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Intelligent Simulation Modeling of a Flexible Manufacturing System with Automated Guided Vehicles
Get PDFAlthough simulation is a very flexible and cost effective problem solving technique, it has been traditionally limited to building models which are merely descriptive of the system under study. Relatively new approaches combine improvement heuristics and artificial intelligence with simulation to provide prescriptive power in simulation modeling. This study demonstrates the synergy obtained by bringing together the "learning automata theory" and simulation analysis. Intelligent objects are embedded in the simulation model of a Flexible Manufacturing System (FMS), in which Automated Guided Vehicles (AGVs) serve as the material handling system between four unique workcenters. The objective of the study is to find satisfactory AGV routing patterns along available paths to minimize the mean time spent by different kinds of parts in the system. System parameters such as different part routing and processing time requirements, arrivals distribution, number of palettes, available paths between workcenters, number and speed of AGVs can be defined by the user. The network of learning automata acts as the decision maker driving the simulation, and the FMS model acts as the training environment for the automata
network; providing realistic, yet cost-effective and risk-free feedback. Object oriented design and implementation of the simulation model with a process oriented world view, graphical animation and visually interactive simulation (using GUI objects such as windows, menus, dialog boxes; mouse sensitive dynamic automaton trace charts and dynamic graphical statistical monitoring) are other issues dealt with in the study
Course/Faculty Scheduler
Get PDFThe CFS is designed as an automated aid in the creation of course schedules for Miami University's SAN department. The CFS does not create schedules but provides an environment that will ease the task of creating schedule. The CFS helps create schedules for the Miami University course catalog. The scheduler is for use as a stand alone product in creating department level course schedules. The CFS is an interactive aid for the creation of a course schedule offerings
Experimental Evaluation of the Cleanroom Software Development Method
Get PDFThe field of software engineering is evolving as various new techniques, languages, paradigms, process models, methodologies, metrics etc., are constantly being developed,
used and improved. In the past, several empirical studies were conducted to experiment with various new ideas in software engineering in order to help us better understand, evaluate,
predict, control and improve these ideas. Basiii et al. review several of these studies and present a general framework for analyzing these experiments[2.5]. They emphasize the need of such experiments for advancement of software engineering discipline. They recommend that the experimental planning process should include a series of experiments for exploration, verification, and application of new ideas. They also implied that the results of empirical experiments in software engineering should be verified by a series of other related experiments.
Cleanroom methodology for software development is a relatively new concept. Currently researchers are attempting to study the benefits and implications of using the Cleanroom methodology. One such attempt was made at the University of Maryland (UM) a
few years ago which empirically characterized various aspects of Cleanroom methodologyj211. The fact that this study was empirical motivates the need for verifying its results. Also, the fact that the methodology is new motivates the need for further experimentation. Therefore, this experiment has been replicated recently at Miami University (MU). The goal of this project is to analyze the data collected in this experiment to verify the results of the previous study
An Empirical Investigation of Four Strategies for Serializing Schedules in Transaction Processing
Get PDFA database management system (DBMS) is a very large program that allows users to create and maintain databases. A DBMS has many capabilities. This study will focus on the capability known as transaction management, the capability to provide correct, concurrent access to the database by many users at the same time. If a DBMS did not provide transaction management, livelocks, deadlocks, and non-serializable schedules could
occur. A livelock can occur when a transaction is waiting on a locked data item, and another transaction appears. After the data item is unlocked, the second transaction locks the data item, which causes the first transaction to continue waiting. Conceivably, the first transaction could wait indefinitely to lock the data item. This situation is called livelock. Deadlock is a situation in which each member of a set of two or more transactions is waiting to lock an item currently locked by some other transaction in the set. None of the transactions can proceed, so they all wait indefinitely. A schedule is serial if for every pair of transactions, all of the operations of one transaction execute before any of the operations of the other transaction. A schedule is serializable if its effect on the database is the same as some serial execution of the same set of transactions. A schedule is nonserializable if its effect on the database is not equivalent to that of any serial schedule
which processes the same transactions. The scheduler is a component of the DBMS, and it is responsible for resolving any livelocks, deadlocks, or non-serializable schedules that
occur. This study looks specifically at non-serializable schedules. There are many methods by which the scheduler can serialize non-serializable schedules. This study proposes and
examines four strategies to detect and resolve non-serializable schedules. Computer simulation is used to examine the four strategies. These strategies reduce a nonserializable schedule to a serializable or a serial schedule, thus eliminating the possibility of incorrectly updating data items within a database. It is shown experimentally that, of the four strategies, the one that delays the transaction which has executed the least number of steps until non-serializability is detected is the best
The Graduate Student Advisor (GSA): An Expert System for SAN Graduate Student Advising
Get PDFThe Graduate Student Advisor (GSA) is an experimental expert system that advises graduate students in systems analysis. It simulates a faculty advisor in suggesting the schedule of courses a student should take based on the student's background and interests. It is implemented in NEXPERT Object. This report first describes the task, knowledge engineering and solution approach of the GSA. The report then gives a sample session to illustrate how to run a consultation. It also includes some maintenance notes about how to modify the knowledge about courses and related rules if necessary. Finally, it discusses some lessons learned
Objects and Types: A Tutorial
Get PDFThis paper is a tutorial explaining the concepts that surround abstract data types and object-oriented programming, and the relationships between these groups of concepts. These concepts include types (languagedefied, user-defied, abstract), instantiations, differences between operations and functions, overloading, objects, state, inheritance and, messages. Some of the these trems, e.g. "type", have been well defied. Many others
are used in seveml contexts with multiple meanings. This paper is an attempt to identify consistent and meaningful definitions which are the most widely accepted
Dare to compare: fact-based versus simulation-based comparison in daily life
Get PDFWe examined the relative frequency of social, counter factual, past-temporal, and future-temporal
comparison in daily life using an experience-sampling method, in which participants were
randomly prompted to record thought samples using palmtop computers carried for two weeks.
Comparative thought accounted for 12% of all thoughts, and all four comparison types occurred
with equivalent frequency. Comparisons may be either fact-based (i.e., based on actuality, as in
social and past-temporal comparison) or simulation-based (i.e., based on imagination, as in
counterfactual and future-temporal comparison). Because the latter are more “unbounded,” and
because greater perceived opportunity invites greater self-improvement, we predicted and found
that counterfactual and future-temporal comparison were more likely to be upward (vs.
downward) than social and past-temporal comparison. All comparison types focused on
approach more than avoidance motives, except for counterfactuals, which showed equivalent
focus on both. These findings reveal the prominence of comparative thought in daily life, and
underscore the value an integrative theory that describes social, counter factual, or temporal
comparison using a common theoretical platform
A Language for Rule-based Systems
Get PDFExpert systems are proliferating in many situations in which it is important to capture expertise in a computer system. This type of system is useful in situations in which human expertise
is expensive or difficult to obtain or in which the operating environment is too dangerous for a person. Expert systems are used to address the following categories of problems: interpretation, prediction, diagnosis, design, planning, monitoring, debugging, repair, instruction, and control.
[Hayes-Roth] Expert system have now moved out of the laboratory and are being used in production environments. Herein lies the problem addressed by this research. Expert systems have traditionally been used in a research environment in which the software engineering of the product is not particularly important. Production environments are much more demanding. The quality necessary for continual use and abuse is not generally built into research quality expert systems. The problem is further exacerbated when an expert system is to be embedded in an autonomous system for which human interaction is difficult. (For example, an expert system could be used to drive a robot in
a hazardous environment. If the expert system fails, it may not be easy for a human to reach the robot for repair.) Quality in these situations is vital
Prototyping in a Centralized vs. Client/Server Environment
Get PDFClient/Sewer technology has become a hot topic. It has changed the way we think about systems development and implementation. In this paper a proposed experimental system is used as a test case to help define whether development using client/sewer technology will change the traditional steps that each developer must go through in order to successfully complete a computer based system
Concepts and Effectiveness of the Cover Coefficient Based Clustering Methodology for Text Databases
Get PDFAn algorithm for document clustering is introduced. The base concept of the algorithm, Cover Coefficient (CC) concept, provides means of estimating the number of clusters within a document database. The CC concept is used also to identify the cluster seeds, to form clusters with the seeds, and to calculate Term Discrimination and Document Significance values (TDV, DSV). TDVs and DSVs are used to optimize document descriptions. The CC concept also relates indexing and clustering analytically. Experimental results indicate that the clustering performance in terms of the percentage of useful information accessed (precision) is forty percent higher, with accompanying reduction in search space, than that of random assignment of documents to clusters. The experiments have validated the indexing-clustering relationships and shown improvements in retrieval precision when TDV and DSV optimizations are used