Singularity in the discrete dynamic Leontief model

A new wave of applications of the dynamic Leontief model brought into the forefront the singularity problem of the capital matrix. In these applications the singularity of the capital matrix is a common occurrence which complicates the solution of the model. In the singular case the model cannot be transformed in a direct forward recursive form. The method presented in this paper determines the length of a backward system (τ). Several applications stop at observing singularity while referring to the theoretical possibility of the solution. In particular, the singularity of the capital matrix played a prominent role in Bródy’s extensive contributions to the input-output literature but he never ventured into the details of its various solutions. We demonstrate that a number of papers dealing with the Leontief model with singular capital matrix based their solutions on similar regularity assumptions. Our formulation in this paper offers a brief overview of the approaches that can be followed in a wide range of applications confronting with the singularity problem

Positive solutions of discrete dynamic Leontief input-output model with possibly singular capital matrix

Mathematical Models in Medicine, Business & Engineering 2009This paper deals with the construction of solutions of the discrete dynamic Leontief input–output model by using Drazin inverses and a singular discrete difference systems approach. After obtaining a closed form solution of the problem, sufficient conditions on the initial output as well as on the relevant matrices of the model are given in order to guarantee positivity.Jódar Sánchez, LA.; Merello Giménez, P. (2010). Positive solutions of discrete dynamic Leontief input-output model with possibly singular capital matrix. Mathematical and Computer Modelling. 52(7-8):1081-1087. doi:10.1016/j.mcm.2010.02.043S10811087527-

AN INTEGRATED WATER RESOURCES MANAGEMENT FRAMEWORK FOR ROBUST DECISION-MAKING IN A TRANSBOUNDARY RIVER BASIN: AN INTER-REGIONAL HYDRO-ECONOMIC APPROACH

Allocating limited amounts of freshwater among competing uses is challenging, particularly in transboundary river basins and under the impact of climate change and increasing demand for water associated with population growth and economic development. This calls for decision support tools that inform decision-makers about the consequences of their water management strategies and the impacts of changes in water availability due to climate change and socio-economic development. Hydro-economic models have proven to be promising for helping understand these impacts from an economic perspective. These models need to be integrated and capture both features of the water system and the economic interdependencies to be effective in multi-sectoral and multi-regional river basin contexts. Many of the hydro-economic models, however, adhere to either hydrological or administrative boundaries due to the limited availability of hydrological and economic data at relevant temporal and spatial scales. These models usually consist of a detailed representation of either the water or the economic system and a simplified representation of the other system. This is mainly because an integrated model including a detailed representation of both water and economic systems is extremely data-demanding and challenging to develop due to the different resolutions of datasets associated with these models. This dissertation attempts to address this gap by developing an integrated hydro-economic model that encompasses an entire transboundary river basin and consists of detailed water and economic components to inform decision-making about sustainable and robust water allocation. This is accomplished through these main steps: (1) developing an Inter-regional Supply-side Input-Output (ISIO) model incorporating water supply data for the transboundary Saskatchewan River Basin; (2) testing the temporal transferability of the ISIO model for different years in predicting the economic response of the river basin to changes in water availability under different climatic conditions; (3) coupling the ISIO model with a node-link water resources system model (MODSIM) to create an integrated hydro-economic model; (4) applying this integrated hydro-economic model to identify the sectoral and regional vulnerabilities of the river basin to changes in water supply; and (5) comparing the economic outcomes of the integrated hydro-economic model with those coming from an engineering model (the MODSIM model linked to a crop yield function) and the ISIO model. The contribution of this dissertation is developing an integrated hydro-economic model that couples detailed water resources system and inter-regional supply-side input-output models to identify sectoral and regional vulnerabilities of transboundary river basins to changes in water availability. The findings of this research have advanced our understanding of the cross-sectoral and inter-regional distribution of economic impacts of water allocation strategies and other drivers, including climate change and socio-economic development. This research also investigates, for the first time, the performance of supply-side input-output models that include water under different climatic conditions and over several years. This dissertation serves as an example for future integrated hydro-economic modelling attempts, particularly for informing decision-making about sustainable and robust water allocation in multi-sectoral and multi-regional river basins

A vision-based optical character recognition system for real-time identification of tractors in a port container terminal

Automation has been seen as a promising solution to increase the productivity of modern sea port container terminals. The potential of increase in throughput, work efficiency and reduction of labor cost have lured stick holders to strive for the introduction of automation in the overall terminal operation. A specific container handling process that is readily amenable to automation is the deployment and control of gantry cranes in the container yard of a container terminal where typical operations of truck identification, loading and unloading containers, and job management are primarily performed manually in a typical terminal. To facilitate the overall automation of the gantry crane operation, we devised an approach for the real-time identification of tractors through the recognition of the corresponding number plates that are located on top of the tractor cabin. With this crucial piece of information, remote or automated yard operations can then be performed. A machine vision-based system is introduced whereby these number plates are read and identified in real-time while the tractors are operating in the terminal. In this paper, we present the design and implementation of the system and highlight the major difficulties encountered including the recognition of character information printed on the number plates due to poor image integrity. Working solutions are proposed to address these problems which are incorporated in the overall identification system.postprin