Integrating water-energy-nexus in carbon footprint analysis in water utility company

The purpose of this paper is to highlight the water-energy-nexus within the context of carbon footprint methodology and water utility industry. In particular, the carbon management for water utility industry is crucial in reducing carbon emission within the upstream water distribution system. The concept of water-energy nexus alone however can be misleading due to exclusion of indirect and embodied energy involved in the water production. The study highlights the total energy use within water supply system as well as embedded carbon emission through carbon footprint methodology. The case study approach is used as a research method. The carbon footprint analysis includes data collection from water utility company; and data identification of direct and indirect carbon emission from corporation operation. The result indicates that the indirect and embodied energy may not be significant in certain operation area but the energy use may be ambiguous when these elements are excluded. Integrating carbon footprint methodology within the water supply system can improve the understanding on water-energy-nexus when direct and indirect energy use is included in the analysis. This paper aims to benefit academics, government agencies and particularly water utility companies in integrating carbon footprint analysis in water production

Sparse models for positive definite matrices

University of Minnesota Ph.D. dissertation. Febrauary 2015. Major: Electrical Engineering. Advisor: Nikolaos P. Papanikolopoulos. 1 computer file (PDF); ix, 141 pages.Sparse models have proven to be extremely successful in image processing, computer vision and machine learning. However, a majority of the effort has been focused on vector-valued signals. Higher-order signals like matrices are usually vectorized as a pre-processing step, and treated like vectors thereafter for sparse modeling. Symmetric positive definite (SPD) matrices arise in probability and statistics and the many domains built upon them. In computer vision, a certain type of feature descriptor called the region covariance descriptor, used to characterize an object or image region, belongs to this class of matrices. Region covariances are immensely popular in object detection, tracking, and classification. Human detection and recognition, texture classification, face recognition, and action recognition are some of the problems tackled using this powerful class of descriptors. They have also caught on as useful features for speech processing and recognition.Due to the popularity of sparse modeling in the vector domain, it is enticing to apply sparse representation techniques to SPD matrices as well. However, SPD matrices cannot be directly vectorized for sparse modeling, since their implicit structure is lost in the process, and the resulting vectors do not adhere to the positive definite manifold geometry. Therefore, to extend the benefits of sparse modeling to the space of positive definite matrices, we must develop dedicated sparse algorithms that respect the positive definite structure and the geometry of the manifold. The primary goal of this thesis is to develop sparse modeling techniques for symmetric positive definite matrices. First, we propose a novel sparse coding technique for representing SPD matrices using sparse linear combinations of a dictionary of atomic SPD matrices. Next, we present a dictionary learning approach wherein these atoms are themselves learned from the given data, in a task-driven manner. The sparse coding and dictionary learning approaches are then specialized to the case of rank-1 positive semi-definite matrices. A discriminative dictionary learning approach from vector sparse modeling is extended to the scenario of positive definite dictionaries. We present efficient algorithms and implementations, with practical applications in image processing and computer vision for the proposed techniques