Bootstrapping non-stationary and irregular time series using singular spectral analysis

This article investigates the consequences of using Singular Spectral Analysis (SSA) to construct a time series bootstrap. The bootstrap replications are obtained via a SSA decomposition obtained using rescaled trajectories (RT-SSA), a procedure that is particularly useful in the analysis of time series that exhibit nonlinear, non-stationary and intermittent or transient behaviour. The theoretical validity of the RT-SSA bootstrap when used to approximate the sampling properties of a general class of statistics is established under regularity conditions that encompass a very broad range of data generating processes. A smeared and a boosted version of the RT-SSA bootstrap are also presented. Practical implementation of the bootstrap is considered and the results are illustrated using stationary, non-stationary and irregular time series examples.</p

Improving Manufacturing Data Quality with Data Fusion and Advanced Algorithms for Improved Total Data Quality Management

Data mining and predictive analytics in the sustainable-biomaterials industries is currently not feasible given the lack of organization and management of the database structures. The advent of artificial intelligence, data mining, robotics, etc., has become a standard for successful business endeavors and is known as the ‘Fourth Industrial Revolution’ or ‘Industry 4.0’ in Europe. Data quality improvement through real-time multi-layer data fusion across interconnected networks and statistical quality assessment may improve the usefulness of databases maintained by these industries. Relational databases with a high degree of quality may be the gateway for predictive modeling and enhanced business analytics. Data quality is a key issue in the sustainable bio-materials industry. Untreated data from multiple databases (e.g., sensor data and destructive test data) are generally not in the right structure to perform advanced analytics. Some inherent problems of data from sensors that are stored in data warehouses at millisecond intervals include missing values, duplicate records, sensor failure data (data out of feasible range), outliers, etc. These inherent problems of the untreated data represent information loss and mute predictive analytics. The goal of this data science focused research was to create a continuous real-time software algorithm for data cleaning that automatically aligns, fuses, and assesses data quality for missing fields and potential outliers. The program automatically reduces the variable size, imputes missing values, and predicts the destructive test data for every record in a database. Improved data quality was assessed using 10-fold cross-validation and the normalized root mean square error of prediction (NRMSEP) statistic. The impact of outliers and missing data were tested on a simulated dataset with 201 variations of outlier percentages ranging from 0-90% and missing data percentages ranging from 0-90%. The software program was also validated on a real dataset from the wood composites industry. One result of the research was that the number of sensors needed for accurate predictions are highly dependent on the correlation between independent variables and dependent variables. Overall, the data cleaning software program significantly decreased the NRMSEP ranging from 64% to 12% of quality control variables for key destructive test values (e.g., internal bond, water absorption and modulus of rupture)

A 128-kbit GC-eDRAM With Negative Boosted Bootstrap Driver for 11.3x Lower-Refresh Frequency at a 2.5% Area Overhead in 28-nm FD-SOI

Gain-cell embedded DRAM (GC-eDRAM) is a high-density logic-compatible alternative to conventional static random-access memory (SRAM) and embedded DRAM (eDRAM). However, GC-eDRAM suffers from a reduced data retention time (DRT) at deeply-scaled process nodes, leading to frequent power-hungry refresh operations. In order to reduce the refresh overhead, GC-eDRAM macros utilize external assist voltages which improve the bitcell write-ability, leading to an enhanced DRT. However, the requirement for external analog supply voltages creates additional overhead and is often impractical in the design of compact systems-on-chip (SoC). This work presents an on-chip write-assist technique implemented with a negative boosted bootstrap driver which generates the required wordline boosting on-chip without external components. The proposed circuitry is integrated compactly inside the GC-eDRAM macro to provide an area-efficient low-power solution which improves the bitcell's write-ability and reduces its refresh requirement. A 128-kbit GC-eDRAM macro utilizing the proposed boosting circuitry has been fabricated in a 28-nm FD-SOI technology, demonstrating an 11.3(X) DRT improvement at only 2.5% area overhead.TC