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

New relationships involving the mean curvature of slant submanifolds in S-space-forms

Relationships between the Ricci curvature and the squared mean curvature and between the shape operator associated with the mean curvature vector and the sectional curvature function for slant submanifolds of an S-space-form are proved, particularizing them to invariant and anti-invariant submanifolds tangent to the structure vector fields.Plan Andaluz de Investigación (Junta de Andalucía