83 research outputs found
Locally Recoverable Streaming Codes for Packet-Erasure Recovery
No full textStreaming codes are a class of packet-level erasure codes that are designed with the goal of ensuring recovery in low-latency fashion, of erased packets over a communication network. It is well-known in the streaming code literature, that diagonally embedding codewords of a [τ+1,τ+1-a] Maximum Distance Separable (MDS) code within the packet stream, leads to rate-optimal streaming codes capable of recovering from a arbitrary packet erasures, under a strict decoding delay constraint τ. Thus MDS codes are geared towards the efficient handling of the worst-case scenario corresponding to the occurrence of a erasures. In the present paper, we have an increased focus on the efficient handling of the most-frequent erasure patterns. We study streaming codes which in addition to recovering from a>1 arbitrary packet erasures under a decoding delay τ, have the ability to handle the more common occurrence of a single-packet erasure, while incurring smaller delay r<τ. We term these codes as (a,τ,r) locally recoverable streaming codes (LRSCs), since our single-erasure recovery requirement is similar to the requirement of locality in a coded distributed storage system. We characterize the maximum possible rate of an LRSC by presenting rate-optimal constructions for all possible parameters {a,τ,r}. Although the rate-optimal LRSC construction provided in this paper requires large field size, the construction is explicit. It is also shown that our (a,τ=a(r+1)-1,r) LRSC construction provides the additional guarantee of recovery from the erasure of h, 1 ≤ h ≤ a, packets, with delay h(r+1)-1. The construction thus offers graceful degradation in decoding delay with increasing number of erasures
Nobel Laureate Abhijit Vinayak Banerjee: A Scientometric Portrait, 1987-2019
No full textNobel Memorial Prize in economics is selected by the Royal Swedish Academy of Sciences and first awarded in the domain in 1969; the latest in 2019 was awarded to the Indian-born American economist Prof. Abhijit Vinayak Banerjee along with Esther Duflo and Michael Kremer. The present study attempted to measure and analyse the research publications of Prof. Banerjee during 1987 to 2019 based on the data available in Google Scholar database. A total of 333 documents published during this period in which 35.74 percent were published as journal articles. Till 2004 the mean relative growth rate of his publications was 0.237 and doubling time was 3.29 whereas from 2005 to 2019 the relative growth rate decreased to 0.077 and the time for doubling increased to 10.20. Esther Duflo was the most prolific co-author of the publications of Prof. Banerjee with 120 documents shared out of 333 by them. The collaboration rate of all publications was 0.89 identifies most of his publications written in collaboration. The journal he used for most of his research to publish was mainly USA based. He has produced numbers of publications which received huge citations, and during May, 2020 the h-index counted 87 according to Goggle Scholar citation counts
Model and control for cooperative energy management
No full textThesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 79-80).Proto/Amorphous Cooperative Energy Management (PACEM) aims to build and deploy a highly scalable system for smart power grids that will enable efficient demand shaping for small-user networks. Two key problems are to provide distributed control algorithm for efficient demand shaping and to provide an incentive structure to encourage both users and the electric power sector to opt-in to PACEM. In this thesis, I address the first problem by designing ColoredPower, a probabilistic control algorithm. I implemented and tested ColoredPower in MIT Proto, building on previous work in spatial computing. Simulations in Proto show that ColoredPower operates within 3% error and provides a stable dynamic response time on the order of minutes. To address the second problem, I provide a model for user and power company incentives in PACEM, in the form of the Colored Procurement Mechanism, which enables further work in optimal algorithmic mechanism design.by Vinayak V. Ranade.M.Eng
Thermal expansion and specific heat of Cr2TeO6 and Fe2TeO6 by first principles calculations
No full textGeneralized Simple Streaming Codes from MDS Codes
No full textStreaming codes represent a packet-level FEC scheme for achieving reliable, low-latency communication. In the literature on streaming codes, the commonly-assumed Gilbert-Elliott channel model, is replaced by a more tractable, delay-constrained, sliding-window (DCSW) channel model that can introduce either random or burst erasures. The known streaming codes that are rate optimal over the DCSW channel model are constructed by diagonally embedding a scalar block code across successive packets. These code constructions have field size that is quadratic in the delay parameter τ and have a somewhat complex structure with an involved decoding procedure. This led to the introduction of simple streaming (SS) codes in which diagonal embedding is replaced by staggered-diagonal embedding (SDE). The SDE approach reduces the impact of a burst of erasures and makes it possible to construct near-rate-optimal streaming codes using Maximum Distance Separable (MDS) code having linear field size. The present paper takes this development one step further, by retaining the staggered-diagonal feature, but permitting the placement of more than one code symbol from a given scalar codeword within each packet. These generalized, simple streaming codes allow us to improve upon the rate of SS codes, while retaining the simplicity of working with MDS codes. We characterize the maximum code rate of streaming codes under a constraint on the number of contiguous packets over which symbols of the underlying scalar code are dispersed. Such a constraint leads to simplified code construction and reduced-complexity decoding
Determining the Generalized Hamming Weight Hierarchy of the Binary Projective Reed-Muller Code
No full textProjective Reed-Muller codes correspond to subcodes of the Reed-Muller code in which the polynomials being evaluated to yield codewords, are restricted to be homogeneous. The Generalized Hamming Weights (GHW) of a code C, identify for each dimension nu, the smallest size of the support of a subcode of C of dimension nu. The GHW of a code are of interest in assessing the vulnerability of a code in a wiretap channel setting. It is also of use in bounding the state complexity of the trellis representation of the code. In prior work 1] by the same authors, a code-shortening algorithm was employed to derive upper bounds on the GHW of binary projective, Reed-Muller (PRM) codes. In the present paper, we derive a matching lower bound by adapting the proof techniques used originally for Reed-Muller (RM) codes by Wei in 2]. This results in a characterization of the GHW hierarchy of binary PRM codes
Binary, Shortened Projective Reed Muller Codes for Coded Private Information Retrieval
No full textThe notion of a Private Information Retrieval (PIR) code was recently introduced by Fazeli, Vardy and Yaakobi 1] who showed that this class of codes permit PIR at reduced levels of storage overhead in comparison with rephcated-server PIR. In the present paper, the construction of an (n, k) tau-server binary linear PIR code having parameters n = Sigma (l)(i=0) ((m)(i)), k = ((m)(l)) and tau = 2(l) for any integer m >= l >= 0 is presented. These codes are obtained through homogeneous-polynomial evaluation and correspond to the binary. Projective Reed Muller (PRM) code. The construction can be extended to yield PIR codes for any tau is an element of{2(l), 2(l) - 1 vertical bar l is an element of Z, l >= 0} and any value of k, through a combination of single-symbol puncturing and shortening of the PRM code. Each of these code constructions above, have smaller storage overhead in comparison with known short block length codes in 1]. For the particular case of tau = 3,4, we show that the codes constructed here are optimal, systematic PIR codes by providing an improved lower bound on the block length n(k, tau) of a systematic PIR code. It follows from a result by Vardy and Yaakobi 2], that these codes also yield optimal, systematic primitive multi-set (n, k, tau)(B) batch codes for tau = 3,4. The PIR code constructions presented here also yield upper bounds on the generahzed Hamming weights of binary PRM codes
China Beat Event: “Nationalism and Religion in Twentieth- Century Asia,” Friday 4/22
No full textChina Beat readers in Southern California are invited to join us this Friday at UC Irvine for a dialogue between James Carter of Saint Joseph’s University and UCI’s Vinayak Chaturvedi, who will be discussing the topic of “Nationalism and Religion in Twentieth-Century Asia.” Carter’s new book is Heart of Buddha, Heart of China: The Life of Tanxu, a Twentieth-Century Monk (read an excerpt here); Chaturvedi is author of Peasant Pasts: History and Memory in Western India
Risk penalties for enhanced reliability in co-optimized markets with uncertain generation
No full textWith increasing proportion of windpower, an important concern is that of maintaining the reliability of the electric grid in the face of higher supply-side volatility. In this paper, we examine the role of risk-based penalties in developing alternate designs in which firms combine energy bids associated with uncertain real-time availability with stable reserves bids. Such a study is carried out in a regime where firms have access to a day-ahead market, an uncertain real-time energy market and a reserves market. The resulting game-theoretic problem is a two-period stochastic Nash game with risk-based objectives and the associated equilibrium conditions are given by a complementarity problem. Preliminary numerical results on a 6-firm problem provide insights regarding the impact of reserves and risk penalties on wind-based generation, particularly in the face of high variability.U of I OnlyU of I Only access applied by request of the author and approved by graduate college
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