26 research outputs found
The Use of Capacity and Inventory in a Rate-Based Planning and Scheduling System to Achieve Strategic Goals in Industrial Applications
In pull or lean manufacturing, the final production schedule is in the form of takt time (drumbeat). All internal and external suppliers are driven by pull signals to feed the production rate. However, variability can be a problem for this drumbeat as the plan should not change more than the ability of the suppliers’ capability to respond. The supply chain should have sufficient flexibility to react quickly to changes in demand, while minimizing week-to-week production variability.
Current planning and scheduling systems do not produce a plan that minimizes fluctuations. If the schedule is frozen for several periods, they are slow to react to changes in demand, which eventually produces many changes in production and inventory (the bullwhip effect). When these systems do not freeze the schedule, variation in the forecast and demand yield nervousness, making the planning difficult.
Rate-Based Planning and Scheduling (RPBS) has been proposed as an alternative to current scheduling techniques. But for the most part, it has remained a concept rather than a method that can be implemented. The philosophy behind RBPS is to allow flexibility to adjust the schedule gradually for the near future, and more for periods farther into the future. If flexibility boundaries are defined strategically, the manufacturer will have the ability to respond to changes in demand, yet the schedule will be smooth and long term forecasts for the production rate will anticipate requirements from external suppliers.
This dissertation consolidates previous material on RBPS for the first time. In addition, it introduces two algorithms (Retailer Smoothing and Production Smoothing) for RBPS. The Production Smoothing technique focuses on leveling production. Whereas, the Retailer Smoothing model allows the customer to create forecasted orders and then limits how much these orders may change. Through statistical experiments and simulations, the impact of the factors such as the standard deviation of demand, the length of the planning period, and the amount of flexibility in the plan are investigated. Irrelevant factors were eliminated as data from further simulations were compiled into tables. The goal of the tables is to allow practitioners to use one of the RBPS strategies with the appropriate levels of the RBPS factors by weighing the impact of capacity and inventory.
For the Retailer Smoothing technique, the closer production follows demand and the shorter the flex fences, less inventory is needed as production will shift more. But as demand varies more, production changes and inventory level will increase significantly. On the other hand, Production Smoothing minimizes production changes by constraining flexibility and lengthening the planning period. This will, in turn, increase inventory. Also, as companies update their plan more frequently, more variation is added to the system which will vastly increase the inventory needed to buffer the production swings
A Map of the Inorganic Ternary Metal Nitrides
Exploratory synthesis in novel chemical spaces is the essence of solid-state
chemistry. However, uncharted chemical spaces can be difficult to navigate,
especially when materials synthesis is challenging. Nitrides represent one such
space, where stringent synthesis constraints have limited the exploration of
this important class of functional materials. Here, we employ a suite of
computational materials discovery and informatics tools to construct a large
stability map of the inorganic ternary metal nitrides. Our map clusters the
ternary nitrides into chemical families with distinct stability and
metastability, and highlights hundreds of promising new ternary nitride spaces
for experimental investigation--from which we experimentally realized 7 new Zn-
and Mg-based ternary nitrides. By extracting the mixed metallicity, ionicity,
and covalency of solid-state bonding from the DFT-computed electron density, we
reveal the complex interplay between chemistry, composition, and electronic
structure in governing large-scale stability trends in ternary nitride
materials
Recommended from our members
Novel phase diagram behavior and materials design in heterostructural semiconductor alloys
Structure and composition control the behavior of materials. Isostructural alloying is historically an extremely successful approach for tuning materials properties, but it is often limited by binodal and spinodal decomposition, which correspond to the thermodynamic solubility limit and the stability against composition fluctuations, respectively. We show that heterostructural alloys can exhibit a markedly increased range of metastable alloy compositions between the binodal and spinodal lines, thereby opening up a vast phase space for novel homogeneous single-phase alloys. We distinguish two types of heterostructural alloys, that is, those between commensurate and incommensurate phases. Because of the structural transition around the critical composition, the properties change in a highly nonlinear or even discontinuous fashion, providing a mechanism for materials design that does not exist in conventional isostructural alloys. The novel phase diagram behavior follows from standard alloy models using mixing enthalpies from first-principles calculations. Thin-film deposition demonstrates the viability of the synthesis of these metastable single-phase domains and validates the computationally predicted phase separation mechanism above the upper temperature bound of the nonequilibrium single-phase region
Considering Reach in Tangible and Table Top Design
Reach heavily impacts all aspects of designing for tangible and tabletop user interfaces. It dictates the input space available to each user and heavily shapes how that space is used. Despite its impact to date tangible, table top, and user interface design have all largely overlooked reach as a design constraint. As a result advancing the state of the art for tangible and table top designs requires rethinking existing designs to consider the repercussions of reach, and starting to formally consider reach as part of our designs process. Designing in consideration of reach will allow for more usable tables, applications supporting diverse environments, and user interfaces which are optimally scaled to their current set of users. 1
Managing Smart Garments
Ease of maintenance and management of smart garments (garments with integrated electronics) is crucial to their user acceptability and commercial viability. This paper presents a system that addresses user needs of easy garment charging, storage, and synchronization. The HBar smart hanger system is a novel system consisting of a set of augmented garments and coat hangers to fulfil the requirements of a smart garment management system. 1