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The Refractive index of a single three-level atom: quantum state separator
No full textIn this paper, we study interaction of quantum fields and a single three-level atom placed in the Mach–Zender interferometer. We demonstrate that the phases acquired by quantum fields depend on the number of photons in the quantum states. Notably, the phases differ between single- and two-photon states, enabling the separation of multiphoton states. This finding highlights new applications related to the dispersion of three-level atoms, which are important in advancing quantum information processing and enhancing quantum communication technologies. The results are crucial for long-distance quantum communication and hold potential for developing quantum field-based linear devices such as beam splitters, lenses, and quantum prisms capable of separating different components of quantum fields. The findings can have interesting applications for manipulating and assembling of multiphoton entanglement states
Applying Machine Learning Methods to Laser Acceleration of Protons: Synthetic Data for Exploring the High Repetition Rate Regime
No full textAdvances in ultra‐intense laser technology have increased repetition rates and average power for chirped‐pulse laser systems, which offer a promising solution for many applications including energetic proton sources. An important challenge is the need to optimize and control the proton source by varying some of the many degrees of freedom inherent to the laser‐plasma interactions. Machine learning can play an important role in this task, as our work examines. Building on our earlier work in Desai et al. 2024, we generate a large ∼1.5 million data point synthetic data set for proton acceleration using a physics‐informed analytic model that we improved to include pre‐pulse physics. Then, we train different machine learning methods on this data set to determine which methods perform efficiently and accurately. Generally, we find that quasi‐real‐time training of neural network models using single‐shot data from a kHz repetition rate ultra‐intense laser system should typically be feasible on a single GPU. We also find that a less sophisticated model, like a polynomial regression, can be trained even faster and that the accuracy of these models is still good enough to be useful. We provide our source code and example synthetic data for others to test new machine learning methods and approaches to automated learning in this regime
Measurements of Test Objects for Maritime Signature Validation
No full textWe present measured inverse synthetic aperture radar (ISAR) signatures of a calibration cylinder and reduced scale ship models. We explore the fidelity of synthetic prediction and its ability to represent the electromagnetic interactions between the test objects and the surrounding surface
Misalignment Uncertainty in Near-Field Terahertz Scattering Experiments
No full textMisalignment uncertainty is estimated for near-field scattering measurements from 550-700 GHz. After correcting translation and rotation error using a physical optics prediction, the mean calibration difference metric is improved by 2.46 dB, and with a variance of 1.07 dB within the band of 585-635 GHz
Uncertainty Quantification for Transient Thermal Management
No full textThermal resource management (TRM) of hypersonic vehicles has received considerable attention from the scientific community in the past few decades. A scramjet engine at hypersonic speed warrants stringent cooling requirements to manage its thermal load: therefore, heat dissipation of hypersonic vehicles remains a challenging research topic worthy of investigation. For this effort, quantification of the uncertainty in a transient heat rejection system is analyzed. The stochastic nature of the initial condition and heat rejection boundary condition is introduced to determine the temperature distribution in the system. Results are presented for the temperature variation as a result of uncertainties in the initial condition and Biot number at the boundary where heat is rejected. The terms that impact the overall uncertainty in the transient regions are investigated to determine the factors that have the greatest risk of exceeding known thermal management limitations
A multi-code, multi-physics approach investigating the impact of vegetation on prompt gamma-ray energy deposition
No full textDuring the age of above-ground nuclear weapons testing, the effect of vegetation on radiation energy deposition in soil was computationally too challenging to study. Today, improvements in high-performance computing, mature and accurate radiation transport models, and user-friendly optimization and statistical analysis software packages enable investigations into modeling and quantifying the impact of forest vegetation on the prompt gamma-ray energy deposition within the soil from an atmospheric nuclear weapon detonation. Our approach simulates radiation transport, amasses results, and statistically analyzes the results using CUBIT ® , Dakota, and MCNP ® to perform meshing, geometry creation, and radiation transport. Depending on the forest parameters, there is 0.16% --1.3% change in photon energy deposition in the soil. This research successfully demonstrates a methodology for streamlining a complex radiation modeling effort across multiple codes to quantify and answer a nuclear weapons effects question
Preliminary Investigation of Cislunar Disposal Reachability via Electric Propulsion for Selected \u3ci\u3eL\u3csub\u3e2\u3c/sub\u3e\u3c/i\u3e Lagrange Point Orbit Families
No full textThis paper investigates the disposal of end-of-life spacecraft from selected orbit families in the Earth-Moon system, specifically the L2 Lyapunov and Halo families. Rather than focusing on impulsive burns with chemical propulsion systems, this paper examines disposal using continuous thrust generated by Hall thrusters, a form of electric propulsion. Leveraging the Circular Restricted Three Body Problem (CR3BP) as the dynamical framework, various levels of ΔV are evaluated in single-maximum burn and multiple-burn concepts of operation to evaluate the potential for spacecraft minimizing their transit of cislunar space and reaching the Earth’s gravitational sphere of influence in order to enter heliocentric space. Analysis indicates that disposal into heliocentric space is possible from the L2 Lyapunov and Halo families for ΔV burns in the range of 10–100 m/s depending on the initial starting location and burn direction. Due to its comparatively higher stability, disposal burns from the L2 Halo family may need to be higher than 100 m/s in order to exit the Earth’s gravitational sphere of influence. These findings establish a preliminary baseline for cislunar disposal research for the L2 Lagrange point, contributing to the emerging dialogue concerning sustainable space traffic management practices
Hypersonic boundary layer flow at an axisymmetric stagnation point on a blunt body
No full textA boundary layer analysis is presented for hypersonic flow at an axisymmetric stagnation point region of a blunt body under isothermal and adiabatic boundary conditions. Consideration is given to variable properties of air. It has been shown that surface drag and heat transfer rates may be controlled by applying magnetic field and vectored surface mass transfer. The range of Mach numbers considered is 1–10. As the magnetic field strength M increases, friction factor and heat transfer rate (in the case of isothermal surface) or surface temperature (in the case of adiabatic surface) increase. Friction factor and surface temperature (in the case of adiabatic surface) can be reduced by applying vectored surface mass transfer
Preliminary investigation and proposal of periodic orbits and their utilization for logistics in the cislunar regime
No full textExcerpt:The world is in the midst of what is widely considered the second Space Age due to the vastly growing commercial space sector and progress with international initiatives such as the Artemis program, led by the National Aeronautics and Space Administration (NASA). Cislunar space is becoming a region of growing interest as nations, international organizations, and private corporations look to expand their presence and outreach. The planned development of space infrastructure, such as lunar habitats, mining operations, and other installations, is driving the need for studies regarding common orbital pathways to ensure logistical support for future cislunar missions. Along with common orbital pathways, comprehensive and internationally acknowledged space policy and doctrine is required to ensure the safety, stability, and peace of this new frontier of human endeavor. This study serves to address one of the mission sets that will come to shape the emerging economy of the wider Earth-Moon system, space logistics. Specifically, this study will discuss potential orbits for a cislunar space situational awareness network that would support a space traffic management service, along with three cislunar logistics missions: personnel and cargo transport, space tourism, and search and rescue.
Abstract © Elsevier
Effect of velocity slip and temperature jump on unsteady magnetohydrodynamic Maxwell ternary hybrid nanofluid flow over a shrinking sheet
No full textExcerpt: This study reveals the unsteady flow and heat transfer of Maxwell ternary hybrid nanofluid over a shrinking sheet under thermal radiation, magnetic field, and slip boundary conditions. The governing equations are transformed into a set of nonlinear ordinary differential equations (ODEs) using proper similarity transformations. The system of ODE’s is solved numerically employing the well-known shooting method that has been implemented by the in-house FORTRAN code