Payload Configuration, Integration and Testing of the Deformable Mirror Demonstration Mission (DeMi) CubeSat

Adaptive optics is an imaging technique that has been used on many ground based telescopes to improve image resolution and reduce the effects of atmospheric turbulence. While adaptive optics has known uses on the ground, applying this technique to space telescopes has major advantages for exoplanet imaging, inter-satellite laser communication, high energy systems, and other military applications. The Deformable Mirror Demonstration Mission (DeMi) is a 6U CubeSat, that will demonstrate the use of adaptive optics, specifically a microelectromechanical system (MEMS) deformable mirror, in space. Not only will the DeMi mission characterize the deformable mirror on-orbit, the mission will also demonstrate deformable mirror control using closed loop image plane sensing and wavefront sensing on internal and external light sources. DeMi uses COTS components like Thorlabs mirrors, Pixelink complementary metal-oxide-semiconductor cameras, and a Boston Micromachines Corporation “multi” deformable mirror. DeMi is currently in the optical integration and testing stage. The payload design and assembly is being tested by assembling 3D printed payload components. Optical alignment and configuration is being tested by mounting the optical components to the 3D printed payload assembly. Current and future testing will inform payload design and payload assembly plan changes. DeMi is expected to launch winter of 2019

Steps to Developing an Effective Integrated Corrosion Management Program to Minimise Costs & Extend Life

An integrated corrosion management program should be part of the overall asset management and preservation program and should not be treated as/in a separate system. Integrity of assets is a characteristic of sound and safe performance for which it was designed. Other subsets of the overall integrity management program include, e.g. mechanical damage and operating stress.This keynote outlines steps for developing an effective integrated corrosion management program with the aim to minimise costs and to extend life whilst reducing the risk for failure. Cost implications of inadequate corrosion control include both direct and indirect costs, which are correlated. For example, inadequate coatingmaintenance (direct cost) will lead to increased maintenance and repair costs later(indirect costs), which often outweigh the initial costs of simply maintaining the adequate condition of the coatings.The implementation of an integrated corrosion management program, that result in the reduction/elimination of corrosion related damage/deterioration of assets, will notonly assist in compliance with regulatory requirements but also has a direct effect on the assets overall economic performance

Kelly Betting Can Be Too Conservative

Kelly betting is a prescription for optimal resource allocation among a set of gambles which are typically repeated in an independent and identically distributed manner. In this setting, there is a large body of literature which includes arguments that the theory often leads to bets which are "too aggressive" with respect to various risk metrics. To remedy this problem, many papers include prescriptions for scaling down the bet size. Such schemes are referred to as Fractional Kelly Betting. In this paper, we take the opposite tack. That is, we show that in many cases, the theoretical Kelly-based results may lead to bets which are "too conservative" rather than too aggressive. To make this argument, we consider a random vector X with its assumed probability distribution and draw m samples to obtain an empirically-derived counterpart Xhat. Subsequently, we derive and compare the resulting Kelly bets for both X and Xhat with consideration of sample size m as part of the analysis. This leads to identification of many cases which have the following salient feature: The resulting bet size using the true theoretical distribution for X is much smaller than that for Xhat. If instead the bet is based on empirical data, "golden" opportunities are identified which are essentially rejected when the purely theoretical model is used. To formalize these ideas, we provide a result which we call the Restricted Betting Theorem. An extreme case of the theorem is obtained when X has unbounded support. In this situation, using X, the Kelly theory can lead to no betting at all.Comment: Accepted in 2016 IEEE 55th Conference on Decision and Control (CDC

Deformable Mirror Demonstration Mission

The Deformable Mirror Demonstration Mission (DeMi) is a 6U cube satellite mission created to demonstrate the use of adaptive optics (AO), specifically a 140 actuator Microelectromechanical systems (MEMS) deformable mirror (DM), in space. While AO has been commonly used on ground based telescopes, it has many useful benefits in space. AO can be a critical difference in reaching the necessary contrast, of 1010, to image Earth-like exoplanets. It allows for corrections of optical imperfections and thermal distortions. These correction capabilities also allow launches of cheaper optics, and have further implications for use with inter-satellite laser communication and high energy applications. DeMi will use a closed-loop adaptive optics system, that incorporates a Shack- Hartmann wavefront sensor (SHWFS), DM, and CMOS cameras, in multiple mission operations to demonstrate the capabilities of this adaptive optics technique. DeMi will launch in to a low-Earth orbit in mid 2019. During its lifetime, DeMi will complete both internal and external observations. The internal observations will use a laser to characterize the DM and test the wavefront correction. The external observations will demonstrate the wavefront correction on stars

Geabacter species enhances pit depth on 304L stainless steel in a medium lacking with electron donor

Geobacter sulfurreducens bacteria increased the open circuit potential of 304L stainless steel by around 320 mV in only a few hours after inoculation. This represents a significant increase in the corrosion risk. In contrast, the oxidation of acetate, which is catalysed by well-established biofilms, shifted the pitting potential towards positive values. In acetate-lacking media, pitting occurred with and without bacteria in the same range of potential values, but the presence of bacteria drastically increased the size of pits. AFM showed pits more than 10 times broader and deeper due to the presence of bacteria. In the absence of acetate, the masking effect due to acetate oxidation disappeared and the full corrosive effect of the biofilm was revealed. This also fully explains why pitting was predominantly observed close to surface areas where bacterial settlement was the densest

Exploring query execution strategies for JIT vectorization and SIMD

This paper partially explores the design space for efficient query processors on future hardware that is rich in SIMD capabilities. It departs from two well-known approaches: (1) interpreted block-at-a-time execution (a.k.a. "vectorization") and (2) "data-centric" JIT compilation, as in the HyPer system. We argue that in between these two design points in terms of granularity of execution and uni

Discussing, Doing, and Teaching Audiovisual Ethnomusicology Today

Our initial encounters on the topic of audiovisual ethnomusicology in Valladolid (2014) and Ljubljana (2016) revealed a rich and diverse landscape of contemporary musical inquiry. Throughout this journey, we have identified various approaches and perspectives within our field. Looking ahead, we recognize an opportunity to reflect on the discourses and debates that have unfolded over the past years. While we celebrate the multiplicity of methodological and theoretical orientations in audiovisual research, we believe that understanding each other's perspectives requires thoughtful consideration of how we construct spaces for critical debate. Here, we summarize some key issues related to doing, discussing, and teaching audiovisual ethnomusicology. In the following pages, we explore how we might rethink the formats through which we share and promote discussion, and we outline some theoretical debates that have emerged since our inaugural meeting. Our focus is not on defining what constitutes audiovisual ethnomusicology but rather on developing vocabularies that help us better articulate and communicate our diverse approaches. This has an immediate impact on the teaching of audiovisual ethnomusicology, a discipline gaining popularity not only among scholars but also among undergraduate, postgraduate, and doctoral students. Our final aim is to open a space for debate about methods, orientations, and potential outcome

The Impact of Execution Delay on Kelly-Based Stock Trading: High-Frequency Versus Buy and Hold

Stock trading based on Kelly's celebrated Expected Logarithmic Growth (ELG) criterion, a well-known prescription for optimal resource allocation, has received considerable attention in the literature. Using ELG as the performance metric, we compare the impact of trade execution delay on the relative performance of high-frequency trading versus buy and hold. While it is intuitively obvious and straightforward to prove that in the presence of sufficiently high transaction costs, buy and hold is the better strategy, is it possible that with no transaction costs, buy and hold can still be the better strategy? When there is no delay in trade execution, we prove a theorem saying that the answer is ``no.'' However, when there is delay in trade execution, we present simulation results using a binary lattice stock model to show that the answer can be ``yes.'' This is seen to be true whether self-financing is imposed or not.Comment: Has been accepted to the IEEE Conference on Decision and Control, 201