Evaluation of unmanned aerial vehicle tactics through the metrics of survivability

Aircraft survivability is a classical consideration of combat aircraft design and tactical development, but the fundamental model of aircraft survivability must be updated to be able to consider modern tactical scenarios that are applicable to unmanned aircraft. This paper seeks therefore to define the set of design tradeoffs and an evaluation of the tactical effectiveness for unmanned aircraft survivability. Traditional and modern survivability evaluation methods are presented and integrated into a computational simulation to create a probabilistic evaluation of unmanned aircraft survivability. The results demonstrate the development of design tradeoffs for a hypothetical unmanned C-130J Hercules against a single man-portable air defense system. The discussion focuses on the demonstration of the utility of this survivability evaluation framework for consideration of survivability in unmanned aerial vehicle (UAV) design, the utility of considering survivability in the design of multi-UAV configurations (including the loyal wingman and swarms), and the value of the probabilistic survivability model for multi-aircraft simulations.

Experimental Evaluation of Dewar Volume and Cryocooler Cold Finger Size in a Small-Scale Stirling Liquid Air Energy Storage (LAES) System

This paper uses an experimental approach to evaluate two design characteristics for a liquid air energy storage (LAES) and generation system as part of the design analysis for a microgrid power system. The system evaluated utilized a Stirling engine based cryocooler that employs a coldfinger placed into a Dewar. Using a design of experiments, the cold finger surface area and Dewar volume were evaluated to determine the criticality and significance of changing their dimensions. Evaluations were made against the total liquid air production mass and average liquid air production rate during the experiments. This analysis found that changing the surface area of the cryocooler cold finger was a statistically significant design characteristic that affected total liquid air production and average production rate while changing the volume of the Dewar was not statistically significant. Additional responses relative to the time when the first gram of liquid air was produced and the minimum cold tip temperature that the cryocooler was able to achieve provided additional insight into design characteristics that can be used to inform the engineer when making design tradeoffs for specific operational environments.

multiverse: Multiplexing Alternative Data Analyses in R Notebooks

There are myriad ways to analyze any given dataset. But which one to trust? In the face of such uncertainty, analysts adopt multiverse analysis: running all reasonable analyses on the dataset. Yet this is cognitively and technically difficult with existing tools—how does one specify and execute all combinations of reasonable analyses of a dataset?—and often requires discarding existing workflows. We present multiverse, a tool for implementing multiverse analyses in R with expressive syntax supporting existing computational notebook workflows. Informed by iterative user testing, multiverse supports building up a multiverse through local changes to a single analysis and optimises execution by pruning redundant computations. We evaluate four existing multiverse tools (including multiverse) using principles of cognitive ergonomics.We identify design tradeoffs (e.g. flexibility in locally defining decisions versus making it easy to understand a multiverse’s global structure), and suggest future directions for multiverse tool design, like more effective debugging support.

CONSTRAINT-BASED ANALYSIS OF PARALLEL KINEMATIC ARTICULATED WRIST MECHANISM

This paper presents a systematic constraint-based analysis of the performance attributes of eight parallel kinematic articulated wrist mechanisms from the existing literature. These performance attributes include the number, nature (i.e. pure rotation, or translation, or a combination), and location of a mechanism's Degrees of Freedom (DoFs) in the nominal and displaced configurations, load transmission capability along these DoFs, and load bearing capability along the constraint directions. This systematic analysis reveals performance tradeoffs between these performance attributes for a given mechanism, as well as design tradeoffs across these mechanisms. This analysis also helps inform the suitability of a given mechanism for specific applications.

A Blueprint for Scaling Tutoring and Mentoring Across Public Schools

In this thought experiment, we explore how to make access to individualized instruction and academic mentoring more equitable by taking tutoring to scale as a permanent feature of the U.S. public education system. We first synthesize the tutoring and mentoring literature and characterize the landscape of existing tutoring programs. We then outline a blueprint for integrating federally funded and locally delivered tutoring into the school day. High school students would serve as tutors/mentors in elementary schools via an elective class, college students in middle schools via federal work-study, and 2- and 4-year college graduates in high schools via AmeriCorps. We envision an incremental, demand-driven expansion process with priority given to high-needs schools. Our blueprint highlights a range of design tradeoffs, implementation challenges, and program costs. We estimate that targeted approaches to scaling school-wide tutoring nationally, such as focusing on K–8 Title I schools, would cost between $5 and $16 billion annually.

Constraint-Based Analysis of Parallel Kinematic Articulated Wrist Mechanisms

This paper presents a systematic constraint-based analysis of the motion attributes of six parallel kinematic articulated wrist mechanisms from the existing literature. These motion attributes include the number, nature (i.e. pure rotation, or translation, or a combination), and location of mechanism’s Degrees of Freedom (DoFs) in the nominal and displaced configurations, range of operation along these DoFs, load transmission capability along these DoFs, and load bearing capability along the constraint directions. This systematic analysis reveals performance tradeoffs between these motion attributes for a given mechanism, as well as design tradeoffs across these multiple mechanisms with respect to these motion attributes. This analysis should help inform the suitability of a given mechanism for specific applications.