intrusion Detection Systems (IDS). This paper proposes the use of Rust to develop a statistics-based IDS, leveraging the language’s fast, efficient, and memory-safe attributes. The paper begins by providing an overview of cybersecurity threats to space infrastructure, introducing the fundamentals of intrusion detection, and outlining the architecture of space systems as background knowledge. It then details the proposed methodology for using Rust to build a statistics-based IDS. By comparing this approach with traditional methods, such as Python’s pandas, the paper aims to evaluate Rust’s speed and efficiency, advocating for its adoption in the development of more secure space systems
Air Force Institute of Technology: introduction
No full textThe Air Force Institute of Technology (AFIT) is a widely recognized leader in optical science and engineering research. This focus issue highlights the breadth and depth of optics-oriented research activities across the institution
Progress in the development of a versatile table-top kHz-rate laser-plasma accelerator for mixed radiation sources
No full textL-Band Pulse Phase Measurements of Pulsar B0329+54 Using a 1.8m Dish Antenna
No full textExcerpt: In this work, pulsar pulse phase measurements were performed using a dish antenna with a diameter of 1.8 m with the goal to characterize the repeatability of pulsar timing measurements using a small-aperture antenna. A low-cost data collection system using a software-defined radio was designed and implemented in support of this goal
Spectral Analysis of Light Interstitial Segregation Energies in Ni: The Role of Local Cr Coordination for Boron and Carbon
No full textUnderstanding interstitial segregation in chemically complex alloys requires accounting for chemical and structural heterogeneity of interfaces, motivating approaches that move beyond scalar descriptors to capture the full spatial and compositional spectra of segregation behavior. Here, we introduce a spectral segregation framework that maps distributions of segregation energies for light interstitials in Ni as a function of local Cr coordination. Boron exhibits a broad, rugged energy spectrum with significant positional flexibility whereas carbon remains confined to a narrow spectrum with minimal displacement. At the free surface, Cr-rich coordination destabilizes both interstitials (e.g., positive segregation energies), in sharp contrast to the stabilizing role of Cr at the GB. This inversion establishes a natural segregation gradient that drives interstitials away from undercoordinated internal surfaces and toward GBs. These results underscore the limitations of single-valued segregation descriptors and demonstrate how a distributional approach reveals the mechanistic origins of interstitial–interface interactions in chemically heterogeneous alloys
Conceptual Design Space Exploration of Hypersonic Aircraft Using Emulator Embedded Neural Networks
No full textThis study proposes a novel acquisition function for constraint boundary identification, with applications to hypersonic air vehicles. Hypersonic vehicles endure extreme thermal loads caused by aerodynamic heating, resulting in a strong coupling between structural performance and aerothermodynamics. Therefore, it is crucial to consider aerothermal-structural interactions from the early stage of conceptual design development. However, modeling coupled system behaviors requires simultaneous consideration of both aerodynamic and structural design variables, including shape variables of the outer mold line, structural component layouts, and material selection for different areas of the vehicle. This increases the dimensionality of the design trade space. As the dimensionality increases, it becomes more difficult to model the constraints with enough accuracy to identify the feasible region. Several active learning schemes have been proposed to accelerate identification of the composite feasible region that satisfies all constraints. Some of these require integrating the surrogate model over the entire design space with each acquisition function evaluation, but this scales poorly to high dimensional spaces. In this work, we propose an alternative acquisition function based on the Expected Magnitude of Incorrectness of a constraint. Each constraint is modeled with either Gaussian Process Regression or an ensemble of neural networks, either of which can provide the uncertainty information needed by the proposed acquisition function. The neural networks used are called Emulator Embedded Neural Networks, and can combine multiple fidelities of data even if they do not form a strict hierarchy. Our approach performs well on analytical functions when compared to current acquisition functions. Additionally, we demonstrate our method on a lift constraint problem for a hypersonic vehicle wing
A study on the halide distribution, halide vacancies, and their diffusion in the δ-CsPb(I\u3csub\u3e0.5\u3c/sub\u3eBr\u3csub\u3e0.5\u3c/sub\u3e)\u3csub\u3e3\u3c/sub\u3e mixed halide structure
No full textMixed halide perovskites are candidates for solar cell applications in space environments. The non-perovskite δ-structure is known to coexist with the perovskite γ-structure and the kinetic barriers for the γ to δ transition are quite small. So, it is important to study this structure. In this work, we performed density functional theory (DFT)-based calculations on δ-CsPbI3 and δ-CsPb(I0.5Br0.5)3. First, no thermodynamic tendency for segregation was observed in the δ-CsPb(I0.5Br0.5)3 structure. The presence of Br in the vicinity lowered the iodine threshold displacement energy. Iodine vacancies were more stable than the Br vacancies. A strong dependence of the halide vacancies on the metallic atom coordination was observed. Finally, the highest migration energy barriers for the halide vacancies were observed for the cases where the hops were occurring between sites with the highest Pb-coordination. The results of this study may help apprise future efforts for realizing radiation-resistant perovskites for space