A Comparative Tradeoff of Electric Power System Architecture Reliabilities in CubeSat Satellites

Small nanosatellites, such as CubeSats, represent an important population of satellites that are currently commissioned in various types of scientific research missions in space travel. CubeSats are small cubic satellites that can vary in size and are most commonly deployed in the “1U” size, measuring one cubic meter. CubeSats are important in scientific research as they follow a standardized design specification, known as the CDS, which aims to normalize the cost of development and deployment, as well as act as a baseline design specification for a community of researchers, students, and inventors. The advent of CubeSat development has enabled thousands of researchers to conduct space missions, which had otherwise been too expensive and resource intensive. For CubeSats, the Electric Power System (EPS) has been documented as being the most unreliable sub-system in the CubeSat architecture. Further, it is the most critical sub-system, as a CubeSat cannot function without the EPS performing its intended functionality. While the CDS provides guidelines for CubeSat development, there is flexibility. The intent of this thesis is to analyze the reliability impact of proposed alternative EPS architectures compared to the current implementation. Alternative architectures consist of the same components as the baseline, but are arranged in varying configurations and quantities. A comparative study is performed between ten alternative EPS architectures against a baseline by determining the failure rate and Mean Time To Failure (MTTF) for each configuration. Reliability calculations are supported by determining each architecture minimal cut set and developing a corresponding Reliability Block Diagram. After, an analysis of the pros and cons between the alternative variants and the baseline is discussed. The proposed alternative architectures investigate the reliability impact of implementing distributed architectures, where redundant components and common connection busses are integrated to introduce varying levels of redundancy and operational flexibility

Human Factors Criteria for Displays: A Human Factors Design Standard Update of Chapter 5

This document contains updates and expands the design criteria and information on displays from the Human Factors Design Standard. A research team of human factors experts evaluated the existing guidelines for relevancy, clarity, and usability. They drafted new guidelines as necessary based on relevant sources, and they reorganized the document to increase usability. This resulted in extensive changes to the original document including the addition of new guidelines, sources, and topic areas

Human Factors Guidance for the Use of Handheld, Portable, and Wearable Computing Devices

This report provides human factors guidance for the selection and use of handheld, portable, and wearable computing devices, including personal digital assistants (PDAs), tablet computers, and, to a more limited extent, head-mounted display systems. These devices are becoming more common in the workplace. The Federal Aviation Administration (FAA) wanted to know if these devices would be beneficial to maintenance specialists. Human factors researchers from the William J. Hughes Technical Center were asked to identify the advantages and disadvantages of these devices. These systems require different usage guidelines than standard desktop computing systems because of their size, portability, human-computer interface (HCI) designs, and intended work environments. In this report, we discuss differences between different maintenance tasks and how these differences may affect the selection of an appropriate device. We summarize the advantages and disadvantages of common handheld, portable, and wearable systems, specifically focusing on areas such as device size, screen size and resolution, input method, one- or two-handed operation, and headsdown time

Optimal Design of Event Lists (ODELS) Phase 1: Does List Format Facilitate Visual Search for Information?

This report documents the first in a series of studies on the optimal design of event lists (ODELs) for Technical Operations use. The ODELs study described in this report examines whether event list format has an impact on user performance when searching for information. The stimuli consisted of four different list formats: delineated, non-delineated, ledger shading, and white text on a blue background. These formats represented list formats currently in existence in the operational environment. Researchers measured task completion time, accuracy, and eye-scanning metrics such as number of fixations, fixation duration, blink frequency, pupil diameter, and number of reversals. Additionally, researchers collected subjective ratings of difficulty and preference rankings for each of the four conditions. The results indicated that the list design did not have a significant impact on task completion time or the number or duration of fixations. However, list design did appear to impact the error rate, subjective ratings of difficulty, and user preference. Participants made fewer errors in the ledger shading and delineated conditions, rated them as less difficult, and ranked them as most preferred

Casting a Wide Net: HIV Drug Resistance Monitoring in Pre-Exposure Prophylaxis Seroconverters in the Global Evaluation of Microbicide Sensitivity Project

Background: Evidence of HIV drug resistance (HIVDR) in individuals using oral pre-exposure prophylaxis (PrEP) who acquire HIV is limited to clinical trials and case studies. More data are needed to understand the risk of HIVDR with oral PrEP during PrEP rollout. Mechanisms to collect these data vary, and are dependent on cost, scale of PrEP distribution, and in-country infrastructure for the identification, collection, and testing of samples from PrEP seroconverters. / Methods: The Global Evaluation of Microbicide Sensitivity (GEMS) project, in collaboration with country stakeholders, initiated HIVDR monitoring among new HIV seroconverters with prior PrEP use in Eswatini, Kenya, South Africa, and Zimbabwe. Standalone protocols were developed to assess HIVDR among a national sample of PrEP users. In addition, HIVDR testing was incorporated into existing demonstration projects for key populations. / Lessons learned: Countries are supportive of conducting a timelimited evaluation of HIVDR during the early stages of PrEP rollout. As PrEP rollout expands, the need for long-term HIVDR monitoring with PrEP will need to be balanced with maintaining national HIV drug resistance surveillance for pretreatment and acquired drug resistance. Laboratory capacity is a common obstacle to setting up a monitoring system. / Conclusions: Establishing HIV resistance monitoring within PrEP programs is feasible. Approaches to drug resistance monitoring may evolve as the PrEP programs mature and expand. The methods and implementation support offered by GEMS assisted countries in developing methods to monitor for drug resistance that best fit their PrEP program needs and resources

Casting a Wide Net: HIV Drug Resistance Monitoring in Pre-Exposure Prophylaxis Seroconverters in the Global Evaluation of Microbicide Sensitivity Project.

BACKGROUND: Evidence of HIV drug resistance (HIVDR) in individuals using oral pre-exposure prophylaxis (PrEP) who acquire HIV is limited to clinical trials and case studies. More data are needed to understand the risk of HIVDR with oral PrEP during PrEP rollout. Mechanisms to collect these data vary, and are dependent on cost, scale of PrEP distribution, and in-country infrastructure for the identification, collection, and testing of samples from PrEP seroconverters. METHODS: The Global Evaluation of Microbicide Sensitivity (GEMS) project, in collaboration with country stakeholders, initiated HIVDR monitoring among new HIV seroconverters with prior PrEP use in Eswatini, Kenya, South Africa, and Zimbabwe. Standalone protocols were developed to assess HIVDR among a national sample of PrEP users. In addition, HIVDR testing was incorporated into existing demonstration projects for key populations. LESSONS LEARNED: Countries are supportive of conducting a time-limited evaluation of HIVDR during the early stages of PrEP rollout. As PrEP rollout expands, the need for long-term HIVDR monitoring with PrEP will need to be balanced with maintaining national HIV drug resistance surveillance for pretreatment and acquired drug resistance. Laboratory capacity is a common obstacle to setting up a monitoring system. CONCLUSIONS: Establishing HIV resistance monitoring within PrEP programs is feasible. Approaches to drug resistance monitoring may evolve as the PrEP programs mature and expand. The methods and implementation support offered by GEMS assisted countries in developing methods to monitor for drug resistance that best fit their PrEP program needs and resources

Safety Evaluation Report related to Hydrogen Control Owners Group assessment of Mark 3 containments

Title 10 of the Code of Federal Regulations (10 CFR), Section 50.44 Standards for Combustible Gas Control System in Light-Water-Cooled Power Reactors,'' requires that systems be provided to control hydrogen concentration in the containment atmosphere following an accident to ensure that containment integrity is maintained. The purpose of this report is to provide regulatory guidance to licensees with Mark III containments with regard to demonstrating compliance with 10 CFR 50.44, Section (c)(3)(vi) and (c)(3)(vii). In this report, the staff provides its evaluation of the generic methodology proposed by the Hydrogen Control Owners Group. This generic methodology is documented in Topical Report HGN-112-NP, Generic Hydrogen Control Information for BWR/6 Mark III Containments.'' In addition, the staff has recommended that the vulnerability to interruption of power to the hydrogen igniters be evaluated further on a plant-specific basis as part of the individual plant examination of the plants with Mark III containments. 10 figs., 1 tab

Diiron macrocyclic catalysts for oxidation, oxidative dehalogenation and C-C bond formation

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