Leon F. Mcginnis

• PhD, North Carolina State University, IE, 1975
• Professor Emeritus at Georgia Institute of Technology

Modern assembly factories increasingly encounter the challenges posed by highly diversified products and fluctuating market demand. Hyperconnected mobile production, which organizes the core production equipment in standard production modules and allows them to be shared among multiple participants in the Physical Internet, is a solution in respons...

Today, parcel logistics hubs, where packages come in from many origins and are sorted to their many destinations, are both capital and labor intensive, with capacity that is largely determined by investments in conveyors. In this paper, in the context of Physical Internet growth, we propose a next-generation hyperconnected parcel hub concept that l...

This paper employs modularity and mobility (M^2) for designing recently introduced hyperconnected logistics hubs (HLH) for the Physical Internet, where parcels are encapsulated in modular tote-sized containers arriving in mobile racks, and these totes are consolidated by switching totes in shuffling cells to mobile racks with other totes with share...

The complex behavior present in modern logistics systems and the rapid growth of the demand for delivery services are pushing companies towards expanding coverage, improving speed, efficiency, and cost-effectiveness, while building agility, sustainability, and resilience capabilities. Novel approaches such as Physical Internet driven multi-tier hyp...

The development of contemporary systems is an extremely complex process. One approach to modeling system behavior uses activity diagrams from Unified Modeling Language (UML)/System Modeling Language (SysML), providing a standard object‐oriented graphical notation and enhancing reusability. However, UML/SysML activity diagrams do not directly suppor...

This paper reviews and classifies literature on operational control of discrete event logistics systems (DELS). Operational control manipulates the flow of items through a DELS. Each control problem addressed in the surveyed literature is classified based on the control decision that the analysis model is formulated to support. These control decisi...

The design of large complex systems, such as warehouses, requires multiple experts and analyses as well as methods to organise and integrate their knowledge. While there are many models for optimising individual aspects of warehouses, there is not, today, a comprehensive design methodology that incorporates and supports all of the design decisions...

Understanding and developing complex systems requires collaboration between individuals with widely varying expertise. Communication between these individuals is facilitated by conceptual models. Conceptual models are early stage artifacts that integrate and provide requirements for many kinds of specialized models. They are living documents that g...

Simulation optimization tools have the potential to provide an unprecedented level of support for the design and execution of operational control in Discrete Event Logistics Systems (DELS). While much of the simulation optimization literature has focused on developing and exploiting integration and syntactical interoperability between simulation an...

A multi-year research project focused on a global aerospace company's design-to-production transition, and in particular how to answer production-related questions much earlier in a program's design cycle than is possible today. A fundamental difficulty is that the time and expertise required to formulate appropriate analysis models prevents their...

Warehouses today are complex dynamic engineered systems, incorporating automation, mechanization, equipment, fixtures, computers, networks, products and people, and they can support the flow of tens or hundreds of thousands of different items to enable fulfilling thousands or tens of thousands of orders daily. In that sense, they represent a design...

The functional design of discrete event logistics systems (DELS) specifies the systems’ transformative functions independently from the technology required to implement those functions. Creating a functional architecture for a new system is as much an art form as a science and often relies on the tacit knowledge of the systems architect. In this pa...

Advancements in computer integrated manufacturing and intelligent devices have spurred a revolution in manufacturing. To maximize their potential, smart operational control mechanisms must not only integrate real-time data from system operations, but also formulate and solve a wide variety of optimal-control analyses quickly and efficiently and the...

For large-scale, complex systems, both simulation and optimization methods are needed to support system design and operational decision making. Integrating the two methodologies, however, presents a number of conceptual and technical problems. This paper argues that the required integration can be successfully achieved, within a specific domain, by...

To provide automated access from a formal system model to multiple analysis tools, such as discrete event simulation or optimization, we extend current model-based systems engineering (MBSE) methodologies by introducing a new model to model transformation method based on object-oriented creational patterns from software design. Implemented in MATLA...

The design and production of complex engineered systems (CES) requires analysis of massive amounts of detailed information, including data on products and materials, engineering designs, manufacturing specifications, supply chain and delivery data, and changing customer needs. Visual analytics promises to offer tools and methods that will help stak...

This paper reports on the results of an ongoing collaboration between the Fraunhofer IML and the Georgia Institute of Technology to develop engineering methods and tools to support warehouse design. The effort has adapted methods and tools from the broader systems engineering discipline, and has exploited the legacy of warehousing research at both...

This article addresses a new class of picker-to-goods order picking systems, in which item retrieval is decoupled from order assembly by a pick-to-buffer technology. This decoupling of item retrieval and order assembly dramatically changes the dynamics of the pick process. Picking to buffers means that the picker is limited by the number of availab...

Model-driven architecture (MDA) is a contemporary strategy for software development using three distinct kinds of models: (1) models expressing the problem to be solved in the semantics of its domain; (2) models of the solution space in terms of hardware and software elements; and (3) models that map from the domain space to the solution space. We...

Fifty years ago, young operations research (OR) professionals, like Dr. Salah Elmaghraby, were exploring the opportunities for using OR to better understand how to make critical decisions about the design and operation of complex production systems. Elmaghaby’s seminal text, The Design of Production Systems, is an inimitable example of that explora...

Supply chain analyses, including those related to material handling systems, are typically purpose-built to answer specific questions and therefore have many different implementations depending on the question, the instance data, and the solver. The purpose-built nature of these models makes it difficult to integrate them into an iterative design w...

The aerospace supply chain network has evolved and become more complex over the years. New methods are needed to design and analyze the system, and to establish the interactions between aircraft (product) design and supply chain (process) design. This paper aims to introduce a strategic multi-product, multi-period design model for the manufacturing...

Tandem queues are the fundamental structure of queueing networks. However, exact queue times of tandem queues are notoriously difficult to compute except in some special cases. Several approximation schemes that are based on mathematical assumptions which enable approximate analyses of tandem queues have been developed previously. In this paper, we...

A Model Driven Architecture approach is employed to support the practice of discrete-event simulation. OMG's System Model Language, OMG SysML™, is used to define a platform independent model (PIM) and auto-translate it into an appropriate platform specific model (PSM). The implementation and the nature of the transformation from PIM to PSM are clea...

Aviation spare parts provisioning is a highly complex problem. Traditionally, provisioning has been carried out using a conventional Poisson-based approach where inventory quantities are calculated separately for each part number and demands from different operations bases are consolidated into one single location. In an environment with multiple o...

Performance evaluation plays a key role in manufacturing system design and productivity improvement. Characterizing performance objectively is the first step. Inspired by the underlying structure of tandem queues, we have derived an approximate model to characterize the system performance. The model decomposes system queue time and variability into...

In a synchronous and fast-paced assembly line operation, it is crucial that the right parts are being supplied at the right time and at the right place. In automotive assembly, the need for efficient material handling part delivery is particularly great because of extensive product customisation and the lack of space to stock all the required parts...

To date, Model Based Systems Engineering (MBSE) has been deployed primarily in the product design domain. However, manufacturing system design problems are equally challenging, but there are many fewer design support tools in the hands of system designers. This paper describes how MBSE principles and methods can be used to make a powerful analysis...

Discrete-event simulation (DES) is used to evaluate alternative resource configurations and production operation plans and schedules in the manufacturing environment. However, benefits from using simulation to guide these decisions has to be weighed against the time and cost usually required to create and exercise the simulations. Where such decisi...

In simulation, perhaps the most common use of the term ‘fidelity’ refers to the faithfulness with which model behavior reflects modeled system behavior. While there have been studies of fidelity seeking absolute and quantitative measures, there is not yet a consensus on a workable fidelity metric. We propose a formal modeling framework for comparin...

Enterprise transformation inevitably requires knowledge that is neither resident in nor immediately available from outside the enterprise. Among the alternatives for obtaining this required knowledge is a collaborative research relationship between a university-based research team and the stakeholders involved in transformation. This chapter discus...

The capability to manufacture products in the global marketplace is being revolutionized by technological advancements, the opportunity to capture innovation and capabilities from worldwide sources, the enticement of entering new markets, and changing business and political models. Many view this opportunity as creating an inflection point for manu...

In transforming any large scale, complex, global supply network, a key challenge is knowledge management. There are many stakeholders, spread across a number of enterprise functions, whose decisions directly or indirectly impact the success of the transformation. Typically, each stakeholder has important, often tacit knowledge that in contemporary...

Modern logistics systems are much more than simply networks of material flow. They involve collaboration between firms that are also competitors. The supply chain can be a key consideration in product design, with its design and operations influenced by concerns about uncertain energy costs, sustainability, economic security, and other complex issu...

Queueing models are commonly applied to quantify the performance of production systems. Prior research has usually focused on deriving queueing models for a specific type of interruptions. However, machines generally suffer multiple types of interruptions in practical manufacturing systems. To satisfy this need, an integrated model is proposed, in...

The challenges in cost-effectively deploying simulation technology are well known. Two major challenges are creating an appropriate conceptual model and translating that conceptual model correctly into a computational model. Ontologies have been widely discussed as one mechanism for capturing modelling knowledge in a reusable form, making it effect...

In this paper, we consider discrete event logistics systems (DELS). DELS are networks of resources through which material flow. They have been the subject of a large body of analytic research. A huge variety of specific models exists that generally require application by model and/or solution experts to answer narrowly-defined logistics questions a...

In this paper, we consider discrete event logistics systems (DELS). DELS are networks of resources through which material flow. They have been the subject of a large body of analytic research. A huge variety of specific models exists that generally require ...

This article describes the development of a modeling hierarchy for complex enterprise networks. Drawing on the extant modeling literature, these network models are elaborated in terms of 4 salient problem characteristics: conversions, flows, controls, and social/organizational relationships. The authors relate these 4 characteristics to phenomena,...

Warehouses are a substantial component of logistic operations and an important contributor to speed and cost in supply chains. While there are widely accepted benchmarks for individual warehouse functions such as order picking, little is known about the overall technical efficiency of warehouses. Lacking a general understanding of warehouse technic...

For most who do it, completing the PhD is the hardest thing they've ever done. There is a tendency to think that life will only get easier afterwards. The truth is that while life may get better, it doesn't necessarily get easier. It is possible, however, to ease the transition, if you pay attention to some basic truths.

Many warehouses store at least some goods in two areas, a reserve area that is efficient for storage and a forward area that is efficient for order picking. The forward-reserve allocation problem determines the set of Stock-Keeping Units and their space allocations in the forward area to maximize the forward area's benefit by trading off the releva...

This paper presents a detailed survey of the research on warehouse design, performance evaluation, practical case studies, and computational support tools. This and an earlier survey on warehouse operation provide a comprehensive review of existing academic research results in the framework of a systematic classification. Each research area within...

Effective benchmarking requires standards for measuring performance across a broad range of organizations. Industry-benchmarking measures the relative performance levels of similar operations, but gathering sufficient data to robustly characterize best performance is the primary hurdle to more widespread implementation. This paper describes the dev...

This panel seeks to initiate a discussion within the production system simulation community about a fundamental change in the way we think about, teach, and implement production system simulation. Today, production system simulation, while based on formal simulation languages, is largely an artistic process. We teach production system simulation as...

Batching plays an important role in semiconductor fabs, and it can lead to inefficiency if not treated with care. The performance of parallel batch processes is often approximated by the G/G/1-based approximate models. By carefully examining the existing models, the dependence between queueing time and wait-to-batch time has been identified. A new...

The successful practice of simulation requires a number of capabilities; two key capabilities are creating a conceptual model of the system to be simulated, and translating the conceptual model to a computational process or simulation program. We describe how OMG's new graphical systems modeling language, OMG SysML¿ (OMG 2009), can be used to crea...

Super efficiency models are useful for computing the Malmquist index and in methods for outlier detection, but conventional super-efficiency models may not have feasible solutions for some data sets. We show that a hyperbolic orientation eliminates the infeasibility problem, and permits zero-valued inputs in certain cases. We also demonstrate the c...

Queueing theory is a well-known method for evaluating the performance of manufacturing systems. When we want to analyze the performance of a single machine, M/M/1 queues or approximations of G/G/1 queues often are considered a proper choice. However, due to the com- plex nature of interruptions in manufacturing, the appro- priate model should be se...

Contemporary factories in capital intensive industries such as semiconductor manufacturing are very complex, with many sources of risk. The highly competitive and global business environment forces companies to analyze, design, and continuously re-design factories with distributed multi-disciplinary teams. Traditional factory design approaches usin...

Competitive forces are driving US domestic manufacturers to source parts globally, which significantly extends their supply chain and introduces new sustainability concerns. This paper addresses the situation from an operating division manager's perspective. We present an approach to packaging system assessment which considers the division manager'...

A computationally effective analysis of the throughput performance of a closed-loop multi-vehicle automated material handling system (AMHS) used in highly automated 300 mm wafer fabrication facilities (fabs) is presented. A probabilistic model is developed, based on a detailed description of AMHS operations, and the system is analyzed as an extende...

In the use of peer group data to assess individual, typical or best practice performance, the effective detection of outliers is critical for achieving useful results, particularly for two-stage analyses. In the DEA-related literature, prior work on this issue has focused on the efficient frontier as a basis for detecting outliers. An iterative app...

Simulation languages and the GUIs supporting them may be excellent tools for creating simulation codes, but are not necessarily the best tools to use for creating descriptions of systems, i.e., for modeling. In 2006, OMG published the initial standard specification (OMG 2006) for SysML (Systems Modeling Language), an extension of UML (OMG 2007) des...

This article gives an overview of a framework for automatically generating large-scale simulation models from a domain specific problem definition data schema, here semiconductor manufacturing. This simulation model uses an object-oriented Petri net data structure. The Petri net based simulation uses the same enabling rules as classical Petri nets,...

Distributed simulation promises benefits in large-scale si- mulations, such as in high fidelity simulation of 300mm wafer fabs, although these benefits have been hard to achieve in practice. This paper examines the fundamentals of distributed simulation, and proposes a hierarchical ap- proach to distributed wafer fab simulation, which has the poten...

Distributed simulation has a long history at the Winter Simulation Conference. Although successful in the military domain it appears, however, that the idea of applying dis- tributed simulation in other fields for modeling and analy- sis of large-scale, heterogeneous systems such as commu- nication networks or supply chains has still not reached th...

We present an analytical approach for estimating the expected time for an automated material handling system (AMHS) to respond to move requests at loading stations in a vehicle-based, unidirectional, closed-loop AMHS. The expected response times are important for estimating the expected work-in-process (WIP) levels at the loading stations for desig...

Queueing theory is a powerful method to evaluate the performance of a manufacturing system. However, when applying it to a real system, both practical and theoretical issues arise. The practical issues are how to determine the parameter values for queuing models from the data available in real manufacturing systems. We explore this issue by compari...

The speed of change, high complexity and risk in the semiconductor industry increases the importance of decision making in manufacturing. In particular, a growing need for faster and better decisions on factory design and operation demands more complexity and higher fidelity in factory simulation models. Two requirements to realize such models econ...

The epitome of the modern enterprise is a large scale, geographically dispersed, complex entity. It interacts with other enterprises, perhaps large numbers of them, in many different locations, often with great frequency. It serves highly competitive markets, which may shift in a matter of days or weeks. Designing, planning, managing, and controlli...

An extensive review on warehouse operation planning problems is presented. The problems are classified according to the basic warehouse functions, i.e., receiving, storage, order picking, and shipping. The literature in each category is summarized with an emphasis on the characteristics of various decision support models and solution algorithms. Th...

Contemporary simulation technology can produce accurate assessments of integrated circuit factory (fab) production performance, including the contribution by the automated material handling systems (AMHS). However, the corresponding simulation models are both expensive and time-consuming to construct, and require long execution times to produce sta...

The assessment of operational performance remains a fundamental challenge both in practice and in theory. Data envelopment analysis (DEA) is one method developed in production economic theory and applied by researchers to study groups of enterprises. In practice, individual enterprises almost universally rely on simple output-input ratios. Each app...

Contemporary technology for product lifecycle management (PLM) integrates computer aided design (CAD) and engineering analysis (CAE) to support rapid, distributed, team-oriented product data development and management, including high fidelity simulation on demand. This technology potentially provides a platform for creating a new generation of fact...

Distributed simulation is attractive for modeling compli- cated manufacturing systems having many tools and prod- ucts, such as a semiconductor wafer fabrication line. However, conservative synchronization approaches can in- troduce excessive overhead in execution, and result in little parallelism, which can eliminate the speedup promised by distri...

This research explores analytical models useful in the design of vehicle-based automated material handling systems (AMHS) to support semiconductor manufacturing. The objective is to correctly estimate the throughput and move request delay. This analysis proposes a computationally effective analytical approach to multi-vehicle AMHS performance model...

In the use of peer group data to assess individual, typical or best practice performance, the effective detection of outliers is critical for achieving useful results, particularly for two-stage analyses. In the DEA-related literature, prior work on this issue has focused on the efficient frontier as a basis for detecting outliers. An iterative app...

The infeasibility problem in traditional super efficiency models has been well established. A generalization of traditional input- or output-oriented super efficiency models, the directional distance function also suffers from infeasibility and related problems. The hyperbolic-oriented efficiency measure provides an alternative to the input-oriente...

This article describes the results of one of the ten pilot pro- grammes under the Integrated Manufacturing and Service Systems (IMSS) initiative pursued by the Agency for Sci- ence, Technology and Research (A*STAR) in Singapore. The objective of this particular programme is to investigate how design, analysis, enhancement and implementation of crit...

Distributed simulation promises to achieve significant parallelism in computation, which is essential in modeling wafer fabs in sufficient detail to support fab design or operational policy decision making. The high level architecture (HLA) is used to synchronize the simulation computations on networked computers. In designing a research and develo...

This research explores analytical models useful in the design of vehicle-based automated material handling systems (AMHS) to support semiconductor manufacturing. The objective is to correctly estimate the throughput and move request delay. The analysis approach is based on queuing network models, but taking into account details of the operation of...

IntroductionDiscrete Event SimulationWarehousing as an Organization TypeThe Structure of a Warehouse Meta-ModelConclusion References

Distributed simulation is attractive for modeling large scale manufacturing systems. However, synchronization requirements present distinct challenges in designing and implementing a suitable modeling structure. Our experience in building a distributed simulation model for 300mm wafer fab using the high level architecture (HLA) shows that time mana...

This research explores analytical models useful in the de- sign of vehicle-based Automated Material Handling Sys- tems (AMHS) to support semiconductor manufacturing. The objective is to correctly estimate the throughput and move request delay. The analysis approach is based on queuing network models, but taking into account details of the operation...

The productivity of small parts order-picking is affected by technology, picking station configuration, the nature of the orders, and the control mechanisms synchronizing and balancing order-picking labor and automation. The goal of this research is to develop a methodology for analyzing systems in which orders are progressively assembled by passin...

The painting process is an important part of the entire automobile manufacturing system. Changing color in the painting process is expensive because of the wasted paint and solvent during color change. By intelligently selecting cars toward downstream operations at the places where conveyors converge or diverge, we can reduce the number of such col...

Distributed simulation based on the High Level Architecture standard is adopted to realize the simulation of a borderless fab that involves two wafer fabs located in close proximity. The two fabs pool together their resources for capacity sharing. To demonstrate the benefits of this concept, experiments were conducted to measure the cycle time chan...

Distributed simulation promises a range of benefits and opportunities, especially for modeling large-scale complex systems, such as wafer fabs. However, as with many promising technologies, the devil is in the details. This paper describes some experiences in distributing a high-fidelity, full fab simulation model with federates implemented in Java...

We address the problem of selecting and specifying material transport technology in a general manufacturing environment, using four steps: 1) filtering and matching of material transport tasks and technologies, 2) clustering of tasks into tasks-resource combinations, 3) flow network design for combinations, and 4) selection of combinations. Step th...

Traditionally, the semiconductor manufacturing industry has been driven by continuous technological advancement of the underlying production processes. Yet, as the industry matures, mere technology development is no longer sufficient. The effective deployment and exploitation of the system production capacity and operational capability become criti...

The need for better understanding, control, and optimization of supply chains is being recognized more than ever in the new economy. Simulation holds a great potential in portraying the dynamic evolution of supply chains and providing appropriate decision support to address challenges arising from high variability and stochastic uncertainty. Realiz...

This paper addresses a difficult problem that often arises in printed circuit card assembly systems: how should circuit cards be grouped into families to decrease total assembly time? Traditional approaches to this problem focus on setup time, without considering the possible impacts on processing time. A new approach for selecting card families to...