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The Large Fiber Array Spectroscopic Telescope (LFAST) concept involves the utilization of 2640 individual, 0.76 m "unit telescopes" to collect light from a target object. Through optical fibers, the lights from all telescope foci are directed to a high-resolution spectrograph, with fibers subtending a 1.47 arcsec diameter on the sky. The total light-collecting area of all telescopes combined is 1200 m2. Given the telescope's application for spectroscopy of seeing-limited images, the need for coherence is eliminated. The primary goal of the LFAST prototype is to demonstrate a telescope design that can be rapidly and cost-effectively replicated to achieve a 1200 m2 collecting area and match the capabilities of extremely large telescopes (ELTs) presently under construction. Engineering, manufacturing, and design challenges unique to LFAST differ significantly from those encountered in traditional ELTs. Considering that the unit telescope is to be replicated thousands of times, reducing the manufacturing cost per telescope is essential. The aim of the described design is to achieve this goal, with strong considerations for manufacturability, alignment, few moving parts, and high yield. Experience from the first prototype unit telescope built in 2022 will be leveraged to build the first 20-unit tracking module in 2024, with a collecting area of a 3.4-m-diameter mirror. The design is minimalistic and features commercial tolerances, thereby ensuring cost-effectiveness in manufacturing, assembly, and alignment processes. Moreover, the telescope is designed to operate at angles as low as 70° from the zenith by laterally translating a single lens to correct for atmospheric dispersion. We present a combined average of over 80% encircled energy across 2640 Monte Carlo trials. Simulations were conducted using commercially specified tolerances and capabilities to model the overall performance of the array. Highlights: LFAST is an "array telescope" designed to combine light from multiple telescopes. We design a telescope that is highly performing, even at elevations as low as 70° from the zenith. Monte Carlo trials show that 80% average encircled energy can be achieved with standard tolerances for 2640 telescopes. [ABSTRACT FROM AUTHOR]

In 2019, the Event Horizon Telescope (EHT) released the first-ever image of a black hole event horizon. Astronomers are now aiming for higher angular resolutions of distant targets, like black holes, to understand more about the fundamental laws of gravity that govern our universe. To achieve this higher resolution and increased sensitivity, larger radio telescopes are needed to operate at higher frequencies and in larger quantities. Projects like the next-generation Very Large Array (ngVLA) and the Square-Kilometer Array (SKA) require building hundreds of telescopes with diameters greater than 10 ms over the next decade. This has a twofold effect. Radio telescope surfaces need to be more accurate to operate at higher frequencies, and the logistics involved in maintaining a radio telescope need to be simplified to support them properly in large quantities. Both of these problems can be solved with improved methods for surface metrology that are faster and more accurate with a higher resolution. This leads to faster and more accurate panel alignment and, therefore, a more productive observatory. In this paper, we present the use of binocular fringe projection profilometry as a solution to this problem and demonstrate it by aligning two panels on a 3-m radio telescope dish. The measurement takes only 10 min and directly delivers feedback on the tip, tilt, and piston of each panel to create the ideal reflector shape. Highlights: Current methods for measuring and aligning radio telescope dishes are insufficient for future astronomy requirements. We've developed a 3D scanning method for measuring full aperture dishes outdoors that is faster, easier, and more reliable than current methods. We demonstrated the method by aligning two panels on a 3-m dish to a high accuracy. [ABSTRACT FROM AUTHOR]

A modular cryogenic cross-disperser MOBIUS for the Large Binocular Telescope (LBT) is being developed to produce a simultaneous zJHK spectrum with a single LUCI, the LBT Utility Cameras in the Infrared. Its compact and exchangeable optical design fit within the existing focal plane mask frame of the LUCI spectrograph without any other hardware modifications. This unique deployable system enables a rapid acquisition of data over a wide wavelength range to better understand the unknown objects in the universe. [ABSTRACT FROM AUTHOR]

A model for predicting the fast transition condition in a riser of a circulating fluidized bed was proposed using the correlation of particle entrainment rate. The saturation carrying capacity of Bai and Kato could be regarded as the particle entrainment rate at the fast transition condition. The correlation of Choi et al. on particle entrainment rate could be used as a tool to predict the fast transition condition. The effect of interparticle forces seemed to be negligible at the fast transition condition. The model was in fair agreement with the measured values at the fast transition condition. [ABSTRACT FROM AUTHOR]

Flow properties of solids in an inclined standpipe were investigated while the solid particle was fed to the bottom of a bubbling fluidized bed (diameter 0.1m, 1.34m tall) via the standpipe and discharged out of the bed through the overflow exit. A group of K-based CO adsorbent particles was used as solids. The pressure drop of the fluidized bed, the height of solids bed in the standpipe, and flow rate of gas bypassing the fluidized bed through the standpipe were measured at room temperature and pressure as varying the fluidizing gas velocity, solids flow rate, and height of the overflow exit of fluidized solids. The pressure drop of the fluidized bed, the height of the solids bed in the standpipe, and the ratio of gas bypassing through the standpipe to the total gas in flow rate decreased with increasing the fluidizing gas velocity. Both the pressure drop of the fluidized bed and the height of the solids bed in the standpipe increased a little with the solids feed rate. The effect of the solids feed rate on the flow rate of gas bypassing through the standpipe could be ignored. The pressure drop of the fluidized bed and the height of the solids bed in the standpipe increased as the height of the overflow exit for solids increased in the fluidized bed. However, the effect of the height of the overflow exit on the flow rate of gas bypassing through the standpipe was negligible. Correlations on the pressure drop of the fluidized bed, the height of the solids bed in the standpipe, and the flow rate of gas bypassing through the standpipe were proposed successfully. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with the general decay result of the quasi-linear wave equation for Kirchhoff type containing Balakrishnan-Taylor damping with a delay in the boundary feedback and acoustic boundary conditions. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine how young publics in the United States and South Korea perceive the corporate social responsibility (CSR) practices of multinational corporations and evaluate the effectiveness of CSR practices in terms of organization-public relationship (OPR). Results showed that young publics in the United States and South Korea differently characterized CSR practices of multinational corporations and evaluated relationships with them. Young American participants evaluated the CSR practices of multinational corporations more favorably than did the young Korean participants. In addition, four CSR practices (internal environment, moral, discretionary, and relational) were associated with OPR dimensions in the United States, while only relational CSR practices were significantly related to OPR dimensions in South Korea. Overall, the findings highlight that cultural and societal meanings were embedded in identifying CSR practices and evaluating the relationship with multinational corporations involved in CSR practices. [ABSTRACT FROM AUTHOR]

This paper is concerned with stabilization of an axially moving Kirchhoff string by boundary feedback control. We derive a nonlinear system describing transverse oscillation of the string using Hamilton's principle and prove exponential stabilization of the system by the direct Lyapunov method. The result shows that oscillation of a nonlinear axially moving Kirchhoff string can be suppressed by a new type of boundary feedback control. [ABSTRACT FROM AUTHOR]

In this paper, we consider a quasilinear viscoelastic wave equation with acoustic boundary conditions. Under some appropriate assumption on the relaxation function g, the function Φ, p>max{ρ+2,m,q,2}, and the initial data, we prove a global nonexistence of solutions for a quasilinear viscoelastic wave equation with positive initial energy. [ABSTRACT FROM AUTHOR]