33 research outputs found
Synthesis and Stochastic Assessment of Cost-Optimal Schedules
We present a novel approach to synthesize good schedules for a class
of scheduling problems that is slightly more general than the
scheduling problem FJm,a|gpr,r_j,d_j|early/tardy. The idea is to prime
the schedule synthesizer with stochastic information more meaningful
than performance factors with the objective to minimize the expected
cost caused by storage or delay. The priming information is
obtained by stochastic simulation of the system environment. The generated
schedules are assessed again by simulation. The approach is
demonstrated by means of a non-trivial scheduling problem from
lacquer production. The experimental results show that our approach
achieves in all considered scenarios better results than the
extended processing times approach
Motor: The MoDeST Tool Environment
The MoDeST Tool Environment (MOTOR) is a tool to facilitate the transformation, analysis and validation of modest models. modest is a modelling language to describe stochastic real-time systems. MOTOR implements the formal semantics of modest and is designed to transform and abstract modest specifications such that analysis can be carried out by third-party tools. For the time being, a fragment of MoDeST can be model-checked using CADP. The main analytical workhorse behind motor is discrete-event simulation, which is provided by the MĂśbius performance evaluation environment. We are experimenting with prototypical connections to the real-time model checker Uppaal
Moderata Fonte y MarĂa Zambrano: por cuenta propia
In this paper, Rosa Rius thinks about feminine identity and its history, based on the expressions of freedom of two authors living four centuries apart: the Venetian humanist Moderata Fonte (1555-1592) and the Malagan philosopher MarĂa Zambrano (1904-1991). The fact that these womenÂżs freedom is taken as one of their main identifying elements, and straining the historical action of this freedom, unforeseen by the establishment, does not at all imply that the undeniable discrimination inflicted upon women throughout centuries is forgotten or goes on without protest
MoDeST: A compositional modeling formalism for real-time and stochastic systems
This paper presents Modest (MOdeling and DEscription language for Stochastic Timed systems), a formalism that is intended to support 1) the modular description of reactive systems' behavior while covering both 2) functional and 3) nonfunctional system aspects such as timing and quality-of-service constraints in a single specification. The language contains features such as simple and structured data types, structuring mechanisms like parallel composition and abstraction, means to control the granularity of assignments, exception handling, and nondeterministic and random branching and timing. Modest can be viewed as an overarching notation for a wide spectrum of models, ranging from labeled transition systems to timed automata (and probabilistic variants thereof), as well as prominent stochastic processes such as (generalized semi-)Markov chains and decision processes. The paper describes the design rationales and details of the syntax and semantics
Cost-optimization of the IPv4 zeroconf protocol
This paper investigates the tradeoff between reliability and effectiveness for the IPv4 Zeroconf protocol, proposed by Cheshire/Adoba/Guttman in 2002, dedicated to the selfconfiguration of IP network interfaces. We develop a simple stochastic cost model of the protocol, where reliability is measured in terms of the probability to avoid an address collision after configuration, while effectiveness is viewed as the average penalty perceived by a user. We derive an analytical expression for the user penalty which we use to derive optimal configuration parameters of the network, restricting to those parameters which are under the control of a consumer electronics manufacturer. In particular we show that minimal cost and maximal reliability are qualities that cannot be achieved at the same time
Maximizing System Lifetime by Battery Scheduling
The use of mobile devices is limited by the battery lifetime. Some devices have the option to connect an extra battery, or to use smart battery-packs with multiple cells to extend the lifetime. In these cases, scheduling the batteries over the load to exploit recovery properties usually extends the system lifetime. Straightforward scheduling schemes, like round robin or choosing the best battery available, already provide a big improvement compared to a sequential discharge of the batteries. In this paper we compare these scheduling schemes with the optimal scheduling scheme produced with a priced-timed automaton battery model (implemented and evaluated in Uppaal Cora). We see that in some cases the results of the simple scheduling schemes are close to optimal. However, the optimal schedules also clearly show that there is still room for improving the battery lifetimes