This article describes queueing systems and queueing networks which are successfully used for performance analysis of different systems such as computer, communications, transportation networks and manufacturing. It incorporates classical Markovian systems with exponential service times and a Poisson arrival process, and queueing systems with individual service. Oscillating queueing systems and queueing systems with Cox and Weibull service time distribution as examples of non-Markovian systems are studied. Jackson's, Kelly's and BCMP networks are also briefly characterized. The model of Fork-Join systems applied to parallel processing analysis and the FES approximation making possible of Fork-Join analysis is also presented. Various types of blocking representing the systems with limited resources are briefly described. In addition, examples of queueing theory applications are given. The application of closed BCMP networks in the health care area and performance evaluation of the information system is presented. In recent years the application of queueing systems and queueing networks to modelling of human performance arouses researchers' interest. Hence, in this paper an architecture called the Queueing Network-Model Human Processor is presented.
We are exploring the relationship between accents and expression in piano performance. Accents are local events that attract a listener's attention and are either evident from the score (immanent) or added by the performer (performed). Immanent accents are associated with grouping (phrasing), metre, melody and harmony. In piano music, performed accents involve changes in timing, dynamics, articulation, and pedalling; they vary in amplitude, form, and duration. We analyzed the first eight bars of Chopin Prelude op. 28 n. 6. In a separate study, music theorists had marked grouping, melodic and harmonic accents on the score and estimated the importance (salience) of each. Here, we mathematically modeled timing and dynamics in the prelude in two ways using Director Musices (DM) - a software package for automatic rendering of expressive performance. The first rendering focused on phrasing following existing and tested procedures in DM. The second focused on accents - timing and dynamics in the vicinity of the accents identified by the theorists. In an informal listening test, 10 out of 12 participants (5 of 6 musicians and 5 of 6 non-musicians) preferred the accent-based formulation, and several stated that it had more variation of timing and dynamics from one phrase to the next.
The increase of ship’s energy utilization efficiency and the reduction of greenhouse gas emissions have been high lightened in recent years and have become an increasingly important subject for ship designers and owners. The International Maritime Organization (IMO) is seeking measures to reduce the CO2emissions from ships, and their proposed energy efficiency design index (EEDI) and energy efficiency operational indicator (EEOI) aim at ensuring that future vessels will be more efficient. Waste heat recovery can be employed not only to improve energy utilization efficiency but also to reduce greenhouse gas emissions. In this paper, a typical conceptual large container ship employing a low speed marine diesel engine as the main propulsion machinery is introduced and three possible types of waste heat recovery systems are designed. To calculate the EEDI and EEOI of the given large container ship, two software packages are developed. From the viewpoint of operation and maintenance, lowering the ship speed and improving container load rate can greatly reduce EEOI and further reduce total fuel consumption. Although the large container ship itself can reach the IMO requirements of EEDI at the first stage with a reduction factor 10% under the reference line value, the proposed waste heat recovery systems can improve the ship EEDI reduction factor to 20% under the reference line value.
The research into the use of less costly modifications of road links and networks, and changes in the service of road surroundings aimed at ensuring an improvement of through traffic performance in suburban areas, and on roads passing through built-up areas as small localities, with application of simulation model, is presented in this paper. From among possible designs, the authors investigated and presented the effectiveness of two, i.e. implementation of an additional multifunctional median lane in the road cross-section, and construction of service roads with different locations of intersections (end or middle of the road section). The analysis is focused on the impact of such changes on traffic performance and road safety. The authors analysed travel speed, delay and share of platoon traffic on a uniform sections of the road for different types of road surroundings service. The study presents the results of analyses of road network before and after modification, and the assessment of: •impact of access points density and level of their use on road traffic performance,•impact of driving through road sections in built-up area on building platoon traffic,•impact of change in the cross-section type on traffic performance.