Adaptive Quantizers for Estimation

In this paper, adaptive estimation based on noisy quantized observations is studied. A low complexity adaptive algorithm using a quantizer with adjustable input gain and offset is presented. Three possible scalar models for the parameter to be estimated are considered: constant, Wiener process and Wiener process with deterministic drift. After showing that the algorithm is asymptotically unbiased for estimating a constant, it is shown, in the three cases, that the asymptotic mean squared error depends on the Fisher information for the quantized measurements. It is also shown that the loss of performance due to quantization depends approximately on the ratio of the Fisher information for quantized and continuous measurements. At the end of the paper the theoretical results are validated through simulation under two different classes of noise, generalized Gaussian noise and Student's-t noise

Optimal Asymmetric Binary Quantization for Estimation Under Symmetrically Distributed Noise

Estimation of a location parameter based on noisy and binary quantized measurements is considered in this letter. We study the behavior of the Cramer-Rao bound as a function of the quantizer threshold for different symmetric unimodal noise distributions. We show that, in some cases, the intuitive choice of threshold position given by the symmetry of the problem, placing the threshold on the true parameter value, can lead to locally worst estimation performance.Comment: 4 pages, 5 figure

Informe sobre las 18 campañas de excavaciones en Tel Beidar en la Alta Mesopotamia (Siria)

Las excavaciones arqueológicas de Tel Beidar fueron interrumpidas en 2.010 debido a inestabilidad en Siria, después de 18 campañas entre 1.992 y 2.010. Dichas excavaciones han sacado a la luz una ciudad del III milenio a.n.e., la antigua Nabada, y un asentamiento de época helenística. En cuanto a la primera, su estudio ha permitido conocer mejor las características del fenómeno urbano en la Alta Mesopotamia de la época. Los niveles helenísticos han proporcionado datos de primer orden sobre las culturas indígenas de raíz semita, sumamente desconocidas en dicho periodoThe Archaeological excavations in Tell Beydar had to be interrupted in 2.010 due to the instability in Syria after 18 campaigns that took place between 1.992 and 2.010. These excavations have allowed us to uncover a city from the 3rd millennium b.c.e., the old Nabada, as well as a settlement from the Hellenistic period. The study of the 3rd millennium city has shed light on the urban processes in Upper Mesopotamia at that time. The Hellenistic levels have produced a set of very interesting data about the indigenous Semitic cultures, very unknown during that perio

Quantification asymétrique optimale pour l'estimation d'un paramètre de centrage dans un bruit de loi symétrique

Présentation oraleNational audienceNous traitons de l'estimation d'un paramètre de centrage à partir d'observations bruitées quantifiées sur deux niveaux. Le comportement de la BCR (Borne de Cramér-Rao) est étudié en fonction du centrage du quantifieur pour différentes distributions symétriques de bruit. Nous montrons que, contrairement à ce qui est mentionné dans la littérature, l'emplacement optimal du centrage du quantifieur dépend radicalement de la loi de bruit et que son emplacement sur le paramètre de centrage, un choix intuitif vu la symétrie du problème, peut donner la performance d'estimation localement la plus mauvaise

Adjustable Quantizers for Joint Estimation of Location and Scale Parameters

Poster SessionInternational audienceAn adaptive algorithm to estimate jointly unknown location and scale parameters of a sequence of symmetrically distributed independent and identically distributed random variables using quantized measurements from a quantizer with adjustable input gain and input offset is presented. The asymptotic variance of estimation is obtained, simulations under Cauchy and Gaussian distributions are presented to validate the asymptotic results and they are compared to the continuous optimal estimator performance

A Fusion Center Approach for Estimation Using Quantized Measurements

Rapport interne de GIPSA-labA fusion center approach to estimate a constant location parameter using quantized noisy measurements from multiple sensors is presented. The asymptotic estimation performance is obtained and simulations for different numbers of sensors under Gaussian and Cauchy noise are used for validation. A performance comparison under constrained communication bandwidth between a fusion center approach with two low resolution sensors and a high resolution single sensor approach is presented to motivate the use of low resolution sensor networks

Asymptotic Approximation of Optimal Quantizers for Estimation

Poster SessionInternational audienceIn this paper, the asymptotic approximation of the Fisher information for the estimation of a scalar parameter based on quantized measurements is studied. As the number of quantization intervals tends to infinity, it is shown that the loss of Fisher information due to quantization decreases exponentially as a function of the number of quantization bits. The optimal quantization interval density and the corresponding maximum Fisher information are obtained. Comparison between optimal nonuniform and uniform quantization for the location estimation problem indicates that nonuniform quantization is slightly better. At the end of the paper, an adaptive algorithm for jointly estimating and setting the thresholds is used to show that the theoretical results can be approximately obtained in practice

Extending Eventually Consistent Cloud Databases for Enforcing Numeric Invariants

Geo-replicated databases often operate under the principle of eventual consistency to offer high-availability with low latency on a simple key/value store abstraction. Recently, some have adopted commutative data types to provide seamless reconciliation for special purpose data types, such as counters. Despite this, the inability to enforce numeric invariants across all replicas still remains a key shortcoming of relying on the limited guarantees of eventual consistency storage. We present a new replicated data type, called bounded counter, which adds support for numeric invariants to eventually consistent geo-replicated databases. We describe how this can be implemented on top of existing cloud stores without modifying them, using Riak as an example. Our approach adapts ideas from escrow transactions to devise a solution that is decentralized, fault-tolerant and fast. Our evaluation shows much lower latency and better scalability than the traditional approach of using strong consistency to enforce numeric invariants, thus alleviating the tension between consistency and availability

A novel method to measure the energy efficiency and performance of an auto-cascade refrigeration cycle

Auto-cascade refrigeration systems are the most used cycles to maintain spaces at ultra-low temperature conditions (-80 to −60 °C). The interest in these systems has risen due to the need to maintain and distribute COVID-19 vaccines. However, there is a lack of experimental validation of the theoretical models that are used to analyse and optimize them. In this work, a novel method to calculate the thermodynamic performance, circulating compositions, and energy efficiency of an auto-cascade refrigeration system is presented. The method is based on the measurements of an experimental auto-cascade plant at temperatures from −83.0 to −59.9 °C. The results of the study showed that the proposed calculation method was able to accurately predict the thermodynamic performance, circulating compositions and energy efficiency of an auto-cascade system. The uncertainty of the predictions was found to be below 1% for circulating compositions and 5.2% for the cooling capacity and COP.Funding for open access charge: CRUE-Universitat Jaume IGrant TED2021-130162B-I00 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe” by the “European Union”. Grant CIAEST/2021/14 funded by the Generalitat Valenciana. Authors want to acknowledge the company Frost-Trol S.A. (www.frost-trol.com) for the implication in the project and by manufacturing the used refrigerated space, and to Gabriele Toffoletti and Emanuele Sicco during the set-up of the plant