Comments on “some results on pole-placement and reachability”

We present various comments on a question about systems over rings posed in a recent note by Sharma, proving that a ring R is pole assignable if and only if, for every reachable system (F, G), G contains a rank-one summand of the state space. We also provide a generalization to deal with dynamic feedback.     

Comments on “bounded-input, bounded-output stability of chemical reactors”

[1] has recently derived a sufficient condition for the global asymptotic stability of a continuous stirred tank reactor. Although the major conclusions of this study appear to be correct, the analysis contains several errors including incorrect stability criteria for the linearized system.     

Visualizing “typical” and “exotic” Internet traffic data

The threat of cyber attacks motivates the need to monitor Internet traffic data for potentially abnormal behavior. Due to the enormous volumes of such data, statistical process monitoring tools, such as those traditionally used on data in the product manufacturing arena, are inadequate. “Exotic” data may indicate a potential attack; detecting such data requires a characterization of “typical” data. We devise some new graphical displays, including a “skyline plot,” that permit ready visual identification of unusual Internet traffic patterns in “streaming” data, and use appropriate statistical measures to help identify potential cyberattacks. These methods are illustrated on a moderate-sized data set (135,605 records) collected at George Mason University.     

Comments on “direct bilinear routh stability criteria for discrete systems”

The above paper¹ discusses useful Routh-like stability criteria for discrete systems. Unfortunately, however, previous work on the subject escaped the attention of the author. This note co-ordinates previous work with results obtained in the above paper. It also points out some of the more recent developments on the subject.     

Comments on “self-tuning adaptive control of cement raw material blending”

In a recent paper Keviczky and co-workers (1978) use results of previous papers (Keviczky and Hetthessy, 1977; Hetthessy, Haber and Keviczky (1975) to present the MIMO-ST-MV and the MIMO-ST-MV-RAFT used in cement industries. In this correspondence an algebraic mistake is shown to have taken place in Keviczky and Hetthessy (1977). Accordingly, the representation in Keviczky and co-workers (1978) of the regulator parameter matrix is not of the minimum variance type.     

Comments on “Approximate output regulation of a class of nonlinear systems”

In the above-mentioned paper [Journal of Process Control 11 (2001) 69–80], the problem of approximate output regulation of a class of nonlinear systems was considered. By a step-by-step systematic design procedure, a nonlinear controller is designed which is a dynamic and state feedback. However, we find that there exist some mistakes in the proof of the main theorem of this paper. This note points out the flaw of the commented paper.     

Comments on “Fully magnetic attitude control for spacecraft subject to gravity gradient”

The Lyapunov argument used in Wi niewski and Blanke, (Automatica 35 (1999) 1201) to establish asymptotic stability of a magnetic control law for an earth-orbiting spacecraft is incorrect. It is shown here that a small change to the assumed form of the control law can remedy the situation.     

“Paraprogramming” manufacturing information systems

Computer integrated manufacturing (CIM) is creating unexpected problems for a growing number of manufacturing companies. Manufacturers are finding it especially difficult to attract programmers who are both willing and able to develop the highly complex software that integrates existing accounting, sales, production, engineering, and quality control information subsystems. Consequently, many companies abdicate their responsibility for manufacturing information systems and seek third party support ranging from consulting assistance to a total takeover of the company's information resources and operations. Companies that “give away” their internal information system capabilities to third parties will ultimately lose control of their enterprise information, a danger to be avoided. Off-the-shelf software for desktop computers has become sufficiently powerful to help solve a major portion of this serious problem. We hypothesize that manufacturing engineers (and others) can be trained to use packaged software to leverage their company's systems programming capabilities. In effect they would become “paraprogrammers” who would help design, develop, and maintain manufacturing information systems. This new type of professional would not require a computer science or similar educational background, but could be trained to satisfy many specialized programming needs in a manner similar to how paramedics and paralegals are trained and used in the medical and legal professions, respectively. This paper reports on the early stages of research to determine whether or not product design engineers can use a desktop relational database management system and its various command languages to develop a master bill of material information system (BOMIS). The purpose of the research is to evaluate the amount of programming complexity reduction and increased operational effectiveness that can be achieved through paraprogramming by manufacturing engineers.     

The depth of monotone Boolean functions with multi input “AND” and “OR” gates

The problem of maximum depth of monotone Boolean functions is investigated when k-input AND and OR gates are used for realisation.