• Energy Research
• Restricted close
• Open Source close
• IT close
• ES close
• AU close

Artículos en revistas Security-constrained unit commitment (SCUC) problem is one of the necessary tools for system operators to make operational planning and real-time operation. The internalization of transmission-network and security constraints (e.g. N-1 criterion) could lead to different decisions in the generation dispatch. However, the computational burden of this problem is challenging mainly due to its inherent large problem size. Therefore, this paper proposes an N-1 security constrained formulation based on the Line Outage Distribution Factors (LODF) instead of the one based on Injection Sensitivity Factors (ISF). This formulation is at the same time more compact than analogous formulations for contingency constraints; hence, it presents a lower computational burden. The computational efficiency of the proposed formulation is shown by solving the SCUC of the IEEE 118 bus system with LODF and ISF. Additionally, an iterative methodology for filtering the active N-1 congestion constraints is detailed, and its implementation for large-scale systems is described. The results show that the proposed filter reduces the computational time by approximately 70% in comparison to the complete formulation of N-1 constraints in SCUC. info:eu-repo/semantics/publishedVersion

Abstract The use of phase change materials (PCMs) for thermal storage in buildings was one of the first applications studied, together with typical storage tanks. An interesting possibility in building application is the impregnation of PCMs into porous construction materials, such as plasterboard or concrete, to increase thermal mass. The thermal improvements in a building due to the inclusion of PCMs depend on the climate, design and orientation of the construction, but also to the amount and type of PCM. Therefore, these projects require a complete simulation of the thermal behaviour of the designed space in the conditions of use established a priori. In this paper a simple methodology for the energetic simulation of buildings including elements with PCMs using the program TRNSYS is presented and validated. This procedure does not aim a simulation of the real transfer processes inside the materials with PCM, but to evaluate the influence of walls/ceiling/floor with PCM in the whole energy balance of a building. The key parameter in the simulations is the equivalent heat transfer coefficient which has to be determined for each material. Experimental evaluation of the coefficient is presented. The methodology is applied in a building such as a prototype room built with concrete panels with PCM.

An experiment in open-top chambers was carried out in summer 2008 in Curno (northern Italy) in order to study the effects of ozone and drought stress on net photosynthesis, growth and stable isotope partitioning on cuttings of an ozone-sensitive poplar clone (Oxford). The biomass (as dry weight) of stems, leaves and roots was assessed five times during the growing season on a set of plants intended for destructive measurements (set 1). Another set of plants (set 2) was used for repeated measurements (net photosynthesis) and then destroyed at the end of the experiment. The dry weight of the stems in set 1 plants was calculated using allometric relations. The results showed that drought stress had a strong effect on all the parameters assessed. Ozone did not have any effect on biomass allocation in woody stems and stable isotope composition but reduced root/shoot ratios and caused loss of leaves during the growing season. The loss of leaves in the lower part of the crown was partly recovered with the emission of new young leaves in the upper part, thus restoring the overall photosynthetic apparatus. We conclude that the metabolic costs suffered to repair damage and support growth, and the reduction in starch reserves in the roots can compromise growth and the capacity to cope with stress factors in subsequent years.

Abstract This study presents an evaluation of the error induced by neglecting the effect of air compressibility in modelling Oscillating Water Column (OWC) wave energy converters. A compressible two phases CFD model in the open-source software package OpenFOAM® is validated and then used to simulate a fixed OWC device, detached from the sea bottom. A comparative analysis of the results obtained by simulating the device at full-scale (1:1) and at four smaller scales (1:50, 1:25, 1:10 and 1:5) is performed in order to assess the scale effects associated with air compressibility. Indeed, for the air pressure levels considered in the simulations (up to 350 Pa at model scale 1:50), the effect of neglecting the air compressibility results in an overestimation up to about 15% for the air pressure in the OWC chamber and the subsequent air volume flux, but less than 10% for the capture width ratio. This overestimation increases with increasing pressure level. Results are analysed in terms of dimensionless parameters and a new parameter, strongly related to the compressible effects, is proposed and used to provide generalized equations delivering correction factors.

Artículos en revistas This paper presents the principles of a centralized underfrequency load-shedding (UFLS) scheme based on a frequency stability boundary curve suitable for small isolated power systems. The centralized UFLS scheme is illustrated in case of two small isolated Spanish power systems. info:eu-repo/semantics/publishedVersion

Blunt force injuries are produced by a variety of objects, including hands and feet (which is human strength) and many different weapons. Some of these objects produce distinctive patterns of injury of potential evidentiary value. This article presents a series of 53 homicides by blunt trauma along the period from 1982 to 2012, representing 16% of all homicides treated by the University Institute of Forensic Medicine in Brescia (northern Italy). Fifty-seven percent (30 cases) of the victims were male. The mean age of the victims was 47.9 years. The weapon most frequently involved was human strength. Not surprisingly, head trauma was the most common cause of death (66%). Forty-seven percent (25 cases) of the victims survived their assaults for varying periods. Homicides due to blunt trauma are still a relevant challenge for the forensic pathologist, who must obtain a complete and accurate history of the crime (including details regarding the crime scene), interpret patterns of injury and other findings at autopsy, and correlate all of the findings to make an accurate ruling of the cause and manner of death.

Reducing agronomic input supply can significantly contribute to decrease the environmental impact of bioenergy cropping systems. Currently, there is a renewed industrial interest in non-food oil crops for different end-uses application. Among species from Brassica genus, Brassica carinata A. Braun is an interesting winter annual crop in warm and semi-arid environments and may provide a rotation alternative with cereal crops, sourcing non-edible oil for the industry, additional incomes to the farmers and soil benefits. The present study compared four Brassica carinata lines (GID-6165, GIP-6164, GID-6091, GID-6084) under two different organic fertilization levels (80 and 160 kg N ha-1) in a semiarid Mediterranean area. These four lines have not been tested in Southern Italy previously, nor under the present low-input cultivation practices in semiarid Mediterranean area. Main findings showed a significant fertilization effect (P=0.05), with the high-input providing higher seed yields and harvest index than low-input. There was no genotype effect, however, the gap between potential (i.e. seed yield at the programmed plant density) and actual yields was rather high for GID-6165 and GID-6080. On the other hand, genotype had the largest effect on the thousand seed weight and the residual biomass yield. In general, GID-6091 and GID-6165 reached seed physiological maturity earlier than GID-6084 and GID-6164 lines. The present study proved that improved B. carinata lines can be grown in semiarid Mediterranean area under low-input organic systems, providing satisfactory seed yields. However, seedbed preparation was noticed to be key to narrow the gap between potential and actual seed yield, particularly under the present clay soil. Proceedings of the 30th European Biomass Conference and Exhibition, 9-12 May 2022, Online, pp. 120-124