| 1. |
- Xi, Fengming, et al.
(författare)
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Substantial global carbon uptake by cement carbonation
- 2016
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Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 9:12, s. 880-883
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Tidskriftsartikel (refereegranskat)abstract
- Calcination of carbonate rocks during the manufacture of cement produced 5% of global CO 2 emissions from all industrial process and fossil-fuel combustion in 2013. Considerable attention has been paid to quantifying these industrial process emissions from cement production, but the natural reversal of the process - carbonation - has received little attention in carbon cycle studies. Here, we use new and existing data on cement materials during cement service life, demolition, and secondary use of concrete waste to estimate regional and global CO 2 uptake between 1930 and 2013 using an analytical model describing carbonation chemistry. We find that carbonation of cement materials over their life cycle represents a large and growing net sink of CO 2, increasing from 0.10 GtC yr â '1 in 1998 to 0.25 GtC yr â '1 in 2013. In total, we estimate that a cumulative amount of 4.5 GtC has been sequestered in carbonating cement materials from 1930 to 2013, offsetting 43% of the CO 2 emissions from production of cement over the same period, not including emissions associated with fossil use during cement production. We conclude that carbonation of cement products represents a substantial carbon sink that is not currently considered in emissions inventories.
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| 2. |
- Berezovskaya, Yulia, et al.
(författare)
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Modular Model of a Data Centre as a Tool for Improving Its Energy Efficiency
- 2020
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Ingår i: IEEE Access. - : IEEE. - 2169-3536. ; 8, s. 46559-46573
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Tidskriftsartikel (refereegranskat)abstract
- For most modern data centres, it is of high value to select practical methods for improving energy efficiency and reducing energy waste. IT-equipment and cooling systems are the two most significant energy consumers in data centres, thus the energy efficiency of any data centre mainly relies on the energy efficiency of its computational and cooling systems. Existing techniques of optimising the energy usage of both these systems have to be compared. However, such experiments cannot be conducted in real plants as they may harm the electronic equipment. This paper proposes a modelling toolbox which enables building models of data centres of any scale and configuration with relative ease. The toolbox is implemented as a set of building blocks which model individual components of a typical data centre, such as processors, local fans, servers, units of cooling systems, it provides methods of adjusting the internal parameters of the building blocks, as well as contains constructors utilising the building blocks for building models of data centre systems of different levels from server to the server room. The data centre model is meant to accurate estimating the energy consumption as well as the evolution of the temperature of all computational nodes and the air temperature inside the data centre. The constructed model capable of substitute for the real data centre at examining the performance of different energy-saving strategies in dynamic mode: the model provides information about data centre operating states at each time point (as model outputs) and takes values of adjustable parameters as the control signals from system implementing energy-saving algorithm (as model inputs). For Module 1 of the SICS ICE data centre located in Luleå, Sweden, the model was constructed from the building blocks. After adjusting the internal parameters of the building blocks, the model demonstrated the behaviour quite close to real data from the SICS ICE data centre. Therefore the model is applicable to use as a substitute for the real data centre. Some examples of using the model for testing energy-saving strategies are presented at the end of the paper.
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| 3. |
- Chen, Genqiang, et al.
(författare)
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Bioconversion of waste fiber sludge to bacterial nanocellulose and use for reinforcement of CTMP paper sheets
- 2017
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 9:9
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Tidskriftsartikel (refereegranskat)abstract
- Utilization of bacterial nanocellulose (BNC) for large-scale applications is restricted by low productivity in static cultures and by the high cost of the medium. Fiber sludge, a waste stream from pulp and paper mills, was enzymatically hydrolyzed to sugar, which was used for the production of BNC by the submerged cultivation of Komagataeibacter xylinus. Compared with a synthetic glucose-based medium, the productivity of purified BNC from the fiber sludge hydrolysate using shake-flasks was enhanced from 0.11 to 0.17 g/(L × d), although the average viscometric degree of polymerization (DPv) decreased from 6760 to 6050. The cultivation conditions used in stirred-tank reactors (STRs), including the stirring speed, the airflow, and the pH, were also investigated. Using STRs, the BNC productivity in fiber-sludge medium was increased to 0.32 g/(L × d) and the DPv was increased to 6650. BNC produced from the fiber sludge hydrolysate was used as an additive in papermaking based on the chemithermomechanical pulp (CTMP) of birch. The introduction of BNC resulted in a significant enhancement of the mechanical strength of the paper sheets. With 10% (w/w) BNC in the CTMP/BNC mixture, the tear resistance was enhanced by 140%. SEM images showed that the BNC cross-linked and covered the surface of the CTMP fibers, resulting in enhanced mechanical strength.
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| 4. |
- Chen, Genqiang, et al.
(författare)
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Scale-up of production of bacterial nanocellulose using submerged cultivation
- 2018
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Ingår i: Journal of chemical technology and biotechnology (1986). - : Wiley. - 0268-2575 .- 1097-4660. ; 93:12, s. 3418-3427
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: More extensive utilization of bacterial nanocellulose (BNC) is severely restricted by the low efficiency and small scale of the traditional static cultivation. Submerged fermentation in stirred-tank reactors (STRs) is potentially favourable for large-scale production of BNC, but scale-up of cultivation remains challenging. Even though the STR is most commonly used for submerged cultivation in the fermentation industry, there are few previous attempts to scale-up production of BNC to pilot scale using an STR. Furthermore, the question of how scale-up of submerged cultivation affects the properties of the BNC has received very little attention. RESULTS: Four strains were compared in 250-mL shake flasks. Strain DHU-ATCC-1 displayed the highest volumetric productivity, 0.56 g L−1 d−1, and was then cultivated in a 400-mL STR, showing a similar productivity of 0.55 g L−1 d−1. Scale-up using a 75-L STR pilot bioreactor resulted in enhancement of the BNC production rate from 0.056 g d−1 in the shake flasks to 17.3 g d−1 in the 75-L STR, although the productivity decreased to 0.43 g L−1 d−1. During scale-up from shake flasks to 400-mL STR and further on to 75-L STR, the BNC fibers formed more bundles, whereas the fiber diameter decreased from 25.6 to 21.7 nm. The BNC from the 75-L STR exhibited a higher degree of polymerization, specifically 3230, higher degree of crystallinity, specifically 83%, larger crystallites, and improved strength including higher tensile energy absorption index and superior stretch at break. CONCLUSION: It is possible to enhance BNC production, and maintain or improve its properties when scaling up submerged cultivation in STRs.
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| 5. |
- Efkarpidis, Nikolaos, et al.
(författare)
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Proactive Scheduling of Mixed Energy Resources at Different Grid Levels
- 2023
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Ingår i: IEEE Transactions on Sustainable Energy. - : Institute of Electrical and Electronics Engineers Inc.. - 1949-3029 .- 1949-3037.
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Tidskriftsartikel (refereegranskat)abstract
- The optimal utilisation of distribution grids requires the proactive management of volatilities caused by mixed energy resources installed into different grid levels, such as buildings, energy communities (ECs) and substations. In this context, proactive control based on predictions for energy demand and generation is applied. The mitigation of conflicts between the stakeholders' objectives is the main challenge for the control of centralized and distributed energy resources. In this paper, a bi-level approach is proposed for the control of stationary battery energy storage systems (SBES) supporting the local distribution system operator (DSO) at the transformer level, as well as distributed energy resources (DERs) operated by end customers, i.e., EC-members. Model predictive control (MPC)- based and hybrid approaches merging rule- and MPC-based control schemes are evaluated. Simulation studies based on a typical European low voltage (LV) feeder topology yield the performance assessment in terms of technical and economic criteria. The results show an advantage of hybrid approaches with respect to the DSO's cost savings from peak shaving. From the EC's perspective, both hybrid and MPC-based schemes can achieve effective cost savings from proactive energy management.
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| 6. |
- Fall, Andreas, et al.
(författare)
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Hybrid Materials of Nanocellulose and Graphene
- 2019
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Ingår i: <em>International Conference on Nanotechnology for Renewable Materials 2019</em>. - : TAPPI Press. ; , s. 1069-1080
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Konferensbidrag (refereegranskat)
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| 7. |
- Federsel, Hans-Jürgen, et al.
(författare)
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C-N Coupling Chemistry as a Means to Achieve a Complicated Molecular Architecture : the AR-A2 Case Story
- 2013
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Ingår i: Transition Metal-Catalyzed Couplings in Process Chemistry. - Weinheim, Germany : Wiley-VCH Verlag. - 9783527658909 - 9783527332793 ; , s. 73-89
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- A major drug project in the neuroscience area aimed at designing and developing a viable manufacturing process for AR-A2. This turned out to be a tough challenge that resulted in the use of three different synthetic routes. One step to be included from the very start was a Pd-catalyzed C-N bond formation, and this was retained throughout the later versions of the synthesis. At the time of initiating this project in 1998, the combined Buchwald and Hartwig protocols for effecting the chemistry in question-coupling of a N-containing moiety to an aromatic nucleus had only been known for a few years. Therefore, a lot of experimentation was needed to increase the insight and understanding of the chemistry to optimize the performance to fit for large-scale application. The outcome of the efforts resulted in successfully carrying out the chemical transformation is described in detail in this chapter.
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| 8. |
- Gagné, Sara, et al.
(författare)
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Conserving biodiversity takes a plan : How planners implement ecological information for biodiversity conservation
- 2020
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Ingår i: Ambio. - : Springer Netherlands. - 0044-7447 .- 1654-7209. ; 49, s. 1490-1505
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Tidskriftsartikel (refereegranskat)abstract
- Conserving biodiversity is critical to the sustainability of human settlements, and stands to benefit from collaboration between ecologists focused on understanding natural systems and planners balancing social, environmental, and economic priorities. Drawing from the socially-situated definition of ‘sustainability’, we sought to understand the relationship between ecologists and planners by probing how planners in the southeastern US prioritize and engage with biodiversity conservation and ecological information, and how context influences these decisions. We find that context matters, e.g., higher jurisdictional population density was positively associated with prioritizing tree cover and diversity. We find, also, that while biodiversity conservation and ecological information are valuable to planners, planners rely heavily on their colleagues to inform conservation-related activities and prioritize conservation topics that differ from ecological research foci. Improved communication by ecologists and context-specific transdisciplinary sustainability research, especially that which incorporates the primary role of elected officials in biodiversity conservation, may help to integrate ecological science and planning practice.
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| 9. |
- Galkin, Nikolai, et al.
(författare)
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On Modelling of Edge Datacentre Microgrid for Participation in Smart Energy Infrastructures
- 2022
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Ingår i: IEEE Open Journal of the Industrial Electronics Society. - : Institute of Electrical and Electronics Engineers Inc.. - 2644-1284. ; 3, s. 50-64
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Tidskriftsartikel (refereegranskat)abstract
- Datacentres are becoming a sizable part of the energy system and are one of the biggest consumers of the energy grid. The so-called “Green Datacentre” is capable of not only consuming but also producing power, thus becoming an important kind of prosumers in the electric grid. Green datacentres consist of a microgrid with a backup uninterrupted power supply and renewable generation, e.g., using photovoltaic panels. As such, datacentres could realistically be important participants in demand/response applications. However, this requires reconsidering their currently rigid control and automation systems and the use of simulation models for online estimation of the control actions impact. This paper presents such a microgrid simulation model modelled after a real edge datacentre. A case study consumption scenario is presented for the purpose of validating the developed microgrid model against data traces collected from the green edge datacentre. Both simulation and real-time validation tests are performed to validate the accuracy of the datacentre model. Then the model is connected to the automation environment to be used for the online impact estimation and virtual commissioning purposes.
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| 10. |
- Ghajeri, Farnaz, et al.
(författare)
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The Influence of Residuals Combining Temperature and Reaction Time on Calcium Phosphate Transformation in a Precipitation Process
- 2022
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Ingår i: Journal of Functional Biomaterials. - : MDPI. - 2079-4983. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Precipitation is one of the most common processes to synthesize hydroxyapatite, which is the human body’s mineral forming bone and teeth, and the golden bioceramic material for bone repair. Generally, the washing step is important in the precipitation method to remove the residuals in solution and to stabilize the phase transformation. However, the influence of residuals in combination with the reaction temperature and time, on calcium phosphate formation, is not well studied. This could help us with a better understanding of the typical synthesis process. We used a fixed starting ion concentration and pH in our study and did not adjust it during the reaction. XRD, FTIR, ICP-OES, and SEM have been used to analyze the samples. The results showed that combining residuals with both reaction temperature and time can significantly influence calcium phosphate formation and transformation. Dicalcium phosphate dihydrate formation and transformation are sensitive to temperature. Increasing temperature (60◦C) can inhibit the formation of acidic calcium phosphate or transform it to other phases, and further the particle size. It was also observed that high reaction temperature (60◦C) results in higher precipitation efficiency than room temperature. A low ion concentration combining reaction temperature and time could still significantly influence the calcium phosphate transformation during the drying. © 2022 by the authors.
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