840 research outputs found
TransPimLib: A Library for Efficient Transcendental Functions on Processing-in-Memory Systems
Processing-in-memory (PIM) promises to alleviate the data movement bottleneck
in modern computing systems. However, current real-world PIM systems have the
inherent disadvantage that their hardware is more constrained than in
conventional processors (CPU, GPU), due to the difficulty and cost of building
processing elements near or inside the memory. As a result, general-purpose PIM
architectures support fairly limited instruction sets and struggle to execute
complex operations such as transcendental functions and other hard-to-calculate
operations (e.g., square root). These operations are particularly important for
some modern workloads, e.g., activation functions in machine learning
applications.
In order to provide support for transcendental (and other hard-to-calculate)
functions in general-purpose PIM systems, we present \emph{TransPimLib}, a
library that provides CORDIC-based and LUT-based methods for trigonometric
functions, hyperbolic functions, exponentiation, logarithm, square root, etc.
We develop an implementation of TransPimLib for the UPMEM PIM architecture and
perform a thorough evaluation of TransPimLib's methods in terms of performance
and accuracy, using microbenchmarks and three full workloads (Blackscholes,
Sigmoid, Softmax). We open-source all our code and datasets
at~\url{https://github.com/CMU-SAFARI/transpimlib}.Comment: Our open-source software is available at
https://github.com/CMU-SAFARI/transpimli
Machine Learning Applications in Estimating Transformer Loss of Life
Transformer life assessment and failure diagnostics have always been
important problems for electric utility companies. Ambient temperature and load
profile are the main factors which affect aging of the transformer insulation,
and consequently, the transformer lifetime. The IEEE Std. C57.911995 provides a
model for calculating the transformer loss of life based on ambient temperature
and transformer's loading. In this paper, this standard is used to develop a
data-driven static model for hourly estimation of the transformer loss of life.
Among various machine learning methods for developing this static model, the
Adaptive Network-Based Fuzzy Inference System (ANFIS) is selected. Numerical
simulations demonstrate the effectiveness and the accuracy of the proposed
ANFIS method compared with other relevant machine learning based methods to
solve this problem.Comment: IEEE Power and Energy Society General Meeting, 201
Harnessing machine learning for fiber-induced nonlinearity mitigation in long-haul coherent optical OFDM
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Coherent optical orthogonal frequency division multiplexing (CO-OFDM) has attracted a lot of interest in optical fiber communications due to its simplified digital signal processing (DSP) units, high spectral-efficiency, flexibility, and tolerance to linear impairments. However, CO-OFDM’s high peak-to-average power ratio imposes high vulnerability to fiber-induced non-linearities. DSP-based machine learning has been considered as a promising approach for fiber non-linearity compensation without sacrificing computational complexity. In this paper, we review the existing machine learning approaches for CO-OFDM in a common framework and review the progress in this area with a focus on practical aspects and comparison with benchmark DSP solutions.Peer reviewe
Estimating Ultimate Recovery in Shale Wells Based on Facts
Natural gas, as one of the nation\u27s major energy sources plays a vital role in the US energy mix. In recent years, the production from Shale has focused much attention on this source of hydrocarbon. As an essential step for the production planning, natural gas professionals estimate production and ultimate recovery (EUR) throughout the life of wells. The fluid production rate (q) usually varies as a function of rock properties, well, and completion design parameters. The variation associated with these parameters is a source of uncertainty in estimating the long term production for unconventional reservoirs.;A number of methodologies have been suggested to estimate the long term production of shale wells. Decline curve analysis is the most widely used methodology in the estimation of the future production profile. However, its results have been determined to be over optimistic.;Discrepancies between actual and estimated production values by Arps decline curves have been observed. This is dominant in low permeability reservoirs characterized by production over-estimation that is a consequence of large values of hyperbolic component (b-values higher than 1). A combination of Arps hyperbolic (in early time) and exponential decline (in later time) is employed to overcome this deficiency (production over estimation). This combination of Arps declines curves are referred to as Combined Decline Curves (CDC).;The major objective of this research is to condition the results of the CDC-EUR of shale wells to rock properties, well characteristics, and completion design parameters in a given shale asset. The first step of this study is CDC-EUR estimation using Arps combined decline curves. In order to have a more accurate (conservative) estimation, the hyperbolic curve will be switched to exponential decline during later time in the well\u27s life. Then, artificial intelligence will be employed to condition the CDC-EUR to rock properties, well characteristics, and completion design parameters.;The major rock properties that will be studied in this research as input parameters include porosity, total organic carbon, net thickness, and water saturation. Moreover, the effect of several design parameters, such as well trajectories, completion, and hydraulic fracturing variables on CDC-EUR will be investigated. This model will help natural gas professionals to have a better understanding of the effect of rock properties and design parameters on future gas production of shale
Detection of Epileptic Seizures on EEG Signals Using ANFIS Classifier, Autoencoders and Fuzzy Entropies
Epileptic seizures are one of the most crucial
neurological disorders, and their early diagnosis will help the
clinicians to provide accurate treatment for the patients. The
electroencephalogram (EEG) signals are widely used for epileptic
seizures detection, which provides specialists with substantial
information about the functioning of the brain. In this paper,
a novel diagnostic procedure using fuzzy theory and deep
learning techniques is introduced. The proposed method is
evaluated on the Bonn University dataset with six classification
combinations and also on the Freiburg dataset. The tunable-
Q wavelet transform (TQWT) is employed to decompose the
EEG signals into different sub-bands. In the feature extraction
step, 13 different fuzzy entropies are calculated from different
sub-bands of TQWT, and their computational complexities are
calculated to help researchers choose the best set for various
tasks. In the following, an autoencoder (AE) with six layers
is employed for dimensionality reduction. Finally, the standard
adaptive neuro-fuzzy inference system (ANFIS), and also its
variants with grasshopper optimization algorithm (ANFIS-GOA),
particle swarm optimization (ANFIS-PSO), and breeding swarm
optimization (ANFIS-BS) methods are used for classification.
Using our proposed method, ANFIS-BS method has obtained
an accuracy of 99.7
Application of Wavelet Decomposition and Phase Space Reconstruction in Urban Water Consumption Forecasting: Chaotic Approach (Case Study)
The forecasting of future value of water consumption in an urban area is highly complex and nonlinear. It often exhibits a high degree of spatial and temporal variability. It is a crucial factor for long-term sustainable management and improvement of the operation of urban water allocation system. This chapter will study the application of two pre-processing phase space reconstruction (PSR) and wavelet decomposition transform (WDT) methods to investigate the behavior of time series to forecast short-term water demand value of Kelowna City (BC, Canada). The research proposes two pre-process technique to improve the accuracy of the models. Artificial neural networks (ANNs), gene expression programming (GEP) and multilinear regression (MLR) methods are the tools that considered for forecasting the demand values. Evaluation of the tools is based on two steps with and without applying the pre-processing methods. Moreover, autocorrelation function (ACF) is used to calculate the lag time. Correlation dimension is used to study the chaotic behavior of the dataset. The models’ relative performance is compared using three different fitness indexes; coefficient of determination (CD), root mean square error (RMSE) and mean absolute error (MAE). The results showed how pre-processing combination of WDT and PSR improved the performance of the models in forecasting short-term demand values
Dynamic non-linear system modelling using wavelet-based soft computing techniques
The enormous number of complex systems results in the necessity of high-level and cost-efficient
modelling structures for the operators and system designers. Model-based approaches offer a very
challenging way to integrate a priori knowledge into the procedure. Soft computing based models
in particular, can successfully be applied in cases of highly nonlinear problems. A further reason
for dealing with so called soft computational model based techniques is that in real-world cases,
many times only partial, uncertain and/or inaccurate data is available.
Wavelet-Based soft computing techniques are considered, as one of the latest trends in system
identification/modelling. This thesis provides a comprehensive synopsis of the main wavelet-based
approaches to model the non-linear dynamical systems in real world problems in conjunction with
possible twists and novelties aiming for more accurate and less complex modelling structure.
Initially, an on-line structure and parameter design has been considered in an adaptive Neuro-
Fuzzy (NF) scheme. The problem of redundant membership functions and consequently fuzzy
rules is circumvented by applying an adaptive structure. The growth of a special type of Fungus
(Monascus ruber van Tieghem) is examined against several other approaches for further
justification of the proposed methodology.
By extending the line of research, two Morlet Wavelet Neural Network (WNN) structures have
been introduced. Increasing the accuracy and decreasing the computational cost are both the
primary targets of proposed novelties. Modifying the synoptic weights by replacing them with
Linear Combination Weights (LCW) and also imposing a Hybrid Learning Algorithm (HLA)
comprising of Gradient Descent (GD) and Recursive Least Square (RLS), are the tools utilised for
the above challenges. These two models differ from the point of view of structure while they share
the same HLA scheme. The second approach contains an additional Multiplication layer, plus its
hidden layer contains several sub-WNNs for each input dimension. The practical superiority of
these extensions is demonstrated by simulation and experimental results on real non-linear
dynamic system; Listeria Monocytogenes survival curves in Ultra-High Temperature (UHT)
whole milk, and consolidated with comprehensive comparison with other suggested schemes.
At the next stage, the extended clustering-based fuzzy version of the proposed WNN schemes, is
presented as the ultimate structure in this thesis. The proposed Fuzzy Wavelet Neural network
(FWNN) benefitted from Gaussian Mixture Models (GMMs) clustering feature, updated by a
modified Expectation-Maximization (EM) algorithm. One of the main aims of this thesis is to illustrate how the GMM-EM scheme could be used not only for detecting useful knowledge from
the data by building accurate regression, but also for the identification of complex systems.
The structure of FWNN is based on the basis of fuzzy rules including wavelet functions in the
consequent parts of rules. In order to improve the function approximation accuracy and general
capability of the FWNN system, an efficient hybrid learning approach is used to adjust the
parameters of dilation, translation, weights, and membership. Extended Kalman Filter (EKF) is
employed for wavelet parameters adjustment together with Weighted Least Square (WLS) which
is dedicated for the Linear Combination Weights fine-tuning. The results of a real-world
application of Short Time Load Forecasting (STLF) further re-enforced the plausibility of the
above technique
Multilayer perceptron network optimization for chaotic time series modeling
Chaotic time series are widely present in practice, but due to their characteristics—such as internal randomness, nonlinearity, and long-term unpredictability—it is difficult to achieve high-precision intermediate or long-term predictions. Multi-layer perceptron (MLP) networks are an effective tool for chaotic time series modeling. Focusing on chaotic time series modeling, this paper presents a generalized degree of freedom approximation method of MLP. We then obtain its Akachi information criterion, which is designed as the loss function for training, hence developing an overall framework for chaotic time series analysis, including phase space reconstruction, model training, and model selection. To verify the effectiveness of the proposed method, it is applied to two artificial chaotic time series and two real-world chaotic time series. The numerical results show that the proposed optimized method is effective to obtain the best model from a group of candidates. Moreover, the optimized models perform very well in multi-step prediction tasks.This research was funded in part by the NSFC grant numbers 61972174 and 62272192, the Science-Technology Development Plan Project of Jilin Province grant number 20210201080GX, the Jilin Province Development and Reform Commission grant number 2021C044-1, the Guangdong Universities’ Innovation Team grant number 2021KCXTD015, and Key Disciplines Projects grant number 2021ZDJS138
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