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  1. null (Ed.)
  2. In this work, we demonstrate a four-core multicore fiber photonic lantern tip/tilt wavefront sensor. To diagnose the low-order Zernike aberrations, we exploit the ability of the photonic lantern to encode the characteristics of a complex incoming beam at the multimode facet of the sensor to intensity distributions at the multicore fiber output. Here, we provide a comprehensive numerical analysis capable of predicting the performance of fabricated devices and experimentally demonstrate the concept. Two receiver architectures are implemented to discern tip/tilt information by (i) imaging the four-core fiber facet on a 2D detector and (ii) direct power measurement of the single mode outputs using a multicore fiber multiplexer and photodetectors. For both receiver schemes, an angular detection window of∼<#comment/>0.4∘<#comment/>at 1064 nm can be achieved. Our results are expected to further facilitate the development of intensity-based fiber wavefront sensors for adaptive optics systems.

     
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  3. Abstract. Light transmission into bare glacial ice affects surfaceenergy balance, biophotochemistry, and light detection and ranging (lidar)laser elevation measurements but has not previously been reported for theGreenland Ice Sheet. We present measurements of spectral transmittance at350–900 nm in bare glacial ice collected at a field site in the westernGreenland ablation zone (67.15∘ N, 50.02∘ W). Empirical irradianceattenuation coefficients at 350–750 nm are ∼ 0.9–8.0 m−1 for ice at 12–124 cm depth. The absorption minimum is at∼ 390–397 nm, in agreement with snow transmissionmeasurements in Antarctica and optical mapping of deep ice at the SouthPole. From 350–530 nm, our empirical attenuation coefficients are nearly1 order of magnitude larger than theoretical values for optically pureice. The estimated absorption coefficient at 400 nm suggests the ice volumecontained a light-absorbing particle concentration equivalent to∼ 1–2 parts per billion (ppb) of black carbon, which is similar topre-industrial values found in remote polar snow. The equivalent mineraldust concentration is ∼ 300–600 ppb, which is similar to values forNorthern Hemisphere warm periods with low aeolian activity inferred from icecores. For a layer of quasi-granular white ice (weathering crust)extending from the surface to ∼ 10 cm depth, attenuationcoefficients are 1.5 to 4 times larger than for deeper bubbly ice. Owing tohigher attenuation in this layer of near-surface granular ice, opticalpenetration depth at 532 nm is 14 cm (20 %) lower than asymptoticattenuation lengths for optically pure bubbly ice. In addition to thetraditional concept of light scattering on air bubbles, our results implythat the granular near-surface ice microstructure of weathering crust isan important control on radiative transfer in bare ice on the Greenland IceSheet ablation zone, and we provide new values of flux attenuation,absorption, and scattering coefficients to support model development andvalidation. 
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  6. Process safety is at the heart of operation of many chemical processing companies. However, the Chemical Safety Board (CSB) has still documented over 800 investigations of process safety failures since the year 2000. While not all of these incidents were severe, some did lead to employee injuries or death and environmental harm. As a result, chemical engineering companies are increasingly dedicated to process safety through training programs and detailed vigilance as part of their operations practice. AIChE and OSHA also offer courses in process safety to help support the industry. These efforts illustrate the paramount importance that chemical engineering graduates have an appreciation and understanding of process safety as they transition from their degree program into industrial positions. Previous studies have shown that despite difficulties due to course load constraints, process safety has been incorporated into chemical engineering curriculum through either the addition of new courses, incorporation of the content within existing classes, or a combination of the two methods. A review performed in Process Safety Progress suggested that a key step for departments moving forward is to perform an assessment of the process safety culture within their institution in order to determine how faculty and students view process safety. An issue with completing this task is the lack of assessment tools that can be used to determine how students are developing their understanding of process safety decision making. This observation led to the development of the Engineering Process Safety Research Instrument (EPSRI). This instrument is modeled after the Defining Issues Test version 2 (DIT2) and the Engineering Ethical Reasoning Instrument (EERI). Similar to these instruments, the EPSRI provides dilemmas, three decisions, and 12 additional considerations that individuals must rate based on their relative importance to their decision making process. The dilemmas developed in the EPSRI are based on case studies and investigations from process safety failures that have occurred in industry to provide a realistic context for the decision making decisions that engineers may be faced with upon employment. The considerations provided after the scenario are derived to reflect pre-conventional, conventional, and post-conventional decision making thinking as described by Kohlberg’s Moral Development Theory. Pre-conventional decision making thinking focuses particularly on what is right/wrong or good/bad from an individual level, whereas post-conventional thinking seeks to determine what is correct from moral and value perspectives at the society level. This WIP paper describes the content validity study conducted while developing the EPSRI. Dilemmas were examined by context experts including professionals in the process industry, chemical engineering departments, and learning sciences field. Content experts reviewed the dilemmas and determined whether they represented accurate examples of process safety decision making that individuals may face in real-world engineering settings. The experts also reviewed the 12 considerations for each dilemma for their accuracy in capturing pre-conventional, conventional and post-conventional thinking. This work represents the first step in the overall instrument validation that will take place over the next academic year. 
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