23,677 research outputs found
Construction and Characterization of a Frequency-Controlled, Picometer-Resolution, Displacement Encoder-Actuator
We have constructed an actuator/encoder whose generated displacement is
controlled through the resonance frequency of a microwave cavity. A compact,
10-micrometer-range, digitally-controlled actuator executing frequency-coded
displacement with picometer resolution is described. We consider this approach
particularly suitable for metrologic-precision scanning probe microscopy.Comment: 4 pages, 4 figure
Limits on Fundamental Limits to Computation
An indispensable part of our lives, computing has also become essential to
industries and governments. Steady improvements in computer hardware have been
supported by periodic doubling of transistor densities in integrated circuits
over the last fifty years. Such Moore scaling now requires increasingly heroic
efforts, stimulating research in alternative hardware and stirring controversy.
To help evaluate emerging technologies and enrich our understanding of
integrated-circuit scaling, we review fundamental limits to computation: in
manufacturing, energy, physical space, design and verification effort, and
algorithms. To outline what is achievable in principle and in practice, we
recall how some limits were circumvented, compare loose and tight limits. We
also point out that engineering difficulties encountered by emerging
technologies may indicate yet-unknown limits.Comment: 15 pages, 4 figures, 1 tabl
Sensitivity Gains by Mismatched Probabilistic Shaping for Optical Communication Systems
Probabilistic shaping of quadrature amplitude modulation (QAM) is used to
enhance the sensitivity of an optical communication system. Sensitivity gains
of 0.43 dB and 0.8 dB are demonstrated in back-to-back experiments by shaping
of 16QAM and 64QAM, respectively. Further, numerical simulations are used to
prove the robustness of probabilistic shaping to a mismatch between the
constellation used and the signal-to-noise ratio (SNR) of the channel. It is
found that, accepting a 0.1 dB SNR penalty, only four shaping distributions are
required to support these gains for 64QAM.Comment: Title and introduction were updated and the discussion of Section
IV-B was extended. Additionally, some minor modifications were made to the
manuscrip
An effective AMS Top-Down Methodology Applied to the Design of a Mixed-SignalUWB System-on-Chip
The design of Ultra Wideband (UWB) mixed-signal SoC for localization applications in wireless personal area networks is currently investigated by several researchers. The complexity of the design claims for effective top-down methodologies. We propose a layered approach based on VHDL-AMS for the first design stages and on an intelligent use of a circuit-level simulator for the transistor-level phase. We apply the latter just to one block at a time and wrap it within the system-level VHDL-AMS description. This method allows to capture the impact of circuit-level design choices and non-idealities on system performance. To demonstrate the effectiveness of the methodology we show how the refinement of the design affects specific UWB system parameters such as bit-error rate and localization estimations
Strategies for Implementing a Mass Digitization Program
[Excerpt] In 2007, OCLC published the report Shifting Gears: Gearing Up to Get Into the Flow to bring to the forefront a much needed conversation about digitization of archival collections, and access to the rich content accessible only through paper or other analog formats. The authors emphasized that any successful large digitization program would focus on access and quantity. They challenged archivists to rethink policies, procedures, and technologies that either slowed the process of mass digitization, or were unfriendly to the implementation of a rapid capture program. Recent articles, blog posts, and columns demonstrate that we as a profession continue to grapple with ways to implement digitization programs that are both sustainable and efficient. The strategies offered in this paper highlight a practical program for the mass digitization of organizational archival records using a rapid capture process that is replicable regardless of the size or resources of the repository. It will review the establishment of a rapid capture workflow at the University of Minnesota Archives; provide details on how it functions, including equipment information, scanner settings, and workflow procedures; explain the selection process for scanning; describe how it has helped to create inreach opportunities; and finally, examine how it has changed not only daily operations, but the perspective on what it means to provide broad access to the collections
A Compact CMOS Memristor Emulator Circuit and its Applications
Conceptual memristors have recently gathered wider interest due to their
diverse application in non-von Neumann computing, machine learning,
neuromorphic computing, and chaotic circuits. We introduce a compact CMOS
circuit that emulates idealized memristor characteristics and can bridge the
gap between concepts to chip-scale realization by transcending device
challenges. The CMOS memristor circuit embodies a two-terminal variable
resistor whose resistance is controlled by the voltage applied across its
terminals. The memristor 'state' is held in a capacitor that controls the
resistor value. This work presents the design and simulation of the memristor
emulation circuit, and applies it to a memcomputing application of maze solving
using analog parallelism. Furthermore, the memristor emulator circuit can be
designed and fabricated using standard commercial CMOS technologies and opens
doors to interesting applications in neuromorphic and machine learning
circuits.Comment: Submitted to International Symposium of Circuits and Systems (ISCAS)
201
- …