J_2 Dynamics and Formation Flight

We study the dynamics of the relative motion of satellites in the gravitational field of the Earth, including the effects of the bulge of the Earth (the J_2 effect). Using Routh reduction and dynamical systems ideas, a method is found that locates orbits such that a cluster of satellites remains close with very little dispersing, even with no controls

The New Horizon Run Cosmological N-Body Simulations

We present two large cosmological N-body simulations, called Horizon Run 2 (HR2) and Horizon Run 3 (HR3), made using 6000^3 = 216 billions and 7210^3 = 374 billion particles, spanning a volume of (7.200 Gpc/h)^3 and (10.815 Gpc/h)^3, respectively. These simulations improve on our previous Horizon Run 1 (HR1) up to a factor of 4.4 in volume, and range from 2600 to over 8800 times the volume of the Millennium Run. In addition, they achieve a considerably finer mass resolution, down to 1.25x10^11 M_sun/h, allowing to resolve galaxy-size halos with mean particle separations of 1.2 Mpc/h and 1.5 Mpc/h, respectively. We have measured the power spectrum, correlation function, mass function and basic halo properties with percent level accuracy, and verified that they correctly reproduce the LCDM theoretical expectations, in excellent agreement with linear perturbation theory. Our unprecedentedly large-volume N-body simulations can be used for a variety of studies in cosmology and astrophysics, ranging from large-scale structure topology, baryon acoustic oscillations, dark energy and the characterization of the expansion history of the Universe, till galaxy formation science - in connection with the new SDSS-III. To this end, we made a total of 35 all-sky mock surveys along the past light cone out to z=0.7 (8 from the HR2 and 27 from the HR3), to simulate the BOSS geometry. The simulations and mock surveys are already publicly available at http://astro.kias.re.kr/Horizon-Run23/.Comment: 18 pages, 10 figures. Added clarification on Fig 6. Published in the Journal of the Korean Astronomical Society (JKAS). The paper with high-resolution figures is available at http://jkas.kas.org/journals/2011v44n6/v44n6.ht

Assessment Study of Small Space Debris Removal by Laser Satellites

Space debris in Earth orbit poses significant danger to satellites, humans in space, and future space exploration activities. In particular, the increasing number of unidentifiable objects, smaller than 10 cm, presents a serious hazard. Numerous technologies have been studied for removing unwanted objects in space. Our approach uses a short wavelength laser stationed in orbit to vaporize these small objects. This paper discusses the power requirements for space debris removal using lasers. A short wavelength laser pumped directly or indirectly by solar energy can scan, identify, position, and illuminate the target, which will then be vaporized or slow down the orbital speed of debris by laser detonation until it re-enters the atmosphere. The laser-induced plasma plume has a dispersive motion of approximately 105 m/sec with a Lambertian profile in the direction of the incoming beam [1-2]. The resulting fast ejecting jet plume of vaporized material should prevent matter recombination and condensation. If it allows any condensation of vaporized material, the size of condensed material will be no more than a nanoscale level [3]. Lasers for this purpose can be indirectly pumped by power from an array of solar cells or directly pumped by the solar spectrum [4]. The energy required for vaporization and ionization of a 10 cm cube (~ 2700 gm) of aluminum is 87,160 kJ. To remove this amount of aluminum in 3 minutes requires a continuous laser beam power of at least 5.38 MW under the consideration of 9% laser absorption by aluminum [5] and 5% laser pumping efficiency. The power needed for pumping 5.38 MW laser is approximately 108 MW, which can be obtained from a large solar array with 40% efficiency solar cells and a minimal area of 450 meters by 450 meters. This solar array would collect approximately 108 MW. The power required for system operation and maneuvering can be obtained by increasing solar panel size. This feasibility assessment covers roughly the power requirement, laser system, and a potential operational scenario

How Artificial Intelligence and Virtual Reality Benefit the Elderly and Individuals with Disabilities

The growing and evolving use  of emerging technology including Artificial Intelligence (AI)  and Virtual Reality (VR),  has significantly impacted the lives of two specific groups—the elderly and the disabled.  This paper investigates potential reasons for this phenomenon.  Clearly, AI and VR Technology alters the everyday lives of people with disabilities and how they navigate the world.  Technological developments increasingly work to address the isolation that people with disabilities as well as the elderly experience for  they are often unable or limited in how they  engage with their communities.  This research paper outlines the way technology has improved  social communication, information distribution, and day-to-day living for those with disabilities and the elderly.Undoubtedly,  the internet has transformed social communication and interaction for most people.   socially isolated individuals with disabilities have gained exposure to social environments through social media.  Moreover, the broad range of information available on the internet  has increased access to resources such as government services, health services, and social services support. On a related point, assistive devices have enabled disabled people including many seniors to overcome motor, sensory, or cognitive difficulties that may have previously hindered them from performing daily tasks.  However, although AI and VR technology has been effectively integrated in the lives of those with disabilities, many such individuals lack access to commonplace technologies, like a personal computer.  This paper examines how  AI and VR technology has enhanced communication, information access, and everyday activities for the disabled and aging communities despite such socio-economic limitations

Solid-state metathesis reactions under pressure: A rapid route to crystalline gallium nitride

High pressure chemistry has traditionally involved applying pressure and increasing temperature until conditions become thermodynamically favorable for phase transitions or reactions to occur. Here, high pressure alone is used as a starting point for carrying out rapid, self-propagating metathesis reactions. By initiating chemical reactions under pressure, crystalline phases, such as gallium nitride, can be synthesized which are inaccessible when initiated from ambient conditions. The single-phase gallium nitride made by metathesis reactions under pressure displays significant photoluminescence intensity in the blue/ultraviolet region. The absence of size or surface-state effects in the photoluminescence spectra show that the crystallites are of micron dimensions. The narrow lines of the x-ray diffraction patterns and scanning electron microscopy confirm this conclusion. Brightly luminescent thin films can be readily grown using pulsed laser deposition

Effects of Principals’ Team Work Capabilities on the Adoption of Strategic Management in Public Secondary Schools in Baringo County, Kenya

Strategic management is a critical component for the effective performance of an organization. Many successful organizations have consistently performed better than their competitors mainly because they have implemented strategic management. The Ministry of Education (MOE) in the Republic of Kenya expects that all secondary schools put in place strategic management for performance improvement and the realization of the national goals of education. The Principal plays a pivotal role in the adoption of school improvement initiatives such as strategic management. This study sought to find out the effects of Principals’ team work capabilities on the adoption of strategic management in Public Secondary Schools. The study found out that Principals’ team work capabilities had a significant effect on the adoption of strategic management in Public Secondary Schools. Keywords: Principals, Team work capabilities, Adoption, Strategic Managemen

Algorithmic Shadow Spectroscopy

We present shadow spectroscopy as a simulator-agnostic quantum algorithm for estimating energy gaps using very few circuit repetitions (shots) and no extra resources (ancilla qubits) beyond performing time evolution and measurements. The approach builds on the fundamental feature that every observable property of a quantum system must evolve according to the same harmonic components: we can reveal them by post-processing classical shadows of time-evolved quantum states to extract a large number of time-periodic signals $N_o\propto 10^8$, whose frequencies correspond to Hamiltonian energy differences with Heisenberg-limited precision. We provide strong analytical guarantees that (a) quantum resources scale as $O(\log N_o)$, while the classical computational complexity is linear $O(N_o)$, (b) the signal-to-noise ratio increases with the number of analysed signals as $\propto \sqrt{N_o}$, and (c) peak frequencies are immune to reasonable levels of noise. Moreover, performing shadow spectroscopy to probe model spin systems and the excited state conical intersection of molecular CH$_2$ in simulation verifies that the approach is intuitively easy to use in practice, robust against gate noise, amiable to a new type of algorithmic-error mitigation technique, and uses orders of magnitude fewer number of shots than typical near-term quantum algorithms -- as low as 10 shots per timestep is sufficient. Finally, we measured a high-quality, experimental shadow spectrum of a spin chain on readily-available IBM quantum computers, achieving the same precision as in noise-free simulations without using any advanced error mitigation.Comment: 31 pages, 13 figures, new results with hardware and figure