AAC (United States)

This book clarifies best practices for creating high-functioning data integration teams, enabling you to understand the skills and requirements, documents.

Abstract Defense and Aerospace applications increasingly rely on commercial off-the shelf electronics. Electronics in defense applications may be exposed to harsh environments including high-g acceleration loads. The horizontal board configuration is most frequently tested. However, other shock orientations may be more damaging depending on technology and design. The out-of-plane displacement and strain values highly depend on the angle of shock on the electronic components in the printed circuit board. The effect of variation in drop angle under high G conditions, and efficacy of supplemental restraint mechanisms on the reliability have not been studied at high-g acceleration loads in the range of 10,000g–50,000g. In this study the reliability of fine-pitch electronics and large 3640 capacitors with C0G dielectric has been studied in presence of potting compounds, different shock orientations. A circular printed circuit board has been designed with daisy-chained packages. The drop angle has been varied from zero-degree to 30-degree. A drop-tower with dual mass shock amplifier has been used to achieve the desired acceleration pulse. Transient dynamic deformation has been measured using high-speed imaging in conjunction with digital image correlation.

Survivability of fine-pitch electronics at high-g loads requires the use of additional structural support and shock damping through the use of potting-materials. The potting compounds may serve additional functions including the ability to sustain thermo-mechanical loads and the high humidity in transport, storage and use environments. Failure of potted assemblies has been shown to be at the interface between the potting material and the printed circuit board. There is a dearth of computational tools to allow for the prediction of the initiation of damage and the progression of damage under high-g shock loads. Defense electronics and military systems have longer lifetimes in the neighborhood of 20-40 years and higher reliability requirements. New packaging architectures, which often push the edge of the envelope in terms of miniaturization, cannot be compared with the state-of-art systems and lack decades of historical data to provide robust proof of their survivability. Tools and techniques are needed to determine the failure envelopes for new component technologies for operation under high acceleration loads in current and next generation military systems. Component's survivability in a product is influenced by many factors including board construction, board size, board thickness, and component design rules. The same component may have large variance in shock survivability depending on the product implementation. The fracture properties and interfacial crack delamination of the PCB/epoxy interface was determined using three-point bend loading with a pre-crack in the epoxy near the interface. The fracture toughness and crack initiation of the three-epoxy systems was compared with the cure schedule and temperature. A finite element model framework was developed for a circular PCB with fine pitch BGA packages, which are encapsulated with potting material. The interface between the PCB and the potting compound was modeled using cohesive zone elements. The test assembly model was subjected to high-g mechanical shock loads up to 25,000g.

Mechanical drop testing and reliability of BGA electronics in consumer markets is conducted using the JEDEC JESD22-B111 standard. The JEDEC form factor PCB may not be suited for use in part survivability assessment at very high-g levels up to 25,000g. Product board geometries may need to be considered for survivability assessment in fuzing applications. Commercial-off-the-Shelf (COTS) parts like fine pitch BGAs of 0.4mm and 0.5mm pitch are increasingly being used for military and defense applications. Use of fine pitch Ball Grid Array (BGA) technology is preferred over the other packaging technologies due to relative ease of procurement relative to leaded parts, high level of integration with small foot print. Commercial parts may need supplemental restraints in form of underfills, and potting compounds to meet the reliability requirement of extreme-acceleration applications such as fuzing. Survivability of fine pitch semiconductor packages under high-g mechanical shock in the range of 10,000g–25,000g is unknown. In addition, the efficacy of the traditional supplemental restraint mechanisms such as underfills and potting in reducing the risk of interconnect failure under high-g mechanical shock, is not available. In this study, instead of using a JEDEC form-factor board, a product form-factor circular board with annular ring typical of end product projectile applications under harsh high-g operating environments of 25,000g was studied. Five different BGA packages of interconnects ranging from 84–360 I/O have been studied. Three configurations of the test board have been studied including non-underfilled, underfilled and potted assemblies. Lord Thermoset ME-531 has been used to underfill the packages in this test study. Two categories of potting compounds have been used including Armstrong A12 is a low modulus material and Henkel STYCAST 2850FT is a high modulus material intended for shock applications. Data on the survivability of BGA's using supplemental restraint mechanisms like underfill reinforcing the packages and potting the PCB with epoxies is presented. Modal analysis of the unreinforced and supplemental restraint configurations has been done to understand the frequency response of the configurations.

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We present a fully-dynamic multi-commodity Network Flow Model (NetFM) representation of the National Airspace System (NAS). NetFM is a high-level aggregate model incorporating time-varying demand and capacity profiles to define the optimal routing and scheduling of all NAS traffic within a matter of minutes. NetFM routing solutions are not limited to a set of user-inputted route options. Rather, spatial-temporal flight paths are computed through a hexagonal network of nodes and arcs over successive time steps. We present the NetFM formulation. NetFM results include a set of diagnostics which show predicted capacity, traffic flow patterns, and regions where additional capacity would be most beneficial. These diagnostic results may offer improved situational awareness and decision support to Traffic Flow Management (TFM) planners. NetFM capabilities also enable a laboratory in which TFM researchers can study advanced TFM concepts such as integrated airspace flow and ground delay programs.

The concept of “relational consciousness” has gained increasing attention in the last decades in the fields of philosophy, sociology, and psychotherapy. Yet human consciousness with its concomitant awareness of self and other as distinct is linguistically and culturally situated in the individual mind. This article explores the lived experience of shared consciousness in the practice of “becoming the other” with a focus on therapy with one couple. The historical development of our understanding of consciousness as a relational phenomenon is addressed with particular attention to the observations, insights, and practices of Lev Vygotsky, George Herbert Mead, and Gregory Bateson, who have each contributed substantially to our understanding of mind as relationally experienced and constructed. The article explores implications for practice and future directions this methodology might take.

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