Engineering Fundamentals

This paper describes a system in which the computer algebra system Maple running on a remote server is used to check the correctness of symbolic answers submitted via the Worldwide Web. The goal is to have a computer grade the kinds of symbolic algebraic, trigonometric, and calculus expressions that arise naturally in engineering and scientific applications, rather than just numerical or multiple-choice options. The ability to grade symbolic answers can be used synchronously (on-line quizzes or exams under monitored conditions) or asynchronously (e.g., homework, tutorials, or readiness tests) for a broad range of quantitative courses and levels. A database keeps extensive, detailed records of student performance. This paper describes a system for symbolic grading via a Web browser. After a giving the background and a brief overview of the system, it presents two simple computergradable problems and the steps used to grade an illustrative problem. The paper concludes with a brief summary of the work in progress toward a system that can be used for a variety of Web-based grading activities over a broad spectrum of on-site or remote quantitative courses.

Abenet---Chips produced during lathe turning should be broken so as to prevent snarling and to enhance heat removal from the tool. At present, conservatively written part programs for computer numerically controlled lathes are fine tuned by a human machine operator to produce desirable chip length. K. W. Yce and coworkers have produced an acoustic emission chip form monitor. The use of such an acoustic emission sensor in a simulated chip length control system is described. In this paper a fuzzy logic controller is then substituted for the conventional linear controller.

This paper proposes a new approach for assessing the organization's vulnerability to information-security breaches. Although much research has been done on qualitative approaches, the literature on numerical approaches to quantify information-security risk is scarce. This paper suggests a method to quantify risk in terms of a numeric value or "degree of cybersecurity". To help quantitatively measure the level of cybersecurity for a computer-based information system, we present two indices, the threat-impact index and the cyber-vulnerability index, based on vulnerability trees. By calculating and comparing the indices for various possible security enhancements, managers can select the best security enhancement choice, prioritize the choices by their relative effectiveness, and statistically justify spending resources on the selected choice. By qualifying information security quantitatively, the method can also help managers establish a specific target of security level that they can track.

A PID type algorithm called Q-PID was developed to improve online quality control of continuous processes. It has adjustable parameters to improve the controlled variable response or to decrease the manipulated variable movements, hence decrease the cost of control. Q-PID has PID type terms, a lead/lag term and dead time compensation. All previously published work using this algorithm considered continuous systems. Discrete implementation must be analyzed so that it can be used practically. This paper presents a sound development and simulation of the three possible dead time implementation schemes, Smith predictor, analytical predictor, and generalized analytical predictor that could be used for discrete implementation. It was discovered that either the Smith predictor or analytical predictor techniques could be used in the Q-PID with satisfactory results. The generalized analytical predictor results in drastic cost increases and instability in the presence of modeling error. The Smith predictor is the suggested method as it performs the best in the presence of modeling error and is simple and easy to implement. #

There has been considerable attention to applications of feedback control to machine tools. Certainly all computer numerically controlled (CNC) machines use servomechanisms for the spindle and feed drives. When feedback control is extended to the metal cutting process itself, there has been an unfortunate tendency to call such systems adaptive controls, for example, adaptive control constraint (ACC) .and adaptive control optimization (ACO), even though they have not been adaptive in the sense of modern control theory. A special name, parameter adaptive control, has been proposed to describe the application of truly adaptive control to metal cutting. Even though there is substantial work on adaptive control within the body of modern control theory, there have been few reductions of parameter adaptive control to actual machine tools. It has been suggested that the primary impediments to such application are the lack of mathematical models of manufacturing processes in forms appropriate to the control problem, and the lack of in-process sensing techniques that would be complementary to such models. This paper describes one step in a sequence of research efforts that is intended to lead to the adaptive control of unattended machine tools. Numerical parameters are used to evaluate coefficients of a previously developed state space model of semi-orthogonal metal cutting on a lathe. An Advanced Continuous Simulation Language (ACSL) program is presented.

Even though there is substantial work on adaptive control within the body of modern control theory, there have been few reductions of parameter adaptive control to actual machine tools on the shop floor. It has been suggested that the primary impediments to such application are the lack of mathematical models of manufacturing processes in forms appropriate to the control problem, and the lack of in-process sensing techniques that would be complementary to such models. This paper describes one step in a sequence of research efforts that is intended to lead to the adaptive control of unattended machine tools. Numerical parameters are used to evaluate coefficients of a previously developed state space model of semi-orthogonal metal cutting on a lathe. An advanced continuous simulation language (ACSL) program is presented.

A microcomputer-based expert system for the diagnosis of lathe machining operations has been developed using the EXSYS shell on an IBM AT. Interviews with a journeyman machinist resulted in an initial knowledge base of rules containing basic concepts and relationships concerning setup and control of lathe machining. The system provides the user with analysis and advice regarding the diagnosis and certain setup aspects of common lathe operations, and has shown that it is feasible to elicit and mimic at least a portion of an expert machinist's knowledge and special skills.

The modeling and control of a typical cyclic polymer process, such as injection molding or thermoforming, are considered. The purpose of control is to achieve a specified product quality for a sequence of parts. First, conventional feedback controllers are compared to statistically based controllers with respect to random noise disturbances. It is shown that conventional controllers may not react quickly to load disturbances without magnifying background noise and reducing product yield. I t is demonstrated that statistically based controllers are able to differentiate between noise and load disturbances, proving them superior when part quality tolerance is tight and noise level relatively large. Next, the responsiveness of conventional controllers (proportional, integral, and proportionalintegral) is compared with several statistically based controllers (CUSUM, Western Electric runs rules, and simple Shewhart) when subjected to load disturbances. Three load disturbances were modeled; steps, ramps, and sinusoids. Again, statistically based methods generally prove superior to and, at worst, comparable to conventional controllers.

The growing dependence of critical infrastructures and industrial automation on interconnected physical and cyber based control systems has resulted in a growing and previously unforeseen cyber security threat to SCADA and DCS systems. Industry organizations such as NERC and AGA as well as government organizations like NIST and SANDIA are responding to the cyber security threat faced by control systems and critical infrastructure through the development of guidelines, best practices, test beds, security tools and new technology. Published papers such as (Byres and Lowe, 2005; Miller, 2005; and Greer, 2006) describe the threats and vulnerabilities faced by SCADA and DCS systems and the challenges presented in attempting to secure these systems. Other papers, such as (Byres and Franz, 2006, Strickles, et al 2003) describe the application of existing security technologies and security practices. The articulation of risk is an important component of a comprehensive, realistic, and long ...

Even though there is substantial work on adaptive control within the body of modern control theory, there have been few reductions of parameter adaptive control to actual machine tools on the shop floor. It has been suggested that the primary impediments to such application are the lack of mathematical models of manufacturing processes in forms appropriate to the control problem, and the lack of in-process sensing techniques that would be complementary to such models. This paper describes one step in a sequence of research efforts that is intended to lead to the adaptive control of unattended machine tools. Numerical parameters are used to evaluate coefficients of a previously developed state space model of semi-orthogonal metal cutting on a lathe. An advanced continuous simulation language (ACSL) program is presented.