11115 research outputs found
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Comprehensive Study of \u3ci\u3ed\u3c/i\u3e + \u3csup\u3e6\u3c/sup\u3eLi via observing simultaneous outgoing neutrons, rays, and charged particles
No full textDeuteron-induced reactions on6Li are important for nuclear structure studies and nuclear ap-plications. A new experimental effort was dedicated to improve incomplete partial cross sections and the angular distribution information for d+6Li reactions and, to address the inconsistencies between various R-matrix evaluations of the8Be system. The new measurements were performed over a deuteron energy range of 1.8 to 10 MeV with an angular distribution coverage of 20°– 170° for outgoing particles. The experiment simultaneously measured neutrons, charged particles, andγ-rays from the various exit channels of the d+6Li reaction. The cross sections for open reaction channels measured simultaneously are presented. In addition, results for the 6Li(d,n)7Be total cross section using the activation method are also presented
Verifying new instances of the multidemand multidimensional knapsack problem with instance space analysis
No full textDevelopment of an Ultrawideband Wire-Grid Polarizer Measurement Standard for Focus Beam System Cross-Polarization Calibration
No full textThis paper introduces an ultrawideband wire-grid polarizer measurement standard for focus beam system cross-polarization calibration. The low-cost design enables polarimetric calibration techniques of precision non-destructive material measurements. Principles from wire-grid polarizers and A-sandwich radomes are combined to develop a highly planar standard. An infinite array simulation is included to predict the co-polarized and cross-polarized transmission from 0.1-100 GHz at incidence angles from 0–60 degrees. The design is physically realizable with a specialized printed circuit board technique allowing for low-cost manufacturing and electrically significant polarizer calibration standards sizes. A prototype 305mm x 305mm design is fabricated and mechanically assessed to determine tolerances. Finally, a time-domain gated response isolation scheme is used to characterize the prototype RF performance from 1–20 GHz. The design introduced in this paper may be extended to achieve wire-grid polarizer measurement standards more than 1m diameter for calibration from very low frequencies all the way through W-band
Sun–Venus CR3BP, Part 1: Periodic Orbit Generation, Stability, and Mission Investigation
No full textVenus is Earth’s closest neighbor, hosting a similar size, density, and location in the Solar System. Due to these similarities, Venus has been suggested as a premier location for particular mission sets to include: near-Venus communications and positioning, navigation, and timing (PNT); planetary science; heliophysics; space weather monitoring; and planetary defense. This paper, for the first time in literature, presents 37 unique planar periodic orbits discovered in the Sun–Venus system that may be used for such missions. The Circular Restricted Three-Body Problem (CR3BP) is the primary dynamical model utilized to generate all periodic orbits in the Sun–Venus system. The discovered orbits are grouped into four categories based on their shape: Near-Venus periodic orbits, Sun–Venus touring periodic orbits, Sun–Venus touring periodic orbits featuring near-Sun flybys, and Sun–Venus touring periodic orbits featuring near-Mercury flybys. Each orbit is discussed in terms of its respective Jacobi constant and stability within the context of the CR3BP. The stability of the orbits provides a preliminary analysis of station-keeping costs related to propellant expenditure, thereby determining the feasibility of implementing these trajectories. Specifically, this research shows that most of the identified orbits possess stability indices below 2, suggesting that minimal propellant is necessary for station-keeping maneuvers to sustain the preferred trajectory. For all orbits, specific initial position and velocity states conditions are provided, accompanied by recommendations for their potential mission applications. This research aims to advance ongoing astrodynamics research by filling a catalog hole and providing a Sun–Venus CR3BP orbit baseline
Optimization of Bluetooth Auracast Broadcast Audio Transmissions via Signal Modeling
Get PDFSince 1994, Bluetooth has been used as a Personal Area Network (PAN) to transfer data between devices within a short range. After thirty years of progressive improvement in functionality, security, range, and power efficiency, the Bluetooth Special Interest Group has released a new feature called Auracast, which allows users to tune into nearby public audio streams and receive the feed directly to their wireless headphones or hearing aids. Soon, venues such as convention centers, museums, public forums, and sporting arenas can implement Auracast to better suit their needs. In addition to these public benefits, the Department of Defense can take advantage of this technology to improve communication within military facilities and in the field. When multiple Auracast devices are broadcasting on the same 2.4 GHz frequency, signal collisions can result in malformed packets. These malformed packets decrease signal reliability, making the process of joining the audio stream take longer. The deliberate positioning of Auracast transmitters can minimize this interference and maximize signal longevity. This research evaluates the effects of two to six simultaneous broadcasts placed various distances apart on the number of malformed packets captured. These broadcasting devices are placed equidistant from a packet sniffing system positioned in the center. The purpose of this experiment is to determine the optimal separation distance for each quantity of broadcasters tested, which is the maximum spacing that still results in a signal strength of at least -62 dBm. It is assumed that the fewer broadcasters communicating at once and the closer they are positioned together, the fewer malformed packets that will result. The signal strength from each individual packet is leveraged to quantitatively achieve this goal. The results from the statistical analysis reveal the optimal separation distance for two or three simultaneous broadcast sources is approximately 45 ft, while four to six Auracast devices should be placed about 30 ft apart. These results enable administrators of multiple Auracast audio streams to maximize signal reliability for an unlimited-sized crowd. Overall, this research contributes to the characterization of this new Auracast technology and emphasizes its potential to improve a variety of applications
Enhancing SeQUeNCe with Quantum Key Distribution Protocols and an Intuitive User Interface
Get PDFThe rapidly growing domain of quantum networks necessitates advancements in associated software packages. This master’s thesis will detail, in part, new protocols added to extend the usefulness of SeQUeNCe. Notably, these added protocols were implemented to ensure compatibility and efficiency with the existing codebase. To complement this expansion in capability, the graphical user interface (GUI) was restructured. Updates to the GUI now allow users to initiate and operate these newly integrated protocols with ease, thereby expanding the accessibility of SeQUeNCe to a wider audience. By prioritizing the incorporation of these new protocols and refining the user interface, this research significantly elevates SeQUeNCe’s position as an evolving tool in quantum computing software
Global Empirical Model of Sporadic-E Occurrence Rates
Get PDFEncompassing the Earth, the ionosphere presents unique challenges to modern communication, navigation, and surveillance technologies. Intense ionization enhancements known as sporadic-E (Es), can degrade and disrupt signals in unpredictable ways. Much work has been done to understand this phenomenon and more recent efforts have attempted to model its behavior and impacts. However, there have been limited efforts at modeling global Es occurrence rates (OR) at high time resolutions. This study develops a global empirical model of blanketing sporadic-E (fbEs) occurrence rates using a Karhunen-Lo´eve Expansion (KLE) of global fbEs OR climatologies built with Global Positioning System radio occultations (GPS-RO) and ionosonde soundings. At a 3 MHz threshold, the model outputs fbEs OR for a given geomagnetic latitude, longitude, day of year, and time of day. The model’s outputs were compared to Digisonde observations at four different locations with correlation coefficients ranging from 0.51 to 0.85 for monthly averaged observations and an uncertainty of 10.5% OR, while the average estimated uncertainty of the model is 8.8% OR. With the availability of COSMIC II data, new opportunities to develop higher resolution fbEs OR climatologies and consequently better models are emerging. A more extensive comparison of the model to more ionosonde locations would also provide greater confidence in the model’s performance
Modeling & Engineering of USMEPCOM Business Intelligence Data
Get PDFThis thesis investigates the USMEPCOM’s issue of modeling and engineering Business Intelligence data centralized around the MEPS of Excellence (MOE) program. MEPS around the US conduct military personnel in-processing and in doing so have a vested interest in the standardization and application of the data associated with such processes. There are currently 65 MEPS stations and one RPS that handle military personnel onboarding paperwork and make determinations for military eligibility. This topic is important due to the MEPS cloud data processing system modernization efforts requiring data processing adaptation to ensure relevant and meaningful usage of current data
Analysis and Visualization of Military Convoy and Supply Utilization in Support of State-specific Freight Plans
Get PDFResearching the United States military’s use of highways and interstates is necessary for the allocation of federal infrastructure spending. As of today, there is no established method, tool, or process routinely utilized by the Surface Deployment and Distribution Command to effectively show a system-wide view of military convoy and supply route usage across CONUS. This research advances this endeavor by providing a by-state characterization of interstates and major highways in 2022, categorized by the volume of military freight they support. Some notable methodologies used to conduct the analyses are the shortest path problem, map matching algorithms, and Global Positioning System (GPS)-Coordinate-to-Network matching. To illustrate these results, we provide a by-state identification of the most frequently and heavily used highways in Ohio and Illinois (I 70 and I 90 respectively) by name and geographical location, that is repeatable for all other 46 CONUS states, and usage across states (OH, IN, and IL). Highways such as US 40, I 70, I 80, and I 90 should be considered in the calculations for federal infrastructure spending for the next budget year