27 research outputs found

    A Genetic Algorithm Driven Linear Programming for Battery Optimal Scheduling in nearly Zero Energy Buildings

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    EU has seen an increasing demand for both nearly zero energy buildings (nZEBs) and building integrated Photovoltaic (BIPV) systems in the last decade. This stems from the energy-driven regulations relating to building efficiency improvements, requiring more realistic and smarter techniques to strengthen their employment and overall performance. Apart from the passive energy-efficiency measures of nZEBs (such as thermal insulation, energy saving appliances, etc.), more advanced and sophisticated energy management mechanisms have to take place in order to accommodate and support their crucial contribution to sustainable development. This paper presents the daily optimum dispatch of a battery, in a building with PV, using Linear Programming (LP) driven by Genetic Algorithm (GA), aiming the minimization of the building's net energy. The obtained results show that there is a high potential of using such approaches for maintaining the net grid energy levels of a building as minimum as possible

    A hybrid optimization approach for autonomy enhancement of nearly-zero-energy buildings based on battery performance and artificial neural networks

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    Reducing the primary energy consumption in buildings and simultaneously increasing self-consumption from renewable energy sources in nearly-zero-energy buildings, as per the 2010/31/EU directive, is crucial nowadays. This work solved the problem of nearly zeroing the net grid electrical energy in buildings in real time. This target was achieved using linear programming (LP)—a convex optimization technique leading to global solutions—to optimally decide the daily charging or discharging (dispatch) of the energy storage in an adaptive manner, in real time, and hence control and minimize both the import and export grid energies. LP was assisted by equally powerful methods, such as artificial neural networks (ANN) for forecasting the building’s load demand and photovoltaic (PV) on a 24 hour basis, and genetic algorithm (GA)—a heuristic optimization technique—for driving the optimum dispatch. Moreover, to address the non-linear nature of the battery and model the energy dispatch in a more realistic manner, the proven freeware system advisor model (SAM) of National Renewable Energy Laboratory (NREL) was integrated with the proposed approach to give the final dispatch. Assessing the case of a building, the results showed that the annual hourly profile of the import and export energies was smoothed and flattened, as compared to the cases without storage and/or using a conventional controller. With the proposed approach, the annual aggregated grid usage was reduced by 53% and the building’s annual energy needs were covered by the renewable energy system at a rate of 60%. It was therefore concluded that the proposed hybrid methodology can provide a tool to maximize the autonomy of nearly-zero-energy buildings and bring them a step closer to implementation

    Crop Litter Has a Strong Effect on Soil Organic Matter Sequestration in Semi-Arid Environments

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    The agricultural soils in the Mediterranean are characterized by low stocks of soil organic matter (SOM) because of the intensive management practices and constraints on litter inputs to the soil imposed by environmental conditions (low precipitation, high evapotranspiration). To date, several studies have provided evidence for a low potential of Mediterranean agroecosystems, especially on its southern part, to store C, even under soil conservation practices (e.g., non-tillage), questioning the capacity of commonly applied practices to restore soil health, mitigate climate change and improve resilience of agroecosystems to climate extremes. Using paired orchards of avocado and olive trees, we show that soils in the South Mediterranean have a high potential for C storage that depends strongly on crop type and soil properties. Soils planted with avocado trees showed higher SOM contents compared to olive trees mainly in the upper soil layer (0–10 cm) which were linked to higher inputs and litter chemistry. Our findings enable us to re-define achievable thresholds of SOC (≈8%) in Southern Mediterranean soils to store C, to quantify the effect of different cropping systems, and the period required to reach this potential and how this potential is affected by soil properties. Thus, the findings have profound implications for the design of soil conservation practices compatible with Mediterranean conditions and developing initiatives describing achievable targets of SOM restoration depending on soil properties and cropping systems

    Crop Litter Has a Strong Effect on Soil Organic Matter Sequestration in Semi-Arid Environments

    No full text
    The agricultural soils in the Mediterranean are characterized by low stocks of soil organic matter (SOM) because of the intensive management practices and constraints on litter inputs to the soil imposed by environmental conditions (low precipitation, high evapotranspiration). To date, several studies have provided evidence for a low potential of Mediterranean agroecosystems, especially on its southern part, to store C, even under soil conservation practices (e.g., non-tillage), questioning the capacity of commonly applied practices to restore soil health, mitigate climate change and improve resilience of agroecosystems to climate extremes. Using paired orchards of avocado and olive trees, we show that soils in the South Mediterranean have a high potential for C storage that depends strongly on crop type and soil properties. Soils planted with avocado trees showed higher SOM contents compared to olive trees mainly in the upper soil layer (0–10 cm) which were linked to higher inputs and litter chemistry. Our findings enable us to re-define achievable thresholds of SOC (≈8%) in Southern Mediterranean soils to store C, to quantify the effect of different cropping systems, and the period required to reach this potential and how this potential is affected by soil properties. Thus, the findings have profound implications for the design of soil conservation practices compatible with Mediterranean conditions and developing initiatives describing achievable targets of SOM restoration depending on soil properties and cropping systems

    Favorable and prolonged changes in blood lipid profile after muscle-damaging exercise

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    Purpose: To examine the effect of repeated muscle-damaging exercise on the time-course changes in blood lipid and lipoprotein profile and compare them with changes in indices of muscle function and damage. Methods: Twelve women underwent an isokinetic exercise session consisting of 75 eccentric knee flexions, which was repeated after 3 wk. Triacylglycerols (TG), total cholesterol (TC), and high-density lipoprotein cholesterol (HDLC) in plasma were measured before, immediately, 1, 2, 3, 4, and 7 d after muscle-damaging exercise. Low-density lipoprotein cholesterol (LDLC) and TC/HDLC were also calculated. Results: The largest changes in TG and lipoproteins appeared 3 d after exercise, returning toward baseline thereafter. The magnitudes of these changes at 3 d compared with rest were -18% and -8% for TG, -14% and -10% for TC, 8% and 7% for HDLC, -25% and -18% for LDLC, and -20% and -15% for TC/HDLC after sessions I and 2, respectively. In addition, the incremental or decremental area under the curve for the TG and lipoproteins measured after the first session was higher than that after the second session-except for HDLC concentration. Conclusion: These findings reveal that lipid and lipoprotein profile was favorably affected by both sessions of muscle-damaging exercise but relatively less so after a repeated session of muscle-damaging exercise

    The LTER-Greece Environmental Observatory Network: Design and Initial Achievements

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    Five years after its establishment (2016), the LTER-Greece network outlines its vision, aims, objectives and its achievements through a series of case studies. The network consists of eight observatories, focusing on innovative research topics, aiming to be both cooperative and complementary, while currently being in the process of expanding. LTER-Greece acknowledges the complexity of ecosystems and the fact that effective management of natural resources may only be achieved by addressing every sector of a nexus system in order to understand inter-dependencies, thus accounting for solutions that promote resilience. Hence, LTER-Greece focuses on the holistic study of the water-environment-ecosystem-food-energy-society nexus, in order to face environmental and socio-ecological challenges at local and global scales, particularly climate change, biodiversity loss, pollution, natural disasters and unsustainable water and land management. Framed around five research pillars, monitoring and research targets nine research hypotheses related to climate change, environmental management, socio-ecology and economics, biodiversity and environmental process dynamics. As environmental monitoring and related research and conservation in Greece face critical shortcomings, LTER-Greece envisages confronting these gaps and contributing with interdisciplinary solutions to the current and upcoming complex environmental challenges

    A Pilot Study About the Dysfunction of Adipose Tissue in Male, Sleep Apneic Patients in Relation to Psychological Symptoms

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    Introduction: Obstructive sleep apnea (OSA) and its cardiometabolic alterations are closely associated with visceral obesity. Patients with OSA frequently present with symptoms of depression and anxiety. Although these subjective symptoms of OSA are the result of complex biological dysregulation, it remains unclear if they have a direct effect on the dysfunction of adipose tissue. Methods: In a pilot, prospective, randomized study, we evaluated 10 recently diagnosed male patients with severe OSA by full polysomnography (PSG) and 4 male non-apneic subjects matched for age and body mass index (BMI) with abdomen adipose tissue biopsies. Subjects with diabetes/prediabetes and cardiovascular and psychiatric diseases and who are current smokers were excluded. All patients underwent anthropometric measurements and completed the following questionnaires: Epworth Sleepiness Scale (ESS), Fatigue Severity Scale (FSS), and Hospital Anxiety and Depression Scale (HADS-A and HADS-D). Fasting venous blood samples were collected on the day after PSG, between 8:00 and 9:00 a.m., after an overnight fast. Fat biopsies were performed at the same time periods and adipose tissue samples of 300 mg were obtained from abdominal fat. Fat cell size, extent of fibrosis, vascularity, leukocyte common antigen inflammatory infiltration, and tissue macrophage accumulation were microscopically evaluated. Results: The mean age of the group was 47.4 +/- 13.8 years, with mean BMI of 35.8 +/- 4.8 kg/m(2) and mean apnea-hypopnea index of 79.4 +/- 46.1 events per hour of sleep (severe OSA). HADS-A and HADS-D scores were 5.8 +/- 2.3 (3.0-8.0) and 4.7 +/- 2.3 (2.0-8.0), respectively. HADS-A score correlated positively with macrophage accumulation in fat biopsy (r = 0.82, p = 0.047), whereas ESS, FSS, and HADS-D did not. Severity of fibrosis correlated largely with waist circumference (r = -0.66, p = 0.038) and neck circumference (r = -0.790, p = 0.006). Respiratory events correlated negatively with the extent of vascularization of adipose tissue (r = -0.614, p = 0.05). Conclusions: In the preliminary results of our pilot study, we assessed that the symptoms of anxiety mainly contribute to macrophage accumulation, whereas the increased number of respiratory events reduces the extent of vascularization in visceral fat in OSA. Based on this observation, further larger studies are required to verify if anxious OSA patients are more vulnerable to the metabolic manifestations of the syndrome

    Simulation of the flow in the Koiliaris river basin (Greece) using a combination use of GIS, the HSPF model and a Karstic–Snow melt model

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    Summarization: The purpose of this study was to model the Koiliaris River flow where flood phenomena appear from time to time. The Koiliaris River basin is located east of the City of Chania, Crete, (Greece). The basin is extended from the White Mountains (Lefka Ori) to the coastline. The geology of the basin is mainly constituted by carbonate (Karstic area), quaternary-neogenic deposits and flysch formation. The main volume of water is discharged from the karstic system of the White Mountains (Lefka Ori) through springs and temporary rivers. In order to calculate the flow from the springs the Maillet Karstic model is used. The main volume of water that is discharged to the springs through the karstic system comes from snow melt. In order to determine with high precision the rate of snow melt, a Snow melt model and the applications of GIS are combined. Using this approach the discharge from springs (for the time of the simulation) is determined. The time-series of the karstic discharge from the springs is entered in the code of the Hydrological Simulation Program - FORTRAN (HSPF) model, in order to calculate both the surface and subsurface discharge. The HSPF is a set of computer codes that simulate the hydrologic process. The hydrologic model of HSPF functions in the frame of the BASINS 4 model. The final step is the Calibration and the Sensitivity analysis of the HSPF model. The main objective of the present study is to develop a tool for the prediction and management of flood events that occur in the area.Παρουσιάστηκε στο: iEMSs 2008: International Congress on Environmental Modelling and Software Integrating Sciences and Information Technology for Environmental Assessment and Decision Making 4th Biennial Meeting of iEMSs
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