8,365 research outputs found
Indicating Asynchronous Array Multipliers
Multiplication is an important arithmetic operation that is frequently
encountered in microprocessing and digital signal processing applications, and
multiplication is physically realized using a multiplier. This paper discusses
the physical implementation of many indicating asynchronous array multipliers,
which are inherently elastic and modular and are robust to timing, process and
parametric variations. We consider the physical realization of many indicating
asynchronous array multipliers using a 32/28nm CMOS technology. The
weak-indication array multipliers comprise strong-indication or weak-indication
full adders, and strong-indication 2-input AND functions to realize the partial
products. The multipliers were synthesized in a semi-custom ASIC design style
using standard library cells including a custom-designed 2-input C-element. 4x4
and 8x8 multiplication operations were considered for the physical
implementations. The 4-phase return-to-zero (RTZ) and the 4-phase return-to-one
(RTO) handshake protocols were utilized for data communication, and the
delay-insensitive dual-rail code was used for data encoding. Among several
weak-indication array multipliers, a weak-indication array multiplier utilizing
a biased weak-indication full adder and the strong-indication 2-input AND
function is found to have reduced cycle time and power-cycle time product with
respect to RTZ and RTO handshaking for 4x4 and 8x8 multiplications. Further,
the 4-phase RTO handshaking is found to be preferable to the 4-phase RTZ
handshaking for achieving enhanced optimizations of the design metrics.Comment: arXiv admin note: text overlap with arXiv:1903.0943
Optimal Crowdsourcing Contests
We study the design and approximation of optimal crowdsourcing contests.
Crowdsourcing contests can be modeled as all-pay auctions because entrants must
exert effort up-front to enter. Unlike all-pay auctions where a usual design
objective would be to maximize revenue, in crowdsourcing contests, the
principal only benefits from the submission with the highest quality. We give a
theory for optimal crowdsourcing contests that mirrors the theory of optimal
auction design: the optimal crowdsourcing contest is a virtual valuation
optimizer (the virtual valuation function depends on the distribution of
contestant skills and the number of contestants). We also compare crowdsourcing
contests with more conventional means of procurement. In this comparison,
crowdsourcing contests are relatively disadvantaged because the effort of
losing contestants is wasted. Nonetheless, we show that crowdsourcing contests
are 2-approximations to conventional methods for a large family of "regular"
distributions, and 4-approximations, otherwise.Comment: The paper has 17 pages and 1 figure. It is to appear in the
proceedings of ACM-SIAM Symposium on Discrete Algorithms 201
The Library of Babel
We show that heavy pure states of gravity can appear to be mixed states to
almost all probes. Our arguments are made for Schwarzschild black
holes using the field theory dual to string theory in such spacetimes. Our
results follow from applying information theoretic notions to field theory
operators capable of describing very heavy states in gravity. For certain
supersymmetric states of the theory, our account is exact: the microstates are
described in gravity by a spacetime ``foam'', the precise details of which are
invisible to almost all probes.Comment: 7 pages, 1 figure, Essay receiving honorable mention in the 2005
Gravity Research Foundation essay competitio
Comparative performance of mechanised peeling machines for unpeeled cashew kernels – A case study
Mechanization of cashewnut processing in India has become inevitable due to growing problem of non-availability of work force at various stages of processing. Peeling is the process of removing the outer skin called testa to obtain edible kernels. Traditionally, shelled kernels were peeled manually using wooden pellets or knives after drying. Qualitative and quantitative efficiency vary depending on the skill of labour involved in the operation. Mechanized peeling machines were introduced in the Indian cashew processing system for twin reasons, to tackle the problem of labour shortage and to enhance rate of production. This study deals about the performance of three different mechanised peeling machines viz., shear type, brush type and abrasion type available in the line of processing in terms of operational capacity, peeling efficiency and whole kernel recovery. Operational capacity found to be in the range of 108 to 332 kg h-1 for the type of peeling machines and origin of the cashewnuts. Variation in the adherence of testa with the kernel after pre-treatment would be the key factor influencing the operation capacity with respect to different origin of cashewnuts considered. Mean values of whole kernel recovery (70.1) and peeling efficiency (79.1) recorded for shear type peeling machine and raw cashewnuts obtained from Maharashtra were found to be higher than all other trials. Whole kernels obtained at the end of peeling process were higher during the first pass than the second pass. Possibly, the forces viz. impact or shear or abrasion force depending on the type of peeling machine, acted on these kernels during first pass, once again applied with the same intensity during second pass resulted in a marginal reduction in the whole kernel recovery. The performance parameters such as operational capacity, whole kernel recovery and peeling efficiency were found to be non-significant among the machines considered for the present investigation. Besides, cost economics was worked out and compared with existing manual peeling process. Increase in the net benefit was 53.9, 68.4 and 47.4 per cent respectively for shear, brush and abrasion type mechanical peeling machines
What we don't know about time
String theory has transformed our understanding of geometry, topology and
spacetime. Thus, for this special issue of Foundations of Physics commemorating
"Forty Years of String Theory", it seems appropriate to step back and ask what
we do not understand. As I will discuss, time remains the least understood
concept in physical theory. While we have made significant progress in
understanding space, our understanding of time has not progressed much beyond
the level of a century ago when Einstein introduced the idea of space-time as a
combined entity. Thus, I will raise a series of open questions about time, and
will review some of the progress that has been made as a roadmap for the
future.Comment: 15 pages; Essay for a special issue of Foundations of Physics
commemorating "Forty years of string theory
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