Operation Of Production Systems Research Articles

RESEARCH NEEDS IN LARGE SCALE INDUSTRIAL SYSTEMS

In today's industry, the requirements concerning the cost effectiveness of the production as well as end product quality are becoming even harder. Companies operating at real time in globalized business require agile production that quickly responds to changes in the business environment.The build-up, operation and maintenance of large scale industrial production systems require a whole network of experts of different domains. In setting up such a network, one must carefully design the roles of the actors in a manner that the network supports the overall performance of the system. Also the views through which each actor accesses the system must be designed to efficiently support his decision making.Recent research has made great advancement in data mining and information discovery in large sets of data. Also the modelling and simulation is slowly but surely being taken up in different phases of the plant life span. The standardization of plant life cycle data as well as on-line interfaces for the exchange of data and events has taken steps forward. Furthermore, mobile solutions and advanced visualization are entering the industry. All of this is surely helpful in managing large scale industrial systems. Often the question remains: what is the overall good performance of the system.What is now needed from the research is practical methods for selecting appropriate performance metrics and for implementing decision support systems for managing and controlling of the operative state in a large scale industrial system. The methods must take into account the network nature of the organization and the human-technology interaction of each actor in the network.

Fuzzy Supervisory Control of Manufacturing Systems

A supervisory controller is derived for scheduling (single/multiple-part-type, reentrant) production networks. The supervisory controller is used to tune a set of lower level distributed fuzzy control modules that reduce work-in-process (WIP) and synchronize the production system's operation. The overall production-control system is viewed as a two-level surplus-based system with the overall control objective to keep the WIP and cycle time as low as possible, while maintaining quality of service by keeping backlog to acceptable levels. The production rate in each production stage is controlled to satisfy demand, avoid overloading, and eliminate machine starvation or blocking. The system's improvement is demonstrated using a set of performance measures. Extensive simulation results show that the supervisory controller, when compared with the single-level distributed fuzzy controllers reduces WIP and cycle time while keeping backlog to acceptable levels.

A Neural Network Model for Prediction of Liquid Holdup in Two-Phase Horizontal Flow

SummaryAccurately predicting the liquid holdup associated with multiphase flow is a critical element in the design and operation of modern production systems. This prediction is made difficult by complex phase distributions and the wide range of fluid properties encountered in production operations. Consequently, the performance of existing correlations is often inadequate in terms of desired accuracy and application range. This investigation focuses on the development of a neural network model, a relatively new approach that has been applied successfully to a variety of complex engineering problems. Data from five independent studies were used to develop a neural network for predicting liquid holdup in two-phase horizontal flow. A detailed comparison with existing empirical correlations and mechanistic models reveals that for this data set, the neural network model shows an improvement in overall accuracy and performs more consistently across the range of liquid-holdup and flow patterns.

Service industries, globalization, and urban restructuring within the Asia-Pacific: new development trajectories and planning responses

While industralization programmes have been central to the development of Asia-Pacific states and city-regions over the past half-century, service industries are increasingly important as instruments of urban growth and change. The purpose of this paper is to establish service industries as increasingly significant aspects of urban development within the Asia-Pacific, and to propose a conceptual and analytical framework for scholarly investigation within this important research domain. To this end the paper explores a sequence of related themes and issues, concerning the larger developmental implications of urban services growth (or tertiarization), the facets of urban transformation associated with tertiarization, and a preliminary typology of urban service functions which acknowledges the rich diversity of service vocations and stages of development within the Asia-Pacific. The paper concludes that “advanced services”—specialized, intermediate service industries, advanced-technology services, and creative service industries—will be quite crucial to the development of city-regions within the Asia-Pacific, with respect to employment growth and human capital formation, to the urban economic (or export) base, to the operation of flexible production systems, and to competitive advantage. The development of these urban service poles will require innovative policy commitments and regulatory adjustments, as will the multi-centred specialized urban service corridors which function as engines of regional economic growth, and which provide platforms for national modernization and responses to the pressures (and opportunities) of globalization. To date, urban and regional development strategies for service industries within the Asia-Pacific have privileged globalization, industrial restructuring, and modernization aims, but there is also an encouraging record of more progressive planning experimentation in some jurisdictions, incorporating principles of sustainability and co-operative development. There is also increasing interest in policies to support cultural and creative industries among Asia-Pacific city-regions, informed by some recent urban policy experimentation in this domain. These experiences can offer models for further policy and programmatic innovation in the 21st century, as service industries continue to play larger roles in urban and regional development within the Asia-Pacific.

The transformational effects of technology on operations management

Over the years, advances in technology have transformed key aspects of operations management. New tools and technologies have been incorporated into the design and operation of service and production systems. Textbooks play an integral role in documenting the transformational effects of technology in specific fields. In this paper, the evolution of technology, its transformational effects, and influence on operations management is studied. Samples of the textbooks published within the last 35 years are searched and the results concluded.

The transformational effects of technology on operations management

Over the years, advances in technology have transformed key aspects of operations management. New tools and technologies have been incorporated into the design and operation of service and production systems. Textbooks play an integral role in documenting the transformational effects of technology in specific fields. In this paper, the evolution of technology, its transformational effects, and influence on operations management is studied. Samples of the textbooks published within the last 35 years are searched and the results concluded.

Lean Manufacturing Principles and their Applicability to the Mining Industry

Lean manufacturing, pioneered by Toyota, has been credited with the most significant improvements in production efficiency and product quality since the transformation from craft manufacturing to mass production in the early 20th century. It represents a comprehensive philosophy for structuring, operation, control, and management of production systems that is believed to have wide applicability. This paper outlines major lean manufacturing principles and discusses their potential for application in the mining industry.

LEAN MANUFACTURING PRINCIPLES AND THEIR APPLICABILITY TO THE MINING INDUSTRY

Lean manufacturing, pioneered by Toyota, has been credited with the most significant improvements in production efficiency and product quality since the transformation from craft manufacturing to mass production in the early 20th century. It represents a comprehensive philosophy for structuring, operation, control, and management of production systems that is believed to have wide applicability. This paper outlines major lean manufacturing principles and discusses their potential for application in the mining industry.

Monitoring of flexible production systems using high-level Petri net specifications

The degree of reliability in the operation of flexible production systems depends not only on the operation of the individual components, but also on the structure and evolution of the embedded supervisory control system. Monitoring of operations and of the behaviour of the components and of the system as a whole is an essential function of such a supervisory control system. This paper focuses on the development and implementation of feature- and model-based monitoring methods using high-level Petri net specifications of flexible production systems and of the embedded discrete-event controllers. The combination of machine–human interface concepts with the developed monitoring methods leads to a user-friendly representation of monitoring information. An application at industrial level is shown by means of a case study, i.e., a sample flexible assembly cell, situated at the Institute for Manufacturing Automation and Production Systems, Germany.

Minimizing production flow time in a process and assembly job shop

Scheduling is one of the most important issues in the planning and operation of production systems, but in medium to large shops, the generation of consistently good schedules has proven to be extremely difficult. The problem is that optimal scheduling solutions involve costly and impractical enumeration procedures. In the literature, most scheduling problems only address jobs with serial or sequential operations. Rarely do they consider jobs in which machining and assembly operations are simultaneously involved. This lack of attention to scheduling problems that involve both machining and assembly goes against what one would normally find in most job shops. In this paper, the problem of scheduling a set of N final products on M machines in a job shop environment that involve both machining and assembly operations is addressed. The objective pursued is the minimization of production flow time (makespan). A mathematical model is developed in an effort to obtain optimal solutions. Because this type of model grows exponentially as the size of the problems increases, an heuristic solution approach is developed to solve the problems more efficiently. The models are tested and compared on several test problems.

Structural Properties of Lot Streaming in a Flow Shop

Lot streaming is the process of splitting a given lot or job to allow the overlapping of successive operations in multi-stage production systems, thereby reducing the makespan of the corresponding schedule. This paper considers the problem of finding sublot sizes to minimize the makespan for a single job in an m-machine flow shop. On each machine, the job is to be partitioned into a given number of sublots, and sublot sizes are the same on each machine. We introduce the concept of machine dominance, and propose an algorithm to reduce the problem so that only dominant machines are considered explicitly. After defining a network representation in which it is required to find the shortest critical path length, we identify the structure of critical paths for optimal sublot sizes. Knowledge of this structure considerably reduces the search for an optimal solution, which we illustrate by presenting algorithms for finding optimal sublot sizes.

Density and composition of microorganisms during long-term (418 day) growth of potato using biologically reclaimed nutrients from inedible plant biomass

A study evaluating alternative methods for long term operation of biomass production systems was recently completed at the Kennedy Space Center (KSC). The 418-day study evaluated repeated batch versus mixed-aged production of potato grown on either standard 1 2 - strength Hoagland's nutrient solution or solutions including nutrients recycled from inedible plant material. The long term effects of closure and recycling on microbial dynamics were evaluated by monitoring the microbial communities associated with various habitats within the plant growth system (i.e., plant roots, nutrient solution, biofilms within the hydroponic systems, atmosphere, and atmospheric condensate). Plate count methods were used to enumerate and characterize microorganisms. Microscopic staining methods were used to estimate total cell densities. The primary finding was that the density and composition of microbial communities associated with controlled environmental plant growth systems are stable during long term operation. Continuous production resulted in slightly greater stability. Nutrient recycling, despite the addition of soluble organic material from the waste processing system, did not significantly increase microbial density in any of the habitats.

Lot streaming in three-stage production processes

Lot streaming is the process of splitting a given lot or job to allow the overlapping of successive operations in multi-stage production systems, thereby reducing the makespan of the corresponding schedule. This paper develops algorithms to minimize the makespan for a single job in three-stage production processes. At each stage, the job is split into s sublots. For both the flow shop and job shop problems, an algorithm is proposed which computes the minimum makespan in O(log s) time. However, for the open shop, it is shown that to evaluate the minimum makespan requires constant time. Various results are derived which are applicable when the number of stages of production exceeds three.

Location and sequencing of imperfect inspection operations in serial multi-stage production systems

Abstract An integrated approach to the problem of allocation of inspection effort in multistage production systems is presented. The problem addresses multiple inspection operations, different disposition policies and inspection, production and repair errors. Quality and cost transfer functions are developed to model production operations and different types of inspection operations in a unified manner and to facilitate the recursive computations required to evaluate alternative system configurations. We formulate the combined inspection location and sequencing problem as a nonlinear mathematical programming problem and solve it with a branch and bound technique, using a heuristic to generate a feasible solution and upper bound. These developments are illustrated with a numerical example.

The Spatial Patterning of Aztec Ceramics: Implications for Prehispanic Exchange Systems in the Valley of Mexico

Data gathered by regional archaeological surveys in the Valley of Mexico are used in the following study to investigate patterns of exchange during Aztec times. Decorated ceramics from 130 sites in the Texcoco, Ixtapalapa, and Chalco Survey Regions were tabulated, and the relative concentrations of ceramic wares and types (six dating to the Early Aztec period, eight to the Late Aztec) at sites in 12 polities were mapped. Ceramic distributions in the Early Aztec period (A.C. 1150–1350), when the valley was divided into a number of autonomous polities, are compared to those of the Late Aztec period (A.C. 1350–1520), a time of greater political unification brought about by the emergence of the Aztec empire. Results for the Early Aztec period indicate an overlapping series of local market systems, in which neighboring city-states exchanged ceramics more frequently than did polities at a greater distance. The results further identified two sub-regions of greater internal exchange, with reduced exchange between these regions. Spatially, these areas are congruent with the territories known to have been occupied by two regional political confederations, suggesting that Early Aztec confederations constrained economic interaction across their boundaries. In the Late Aztec period, more similar ceramic assemblages overall indicate a greater level of exchange among all polities. The restricted spatial distribution of particular ceramic types in the southern lakeshore polities, however argues for the continued operation of local production and exchange systems in this area and a lesser degree of integration into the regional Late Aztec exchange system. Documentary evidence indicates that these polities were conquered and incorporated into the empire later than others in the study area, and thus they may represent an area of the Valley of Mexico where tribute outweighed trade as an imperial strategy for economic integration.

Intelligent Actuators for Low Cost Automation

Most of the problems which occur during the operation of complex production systems are linked with faulty sensors or actuators. Such faults have a considerable effect on the safety of the system (non detected faults) or on its productivity (false alarm, stopping the operation of the system).In a great number of cases, it is possible to make use of locally available informations, and to detect actuators faults via local treatment of information. This approach needs no relevant modification of the whole system but makes use of the redundancy which already exists in the actuator’s instrumentation. In that sense, we develop a supervision procedure based on the description of the actuator by means of state graphs. This procedure gives as an output the actual state of the actuator as well as the list of its faulty instruments.We propose a functional architecture for smart actuators, which integrates not only the supervision function but also generates the necessary informations to meet the needs expressed by the different operators which have to manage the system.

Financial analysis of shrimp production: an electronic spreadsheet model

This paper describes an electronic spreadsheet model developed for financial evaluation of alternative design and operation of shrimp production systems. The model includes maturation, hatchery, nursery, and growout phases. A separate earthworks sub-model is also included for calculating the construction cost for earthen ponds of a given farm design. The model is created using Lotus 1-2-3™ and designed to be run interactively by someone not necessarily familiar with a spreadsheet program. Although the model was designed to analyze shrimp production systems, the format is such that other aquaculture systems can be evaluated.

Goal Setting in the Management of Operations

This paper addresses the importance of goal setting in the operations function. The importance of goal setting and its possible role in the implementation and operation of production systems is considered with particular emphasis on Material Requirements Planning (MRP). It has been argued that an operative goal setting process can improve employees' performance in any area of the organisation. Likewise, companies with a high‐level MRP system are expected to show high performance levels. This paper offers empirical support for these claims and further argues that the combination and interaction of the two processes results in synergistic effects. To support these arguments the paper draws on both theoretical studies and the results of a small regional survey.

Applications of systems modeling in aquaculture

This paper deals with the applications of systems modeling in aquaculture. Different types of biological models and techniques of economic analysis such as optimization and simulation are discussed in the context of aquaculture production. Emphasis is on the applicability of such modeling techniques for production system design and operation management. Past modeling efforts for several aquatic species are reviewed and surveyed with a special discussion on an on-going modeling effort of prawn production in Hawaii.

Modelling and Optimization of Hydrothermal Generation Scheduling

An approach is proposed to optimize the operation of energy production systems over middle term planning periods. Randomness of primary load is explicitly considered. A precise model is used to represent the hydraulic system (with individualized reservoir in cascade, water transportation delays, nonlinear generation, ...) as well as the non-hydraulic system (thermal generations, interchanges, load shedding, ...). Difficulties resulting from the large scale are overcome by decomposition techniques.