A Digital Twin Framework for Production Planning Optimization: Applications for Make-To-Order Manufacturers

In this dissertation, we develop a Digital Twin framework for manufacturing systems and apply it to various production planning and scheduling problems faced by Make-To-Order (MTO) firms. While this framework can be used to digitally represent a particular manufacturing environment with high fidelity, our focus is in using it to generate realistic settings to test production planning and scheduling algorithms in practice. These algorithms have traditionally been tested by either translating a practical situation into the necessary modeling constructs, without discussion of the assumptions and inaccuracies underlying this translation, or by generating random instances of the modeling constructs, without assessing the limitations in accurately representing production environments. The consequence has been a serious gap between theory advancement and industry practice. The major goal of this dissertation is to develop a framework that allows for practical testing, evaluation, and implementation of new approaches for seamless industry adoption. We develop this framework as a modular software package and emphasize the practicality and configurability of the framework, such that minimal modelling effort is required to apply the framework to a multitude of optimization problems and manufacturing systems. Throughout this dissertation, we emphasize the importance of the underlying scheduling problems which provide the basis for additional operational decision making. We focus on the computational evaluation and comparisons of various modeling choices within the developed frameworks, with the objective of identifying models which are both effective and computationally efficient. In Part 1 of this dissertation, we consider a class of Production Planning and Execution problems faced by job shop manufacturing systems. In Part 2 of this dissertation, we consider a class of scheduling problems faced by manufacturers whose production system is dominated by a single operation

Assessment of Indoor and Outdoor Air Pollution in a Residential High-Rise

Almost half of the world’s population resides in cities and many urban residents live in highrise apartments. It has been hypothesized that living in a highrise building might reduce exposure to ambient air pollution due to vertical gradients in outdoor air pollution and particulate removal by filtered air intake systems. However, few studies have examined air pollution levels in residential highrise buildings. Previous studies in Korea and Singapore reported significant differences in average indoor concentrations by floor (Jo and Kim, 2002; Jo et al., 2003; Jo and Lee, 2006; Kalaiarasan et al., 2009). However, extrapolation from these studies to cities in Europe and North America is difficult because of differences in construction, ventilation systems, and the components of urban pollution. This is the first study to examine the influence of vertical distribution and betweenunit infiltration on air pollutant concentrations in a Canadian residential highrise building

diffraction structural biology 968 doi:10.1107/S0909049513021596 J. Synchrotron Rad. (2013). 20, 968–973 Journal of Synchrotron Radiation

The Japan Aerospace Exploration Agency (JAXA) started a high-quality protein crystal growth project, now called JAXA PCG, on the International Space Station (ISS) in 2002. Using the counter-diffusion technique, 14 sessions of experiments have been performed as of 2012 with 580 proteins crystallized in total. Over the course of these experiments, a user-friendly interface framework for high accessibility has been constructed and crystallization techniques improved; devices to maximize the use of the microgravity environment have been designed, resulting in some high-resolution crystal growth. If crystal-lization conditions were carefully fixed in ground-based experiments, high-quality protein crystals grew in microgravity in many experiments on the ISS, especially when a highly homogeneous protein sample and a viscous crystal-lization solution were employed. In this article, the current status of JAXA PCG is discussed, and a rational approach to high-quality protein crystal growth in microgravity based on numerical analyses is explained