Engineering Systems Theory Research Articles

Multivariable Beurling–Lax representations: the commutative and free noncommutative settings

The original theorem of Beurling asserts that any invariant subspace for the shift operator (multiplication by the coordinate function \( \chi(\lambda) =\lambda\)) on the Hardy space over the unit disk can be represented as an inner function times H2. We survey various approaches (including ideas and techniques from engineering systems theory and reproducing kernel Hilbert spaces) beyond Beurling’s original approach developed over the years for proving this result and then focus on understanding how these approaches can be adapted to handle the more delicate situation where the Hardy-space shift is replaced by the shift operator on a weighted Bergman space over the unit disk. We then indicate how all these results can be extended further to the setting of freely noncommutative shift-operator tuples on a weighted Bergman space in several freely noncommuting indeterminates.

Complex composite structures with integrated piezoelectric transducers

Nowadays, in different industrial fields as transport or aerospace, a research effort is conducted to reduce the structural weight. One of the most promising solutions is the use of composite structures due to their high stiffness, their low mass density and their low damping factor. At the same time, there is an intensification of the operational dynamic environment and an increase of durability requirements. These different expectations seem to be contradictory. One solution to manage these points is to design and manufacture smart composite structures with a fully distributed set of integrated piezoelec-tric transducers. These structures are able to modify their mechanical properties with respect to their environment (e.g. active vibration control), to interact with other structures (e.g. mechatronic) or with human beings (e.g. Human-Machine Interaction). To meet the technical specifications of smart composite structures, in particular for complex geom-etries, it is necessary to master the manufacturing process and consequently the material parameters of the manufactured composite. Indeed, during the design phase, these parameters have to be absolutely known. A design approach based on engineering system theory and uncertainty calculation is applied to our manufacturing process of smart composite structures. In this paper, two different material identification methods (the Resonalyser technique and the Time-of-Flight technique) were selected and are applied to several test plates and, finally, on a large smart spherical cap. The Resonalyser technique is a good method to extract overall material parameters. Its major drawback in terms of cost and difficulty of implementation is the use of contactless devices for the measurements. The Time-of-Flight technique is based on the duration measurements of pulse propagation with a simple and low cost experimental setup. Integrated piezoelectric transducers are used for this purpose in the present analysis. The results obtained are quite local (mean values along the propagation path) and need a strong physical interpretation. The different material parameters obtained are compared and discussed.

Forward design of a complex enzyme cascade reaction.

Enzymatic reaction networks are unique in that one can operate a large number of reactions under the same set of conditions concomitantly in one pot, but the nonlinear kinetics of the enzymes and the resulting system complexity have so far defeated rational design processes for the construction of such complex cascade reactions. Here we demonstrate the forward design of an in vitro 10-membered system using enzymes from highly regulated biological processes such as glycolysis. For this, we adapt the characterization of the biochemical system to the needs of classical engineering systems theory: we combine online mass spectrometry and continuous system operation to apply standard system theory input functions and to use the detailed dynamic system responses to parameterize a model of sufficient quality for forward design. This allows the facile optimization of a 10-enzyme cascade reaction for fine chemical production purposes.

See "Engineering Community" from "Scientific Community" ——Discussing with Pro. Li Bocong

As a new discipline, Engineering Sociology is emerging in China nowadays. There are three research paradigms, including "engineering community theory" , "social assessment theory" and "construction engineering system theory" , and "engineering community theory" has been widely recognized by the concerned academic circles. This paper firstly traces the origin of the community concept, then analyses the interaction mechanism of science and engineering activities with society comparatively. At the same time, this paper examines the differences between scientific community and Engineering community critically. Lastly, this paper puts forward the discussing points of "engineering community theory" . Engineering community itself is a "black box" and "engineering community theory" cannot reflect the social impact of engineering activities. Therefore, could engineering community be the basic category and core concept of Engineering Sociology is still a question.

Research on Campus Bike Path Planning Scheme Evaluation Based on TOPSIS Method: Wei'shui Campus Bike Path Planning as an Example

Campus bike path planning is an important part of campus planning. Reasonable planning not only needs to meet the requirements of bicycle traffic on campus, but also should be coordinated with the whole campus system. Campus bike path planning index system was built based on engineering system theory. The objective TOPSIS evaluation method was applied to evaluate the campus bike path planning schemes. TOPSIS method was combined with evaluation index system to evaluate a specific case. The result shows that the combination of TOPSIS method and the established evaluation index system can objectively judge the advantages and disadvantages of bike path plans.

Toeplitz Corona and the Douglas property for free functions

The well known Douglas Lemma says that for operators A, B on Hilbert space that AA⁎−BB⁎⪰0 implies B=AC for some contraction operator C. The result carries over directly to classical operator-valued Toeplitz operators simply by replacement of operator by Toeplitz operator throughout. Free functions generalize the notion of free polynomials and formal power series and trace back to the work of J. Taylor in the 1970s. They are of current interest, in part because of their connections with free probability and engineering systems theory. In this article, for given free functions a and b with noncommutative domain K defined by free polynomial inequalities, we obtain a sufficient condition in terms of the difference aa⁎−bb⁎ for the existence of a free function c taking contractive values on K such that b=ac. The connection to recent work of Agler and McCarthy and their free Toeplitz Corona Theorem is expounded.

Internal Sociology of Engineering and External Sociology of Engineering:an Attempt to Conceive the System of Engineering Sociology

As a new discipline, Engineering Sociology is emerging in China nowadays. There are three research paradigms, including "engineering community theory" , "social assessment theory" and "construction engineering system theory" . The concerning scholars are unable to agree with each other on the system of Engineering Sociology. Firstly, this paper critically reviews these three paradigms and points out their function and significance to the construction of Engineering Sociology. Secondly, with reference to the types of sociology of science suggested by British sociologist of science John Ziman, this paper divides the system of Engineering Sociology into Internal Sociology of Engineering and External Sociology of Engineering. The paper also conceives "engineering field" and "project-induced community" , and two concepts are not only basic categories of Engineering Sociology,but also core concepts of Internal Sociology of Engineering and External Sociology of Engineering separately.Lastly, this paper looks into the future development of Engineering Sociology, believing that it will become an important member of the "big academic family" of sociology.

My Stanford Days as a Graduate Student with R.E. Kalman [Historical Perspectives

I started my graduate studies at Stanford University during the autumn quarter of 1967, after having obtained the bachelor's degree in electrical engineering from the Georgia Institute of Technology in 1967. For me, the biggest shift in going from undergraduate student to graduate study at Stanford was the level of mathematics. In particular, the system theory course sequence in electrical engineering at Stanford required that students have a strong understanding and working knowledge of linear algebra, which I did not begin to acquire until the spring quarter of 1969 when I took a linear algebra course in the Department of Mathematics. After that course, I was finally able to take System Theory 363A, the first course in Stanford's electrical engineering system theory sequence at that time. I took the course from a remarkable adjunct professor named Rod Edwards who turned me on to mathematical system theory as an area of study. In the next quarter, I took the first course of a two-course sequence in the Department of Operations Research titled Mathematical System Theory 347A and B, which was taught by Prof. R.E. Kalman.

Convex Noncommutative Polynomials Have Degree Two or Less

A polynomial p (with real coefficients) in noncommutative variables is matrix convex provided \[ p(tX+(1-t)Y) \le tp(X)+(1-t)p(Y) \] for all $0 \le t \le 1$ and for all tuples X=(X1 ,. . .,Xg and Y=(Y1 ,. . .,Yg) of symmetric matrices on a common finite dimensional vector space of a sufficiently large dimension (depending upon p). The main result of this paper is that every matrix convex polynomial has degree two or less. More generally, the polynomial p has degree at most two if convexity holds only for all matrices X and Y in an "open set." An analogous result for nonsymmetric variables is also obtained. Matrix convexity is an important consideration in engineering system theory. This motivated our work, and our results suggest that matrix convexity in conjunction with a type of "system scalability" produces surprisingly heavy constraints.

Systems and design as the basis of engineering knowledge

Engineering knowledge has evolved into the traditional disciplines of electrical/electronic, mechanical/production and civil engineering, and it is strongly science-based. Engineering activity concerned with converting resources into forms suitable for use, suggests that engineering knowledge ought to be systems and design oriented. The objective of the paper is to describe the factors which are thought to facilitate development in this direction. In particular, the notion of a ‘system’ is defined in relation to the logic of explanation, and statements which describe the ‘physics’ of systems are formulated. The use of natural language, suitably processed as a modelling technique leading to the application of Prolog, is described. An engineering systems theory including control, which is based on the pertinent principles of physics, is explained. Present-day control theory is far removed from the framework of physics, engineering systems theory is intended to alleviate this remoteness; thus, removing fragmentation in this area of knowledge. A framework required for the development of systems component knowledge is outlined. Finally, a systems and product design method using natural language and Prolog is described. This method brings the design process closer to deductive thinking, thus facilitating its use and teaching. Accordingly, the consideration of synthesis, rather than the more usual analysis type problems, should become easier.

Experiments on Information coding in nerve impulse trains

Shannon has provided us with a quantitative measure of information flow, channel capacity, which we apply to trains of nerve pulses. It is of course necessary to consider portions of a communication system—the coder and decoder—as well as the channel. With the help of a model, two possible codes are contrasted: a simple average-frequency code (3 bits/sec) and a complex pulse interval code (100 bits/sec). Neurophysiological experiments are described on the crayfish adversive walking response to light. Dissection of this “simple” invertebrate permits quantitative study of several single units separately and simultaneously, while the animal is in physiological condition. Critical experiments yield evidence to show that the complex code is not carrying physiological signal information: the simple 3 bit/sec code is proposed as adequate for the signal transfer requirements of the animal. The additional information (97 bits/sec) not used as meaningful signal for the crayfish may be used to give the neurophysiologist information concerning the noise processes in the coding mechanism: that is, in the process of generating nerve pulses. We hope that this article demonstrates the utility of embedding classical neurophysiological techniques within a framework of engineering systems theory: in this particular case, Shannon's mathematical theory of communication.