Object Computing (United States)

Robotic testbeds used for flight and research technology development are highly complicated electromechanical systems demanding large engineering effort to configure and manage safety-critical hardware. The software that interoperates with robotic testbeds needs to be robust yet flexible to accommodate rapidly changing testbed needs and other operational demands in a cost-efficient manner. The Jet Propulsion Laboratory (JPL) presents a new open-source C++ library called Fastcat for powerful and flexible EtherCAT device configuration for testbed and robotic applications. Fastcat implements a set of C drivers called `Just SOEM Drivers' built on the popular Simple Open EtherCAT Master library for a small, but highly tested set of supported EtherCAT devices. Fastcat offers a rich set of capabilities such as supporting an arbitrary number of EtherCAT Masters, a YAML input configuration file, and a visualization tool `Fcviz' to graph the bus topology using the open-source Graphiz library. Furthermore, a novel feature called `Fastcat Signals' can efficiently route data and commands between devices to compose self-contained closed loop control systems such as heaters or joint-torque controllers with zero added latency. Abstract device types like signal generators, functions, and PID controllers and offline versions of device hardware drivers allow for powerful composability, offline-only testing, and flexible hybrid partial online - offline bus topologies. The Fastcat core library is middleware agnostic, but ROS2 wrappers are developed for ease-of-use. This paper will describe design tradeoffs, an overview of the implementation of these capabilities, and early results from the first JPL Robotic testbed use.

Abstract Determining the optimal number of wells for infill drilling in an unconventional reservoir is a critical endeavor for shale gas operators as many leases are held only by production. To develop a given section, operators must select locations and completion designs for all wells. The planned well placement and completion design will dictate the economic viability and production of the field for the asset's life. The key factors impacting performance in shale gas reservoirs can be broadly divided into two categories: controllable and uncontrollable. Uncontrollable factors include rock properties such as porosity, water saturation, net-to-gross, initial pressure, permeability, natural fractures, and fluid properties. Controllable factors related to producibility that can be optimized include well design, completion design, well placement, surface facilities design, and operating conditions. Development schemes must consider both engineering and economic risks that include reduction of reservoir permeability due to rock compaction and changes in completion characteristics/efficiency. To determine optimal development, these factors have to be evaluated. This paper outlines the results of well optimization studies initiated from a production performance analysis of over 100 wells in the Haynesville Shale and over 300 wells in the Marcellus Shale. Both analytical and numerical tools were used in the presented workflow. The study results indicate a threshold of reservoir and completion properties below which any well drilled may be uneconomic based on our financial assumptions. Original gas-in-place (OGIP), rock brittleness, and fracture height containment were considered with regard to stimulated reservoir volume, SRV. The effect of natural fractures was also studied. With low gas prices, optimal capital allocation is a critical development component and is an issue that all operators face. The subsequent results presented could save operators myriad hours of simulation effort while potentially saving millions of dollars by eliminating unnecessary wells.

We use multi-band spatially resolved photometry from the Cosmic Assembly Near-IR Deep Legacy Survey (CANDELS) in the 4 MSec Chandra Deep Field-South (CDF-S) to explore the nuclear and extended colors, color gradients and stellar populations of X-ray selected AGN host galaxies out to z=3. Based on a study of their central light, we develop X-ray based criteria to exclude objects with strong AGN contamination. We use stellar masses from the FIREWORKS database to understand and account for stellar mass selection effects, and carefully study, for the first time, the resolved host galaxy properties of AGNs at z~2 in their rest-frame optical light without substantial nuclear contamination. AGN hosts span a sizable range of stellar masses, colors and color gradients at these redshifts. Their colors, color gradients and stellar population properties are very similar to inactive galaxies of the same stellar mass. At z~1, we find a slightly narrower range in host colors compared to inactive galaxies, as well as hints of more recent star-formation. These differences are weaker or non-existent among AGN hosts at z~2. We discuss the importance of AGN driven feedback in the quenching of galaxies at z>~1 and speculate on possible evolution in the relationship between black hole accretion and the host galaxy towards high redshifts.

Using natural language to communicate with computers remains a grand-challenge question. The authors LingoLogic interface technology can be seen as a widely useful human interface technology that can extend the semantic Web.

We present a revision of the hierarchical, modular Discrete Event System Specification (DEVS) modeling formalism. The revision distinguishes between transition collisions and ordinary external events in the external transition function of DEVS models. Such separation enables us to extend the modeling capability of the collisions. The revision also does away with the necessity for tie-breaking of simultaneously scheduled events, as embodied in the select function. The latter is replaced by a well-defined and consistent formal construct that allows all transitions to be simultaneously activated. The revision provides a modeler with both conceptual and parallel execution benefits.

For manageability, large agent societies incorporate features that allow for self-healing in the face of individual failures. Individual features may support or conflict with each other; thus, it may not be optimal for them to act completely autonomously. An adaptive control defense coordinator chooses and mediates such actions to repair a damaged agent society or to protect it against future problems is described. The coordinator attempts to determine the real state of the agent system in the face of multiple diagnoses, then selects a course of action from a collection of potentially conflicting defense actions. In this selection process, it takes into account both any uncertainty about the exact nature of a perceived problem and any high-level policy defining the relative importance of application properties such as completeness, timeliness and security. The coordinator described in this paper is model driven, allowing it to be deployed in a variety of settings. This also allows operators to adapt its behavior to evolving situations by making changes to human-understandable profiles of anticipated stresses or by changing high-level policy describing system goals.

The Coalition Agents Experiment aims to show that multi-agent systems offer effective tools for dealing with complex real-world problems by enabling agile and robust coalition operations and interoperability between heterogeneous military systems.

The detection of resonance absorption lines against known objects such as individual galaxies and clusters of galaxies is a powerful approach for studying the gas content of these systems. We describe an efficient method of identifying background quasars suitable for absorption line studies. In this finding technique, we identify serendipitous X-ray sources, about 1/8 of which are suitably bright quasars at moderate redshift. We identify 16 new quasars and galaxies with active galactic nuclei (AGNs), and confirm 5 known quasars and AGNs, superimposed behind elliptical galaxies and clusters of galaxies. We also present 3 QSO/AGN candidates with uncertain redshift identifications.