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 $\rm{AdS}_5$ 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