1,194,102 research outputs found
Single Value Devices
We live in a world of continuous information overflow, but the quality of information and communication is suffering. Single value devices contribute to the information and communication quality by fo- cussing on one explicit, relevant piece of information. The information is decoupled from a computer and represented in an object, integrates into daily life. However, most existing single value devices come from conceptual experiments or art and exist only as prototypes. In order to get to mature products and to design meaningful, effective and work- ing objects, an integral perspective on the design choices is necessary. Our contribution is a critical exploration of the design space of single value devices. In a survey we give an overview of existing examples. The characterizing design criteria for single value devices are elaborated in a taxonomy. Finally, we discuss several design choices that are specifically important for moving from prototypes to commercializable products
Single value devices
Ein Single Value Device ist ein physisches Objekt in unserer alltaĚglichen Umgebung, das genau eine Art von Information oder Mitteilung anzeigt. Dabei kann es sich um den GemuĚtszustand der GroĂmutter handeln, um das Wetter am Urlaubsort oder um die Zeit, die zum FruĚhstuĚcken bleibt, bevor man bei der aktuellen Verkehrslage zur Arbeit aufbrechen muss. Der Fokus auf persoĚnlich relevante Informationen bildet dabei einen Gegensatz zum InformationsuĚberfluss im Internet. Die Anzeige durch das physische Objekt kommt unseren kognitiven FaĚhigkeiten entgegen. Beide Faktoren tragen dabei zur sogenannten calm technology1 bei, die der Beruhigung und BewaĚltigung dieser Informationsflut dienen soll. Die individuellen Bedeutungen, die der Form und dem Inhalt der Objekte zugeschrieben werden koĚnnen, sind wichtig fuĚr die EffektivitaĚt von Single Value Devices. Wir stellen hier die Frage, welche MoĚglichkeiten Designerinnen und Designer haben, Single Value Devices so zu entwerfen, dass Benutzerinnen und Benutzer die MoĚglichkeit bekommen, diesen Objekten persoĚnliche Bedeutungen zu geben und sie auf diese Weise als Schnittstellen einzusetzen
Shot Noise in Graphene
We report measurements of current noise in single- and multi-layer graphene
devices. In four single-layer devices, including a p-n junction, the Fano
factor remains constant to within +/-10% upon varying carrier type and density,
and averages between 0.35 and 0.38. The Fano factor in a multi-layer device is
found to decrease from a maximal value of 0.33 at the charge-neutrality point
to 0.25 at high carrier density. These results are compared to theoretical
predictions for shot noise in ballistic and disordered graphene.Comment: related papers available at http://marcuslab.harvard.ed
1/f noise in graphene
We present a novel and comprehensive model of 1/f noise in nanoscale graphene
devices that accounts for the unusual and so far unexplained experimental
characteristics. We find that the noise power spectral density versus carrier
concentration of single-layer sheet devices has a behavior characterized by a
shape going from the M to the Gamma type as the material inhomogeneity
increases, whereas the shape becomes of V type in bilayer sheet devices for any
inhomogeneity, or of M type at high carrier concentration. In single-layer
nanoribbons, instead, the ratio of noise to resistance versus the latter
quantity is approximately constant, whereas in the bilayer case it exhibits a
linear decrease on a logarithmic scale as resistance increases and its limit
for zero resistance equals the single-layer value. Noise at the Dirac point is
much greater in single-layer than in bilayer devices and it increases with
temperature. The origin of 1/f noise is attributed to the traps in the device
and to their relaxation time dispersion. The coupling of trap charge
fluctuations with the electrode current is computed according to the
electrokinematics theorem, by taking into account their opposite effects on
electrons and holes as well as the device inhomogeneities. The results agree
well with experiments.Comment: 27 pages, 5 figures. The final publication is available at
link.springer.co
Field-Effect Transistors on Tetracene Single Crystals
We report on the fabrication and electrical characterization of field-effect
transistors at the surface of tetracene single crystals. We find that the
mobility of these transistors reaches the room-temperature value of $0.4 \
cm^2/Vs$. The non-monotonous temperature dependence of the mobility, its weak
gate voltage dependence, as well as the sharpness of the subthreshold slope
confirm the high quality of single-crystal devices. This is due to the
fabrication process that does not substantially affect the crystal quality.Comment: Accepted by Appl. Phys. Lett, tentatively scheduled for publication
in the November 24, 2003 issu
Thermoelectric bolometers based on ultra-thin heavily doped single-crystal silicon membranes
We present ultra-thin silicon membrane thermocouple bolometers suitable for
fast and sensitive detection of low levels of thermal power and infrared
radiation at room temperature. The devices are based on 40 nm-thick strain
tuned single crystalline silicon membranes shaped into heater/absorber area and
narrow n- and p-doped beams, which operate as the thermocouple. The
electro-thermal characterization of the devices reveal noise equivalent power
of 13 pW/rtHz and thermal time constant of 2.5 ms. The high sensitivity of the
devices is due to the high Seebeck coefficient of 0.39 mV/K and reduction of
thermal conductivity of the Si beams from the bulk value. The bolometers
operate in the Johnson-Nyquist noise limit of the thermocouple, and the
performance improvement towards the operation close to the temperature
fluctuation limit is discussed.Comment: 11 pages, 3 figure
Analytical Modeling of a Novel High-\u3cem\u3eQ\u3c/em\u3e Disk Resonator for Liquid-Phase Applications
To overcome the detrimental effects of liquid environments on microelectromechanical systems resonator performance, the in-fluid vibration of a novel disk resonator supported by two electrothermally driven legs is investigated through analytical modeling and the effects of the systemâs geometric/material parameters on the dynamic response are explored. The all-shear interaction device (ASID) is based on engaging the surrounding fluid primarily through shearing action. The theory comprises a continuous-system, multimodal model, and a single-degree-of-freedom model, the latter yielding simple formulas for the fundamental-mode resonant characteristics that often furnish excellent estimates to the results based on the more general model. Comparisons between theoretical predictions and previously published liquid-phase quality factor (Q) data (silicon devices in heptane) show that the theoretical results capture the observed trends and also give very good quantitative estimates, particularly for the highest Q devices. Moreover, the highest Q value measured in the earlier study (304) corresponded to a specimen whose disk radius-to-thickness ratio was 2.5, a value that compares well with the optimal value of 2.3 predicted by the present model. The insight furnished by the proposed theory is expected to lead to further improvements in ASID design to achieve unprecedented levels of performance for a wide variety of liquid-phase resonator applications
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