The Amazing Blue Dot: How Earth's Biology Is Inspiring Engineering for the Stars

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Robotic Specialization in Autonomous Robotic Structural Assembly

Robotic in-space assembly of large space structures is a long-term NASA goal to reduce launch costs and enable larger scale missions. Recently, researchers have proposed using discrete lattice building blocks and co-designed robots to build high-performance, scalable primary structure for various on-orbit and surface applications. These robots would locomote on the lattice and work in teams to build and reconfigure building-blocks into functional structure. However, the most reliable and efficient robotic system architecture, characterized by the number of different robotic 'species' and the allocation of functionality between species, is an open question. To address this problem, we decompose the robotic building-block assembly task into functional primitives and, in simulation, study the performance of the the variety of possible resulting architectures. For a set consisting of five process types (move self, move block, move friend, align bock, fasten block), we describe a method of feature space exploration and ranking based on energy and reliability cost functions. The solution space is enumerated, filtered for unique solutions, and evaluated against energy and reliability cost functions for various simulated build sizes. We find that a 2 species system, dividing the five mentioned process types between one unit cell transport robot and one fastening robot, results in the lowest energy cost system, at some cost to reliability. This system enables fastening functionality to occupy the build front while reducing the need for that functional mass to travel back and forth from a feed station. Because the details of a robot design affect the weighting and final allocation of functionality, a sensitivity analysis was conducted to evaluate the effect of changing mass allocations on architecture performance. Future systems with additional functionalities such as repair, inspection, and others may use this process to analyze and determine alternative robot architectures

Androgynous Fasteners for Robotic Structural Assembly

We describe the design and analysis of an androgynous fastener for autonomous robotic assembly of high performance structures. The design of these fasteners aims to prioritize ease of assembly through simple actuation with large driver positioning tolerance requirements, while producing a reversible mechanical connection with high strength and stiffness per mass. This can be applied to high strength to weight ratio structural systems, such as discrete building block based systems that offer reconfigurability, scalability, and system lifecycle efficiency. Such periodic structures are suitable for navigation and manipulation by relatively small mobile robots. The integration of fasteners, which are lightweight and can be robotically installed, into a high performance robotically managed structural system is of interest to reduce launch energy requirements, enable higher mission adaptivity, and decrease system life-cycle costs

Therapeutic alliance in psychological therapy for people with recent onset psychosis who use cannabis

Background This paper examines the role of therapeutic alliance in predicting outcomes in a Randomised Controlled Trial of Motivational Interviewing and Cognitive Behavioural Therapy (MICBT) for problematic cannabis use in recent onset psychosis. Methods All clients were participating in a three arm pragmatic rater-blind randomised controlled trial of brief MICBT plus standard care compared with longer term MICBT plus standard care and standard care alone. Participants completed measures to assess clinical symptoms, global functioning and substance misuse at baseline, 4.5 months, 9 months and 18 months. Clients and therapists completed the Working Alliance Inventory approximately one month into therapy. Client alliance data was available for 35 participants randomised to therapy and therapist alliance data was available for 52 participants randomised to therapy. Results At baseline, poorer client-rated alliance was associated with more negative symptoms, poorer insight and greater cannabis use, whereas poorer therapist-rated alliance was only associated with amount of cannabis used per cannabis using day. Alliance ratings were also positively associated with amount of therapy: client-rated alliance was higher in the longer compared to the briefer therapy; therapist-rated alliance was associated with greater number of sessions attended (controlling for type of therapy) and therapy completion. In predicting outcome, client-rated alliance predicted total symptom scores and global functioning scores at follow-up. Neither client nor therapist alliance predicted changes in substance misuse at any time point. Conclusions Findings demonstrate that individuals with psychosis and substance misuse who form better alliances with their therapists gain greater benefits from therapy, at least in terms of improvements in global functioning

Characterizing Material Scalability for Ultralight Lattice Design

Stiff yet ultra-light lattice structures constructed using digital materials have many practical applications as the building block for aircraft and other structures. By furthering our understanding of how material configuration affects the structural properties of an ultralight lattice, we can intelligently design these structures based on their intended function. Here we compare the behavior of ultralight lattice structures when fabricated by different materials. The individual unit cells of the lattice structures are referred to as voxels. The stiffness, elastic modulus, and yield strength of the specimens in compression and tension are determined through mechanical testing. Specimens are tested both as single voxel as well as 4x4x4 voxel constructions on an Instron 5982 Universal Testing System until failure. Each voxel is manufactured in bulk through injection molding, with a unit cell pitch of 76.2 mm. Individual voxels are fastened with machine screws and nuts to create assemblies. Four separate materials are used as voxel compositions in this experiment. These include a homogeneous polymer referred to as Ultem 1000, a glass-fiber reinforced polymer referred to as Ultem 2200, a polymer with chopped carbon fibers as 30% of its fill, and homogenous polypropylene. This work compares mechanical behavior, as well as the convergence behavior of the lattice as the size of the lattice assembly increases for various materials. The goal of this study is to characterize the behavior of homogenous lattices such that heterogenous lattices can be designed with different material voxels to achieve target material properties for ultralight space applications

Meso-Scale Digital Materials: Modular, Reconfigurable, Lattice-Based Structures

We present a modular, reconfigurable system for building large structures. This system uses discrete lattice elements, called digital materials, to reversibly assemble ultralight structures that are 99.7% air and yet maintain sufficient specific stiffness for a variety of structural applications and loading scenarios. Design, manufacturing, and characterization of modular building blocks are described, including struts, nodes, joints, and build strategies. Simple case studies are shown using the same building blocks in three different scenarios: a bridge, a boat, and a shelter. Field implementation and demonstration is supplemented by experimental data and numerical simulation. A simplified approach for analyzing these structures is presented which shows good agreement with experimental results

Mom Made Me: Students Respond to the Flu Shot

The University of Tennessee Knoxville’s on-campus Student Health Center publicizes the opportunity for students to receive the influenza immunization for $25 during the flu season. Despite on-campus convenience, many students are still deterred from receiving the shot. Advertising and Public Relations research students used survey research to sample more than 200 students in six major colleges across the University of Tennessee’s campus. The research team gathered relevant information about student perceptions of a healthy lifestyle, flu experience (diagnosis and shot), motivations and deterrence from the flu shot, and general knowledge of the Student Health Center. Results show that 27.5% of student respondents received a flu shot in the past year; key deterrents from receiving the immunization for both genders are inconvenience and lack of experience with the virus. The survey results indicate relationships among class year in school and the influences on individual health. Through these findings, the research team developed recommendations for the Student Health Center in regards to advertising campaigns, media relations, and specific targeting associated with year in school

Optical Measurement System for Strain Field Ahead of a Crack Tip for Lattice Structures

The aim of the ARAMADAS project is to automate the construction of cuboctahedral lattice structures. Lattice materials are appealing for aerospace applications due to their strength and stiffness at ultra-light densities. However, in order for any material to be realistically considered for such environments, it must also be damage tolerant. The ability of a material to absorb damage is characterized by its fracture toughness, which remains poorly characterized for lattice materials. Consequently, the objective of this research is to develop an optical measurement system to experimentally validate the strain field ahead of a crack tip in architecture lattice materials. Although the ability to predict the strain field ahead of a crack tip has been investigated for continuum materials, such behaviour of three-dimensional architectures is under-investigated. As such, we will use a custom optical measurement system to track deformation of the voxels in a side-cracked plate fracture specimen. The system shall use 3D pose estimation, stereo imaging, and possibly color tracking, in combination with optical flow algorithms, to compute information regarding the three-dimensional movement movement of the lattice nodes during mechanical testing. Bench top experiments will validate the optical measurement system and characterize precision. Additionally, the effect of multiple cameras on precision, as well as system scalability will be investigated. Final results will compare measured lattice deformation with finite element predictions