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| 2. |
- Binbin, Song, et al.
(författare)
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Oxidation properties of self-propagating high temperature synthesized niobium disilicide
- 2014
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 85, s. 311-317
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Tidskriftsartikel (refereegranskat)abstract
- NbSi2 monoliths were prepared by self-propagating high temperature synthesis (SHS) and hot pressing (HP) and their oxidation behavior was investigated at various temperatures (823-1123 K) in air. The combustion mode of SHS reaction was steady state combustion, and the combustion product was single-phase NbSi2. Oxidation studies show that the highest mass gain was 0.95675 kg m(-2) at 1023 K. In cyclic oxidation, the oxidation rate was reduced and the mass gain was only 0.15507 kg m(-2). A dense protective amorphous SiO2 scale formed at 823 K and 923 K whereas a porous multilayer SiO2 and alpha/beta-Nb2O5 oxide scales formed at and above 1023 K and spalled off. Pest oxidation of NbSi2 monoliths was not observed in hot pressed NbSi2 monoliths.
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| 3. |
- Campillo, Javier, 1982-
(författare)
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From Passive to Active Electric Distribution Networks
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Large penetration of distributed generation from variable renewable energy sources, increased consumption flexibility on the demand side and the electrification of transportation pose great challenges to existing and future electric distribution networks. This thesis studies the roles of several actors involved in electric distribution systems through electricity consumption data analysis and simulation models. Results show that real-time electricity pricing adoption in the residential sector offers economic benefits for end consumers. This occurs even without the adoption of demand-side management strategies, while real-time pricing also brings new opportunities for increasing consumption flexibility. This flexibility will play a critical role in the electrification of transportation, where scheduled charging will be required to allow large penetration of EVs without compromising the network's reliability and to minimize upgrades on the existing grid. All these issues add significant complexity to the existing infrastructure and conventional passive components are no longer sufficient to guarantee safe and reliable network operation. Active distribution networks are therefore required, and consequently robust and flexible modelling and simulation computational tools are needed for their optimal design and control. The modelling approach presented in this thesis offers a viable solution by using an equation-based object-oriented language that allows developing open source network component models that can be shared and used unambiguously across different simulation environments.
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| 4. |
- Fu, Hao, et al.
(författare)
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A compact real-time simulator with spatial-temporal parallel design for large-scale wind farms
- 2021
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Ingår i: CSEE Journal of Power and Energy Systems. - : Power System Technology Press. - 2096-0042. ; 9:1, s. 50-65
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Tidskriftsartikel (refereegranskat)abstract
- Real-time simulation of large-scale wind farms with detailed modelling can provide accurate insights into system transient behaviors, but entails challenges in computing resources. This paper develops a compact real-time simulator based on field programmable gate array (FPGA) for large-scale wind farms, in which the spatial-temporal parallel design method is proposed to address the huge computation resource demand associated with detailed modelling. The wind farm is decoupled into several subsystems based on model consistency, and the electrical system and control system of each subsystem are solved in parallel. Both module-level pipeline technique and superscalar pipeline technique are introduced to the wind farms' simulation to effectively improve the utilization of hardware resources. In Case Studies, real-time simulations of two modified wind farms are carried out on a single FPGA separately, including one with 13 permanent magnet synchronous generators under a time-step of 11 μβ, and the other with 30 squirrel-cage induction generators under a time-step of 8μβ. Simulation tests under different scenarios are implemented to validate the numerical performance of the real-time simulator, and a comparison with the commercial tool PSCAD/EMTDC demonstrates the accuracy and effectiveness of the proposed design.
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| 5. |
- Fu, Hao, et al.
(författare)
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Asynchronous multi-rate method of real-time simulation for active distribution networks
- 2023
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Ingår i: IET Renewable Power Generation. - : INST ENGINEERING TECHNOLOGY-IET. - 1752-1416 .- 1752-1424.
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Tidskriftsartikel (refereegranskat)abstract
- The real-time simulation of active distribution networks (ADNs) can provide an accurate insight into transient behaviours, but faces challenges in simulation efficiency and flexibility brought by larger system scales and wider time-scale ranges. This paper presents an asynchronous multi-rate (AMR) method and design for the real-time simulation of large-scale ADNs. In the proposed method, the entire ADN was decoupled into different subsystems according to accuracy requirements, and optimized time-steps were allocated to each subsystem to realize a fully distributed simulation. This not only alleviated the time-step coordination problem existing in multi-rate real-time simulations, but also enhanced the flexible expansion capabilities of the real-time simulator. To realize the AMR real-time simulation, a multi-rate interfacing method, synchronization mechanism, and data communication strategy are proposed in this paper, and their hardware design is also presented in detail. A modified IEEE 123-node system with photovoltaics and wind turbine generators was simulated on a 3 field-programmable gate arrays (FPGAs)-based AMR real-time simulator. The real-time results were captured by the oscilloscope and verified with PSCAD/EMTDC, which demonstrated the superiority in simulation flexibility and accuracy compared with the synchronous multi-rate (SMR) method.
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| 6. |
- Huo, Yanda, et al.
(författare)
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Data-Driven Adaptive Operation of Soft Open Points in Active Distribution Networks
- 2021
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Ingår i: IEEE Transactions on Industrial Informatics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1551-3203 .- 1941-0050. ; 17:12, s. 8230-8242
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Tidskriftsartikel (refereegranskat)abstract
- The integration of soft open point (SOP) effectively improves the flexibility of active distribution networks (ADNs). However, in practical operation, accurate network parameters are difficult to obtain and the operation state changes rapidly with distributed generators (DGs). With the development of information technologies, massive operation data can be acquired in ADNs. How to utilize multisource data has become the key to realize the intelligent operation of ADNs. This article proposes a data-driven operation strategy of SOP based on model-free adaptive control (MFAC). First, considering the inaccurate parameters and frequent change of operation states, a data-driven framework is formulated for the real-time operation of SOP. Then, the operation strategies of multiple SOPs are further improved with interarea coordination. The results of case studies show that driven by the measurement data, the potential benefits of SOPs are explored to adaptively respond to system state changes and improve the operational performance of ADNs.
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| 7. |
- Huo, Yanda, et al.
(författare)
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Data-driven Coordinated Voltage Control Method of Distribution Networks with High DG Penetration
- 2023
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Ingår i: IEEE Transactions on Power Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8950 .- 1558-0679. ; 38:2, s. 1543-1557
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Tidskriftsartikel (refereegranskat)abstract
- The highly penetrated distributed generators (DGs) aggravate the voltage violations in active distribution networks (ADNs). The coordination of various regulation devices such as on-load tap changers (OLTCs) and DG inverters can effectively address the voltage issues. Considering the problems of inaccurate network parameters and rapid DG fluctuation in practical operation, multi-source data can be utilized to establish the data-driven control model. In this paper, a data-driven coordinated voltage control method with the coordination of OLTC and DG inverters on multiple time-scales is proposed without relying on the accurate physical model. First, based on the multi-source data, a data-driven voltage control model is established. Multiple regulation devices such as OLTC and DG are coordinated on multiple time-scales to maintain voltages within the desired range. Then, a critical measurement selection method is proposed to guarantee the voltage control performance under the partial measurements in practical ADNs. Finally, the proposed method is validated on the modified IEEE 33-node and IEEE 123-node test cases. Case studies illustrate the effectiveness of the proposed method, as well as the adaptability to DG uncertainties.
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| 8. |
- Li, Jiyun, et al.
(författare)
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Inter-host Transmission of Carbapenemase-Producing Escherichia coli among Humans and Backyard Animals
- 2019
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Ingår i: Journal of Environmental Health Perspectives. - : U.S. Department of Health and Human Services, National Institute of Environmental Health Sciences. - 0091-6765 .- 1552-9924. ; 127:10
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The rapidly increasing dissemination of carbapenem-resistant Enterobacteriaceae (CRE) in both humans and animals poses a global threat to public health. However, the transmission of CRE between humans and animals has not yet been well studied.OBJECTIVES: We investigated the prevalence, risk factors, and drivers of CRE transmission between humans and their backyard animals in rural China.METHODS: We conducted a comprehensive sampling strategy in 12 villages in Shandong, China. Using the household [residents and their backyard animals (farm and companion animals)] as a single surveillance unit, we assessed the prevalence of CRE at the household level and examined the factors associated with CRE carriage through a detailed questionnaire. Genetic relationships among human- and animal-derived CRE were assessed using whole-genome sequencing-based molecular methods.RESULTS: A total of 88 New Delhi metallo beta lactamasesmetallo-β-lactamases–type carbapenem-resistant Escherichia coli (NDM-EC), including 17 from humans, 44 from pigs, 12 from chickens, 1 from cattle, and 2 from dogs, were isolated from 65 of the 746 households examined. The remaining 12 NDM-EC were from flies in the immediate backyard environment. The NDM-EC colonization in households was significantly associated with a) the number of species of backyard animals raised/kept in the same household, and b) the use of human and/or animal feces as fertilizer. Discriminant analysis of principal components (DAPC) revealed that a large proportion of the core genomes of the NDM-EC belonged to strains from hosts other than their own, and several human isolates shared closely related core single-nucleotide polymorphisms and bla sub NDMblaNDM genetic contexts with isolates from backyard animals.CONCLUSIONS: To our knowledge, we are the first to report evidence of direct transmission of NDM-EC between humans and animals. Given the rise of NDM-EC in community and hospital infections, combating NDM-EC transmission in backyard farm systems is needed. https://doi.org/10.1289/EHP5251.
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| 9. |
- Li, Juan, et al.
(författare)
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Plasmid-mediated quinolone resistance genes and antibiotic residues in wastewater and soil adjacent to swine feedlots : potential transfer to agricultural lands
- 2012
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Ingår i: Journal of Environmental Health Perspectives. - : National Institute of Environmental Health Science. - 0091-6765 .- 1552-9924. ; 120:8, s. 1144-1149
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Inappropriate use of antibiotics in swine feed could cause accelerated emergence of antibiotic resistance genes, and agricultural application of swine waste could spread antibiotic resistance genes to the surrounding environment.OBJECTIVES: We investigated the distribution of plasmid-mediated quinolone resistance (PMQR) genes from swine feedlots and their surrounding environment.METHODS: We used a culture-independent method to identify PMQR genes and estimate their levels in wastewater from seven swine feedlot operations and corresponding wastewater-irrigated farm fields. Concentrations of (fluoro)quinolones in wastewater and soil samples were determined by ultra-performance liquid chromatography-electrospray tandem mass spectrometry.RESULTS: The predominant PMQR genes in both the wastewater and soil samples were qnrD, qepA, and oqxB, whereas qnrS and oqxA were present only in wastewater samples. Absolute concentrations of all PMQR genes combined ranged from 1.66 × 107 to 4.06 × 108 copies/mL in wastewater and 4.06 × 106 to 9.52 × 107 copies/g in soil. Concentrations of (fluoro)quinolones ranged from 4.57 to 321 ng/mL in wastewater and below detection limit to 23.4 ng/g in soil. Significant correlations were found between the relative abundance of PMQR genes and (fluoro)quinolone concentrations (r = 0.71, p = 0.005) and the relative abundance of PMQR genes in paired wastewater and agricultural soil samples (r = 0.91, p = 0.005).CONCLUSIONS: Swine feedlot wastewater may be a source of PMQR genes that could facilitate the spread of antibiotic resistance. To our knowledge, this is the first study to examine the occurrence of PMQR genes in animal husbandry environments using a culture-independent method.
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| 10. |
- Wang, Chengshan, et al.
(författare)
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Distributed Energy and Microgrids (DEM)
- 2018
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Ingår i: Applied Energy. - : ELSEVIER SCI LTD. - 0306-2619 .- 1872-9118. ; 210, s. 685-689
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 11. |
- Wu, Haijing, et al.
(författare)
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Molecular control of follicular helper T cell development and differentiation
- 2018
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 9:OCT
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Forskningsöversikt (refereegranskat)abstract
- Follicular helper T cells (Tfh) are specialized helper T cells that are predominantly located in germinal centers and provide help to B cells. The development and differentiation of Tfh cells has been shown to be regulated by transcription factors, such as B-cell lymphoma 6 protein (Bcl-6), signal transducer and activator of transcription 3 (STAT3) and B lymphocyte-induced maturation protein-1 (Blimp-1). In addition, cytokines, including IL-21, have been found to be important for Tfh cell development. Moreover, several epigenetic modifications have also been reported to be involved in the determination of Tfh cell fate. The regulatory network is complicated, and the number of novel molecules demonstrated to control the fate of Tfh cells is increasing. Therefore, this review aims to summarize the current knowledge regarding the molecular regulation of Tfh cell development and differentiation at the protein level and at the epigenetic level to elucidate Tfh cell biology and provide potential targets for clinical interventions in the future.
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| 12. |
- Zhang, Yang, 1991-
(författare)
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Integration of Battery and Hydrogen Storage with a Grid-Connected Photovoltaic System in Buildings
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The integration of Photovoltaic (PV) with buildings changes the previous electricity consumers into prosumers. The reduced PV subsidies and the grid stable operation requirements are pushing prosumers from direct exportation to self-consumption of the produced electricity. Electricity storage increases the self-consumption, while comes with higher investment. During the system planning stage, the benefits of storage should be clarified to prosumers. The storage type, the storage capacity and the system operation strategy should be determined at the same time. This thesis dealt with a grid-connected PV-storage system and proposed an optimization method, which simultaneously determined the storage capacity and rule-based operation strategy parameters. This method eliminated the necessity of forecasting and could be easily implemented. A typical residential building in Sweden was taken as a case study. Different operation strategies as well as two storage technologies – battery storage and hydrogen storage – were compared. For the battery storage system, the proposed battery hybrid operation strategy, which carries out the conventional operation strategy during warm months and the peak shaving strategy during cold months, provides the best performance in Self Sufficiency Ratio (SSR) and Net Present Value (NPV). For the hydrogen storage system, the hydrogen hybrid operation strategy outperforms other studied operation strategies under different scenarios, which have optimistic or pessimistic cost assumptions of the hydrogen storage system. The comparison between hydrogen storage and battery storage suggests that battery storage has much better performance in SSR and NPV under the pessimistic cost scenario. Under the optimistic cost scenario, battery storage and hydrogen storage achieve comparable performance in SSR and NPV. However, hydrogen storage is more favorable when considering reducing the prosumer’s negative impact on the grid.
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