| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Aronsson, Pär, et al.
(författare)
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Impact of nitrogen fertilization to short-rotation willow coppice plantations grown in Sweden on yield and economy
- 2014
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Ingår i: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 7, s. 993-1001
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Tidskriftsartikel (refereegranskat)abstract
- A fertilization trial was carried out in established short-rotation willow coppice (SRWC) plantations of two bred varieties of willow (Salix spp.; "Tora" and "Jorr") at five sites in central Sweden between 2008 and 2010. Mineral nitrogen was applied at four different rates: No fertilization (Control), 160 kg nitrogen ha(-1) as a single dose after harvest (Economy), 60-100-60 kg nitrogen ha(-1) in year 1-2-3 (Normal), and 160 kg nitrogen ha(-1) year(-1) in years 1-3 (Intensive), using a randomized block design with four replicates. The yield response (biomass increase per kg fertilizer nitrogen) was 65, 67 and 46 kg kg(-1) in the Economy, Normal and Intensive treatments, respectively. The results from the fertilization trial were used for economic calculations of different fertilization strategies given varying costs for fertilization and marginal value of the increased yield (price received for wood chips minus the costs for harvest and transportation of wood chips to a district heating plant). Comparative calculations were made based on data from a previous fertilization trial during the first cutting cycle of old, non-bred varieties. The calculations showed positive net present values of fertilizing bred willow varieties given a realistic fertilization response and a price for wood chips close to the market price for forestry-based wood chips in Sweden.
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| 6. |
- Aronsson, Pär, et al.
(författare)
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Treatment of landfill leachate by irrigation of willow coppice - Plant response and treatment efficiency
- 2010
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 158:3, s. 795-804
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Tidskriftsartikel (refereegranskat)abstract
- Landfill leachates usually need to be treated before discharged. and using soil-plant systems for this has gained substantial interest in Sweden and in the UK A three-year field study was conducted in central Sweden to quantify plant response, treatment efficiency and impact on groundwater quality of landfill leachate irrigation of short-rotation willow coppice (Salix) Two willow varieties were tested and four irrigation regimes in sixteen 400-m(2) plots. The willow plants did not react negatively, despite very high annual loads of nitrogen (<= 2160 kg N/ha), chloride (<= 8600 kg Cl/ha) and other elements. Mean annual growth was 15. 98 and 12.6 tonnes DM/ha during years 1-3 For one of two willow varieties tested. relative leaf length accurately predicted growth rate. Irrigation resulted in elevated groundwater concentrations of all elements applied. Treatment efficiency varied considerably for different elements, but was adequate when moderate loads were applied. (C) 2009 Elsevier Ltd All rights reserved.
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| 7. |
- Dale, Virginia H., et al.
(författare)
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Status and prospects for renewable energy using wood pellets from the southeastern United States
- 2017
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Ingår i: Global Change Biology Bioenergy. - : Wiley-Blackwell. - 1757-1693 .- 1757-1707. ; 9:8, s. 1296-1305
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Tidskriftsartikel (refereegranskat)abstract
- The ongoing debate about costs and benefits of wood-pellet based bioenergy production in the southeastern United States (SE USA) requires an understanding of the science and context influencing market decisions associated with its sustainability. Production of pellets has garnered much attention as US exports have grown from negligible amounts in the early 2000s to 4.6 million metric tonnes in 2015. Currently, 98% of these pellet exports are shipped to Europe to displace coal in power plants. We ask, 'How is the production of wood pellets in the SE USA affecting forest systems and the ecosystem services they provide?' To address this question, we review current forest conditions and the status of the wood products industry, how pellet production affects ecosystem services and biodiversity, and what methods are in place to monitor changes and protect vulnerable systems. Scientific studies provide evidence that wood pellets in the SE USA are a fraction of total forestry operations and can be produced while maintaining or improving forest ecosystem services. Ecosystem services are protected by the requirement to utilize loggers trained to apply scientifically based best management practices in planning and implementing harvest for the export market. Bioenergy markets supplement incomes to private rural landholders and provide an incentive for forest management practices that simultaneously benefit water quality and wildlife and reduce risk of fire and insect outbreaks. Bioenergy also increases the value of forest land to landowners, thereby decreasing likelihood of conversion to nonforest uses. Monitoring and evaluation are essential to verify that regulations and good practices are achieving goals and to enable timely responses if problems arise. Conducting rigorous research to understand how conditions change in response to management choices requires baseline data, monitoring, and appropriate reference scenarios. Long-term monitoring data on forest conditions should be publicly accessible and utilized to inform adaptive management.
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| 8. |
- Dimitriou, Ioannis, et al.
(författare)
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A Queue-based Random Access Scheme in Network-level Cooperative Wireless Networks
- 2019
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Ingår i: ICC 2019 - 2019 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC). - : IEEE. - 9781538680889
-
Konferensbidrag (refereegranskat)abstract
- In this work, we consider a relay assisted adaptive queue-aware cooperative random access wireless network with multipacket (MPR) reception capabilities. The network consists of N sources transmitting packets to a common destination node with the aid of two relay nodes equipped with queues. The relays assist the sources by forwarding the packets that failed to reach the destination, by using a queue-based transmission control mechanism. Moreover, the relays have also their own traffic. We investigate the stability conditions and the throughput performance of the network for the full MPR channel model. Moreover, we derive expressions for the average queueing delay with the aid of the theory of boundary value problems for the asymmetric two-user network. We evaluate numerically the presented theoretical analysis.
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| 9. |
- Dimitriou, Ioannis, et al.
(författare)
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A RANDOM ACCESS G-NETWORK: STABILITY, STABLE THROUGHPUT, AND QUEUEING ANALYSIS
- 2021
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Ingår i: Probability in the engineering and informational sciences (Print). - : CAMBRIDGE UNIV PRESS. - 0269-9648 .- 1469-8951. ; 35:1, s. 111-137
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Tidskriftsartikel (refereegranskat)abstract
- The effect of signals on stability, stable throughput region, and delay in a two-user slotted ALOHA-based random-access system with collisions is considered. This work gives rise to the development of random access G-networks, which can model security attacks, expiration of deadlines, or other malfunctions, and introduce load balancing among highly interacting queues. The users are equipped with infinite capacity buffers accepting external bursty arrivals. We consider both negative and triggering signals. Negative signals delete a packet from a user queue, while triggering signals cause the instantaneous transfer of packets among user queues. We obtain the exact stability region, and show that the stable throughput region is a subset of it. Moreover, we perform a compact mathematical analysis to obtain exact expressions for the queueing delay by solving a non-homogeneous Riemann boundary value problem. A computationally efficient way to obtain explicit bounds for the expected number of buffered packets at user queues is also presented. The theoretical findings are numerically evaluated and insights regarding the system performance are derived.
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| 10. |
- Dimitriou, Ioannis
(författare)
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A review of the impacts of Short Rotation Coppice cultivation on water issues
- 2009
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Ingår i: Landbauforschung. - 0458-6859. ; 59, s. 197-206
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Forskningsöversikt (refereegranskat)abstract
- Cultivation of Short Rotation Coppice (SRC) with poplars (Populus sp.) and willows (Salix sp.) for production of biomass for heat and/or electricity is energy effective and coincides with several environmental objectives. Since an increase of cultivation of poplar and willow SRC has been projected in Europe, the consequent implications on water issues arises. For instance, water use of SRC can be higher compared to annual agricultural crcps or previous set-aside land, but water quality can be improved The paper examines such implications based on a review of the existing scientific literature. Rates of evapotranspiration (V(ET)) of SRC are reported to be fairly higher than arable crops, but reported values vary markedly and are related to site-specific factors such as the local precipitation and conditions (e.g soil type, temperature, groundwater level), the species/sorts and the age of the crop, and their interactions. Despite the predicted local effects on water balances, effects on water balances/hydrology on catchment levels have not been reported or justified This, combined with the reported positive effects of SRC on groundwater quality in terms of nutrient leaching, imoly average positive effects of SRC on water issues, if the identified potentially negative impacts would be considered and minimized. For this, comparisons of V ET between SRC and arable crops, and the relation of V ET with local precipitation and other local factors (root development, groundwater availability) should be better examined and combined with positive effects of SRC on groundwater leaching compared to other crops Upscaling of water issues for SRC is needed to promote future decision-making processes with respect to the envisaged broadening of SRC on productive but also on marginal soils.
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| 11. |
- Dimitriou, Ioannis
(författare)
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Agronomic Practices for Improving Gentle Remediation of Trace Element-Contaminated Soils
- 2015
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Ingår i: International Journal of Phytoremediation. - : Informa UK Limited. - 1522-6514 .- 1549-7879. ; 17, s. 1005-1037
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Forskningsöversikt (refereegranskat)abstract
- The last few decades have seen the rise of Gentle soil Remediation Options (GRO), which notably include in situ contaminant stabilization ("inactivation") and plant-based (generally termed "phytoremediation") options. For trace element (TE)-contaminated sites, GRO aim to either decrease their labile pool and/or total content in the soil, thereby reducing related pollutant linkages. Much research has been dedicated to the screening and selection of TE-tolerant plant species and genotypes for application in GRO. However, the number of field trials demonstrating successful GRO remains well below the number of studies carried out at a greenhouse level. The move from greenhouse to field conditions requires incorporating agronomical knowledge into the remediation process and the ecological restoration of ecosystem services. This review summarizes agronomic practices against their demonstrated or potential positive effect on GRO performance, including plant selection, soil management practices, crop rotation, short rotation coppice, intercropping/row cropping, planting methods and plant densities, harvest and fertilization management, pest and weed control and irrigation management. Potentially negative effects of GRO, e.g., the introduction of potentially invasive species, are also discussed. Lessons learnt from long-term European field case sites are given for aiding the choice of appropriate management practices and plant species.
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| 12. |
- Dimitriou, Ioannis
(författare)
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Bio-hubs as keys to successful biomass supply integration for bioenergy within the bioeconomy : Report from joint IEA Bioenergy task 43 & BioEast initiative workshop 10th October 2019, Sopron, Hungary
- 2020
-
Rapport (refereegranskat)abstract
- IEA Bioenergy Task 43: Sustainable Biomass Supply Integration for Bioenergy Within the Broader Bioeconomy has launched an initiative to identify successful examples of biomass logistic and distribution points for bioenergy and the bioeconomy: bio-hubs. The goal of this initiative is to explore integrated bioeconomy supply chains to develop solutions for the reliable production and supply of higher-quality biomass for energy. These examples are also meant to serve as sources of inspiration that other biomass producers can use to enhance the sustainability of their own activities, as well as for policy makers to familiarize themselves with the bio-hub concept.The Sopron workshop took bioenergy a step forward towards new biomass supply chains within a concept of bioeconomy. The innovative examples selected for this workshop show how biomass can be produced together with wood products and food in sustainably managed landscapes. The aim of the workshop was to develop a framework for the successful establishment of bio-hubs in support of the bioeconomy. The workshop had a proactive format, consisting of showcase presentations and participatory SWOT analysis. Examples of four existing and emerging bio-hubs were presented, and workshop participants had the opportunity to consider how different biomass supply chains (forestry, agriculture, SRC) could evolve to bio-hub concepts. In the second part of the workshop, biomass as a commodity was presented. Participants jointly outlined strengths, weaknesses, opportunities and threats (SWOT analysis) of having bio-hub as an alternative to the existing biomass supply. The SWOT analysis was performed in real -time, capturing, scoring and ranking inputs from 30 workshop attendees using the Sli.do application. The joint IEA Bioenergy Task 43 and BioEast Initiative workshop was well attended with 55 participants from 17 countries. Most participants (64%) were from the BioEast macro-region and 90% of participants from the EU, but reaching as far as to Australia, Canada and New Zealand (10%).BioEast Initiative and IEA Bioenergy foresee that the gathered knowledge and shared experience at the workshop will contribute to the improvement of sustainable biomass mobilisation for energy purposes, notably in the BioEast macro-region and in other member countries of the IEA Bioenergy Technology Collaboration Programme. The results of the workshop will feed into the development of the framework for bio-hubs, which will then be further applied and tested as part of following activities.To access the workshop presentations, please visit the IEA Bioenergy Task 43 website.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Dimitriou, Ioannis, et al.
(författare)
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From preferences to concerted policy on mandated share for renewable energy in transport
- 2021
-
Ingår i: Energy Policy. - : Elsevier BV. - 0301-4215 .- 1873-6777. ; 155
-
Tidskriftsartikel (refereegranskat)abstract
- Environmental, energy, transport and agriculture policies are intersecting when deciding on renewable energy in transport (RES-T) implementation strategies. The uncertainty related to the advanced biofuels, limitations and underperformance of readily available technologies for decarbonization of transport sector challenges RES-T policy making. This paper employs partitioning as a choice architecture tool to create a concerted RES-T policy. The approach collects the preferred attributes of an alternative fuel rather than the preferred fuel by guiding stakeholders through RES-T policy, ensuring that all aspects of concerted policy are covered. Fuzzy analytical hierarchical process (fAHP) has been superimposed on the partitioning related to the biofuels to mathematically weight the alternatives. fAHP ranks the weighted preferences on biofuels to build a consensus among stakeholder groups, later translated to the actual RES-T mix, quantities and investments needed to meet the mandated share. Applied on Croatia, the preferences of three stakeholder groups were weighted and ranked; whereas some discrepancies were identified, the consensus outlined the national transport decarbonization policy with related investments. When the consensual RES-T mix contrasted with the least-cost alternative, the investment needed was reduced to a quarter. The collaborative management process proved to be a time-effective participatory approach for a silo-based policy structure.
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| 20. |
- Dimitriou, Ioannis
(författare)
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Growth Performance of Willow Clones in Short Rotation Coppice after Sewage Sludge Application
- 2014
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Ingår i: Baltic Forestry. - 1392-1355. ; 20, s. 70-77
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the current study was to compare the growth performance of willow clones from different breeding programmes in short rotation coppice field trials established in different European countries when applied with sewage sludge. In general, willow clones from the European Willow Breeding Programme (clones "Resolution" and "Endeavour") had lower survival rate, but higher aboveground shoot biomass than willow clones from the Swedish State Willow Selection Programme (clone 78183) and the Willow Breeding Programme of Agrobransle AB (clones "Tora" and "Inger"). Sludge application did not have any significant impact on growth performance. The average aboveground biomass production of willows in Poland was larger than that in Estonia or Germany, and in the three-year-old plantations it was not correlated to the actual plant density.
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| 21. |
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| 22. |
- Dimitriou, Ioannis, et al.
(författare)
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Impact of Populus plantations on water and soil quality
- 2017
-
Ingår i: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 10, s. 750-759
-
Tidskriftsartikel (refereegranskat)abstract
- Trees of genus Populus (in our context primarily poplars) are predominantly grown in Sweden in small plantations on arable land in southern and central parts of the country to produce biomass for energy and other purposes. This study evaluated the effects (i) of poplar plantations on groundwater quality, by determining differences in leaching of nitrogen and phosphorus to groundwater, and (ii) of poplar and hybrid aspen plantations on soil quality in terms of carbon in the top- and subsoil. The study was conducted comparing Populus plantations in Sweden with adjacent fields with cereals and grasslands. The experiment concerning the groundwater leaching was conducted in eight poplar plantations along three growing seasons (2012-2015). For the soil carbon experiments, 19 poplar and two hybrid aspen plantations and the respective reference fields were sampled. NO3-N leaching from poplar plantations was significantly lower than that from reference fields with cereals, but not when compared with grasslands. Spring NO3-N leaching was significantly lower in poplars than in the reference fields, whereas leaching of NO3-N in autumn did not differ. Concentrations of PO4-P in the groundwater of poplar plantations were lower compared to the respective ones of the reference fields. There were no clear trends observed when comparing carbon concentrations in the topsoil of the poplar and hybrid aspen plantations compared to the respective adjacent reference fields. For the subsoil, the average carbon concentrations in the poplar and hybrid aspen plantations were equal to the respective ones of cereals, but were higher when compared to grassland.
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| 23. |
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| 24. |
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| 25. |
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| 26. |
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| 27. |
- Dimitriou, Ioannis
(författare)
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Long-Term Effects of Soil Remediation with Willow Short Rotation Coppice on Biogeographic Pattern of Microbial Functional Genes
- 2022
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Ingår i: Microorganisms. - : MDPI AG. - 2076-2607. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Short rotation coppice (SRC) is increasingly being adopted for bioenergy production, pollution remediation and land restoration. However, its long-term effects on soil microbial communities are poorly characterized. Here, we studied soil microbial functional genes and their biogeographic pattern under SRC with willow trees as compared to those under permanent grassland (C). GeoChip analysis showed a lower functional gene diversity in SRC than in C soil, whereas microbial ATP and respiration did not change. The SRC soil had lower relative abundances of microbial genes encoding for metal(-oid) resistance, antibiotic resistance and stress-related proteins. This indicates a more benign habitat under SRC for microbial communities after relieving heavy metal stress, consistent with the lower phytoavailability of some metals (i.e., As, Cd, Ni and Zn) and higher total organic carbon, NO3--N and P concentrations. The microbial taxa-area relationship was valid in both soils, but the space turnover rate was higher under SRC within 0.125 m(2), which was possibly linked to a more benign environment under SRC, whereas similar values were reached beyond thisarea. Overall, we concluded that SRC management can be considered as a phytotechnology that ameliorates the habitat for soil microorganisms, owing to TOC and nutrient enrichment on the long-term.
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| 28. |
- Dimitriou, Ioannis
(författare)
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Microbial community structure and activity in trace element-contaminated soils phytomanaged by Gentle Remediation Options (GRO)
- 2017
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 231, s. 237-251
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Tidskriftsartikel (refereegranskat)abstract
- Gentle remediation options (GRO) are based on the combined use of plants, associated microorganisms and soil amendments, which can potentially restore soil functions and quality. We studied the effects of three GRO (aided-phytostabilisation, in situ stabilisation and phytoexclusion, and aided-phytoextraction) on the soil microbial biomass and respiration, the activities of hydrolase enzymes involved in the biogeochemical cycles of C, N, P, and S, and bacterial community structure of trace element contaminated soils (TECS) from six field trials across Europe. Community structure was studied using denaturing gradient gel electrophoresis (DGGE) fingerprinting of Bacteria, alpha- and beta-Proteobacteria, Actinobacteria and Streptomycetaceae, and sequencing of DGGE bands characteristic of specific treatments. The number of copies of genes involved in ammonia oxidation and denitrification were determined by qPCR.Phytomanagement increased soil microbial biomass at three sites and respiration at the Biogeco site (France). Enzyme activities were consistently higher in treated soils compared to untreated soils at the Biogeco site. At this site, microbial biomass increased from 696 to 2352 mg ATP kg(-1) soil, respiration increased from 7.4 to 40.1 mg C-CO2 kg(-1) soil d(-1), and enzyme activities were 2-11-fold higher in treated soils compared to untreated soil. Phytomanagement induced shifts in the bacterial community structure at both, the total community and functional group levels, and generally increased the number of copies of genes involved in the N cycle (nirK, nirS, nosZ, and amoA). The influence of the main soil physico-chemical properties and trace element availability were assessed and eventual site-specific effects elucidated. Overall, our results demonstrate that phytomanagement of TECS influences soil biological activity in the long term. (C) 2017 Elsevier Ltd. All rights reserved.
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| 29. |
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| 30. |
- Dimitriou, Ioannis, et al.
(författare)
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Nitrogen fertilization of poplar plantations on agricultural land: effects on diameter increments and leaching
- 2017
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 32, s. 700-707
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Tidskriftsartikel (refereegranskat)abstract
- Fast-growing poplar plantations on agricultural land require intensive management activities, often involving fertilization. The present paper aims at investigating the effect of fertilization on growth and on groundwater quality, by examining four trials established in commercial poplar plantations in central and south Sweden. The treatments consisted of nitrogen applications (Urea N46, Tot. N: 46%) in two different dosages, 75 and 150 kg ha(-1) for two years, and a control, in three replicates (plot size: 20 x 20 m) following a randomized block design. Diameters were measured at each plot at the end of each growing season for the period 2012-2015. At the same time, groundwater pipes were installed in the center of each plot, at ca. 1.5 m depth. Samples were regularly collected and analyzed for NO3-N and PO4-P. The results show a large variation in the diameter growth response to nitrogen fertilization and the leaching of poplar plantations after canopy closure. In young plantations, the effect on growth was clear with moderate fertilization rates although it was not observed on sandy soils with already good growth, leading to high nitrogen leaching.
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| 31. |
- Dimitriou, Ioannis
(författare)
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Optimising the Environmental Sustainability of Short Rotation Coppice Biomass Production for Energy
- 2014
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Ingår i: South-East European Forestry. - : Hrvatski Sumarski Institut (Croatian Forest Research). - 1847-6481 .- 1849-0891. ; 5, s. 81-91
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Forskningsöversikt (refereegranskat)abstract
- Background and Purpose: Solid biomass from short rotation coppice (SRC) has the potential to significantly contribute to European renewable energy targets and the expected demand for wood for energy, driven mainly by market forces and supported by the targets of national and European energy policies. It is expected that in the near future the number of hectares under SRC will increase in Europe. Besides producing biomass for energy, SRC cultivation can result in various benefits for the environment if it is conducted in a sustainable way. This paper provides with an overview of these environmental benefits. Discussion and Conclusions: The review of existing literature shows that SRC helps to improve water quality, enhance biodiversity, prevent erosion, reduce chemical inputs (fertilizers, pesticides) and mitigate climate change due to carbon storage. To promote and disseminate environmentally sustainable production of SRC, based on existing literature and own project experience, a set of sustainability recommendations for SRC production is developed. In addition to numerous environmental benefits, sustainable SRC supply chains can bring also economic and social benefits. However, these aspects of sustainability are not addressed in this paper since they are often country specific and often rely on local conditions and policies. The sustainable practices identified in this manuscript should be promoted among relevant stakeholder to stimulate sustainable local SRC production.
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| 32. |
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| 33. |
- Dimitriou, Ioannis, et al.
(författare)
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Performance analysis of a cooperative wireless network with adaptive relays
- 2019
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Ingår i: Ad hoc networks. - : ELSEVIER SCIENCE BV. - 1570-8705 .- 1570-8713. ; 87, s. 157-173
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we investigate a slotted-time relay assisted cooperative random access wireless network with multipacket (MPR) reception capabilities. MPR refers to the capability of a wireless node to successfully receive packets from more than two other modes that transmit simultaneously at the same slot. We consider a network of N saturated sources that transmit packets to a common destination node with the cooperation of two infinite capacity relay nodes. The relays assist the sources by forwarding the packets that failed to reach the destination. Moreover, the relays have also packets of their own to transmit to the destination. We further assume that the relays employ a state-dependent retransmission control mechanism. In particular, a relay node accordingly adapts its transmission probability based on the status of the other relay. Such a protocol is towards self-aware networks and leads to substantial performance gains in terms of delay. We investigate the stability region and the throughput performance for the full MPR model. Moreover, for the asymmetric two-sources, two-relay case we derive the generating function of the stationary joint queue-length distribution with the aid of the theory of boundary value problems. For the symmetric case, we obtain explicit expressions for the average queueing delay in a relay node without solving a boundary value problem. Extensive numerical examples are presented and provide insights on the system performance. (C) 2018 Elsevier B.V. All rights reserved.
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| 34. |
- Dimitriou, Ioannis, et al.
(författare)
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Performance Analysis of an Adaptive Queue-Aware Random Access Scheme with Random Traffic
- 2018
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Ingår i: 2018 IEEE International Conference on Communications (ICC) Proceedings Kansas City, MO, USA 20–24 May 2018. - : IEEE Communications Society. - 9781538631805 - 9781538631812 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- In this work, we consider an adaptive two-user random access scheme with multipacket reception (MPR) ca- pabilities. A user adapts its transmission characteristics based on the status of the other user. The users have external random traffic stored in their queues. We derive the stable throughput region of the system and the convexity conditions of this region. We derive analytically the queueing delay by formulating and solving a Riemann-Hilbert boundary value problem. Finally, we evaluate numerically the presented theoretical results.
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| 35. |
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| 36. |
- Dimitriou, Ioannis, et al.
(författare)
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Poplar and willow plantations on agricultural land in Sweden: Area, yield, groundwater quality and soil organic carbon
- 2017
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 383, s. 99-107
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Tidskriftsartikel (refereegranskat)abstract
- Poplars (Populus spp.) and Willows (Salix spp.) are predominantly grown in plantations on arable land in southern and central parts of Sweden to produce biomass for energy and other purposes. The present study aims at characterizing their present situation with special emphasis on the current extension of the cultivation, expected yield levels as well as on their effects on soil and water. The data sources combine own measurements with existing data, trials and records from previous studies. The results show that poplar and willow currently entail 1322 and 9830 ha in Sweden, respectively, being distributed in similar areas in central and south parts of the country, with an average plantation size of 2.59 and 3.87 ha. Productivity varies depending on the measurement methods, being 6.90 and 7.7 Mg-1 ha(-1) year for poplar and willow, respectively, when estimating standing biomass based on small plots but being about half this value when based on harvesting records from commercial experience. Concerning the impact on groundwater quality, poplar plantations presented higher values of NO3-N and lower values of PO4-P than willow. These differences were consistent along seasons in case of NO3-N, and were only observed in autumn in the case of PO4-P. The results showed no differences between the plantations systems concerning the organic carbon on soil, although in the subsoil (>40 cm) there were slight higher values in case of willow plantations. (C) 2016 Elsevier B.V. All rights reserved.
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| 37. |
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| 38. |
- Dimitriou, Ioannis, et al.
(författare)
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Positioning the biofuel policy in the bioeconomy of the BioEast macro-region
- 2022
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Ingår i: Biofuels. - : Informa UK Limited. - 1759-7269 .- 1759-7277. ; 13, s. 833-842
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Tidskriftsartikel (refereegranskat)abstract
- This study outlines and reviews the concerted biofuels' policy for transport of eleven countries in central and eastern Europe (BioEast macro-region). Policy preferences collected from relevant government representatives of the region are analyzed using choice architecture and fuzzy Analytical Hierarchy Process. The experts' preferences concerning criteria related to land use, decarbonization and development of a national market are ranked with similar importance, with a slight preference for the latter. The results demonstrate a great variation in the priorities for forming and implementing biofuel policies in the region, strongly related to national realities (e.g. available land for biofuel production, target fulfilment). Countries delaying in their biofuel targets aim at policies that fulfil internal demands without considering other criteria related to land use issues and own sources. The results show a general agreement (95% consensus) of having about 66% of renewable energy in transport covered from biofuels resulting from domestic biomass supply. Yet, there are differing preferences in the policy options at country level, which makes a single consensus policy for the macro-region challenging. Finally, the results highlight the different degrees of policy intervention that are implicit in the policy preferences of the national decision makers.
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| 39. |
- Dimitriou, Ioannis, et al.
(författare)
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Potential of short rotation forestry
- 2014
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Ingår i: Forest Bioenergy for Europe.. - 9789525980110 ; :4, s. 75-80
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Bokkapitel (refereegranskat)
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| 40. |
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| 41. |
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| 42. |
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| 43. |
- Dimitriou, Ioannis
(författare)
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Short Rotation Coppice Moving Forward in a Bio-Based Economy
- 2016
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Ingår i: European Biomass Conference and Exhibition Proceedings. - 2282-5819. ; , s. 264-269
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Konferensbidrag (refereegranskat)abstract
- Perennial Short Rotation Woody Crops ("SRC" or "Short Rotation Coppice") are woody species such as willow, poplar, robinia and others. Their cultivation is a good alternative to annual energy crops and can be complementary to existing agricultural systems. Aside from being harvested for energy production, the cultivation of SRCs has many potential benefits compared to annual crops. For instance, they may help to improve water quality, enhance biodiversity, provide ecosystem services (hunting, beekeeping, water supply, fire protection), mitigate animal diseases between farms, prevent erosion, reduce artificial input materials (fertilizers, pesticides) and mitigate climate change due to carbon storage. These advantages have to be promoted to produce sustainable woodchips from SRC, enhancing the positive impacts of SRC to the environment. Thereby, the following sustainability aspects must be considered: SRC has most positive impacts on marginal land and especially as structural elements in the landscape, bordering for instance fields, roads, and electricity lines. The sustainability of the supply chains is specifically addressed in the project SRCplus. The SRCplus project contributes to remove the non-technological barriers of SRC development in Europe through the support of implementing local SRC supply chains. Thereby, synergies with other agricultural uses, ecosystem services and nature conservation measures are exploited. This paper presents first results of the SRCplus project, and discusses sustainability aspects of SRC.
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| 44. |
- Dimitriou, Ioannis
(författare)
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Short Rotation Woody Crops: Experiences from the EU Project SRCplus
- 2017
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Ingår i: European Biomass Conference and Exhibition Proceedings. - 2282-5819. ; , s. 143-149
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Konferensbidrag (refereegranskat)abstract
- Perennial Short Rotation Woody Crops ("SRC" or "Short Rotation Coppice") are woody species such as willow, poplar, robinia and others. Their cultivation is a good alternative to annual energy crops and can be complementary to existing agricultural systems. Aside from being harvested for energy production, the cultivation of SRCs has many potential benefits compared to annual crops. For instance, they may help to improve water quality, enhance biodiversity, provide ecosystem services (hunting, beekeeping, water supply, fire protection), mitigate animal diseases between farms, prevent erosion, reduce artificial input materials (fertilizers, pesticides) and mitigate climate change due to carbon storage. These advantages have to be promoted to produce sustainable woodchips from SRC, enhancing the positive impacts of SRC to the environment. Thereby, the following sustainability aspects must be considered: SRC has most positive impacts on marginal land and especially as structural elements in the landscape, bordering for instance fields, roads, and electricity lines. The sustainability of the supply chains is specifically addressed in the project SRCplus. The SRCplus project contributes to remove the non-technological barriers of SRC development in Europe through the support of implementing local SRC supply chains. Thereby, synergies with other agricultural uses, ecosystem services and nature conservation measures are exploited. This paper presents the final results of the SRCplus project.
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| 45. |
- Dimitriou, Ioannis
(författare)
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Short Rotation Woody Crops for Local Supply Chains and Heat Use in Europe
- 2015
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Konferensbidrag (refereegranskat)abstract
- Perennial Short Rotation Woody Crops ("SRC" or "Short Rotation Coppice") are woody species such as willow, poplar, robinia and others. Their cultivation is a good alternative to annual energy crops and can be complementary to existing agricultural systems. Aside from being harvested for energy production, the cultivation of SRCs has many potential benefits compared to annual crops. For instance, they may help to improve water quality, enhance biodiversity, provide ecosystem services (hunting, beekeeping, water supply, fire protection), mitigate animal diseases between farms, prevent erosion, reduce artificial input materials (fertilizers, pesticides) and mitigate climate change due to carbon storage. These advantages have to be promoted to produce sustainable woodchips from SRC, enhancing the positive impacts of SRC to the environment. Thereby, the following sustainability aspects must be considered: SRC has most positive impacts on marginal land and especially as structural elements in the landscape, bordering for instance fields, roads, and electricity lines. The sustainability of the supply chains is specifically addressed in the project SRCplus. The SRCplus project contributes to remove the non-technological barriers of SRC development in Europe through the support of implementing local SRC supply chains. Thereby, synergies with other agricultural uses, ecosystem services and nature conservation measures are exploited. This paper presents first results of the SRCplus project, and discusses sustainability aspects of SRC.
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| 46. |
- Dimitriou, Ioannis, et al.
(författare)
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Slow expansion and low yields of willow short rotation coppice in Sweden; implications for future strategies
- 2011
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 35:11, s. 4613-4618
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Tidskriftsartikel (refereegranskat)abstract
- About 16 000 ha of commercial willow Short Rotation Coppice (SRC) fields for production of biomass for energy were planted in the early 1990s in Sweden. The cultivated with SRC area has remained almost stable and was slightly decreased during the last years despite the incentives and predictions for drastic increases. Similar incentives and predictions in other countries have been lately launched. The bioenergy produced in the planted SRC areas in Sweden has been lower than anticipated, partly due to the lower than expected biomass yields and the termination of some willow SRC plantations. Explanations for the low yields are depicted based on analyzing the results of a survey where 175 willow SRC growers participated. Lower biomass yields are attributed to: (i) the low input in management activities; (ii) the choice of land for the willow SRC plantation; (iii) and the level of personal involvement of the farmer. Understanding the reasons to earlier years' performance of willow SRC is important for development of better performing systems in the future, in Sweden as well as in other countries. © 2011 Elsevier Ltd.
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| 47. |
- Dimitriou, Ioannis, et al.
(författare)
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Stability and Delay Analysis of an Adaptive Channel-Aware Random Access Wireless Network
- 2017
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Ingår i: ANALYTICAL AND STOCHASTIC MODELLING TECHNIQUES AND APPLICATIONS, ASMTA 2017. - Cham : SPRINGER INTERNATIONAL PUBLISHING AG. - 9783319614281 - 9783319614274 ; , s. 63-80
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Konferensbidrag (refereegranskat)abstract
- In this work, we consider an asymmetric two-user random access wireless network with interacting nodes, time-varying links and multipacket reception capabilities. The users are equipped with infinite capacity buffers where they store arriving packets that will be transmitted to a destination node. Moreover, each user employs a general transmission control protocol under which, it adapts its transmission probability based both on the state of the other user, and on the channel state information according to a Gilbert-Elliot model. We study a two-dimensional discrete time Markov chain, investigate its stability condition, and show that its steady state performance is expressed in terms of a solution of a Riemann-Hilbert boundary value problem. Moreover, for the symmetrical system, we provide closed form expressions for the average delay at each user node. Numerical results are obtained and show insights in the system performance.
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| 48. |
- Dimitriou, Ioannis, et al.
(författare)
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Stable Throughput and Delay Analysis of a Random Access Network With Queue-Aware Transmission
- 2018
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Ingår i: IEEE Transactions on Wireless Communications. - : IEEE Communications Society. - 1536-1276 .- 1558-2248. ; 17:5, s. 3170-3184
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Tidskriftsartikel (refereegranskat)abstract
- In this work we consider a two-user and a three-user slotted ALOHA network with multi-packet reception (MPR) capabilities and a queue-aware transmission control. In this setting, the nodes can adapt their transmission probabilities and their transmission parameters based on the status of the other nodes. Each user has external bursty arrivals that are stored in their infinite capacity queues. We focus on the fundamental problem of characterizing the stable throughput region, as well as of investigating the queueing delay. For the two- and the three-user cases we obtain the exact stability region, whereas in the former case we also provide the conditions under which the stability region is a convex set. We perform a detailed mathematical analysis to study the queueing delay in the two-user case by formulating two boundary value problems, the solution of which provide the generating function of the joint stationary probability distribution of the queue size at user nodes. Furthermore, for the two-user symmetric case with MPR we obtain a lower and an upper bound for the average delay without the need of solving a boundary value problem. In addition, we provide a closed form expression for the gap between the lower and the upper bound. The bounds as it is seen in the numerical results appear to be tight. Explicit expressions for the average delay are obtained for the symmetrical model with capture effect. We also provide a closed form expression for the optimal transmission probability that minimizes the average delay in the symmetric capture case. Finally, we evaluate numerically the presented theoretical results.
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| 49. |
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| 50. |
- Dimitriou, Ioannis
(författare)
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Sustainable landscape management for bioenergy and the bioeconomy : Report from joint IEA Bioenergy task 43 & FAO workshop 11-12th October 2018, Rome, Italy
- 2019
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Rapport (refereegranskat)abstract
- In October 2018, IEA Bioenergy Task 43 “Biomass Feedstocks for Energy Markets” and FAO organized a joint workshop “Sustainable Landscape Management for Bioenergy and the Bioeconomy”. The workshop’s leitmotiv was how to communicate bioenergy beyond the typical bioenergy stakeholders. Despite the effort of the scientific community and international organizations such as IEA Bioenergy, FAO and IRENA, bioenergy uptake is occurring at slower pace despite the sustainable biomass potential, economic feasibility and availability of mature technology. Bioenergy uptake is greatly influenced with social aspects of sustainability, both as dynamic performance of each bioenergy pathway along the social dimension of sustainable development (jobs, health, energy access, etc.) and perceptions in society on the general sustainability of bioenergy (encompassing the environmental, economic and social dimensions). Past failures of bioenergy policy to form positive synergies with agriculture, forestry and waste, e.g. biofuels from food and feed, tend to attract much more attention of the public than dominating good practice examples, backed up with scientific evidence. General knowledge of biomass issues among policy makers, the scientific community as well as civil society associations must be improved to enable a worldwide transition to a decarbonized society. More than 30 bioenergy experts and scientists around the world from 14 bioenergy related entities gathered to express their views how to improve the communications. Some of the highlights are: “Bioenergy represents a major type of renewable energy. As such, it is key to supporting the UN Sustainable Development Goals (SDGs) in the context of climate change and energy security. As summarized by the IPCC 5th Assessment Report, integrated assessment modelling indicates a high risk of failing to meet long-term climate targets without bioenergy. Global assessments by REN 21, IEA and IRENA find that bioenergy accounts for three-quarters of all renewable energy use today and half of the most cost-effective options for doubling renewable energy use by 2030. Bioenergy is part of a larger bioeconomy, including agriculture, forestry and manufacturing.” [1] “Bioenergy is multi-disciplinary in nature, so it is important to ensure that it is tackled in a multidisciplinary fashion that includes all perspectives. This workshop was a first step to approach bioenergy across institutions and disciplines, in a more cohesive way – we hope that working together we can move forward.” explained Olivier Dubois, the FAO Energy team leader. The workshop was an occasion to better understand one another’s skills and expertise for future collaboration. The results of the work in groups were translated in this report, with a feedback of an ecological sociologist on how to narrow the knowledge gap by inclusion of the epistemic community.
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