Circulation, Vol. 22, No. 2

Spring 2017 issue of CCPO Circulation featuring article Reflections from Dr. Grosch By Dr. Chet Grosch, Emeritus Professor and Founding Member of CCPO.https://digitalcommons.odu.edu/ccpo_circulation/1052/thumbnail.jp

Gender differences in leader's compliant behaviour: an interview with Kerstin Grosch and Holger A. Rau

Interview mit Kerstin Grosch und Holger A. Rau über Gender Differences in Leader's compliant Behaviour.Interview with Kerstin Grosch and Holger A. Rau concerning Gender Differences in Leader's compliant Behaviour

Quantitative measurement of combustion gases in harsh environments using NDIR spectroscopy

The global climate change calls for a more environmental friendly use of energy and has led to stricter limits and regulations for the emissions of various greenhouse gases. Consequently, there is nowadays an increasing need for the detection of exhaust and natural gases. This need leads to an ever-growing market for gas sensors, which, at the moment, is dominated by chemical sensors. Yet, the increasing demands to also measure under harsh environmental conditions pave the way for non-invasive measurements and thus to optical detection techniques. Here, we present the development of a non-dispersive infrared absorption spectroscopy (NDIR) method for application to optical detection systems operating under harsh environments.Comment: 10 pages, 8 figure

A Criterion for Vortex Breakdown

Spall, R.E., Gatski, T.B., & Grosch, C.E. (1987). A criterion for vortex breakdown. Physics of Fluids, 30(11), 3434-3440. doi: 10.1063/1.86647

Views on computer program documentation and automation

Various aspects of the problem of program documentation and description are discussed. Particular emphasis is placed on the problem of semantics. It is pointed out that the information produced by documentation of a program, if presented to several different groups, may mean entirely different things to these groups. Recognition of the fact that people look at problems differently is proposed as a more practical approach to the problem of documentation rather than extensive use of standards or strict formatting. The difficulties involved in searching for ways to provide a common ground for the transmission and use of information are discussed

Absolute and convective instabilities in an inviscid compressible mixing layer

We consider the stability of a compressible shear flow separating two streams of different speeds and temperatures. The velocity and temperature profiles in this mixing layer are hyperbolic tangents. The normal mode analysis of the flow stability reduces to an eigenvalue problem for the pressure perturbation. We briefly describe the numerical method that we used to solve this problem. Then, we introduce the notions of the absolute and convective instabilities and examine the effects of Mach number, and the velocity and temperature ratios of each stream on the transition between convective and absolute instabilities. Finally, we discuss the implication of the results presented in this paper for the heliopause stability.Comment: 5 pages, 6 figures, accepted by Astronomical Notes (Astron. Nachrichten

Grosch's law: a statistical illusion?.

In this paper a central law on economies of scale in computer hardware pricing, Grosch's law is discussed. The history and various validation efforts are examined in detail. It is shown how the last set of validations during the eighties may be interpreted as a statistical misinterpretation, although this effect may have been present in all validation attempts, including the earliest ones. Simulation experiments reveal that constant returns to scale in combination with decreasing computer prices may give the illusion of Grosch's law when performing regression models against computer prices over many years. The paper also shows how the appropriate definition of computer capacity, and in particular Kleinrock's power definition, plays a central role in economies of scale for computer prices.Law;

Absolute/convective instabilities and the convective Mach number in a compressible mixing layer

Two aspects of the stability of a compressible mixing layer: Absolute/Convective instability and the convective Mach number were considered. It was shown that, for Mach numbers less than one, the compressible mixing layer is convectively unstable unless there is an appreciable amount of backflow. Also presented was a rigorous derivation of a convective Mach number based on linear stability theory for the flow of a multi-species gas in a mixing layer. The result is compared with the heuristic definitions of others and to selected experimental results

Geometric path planning without maneuvers for nonholonomic parallel orienting robots

Current geometric path planners for nonholonomic parallel orienting robots generate maneuvers consisting of a sequence of moves connected by zero-velocity points. The need for these maneuvers restrains the use of this kind of parallel robots to few applications. Based on a rather old result on linear time-varying systems, this letter shows that there are infinitely differentiable paths connecting two arbitrary points in SO(3) such that the instantaneous axis of rotation along the path rest on a fixed plane. This theoretical result leads to a practical path planner for nonholonomic parallel orienting robots that generates single-move maneuvers. To present this result, we start with a path planner based on three-move maneuvers, and then we proceed by progressively reducing the number of moves to one, thus providing a unified treatment with respect to previous geometric path planners.Peer ReviewedPostprint (author's final draft