Tape recorder Patent

Tape recorder designed for low power consumption and resistance to operational failure under high stress condition

An improved magnetic tape recorder

Magnetic tape recorder employs a single capstan for simultaneously driving the supply and take-up reels in such a manner that the tape passing between the reels is kept under a predetermined constant tension. This recorder operates with little power and is sufficiently rugged to withstand the severe stresses encountered in high-altitude balloon flight tests

Software system safety

Software itself is not hazardous, but since software and hardware share common interfaces there is an opportunity for software to create hazards. Further, these software systems are complex, and proven methods for the design, analysis, and measurement of software safety are not yet available. Some past software failures, future NASA software trends, software engineering methods, and tools and techniques for various software safety analyses are reviewed. Recommendations to NASA are made based on this review

Thinking infrastructures and decentering digital platforms in the sharing economy: from matchmaking to boundary making

While digital platforms tend to be unproblematically presented as the infrastructure of the sharing economy – as matchmakers of supply and demand – the authors argue that constituting the boundaries of infrastructures is political and performative, that is, it is implicated in ontological politics, with consequences for the distribution of responsibilities (Latour, 2003; Mol, 1999, 2013; Woolgar & Lezaun, 2013). Drawing on an empirical case study of Uber, including an analysis of court cases, the authors investigate the material-discursive production of digital platforms and their participation in the reconfiguring of the world (Barad, 2007), and examine how the (in)visibility of the digital infrastructure is mobilized (Larkin, 2013) to this effect. The authors argue that the representation of Uber as a “digital platform,” as “just the technological infrastructure” connecting car drivers with clients, is a political act that attempts to redefine social responsibilities, while obscuring important dimensions of the algorithmic infrastructure that regulates this socioeconomic practice. The authors also show how some of these (in)visibilities become exposed in court, and some of the boundaries reshaped, with implications for the constitution of objects, subjects and their responsibilities. Thus, while thinking infrastructures do play a role in regulating and shaping practice through algorithms, it could be otherwise.Thinking infrastructures relationally decentre digital platforms and encourage us to study them as part of ongoing and contested entanglements in practice

Time Domain Analysis of Electromagnetic Scattering From Multiple Cavities Embedded in a Ground Plane

This work examines the scattered fields produced when a transient wave is reflected from an infinite perfect electric conductor (PEC) ground plane with multiple embedded cavities. Incident and reflected waves will be decomposed into transverse magnetic to the z direction (TMz) and transverse electric to the z direction (TEz) polarizations, with primary focus given to the TMz. Cavities may be unfilled, partially filled, or fully filled with non-magnetic dielectric material and no assumptions are made regarding similarity, regularity, or periodicity. The Newmark method is used to discretize time and a variational formulation is presented for each time step. The principle outcome is to show that the variational formulation of the scalar problem is well posed. Additionally, the variational formulation is applied in a stable numerical model using the finite element-boundary integral (FE-BI) method. Interior fields are approximated using the finite element method (FEM) for each time step, then the boundary integral is applied using the appropriate Green’s function to approximate exterior scattered fields. The exterior fields for one time step provide the boundary conditions for the interior problem at the next time step. In this way, the numerical model marches through time. Various numerical experiments are run to examine the effect of coupling on aperture and external fields. Of particular interest are the differences between single-cavity and multiple-cavity solutions

How Do Modeling Choices and Erosion Zone Locations Impact the Representation of Connectivity and the Dynamics of Suspended Sediments in a Multi-Source Soil Erosion Model?

[Abstract] Soil erosion and suspended sediment transport understanding is an important issue in terms of soil and water resources management in the critical zone. In mesoscale watersheds (>10 km2) the spatial distribution of potential sediment sources within the catchment associated with rainfall dynamics is considered to be the main factor in the observed suspended sediment flux variability within and between runoff events. Given the high spatial heterogeneity that can exist for such scales of interest, distributed physically based models of soil erosion and sediment transport are powerful tools to distinguish the specific effect of structural and functional connectivity on suspended sediment flux dynamics. As the spatial discretization of a model and its parameterization can crucially influence how the structural connectivity of the catchment is represented in the model, this study analyzed the impact of modeling choices in terms of the contributing drainage area (CDA) threshold to define the river network and of Manning's roughness parameter (n) on the sediment flux variability at the outlet of two geomorphologically distinct watersheds. While the modeled liquid and solid discharges were found to be sensitive to these choices, the patterns of the modeled source contributions remained relatively similar when the CDA threshold was restricted to the range of 15 to 50 ha, with n restricted to the range 0.4–0.8 on the hillslopes and to 0.025–0.075 in the river. The comparison of the two catchments showed that the actual location of sediment sources was more important than the choices made during discretization and parameterization of the model. Among the various structural connectivity indicators used to describe the geological sources, the mean distance to the stream was the most relevant proxy for the temporal characteristics of the modeled sedigraphs.Francia. Agence Nationale de la Recherche; ANR-11-EQPX-0011This research has been supported by the Draix Bléone and OHMCV long-term observatories, funded by the National Institute of Science of the Universe, for access to datasets and the OZCAR research infrastructure (grant no. ANR-11-EQPX-0011)