55 research outputs found
Challenges in Survey Research
While being an important and often used research method, survey research has
been less often discussed on a methodological level in empirical software
engineering than other types of research. This chapter compiles a set of
important and challenging issues in survey research based on experiences with
several large-scale international surveys. The chapter covers theory building,
sampling, invitation and follow-up, statistical as well as qualitative analysis
of survey data and the usage of psychometrics in software engineering surveys.Comment: Accepted version of chapter in the upcoming book on Contemporary
Empirical Methods in Software Engineering. Update includes revision of typos
and additional figures. Last update includes fixing two small issues and
typo
Multivariable adaptive control of nonlinear completely mixed bioreactors
It is shown how to extend adaptive linearizing control laws of single-input-single-output (SISO) stirred bioreactors to the multi-input-multi-output (MIMO) case. More precisely, the problem of controlling two reactant concentrations with two control inputs is considered and illustrated by three process examples (activated sludge process, yeast growth, and anaerobic digestion). The performance of the multivariable adaptive nonlinear controller is further illustrated by simulation in the first example.Anglai
Estimation in random fields with scattered data
The design of linear minimum-variance unbiased estimates in 2-D random fields (RF) is a standard problem when the mean and the covariance function of the field are known. A case is investigated where the data are so scarce and so scattered in space that reliable estimates of the covariance function are impossible to obtain by classical procedures. Using the variogram of the RF rather than the covariance function, a procedure is developed for the estimation of a variogram model which leads to meaningful estimates of various functionals of the RF.Anglai
Conservative cascades: an invariant of Internet traffic
Conservative cascades are among the class of multiscaling processes that accommodate the two competing objectives of deterministic and random cascades. This paper discusses in what sense the cascade model can be seen as an invariant of the Internet traffic. It explains why conservative cascades model the time-invariant properties of the Internet traffic at timescales up to hundreds of milliseconds. Furthermore, it shows the limitations of the conservative cascades to model part of the time-dependent scaling properties of Internet traffic.Anglai
Two-mode stochastic process control
The minimum variance control of a stochastic process, the dynamics of which is time-varying according to two distinct linear modes, is studied. An approximate solution is proposed, combining the implementation of an adaptive minimum error classifier performed by means of the window function technique and the use of the control theory of linear systems developed by Astrom.Anglai
[St1884] Sturm, R., “Bemerkungen und Zusatze zu Steiners Aufsazen uber Maxima und Minima,”
[YKII88] Yamamoto, P., Kato, K., Imai, K. and Imai, H., “Algorithms for vertical and orthogona
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