William Leigh

Maintenance Scheduling: Issues, Results and Research Needs

Productivity, based on estimated and actual hours, of most maintenance workers is only 30 to 50 per cent. Given the significance of maintenance to manufacturing competitiveness, it is surprising how little research is being carried out. Scheduling is a crucial component of maintenance management and is a focus of research. Identifies the areas of concern in maintenance scheduling and surveys representative work from the academic and practitioner literature. Specific points of practice and theory which need further investigation are pinpointed.

An analysis of a hybrid neural network and pattern recognition technique for predicting short-term increases in the NYSE composite index

We introduce a method for combining template matching, from pattern recognition, and the feed-forward neural network, from artificial intelligence, to forecast stock market activity. We evaluate the effectiveness of the method for forecasting increases in the New York Stock Exchange Composite Index at a 5 trading day horizon. Results indicate that the technique is capable of returning results that are superior to those attained by random choice.

Market timing: a test of a charting heuristic

Abstract We implement a graphical (or ‘charting’) heuristic, the ‘bull flag’, which accepts a particular pattern of historical prices as a signal for a future market price increase, test it with several years of New York Stock Exchange Composite Index history, and find positive results. The results support the validity of technical analysis for stock market price prediction and fail to confirm the efficient markets hypothesis.

International Building Code IBC-2000

The IBC-2000 is similar to the UBC-97, but it contains some significant differences. An important difference is that the IBC-2000 includes a set of maps to obtain seismic response spectral values that will result in the same level of risk at any given geographic location in the United States. This code also introduces the concept of Seismic Use Group, which is somewhat analogous to the Importance Factor in the UBC-97. In addition, the IBC-2000 classifies every building in a Seismic Design Category which determines the analysis procedure to be used, the maximum allowed height and drift limitations.

Trading With a Stock Chart Heuristic

The efficient market hypothesis (EMH) is a cornerstone of financial economics. The EMH asserts that security prices fully reflect all available information and that the stock market prices securities at their fair values. Therefore, investors cannot consistently ldquobeat the marketrdquo because stocks reside in perpetual equilibrium, making research efforts futile. This flies in the face of the conventional nonacademic wisdom that astute analysts can beat the market using technical or fundamental stock analysis. The purpose of this research is to partially assess whether technical analysts, who predict future stock prices by analyzing past stock prices, can consistently achieve a trading return that outperforms the stock market average return. This is tested using knowlege engineering experimentation with one price history pattern - the ldquobull flag stock chartrdquo - which signals technical analysts of a future stock market price increase. A recognizer for the stock chart pattern is built using a template-matching technique from pattern recognition. The recognizer and associated trading rules are then tested by simulating trading on over 35 years of daily closing price data for the New York stock exchange composite index. The experiment is then replicated using the horizontal rotation or mirror image pattern of the ldquobull flagrdquo (or ldquobear flagrdquo stock chart) that signals a future stock market decrease. Results are systematic, statistically significant, and fail to confirm the null hypothesis based on a corollary to the EMH: that profit realized from trading determined by this heuristic method is no better than what would be realized from trading decisions based on random choice.

Utilizing knowledge links in the implementation of system development methodologies

Abstract Developing technical ‘know-how’ is a slow process that can become a barrier in implementing complex administrative technologies such as a software development methodology. To overcome this barrier, organizations often seek knowledge links that can enhance learning and minimize inevitable problems that are encountered in an implementation process. This paper presents the findings of an empirical study that examines the prescribed versus actual use of external consultants, universities and vendors as knowledge links during the implementation of systems development methodologies (SDM). First, the study assesses the need and value of establishing and utilizing links to external sources of expertise for successful SDM implementation. We then identify and analyze a gap that exists between what the links to external knowledge are perceived to be capable of contributing and what the links to external knowledge are actually contributing during SDM implementation. In conclusion, possible reasons for the gap are discussed.

The development of knowledge for maintenance management using simulation

The management of maintenance is an area of concern for any industry that depends on the smooth running of equipment to produce a product or carry out a mission at profit or low cost. Maintenance managers must have access to advanced information systems to help them plan their work forces and control operating costs efficiently. This paper describes a method and demonstrates its use to develop a knowledge base for a maintenance supervisor assistant system (MSAS). MSAS interacts with the maintenance manager on a periodic basis to select, for the next period of operations, the proper policies and techniques to meet objectives. The first stage of the method is the knowledge acquisition phase. For this phase, an object-oriented computer simulation model has been developed as a testbed for examining different scheduling heuristics and manning policies in a range of maintenance environments. The dimensions of the environment considered include: preventive maintenance policies, staffing policies, downtime costs, simultaneous downtime practices, travel time impacts, and backlog policies. The dependent variables of interest include: overall machine availability, critical machine availability, worker utilization, cost of the maintenance function, and work order completion time. The second stage is a knowledge engineering effort to codify what is learned from the stage one simulation experiments into a knowledge base for a MSAS. A procedure for deriving expert system rules from simulation experiments is demonstrated. This is followed by validation of the knowledge base through re-employment of the simulation model. >

Nonlinear Structural Response

In discussing the dynamic behavior of single-degree-of-freedom systems, we assumed that in the model representing the structure, the restoring force was proportional to the displacement. We also assumed the dissipation of energy through a viscous damping mechanism in which the damping force was proportional to the velocity. In addition, the mass in the model was always considered to be unchanging with time. As a consequence of these assumptions, the equation of motion for such a system resulted in a linear, second order ordinary differential equation with constant coefficients, namely,

Static Condensation and Substructuring

m\ddot{u} + c\dot{u} + ku = F(t)