In descriptive statistics, there are two computational algorithms for determining the variance S2, of a set of observations : Algorithm 1: S2= - , Algorithm 2: S2= , where . It is interesting to discuss, which of the above formulas is numerically more trustworthy in machine numbers sets. I this paper, based on total effect of rounding error, we prove that the second Algorithm is better...

Nowadays, the pump-storage power plants are a proven solution for storing electricity at large scale and offering flexibility to the power management. Therefore, the hydraulic machines are increasingly subject to off-design operation, start-up and shutdown sequences. However, the fast and frequent switching between pumping mode and generating mode presents technical challenges. In the present s...

Within the Semantic Web community, resource description frameworks (RDF) and logical reasoning engines work together to provide semantic support and reasoning for Web applications. This paper explores the use of RDF graphs for the representation of graphs of requirements and specification of design component properties. We show that the component selection design problem and associated trade-sp...

Trade-off is one of the main design parameters in the field of electronic circuit design. Whereas smaller electronics devices which use less hardware due to techniques like hardware multiplexing or due to smaller devices created due to techniques developed by nanotechnology and MEMS, are more appealing, a trade-off between area, power and speed is inevitable. This paper analyses the trade-off i...

The engineering of complex computer-based systems is commonly underpinned by the development of various models attempting to structure both the problem at hand and the various solution alternatives. Typically this results in a combinatorial explosion of informational and design elements that are both conceptual and resource intensive. The following position paper presents a model-based approach...

The efficiency and output power of gas turbine power plants are heavily affected by ambient air temperature. To compensate this defect, some cooling technologies and technics are applied. In this paper, the effect of applying an absorption chiller by recovering waste heat from gas turbine flue gas has been investigated. For this purpose, the behavior of a GE-F5 gas turbine was modeled by coding...

Performance evaluation of a thermodynamic system under off-design conditions is very important for reliable and cost-effective operation. In this study, an off-design model of an organic Rankine cycle driven by solar energy is established with compound parabolic collector (CPC) to collect the solar radiation and thermal storage unit to achieve the continuous operation of the overall system. The...

Ship designs with captured air plenums can provide benefits of reduced resistance and improved seakeeping performance. In order to design such ships, hydrodynamics computations are needed. We have extended our boundary element method code, 3DYNAFS, to the study of multi-hulls with air plenums and to predict wave resistance in the presence of the air plenum free surface. We also utilized an Unst...

Changes in technology, economy and society create challenges that force us to rethink the way we develop systems. ModelBased Systems Engineering is an approach that can prove catalytic in this new era of systems development. In this paper we introduce the idea of the modeling in order to realize the vision of Model-Based Systems Engineering and especially we focus on the trade-off path of this ...