Autonomic computing systems adapt themselves thousands of times a second, to accomplish their goal despite changing environmental conditions and demands. The literature reports many decision mechanisms, but in most realizations a single one is applied. This paper compares some state-of-the-art decision making approaches, applied to a self-optimizing autonomic system that allocates resources to a s

Tuning an ideal PID and then using its parameters in a real one, can yield undesired results. Nonetheless, many rules conceived for the ideal PID are successfully used in practice, owing to their greater flexibility. A systematic method would thus be useful to extend ideal PID tuning rules to the real PID, so as to preserve said flexibility while synthesising a realistic controller. This manuscrip

This manuscript addresses the problem of process scheduling in a multitasking computing environment. The mainstream feedback-based approach to that problem preserves the existing scheduler, and adapts some of its parameters by means of convenient loops. On the contrary, in this research, the scheduler is entirely replaced by suitable control structures, synthesised and analysed in the discrete-tim

Feedback controllers are typically applied to computing systems by acting on some quantities ("tunable parameters" in the computer science lexicon, think e.g. of a packet drop rate) in order to attain some goal (e.g., a required bandwidth allocation). In other words, control loops are closed around the computing system, that exposes tunable parameters as control actuators, and allows to measure so

Many model-based tuning methods for PI(D) controllers, especially - but not exclusively - in the process control domain, employ models with delay. Doing so has advantages, basically in terms of tuning rules' simplicity, but also potential drawbacks, especially from the standpoint of performance (and sometimes robustness). This manuscript aims at initiating and fostering a critical discussion on th

A formalism was recently introduced to instrument, monitor and control computer applications based on the rate of heartbeats they emit, thereby quantitatively signaling their progress toward goals. To date, the idea was however used essentially in an heuristic manner. This work first shows that a very simple dynamic heartbeat rate model can be devised, an that said model allows to address the corr

Self-Aware Adaptive computing systems are capable of adapting their behavior and resources thousands of times based on changing environmental conditions and demands. This allows them to automatically find the best way to accomplish a given goal with the resources at hand. This capability would benefit the full range of computer systems, from embedded devices to servers to supercomputers. Although

A feedback-based approach to process scheduling in a single-processor system was recently proposed, that deeply relies on the control theory for its entire design. In this work, a literature benchmark is used to compare said approach to classical ones, with particular reference to the real-time case. Two are the main results. First, in the case of a schedulable process set, the proposed "control-t

Recent papers [6, 8] have demonstrated that process schedulers can be designed entirely as feedback controllers - quite novel an approach with respect to the way the control theory is typically applied to computing systems. This work takes a more technological attitude with respect to the methodological ones just quoted. The realisation of a control-theoretical process scheduler on a kernel writte

A novel way to formalise the problem of preemptive feedback scheduling is presented, based on discrete-time linear dynamic systems. Despite its extreme simplicity, the obtained formalism is suitable both for representing (and therefore dynamically analysing) existing scheduling methods, and for synthesizing new ones in a totally system-theoretical perspective. Also, by further specialising the cla

In the production of beer, good temperature control of the starch mashing phase is very important for both the final product quality and the process efficiency. A precise tuning of the said control is, however, complicated by the highly non-linear nature of the process, and often also by the actuation scheme. Based on suitably extended literature models, this article shows how object-oriented mode

This manuscript is part of a long-term research, aimed at establishing methodologically grounded relationships between model- and relay-based tuning of industrial regulators, and at consequently deriving synthesis procedures that couple the advantages of model-based tuning to the simplicity and clarity of relay-based identification. In this work, the addressed controller structure is the "PI+p", i

A closed-loop and an open-loop active vibration control technique are critically compared, accounting for the effects of finite precision arithmetic. The main result is that the relevance of such effects is pointed out and characterised, as rigorously as possible at the present state of the research, in a suitably idealised context, and with specifically devised indicators. Also, the differences b

The domain of active control of narrowband disturbances, of either vibrational or acoustic noise source, poses several methodological and implementational issues. Besides all the problems that normally arise in digital control, some specific issues are related to the attenuation of harmonic or quasi-harmonic signals, which require the usage of control blocks approaching, or even touching, the stab

recension av två böcker om vetenskapligt biografiskrivandeBoth in the Scandinavian countries and in Germany, the status of biographical writing has changed to a far greater extent in the last fifty years than in the Anglo-Saxon world. In the latter context, biography has been more popular than in Germany and, for example, Denmark and Sweden. It has continuously been regarded as both a genre worthy from a scholarly career point of view and as a means for

This article is a case study of the contacts between the music sector in Sweden and the GDR in the 1970s, 1980s and 1990s. The case is the activities of the East-German musicologist and music administrator Gerd Schönfelder (1936–2000) in Sweden at that time, and the debate that arose in the early 1990s when he was accused of having worked for the East German security service, Stasi. The purpose is

In this article I explore the different and changing meanings of the concept “privat” in records from the Swedish Riksdag (state assembly) from the sixteenth to the beginning of the eighteenth century. I analyze how the concept was used in different contexts, such as questions concerning e.g. private and public religious practices, relations between individuals and communities, and relations betweIn this article I explore the different and changing meanings of the concept “privat” in records from the Swedish Riksdag (state assembly) from the sixteenth to the beginning of the eighteenth century. I analyze how the concept was used in different contexts, such as questions concerning e.g. private and public religious practices, relations between individuals and communities, and relations betwe

Precarious manhood beliefs portray manhood, relative to womanhood, as a social status that is hard to earn, easy to lose, and proven via public action. Here, we present cross-cultural data on a brief measure of precarious manhood beliefs (the Precarious Manhood Beliefs scale [PMB]) that covaries meaningfully with other cross-culturally validated gender ideologies and with country-level indices of