| 41. |
- Wu, Yiming, 1987-, et al.
(författare)
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Perspectives on Peer-to-Peer Data Delivery Architectures for Next Generation Power Systems
- 2013
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Ingår i: Smart Grid Management.
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Konferensbidrag (refereegranskat)abstract
- Introduction of new Information and Communication Technologies (ICT) and aggregation of equipment bring in new perspectives in terms of the increasing number of data users. It also brings new data delivery requirements which are difficult to be met by the legacy systems. Off-the-shelf standards and communication technologies are the enablers to push current data delivery solutions to a new level. At this level this new data delivery system can fulfill Quality of Service (QoS) requirements of next generation power system. This paper proposes a comprehensive architecture of Peer-to-Peer (P2P) based overlay-control data delivery system covering all levels of data delivery. The core technology of such an architecture lays on the Intelligent Substation Gateway (ISG), which is employed to provide data delivery service to meet the QoS requirements. Proposed data delivery system brings advantages as autonomy, flexibility, scalability, and efficient to the power system.
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| 42. |
- Xie, M., et al.
(författare)
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A seasonal ARIMA model with exogenous variables for elspot electricity prices in Sweden
- 2013
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Ingår i: European Energy Market (EEM), 2013 10th International Conference on the. - : IEEE. - 9781479920082 ; , s. 6607293-
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Konferensbidrag (refereegranskat)abstract
- In a spot market, price prediction plays an indispensable role in maximizing the benefit of a producer as well as optimizing the utility of a consumer. This paper develops a seasonal ARIMA model with exogenous variables (SARIMAX) to predict day-ahead electricity prices in Elspot market, the largest day-ahead market for power trading in the world. Compared with the basic ARIMA model, SARIMAX has two distinct features: 1) A seasonal component is introduced to cope with weekly effect on price fluctuations. 2) Exogenous variables that exert influence on electricity prices are incorporated to make price predictions in the context of an integrated energy market. A detailed implementation of SARIMAX for Elspot market in Sweden is presented.
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| 43. |
- Ye, Chenhui, et al.
(författare)
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All-Optical Approach to Microwave Frequency Measurement With Large Spectral Range and High Accuracy
- 2012
-
Ingår i: IEEE Photonics Technology Letters. - : IEEE. - 1041-1135 .- 1941-0174. ; 24:7, s. 614-616
-
Tidskriftsartikel (refereegranskat)abstract
- An all-optical approach for microwave frequency (MWF) measurement with a low-speed oscilloscope is proposed and experimentally demonstrated. In this scheme, an optical filter with a single and ultranarrow passband, together with a tunable laser and a low-speed photodiode is utilized to calculate the MWF by measuring the time delay between the sweeping optical carrier and its upper/lower sideband passing through the filter. Single-frequency and multifrequency measurements are experimentally demonstrated. The measurement recognition, accuracy, and resolution are below 0.1, 0.09, and 0.2 GHz, respectively. This proposed scheme can be easily upgraded to higher frequencies using a modulator with higher bandwidth proportional to the desired measurement range.
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| 44. |
- Ye, Chenhui, et al.
(författare)
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An All-Optical Transformer From Differential NRZ Data to Ultra-Wideband Pulse Stream
- 2011
-
Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 23:9, s. 579-581
-
Tidskriftsartikel (refereegranskat)abstract
- We propose and experimentally demonstrate a compact and cost-effective scheme based on a fiber Sagnac structure to realize real time conversion from differential nonreturn-to-zero (NRZ) data to ultra-wideband (UWB) pulse stream. The proposed conversion system for the UWB signal generation consists of a single-wavelength laser, a phase modulator, several polarization controllers, and optical couplers. Due to the optical interference between the two phase-modulated light waves with slight phase difference in the Sagnac loop, two sharp optical pulses with opposite polarities are obtained. With proper time delay, a UWB monocycle pulse stream is generated from the original differential NRZ data. Our proposed method gives a reliable, easy, and low-cost transformer from differential NRZ signal to UWB pulse stream, and no high-speed arbitrary waveform generator (AWG) is required in this all-optical transformer.
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| 45. |
- Zhang, Shuai, et al.
(författare)
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MIMO reference antennas for OTA applications
- 2013
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Ingår i: 2013 7th European Conference on Antennas and Propagation, EuCAP 2013. - New York : IEEE. - 9788890701832 ; , s. 2556-2557, s. 2243-2244
-
Konferensbidrag (refereegranskat)abstract
- In this paper, MIMO reference antennas with different correlation coefficients are proposed for Over-The-Air (OTA) applications. The correlation can be simply controlled through a slot etched on a dual-feed PIFA with the similar total efficiency. Three kinds of situations are investigated with the proposed method: high correlation (HC), mid correlation (MC), and low correlation (LC). In order to verify the introduced idea, the measurements of correlations and efficiencies are carried out in a reverberation chamber. The simulation and measurement agree well with each other.
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| 46. |
- Zhang, Shuai, et al.
(författare)
-
MIMO Reference Antennas with Controllable Correlations and Total Efficiencies
- 2014
-
Ingår i: Progress In Electromagnetics Research. - 1070-4698 .- 1559-8985. ; 145, s. 115-121
-
Tidskriftsartikel (refereegranskat)abstract
- MIMO reference antennas are proposed for over the air (OTA) measurement applications. The reference antennas could get rid of feeding cable interference and control envelope correlation coefficients (ECC) continuously by only changing the length of an etched slot on a dual-feed PIFA. If only the ECC is investigated, the MIMO reference antenna is optimized to have a small variation of total efficiency from 70% to 50% when the ECC increases from 0.1 to 0.88. The prototypes are fabricated and measured in a scattered field chamber (SFC). Measurements agree well with the simulations. If the MIMO performance is studied, the MIMO reference antenna is proposed to own a large variation of total efficiencies from 90% to 47% while the ECC increases from 0 to 0.98. The bandwidth of the proposed reference antennas depend on the size of the antennas. This method is valid for all the frequencies.
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| 47. |
- Zhang, S. W., et al.
(författare)
-
Synthesis of narrowly distributed polystyrene-encapsulated silica nanoparticles via emulsion polymerization
- 2017
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Ingår i: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 38:3, s. 451-456
-
Tidskriftsartikel (refereegranskat)abstract
- Polystyrene (PS)-encapsulated silica nanoparticles were successfully synthesized by conventional emulsion polymerization for solving the aggregation matter of nanoscaled silica. The grafting coupling agents and PS on the silica surface were detected by Fourier Transform Infrared (FTIR) spectroscopy. The influence of silica and monomer to water ratios and initiator concentration on particle size distribution of the nanocomposite latex was investigated. The particle size distribution firstly narrowed and then broadened with the increase of silica and monomer to water ratios and initiator concentration. The narrow distribution could be controlled in an appropriate silica and monomer to water ratio and an initiator concentration of 1/15 and 2wt%, respectively. From the evaluation of transmission electron microscopy (TEM) micrographs and dynamic light scattering (DLS) measurement, it was proved that the nanocomposite latex did not have all sphere-like shape, but contained tiny amounts of irregular bodies. The formation mechanism of PS-encapsulated silica nanoparticles was also discussed.
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| 48. |
- Zhou, Yongqiang, et al.
(författare)
-
Inflow rate-driven changes in the composition and dynamics of chromophoric dissolved organic matter in a large drinking water lake
- 2016
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 100, s. 211-221
-
Tidskriftsartikel (refereegranskat)abstract
- Drinking water lakes are threatened globally and therefore in need of protection. To date, few studies have been carried out to investigate how the composition and dynamics of chromophoric dissolved organic matter (CDOM) in drinking water lakes are influenced by inflow rate. Such CDOM can lead to unpleasant taste and odor of the water and produce undesirable disinfection byproducts during drinking water treatment. We studied the drinking water Lake Qiandao, China, and found that the concentrations of suspended particulate matter (SPM) in the lake increased significantly with inflow rate (p
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| 49. |
- Zhou, Yongqiang, et al.
(författare)
-
Rainstorm events shift the molecular composition and export of dissolved organic matter in a large drinking water reservoir in China : High frequency buoys and field observations
- 2020
-
Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 187
-
Tidskriftsartikel (refereegranskat)abstract
- Rainstorm events can flush large amounts of terrestrial organic-rich material into lakes that are used for drinking water. To date, few studies have been carried out to investigate how rainstorm events change the molecular composition, bio-lability, and flux of upstream-imported dissolved organic matter (DOM), which can impact the odor and taste of drinking water as well as the efficiency of wastewater treatment. We undertook high-frequency buoy monitoring and point sample collection (n = 495), during high, moderate, and low inflow discharge, in Lake Qiandao, a key drinking water source for about 10 million people. Data from two online fluorescent DOM sensors deployed and field samples collected at the river site, Jiekou, and the lake site, Xiaojinshan, showed that rainstorm events increased the specific UV absorbance (SUVA254), humification index (HIX), humic-like components (C1-C2), and FT-ICR MS derived condensed aromatic and polyphenolic compounds (p < 0.001) and decreased the spectral slope of DOM (S275–295), spectral slope ratio (SR), biological index (BIX), and highly bio-degradable peptide-like and aliphatic substances (p < 0.001). Our results suggest that rainstorm events enhanced the export to the lake of colored, hydrophobic, and aromatic DOM. Upstream-derived dissolved organic carbon (DOC) concentrations decreased (p < 0.001), while DOC bio-availability (BDOC) increased only slightly (p < 0.05) during rainstorm events. The loss rate of DOC in Lake Qiandao is 0.82 × 104 t C yr−1, of which 0.30 × 104 t C yr−1 is highly bio-labile, and higher occurrences of both ≥ 25 mm d − 1 and ≥ 50 mm d − 1 rainfall events are anticipated by linear fittings for this region in the future. The application of in situ fluorescence sensors provides an early warning of DOC surge incidents caused by rainstorm events and may be useful in advising drinking water treatment plant managers of changes in raw water DOM quality and treatability.
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| 50. |
- Zhu, Jie, 1990, et al.
(författare)
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Bi-level ramp merging coordination for dense mixed traffic conditions
- 2024
-
Ingår i: Fundamental Research. - 2096-9457 .- 2667-3258. ; In Press
-
Tidskriftsartikel (refereegranskat)abstract
- Connected and Autonomous Vehicles (CAVs) hold great potential to improve traffic efficiency, emissions and safety in freeway on-ramp bottlenecks through coordination between mainstream and on-ramp vehicles. This study proposes a bi-level coordination strategy for freeway on-ramp merging of mixed traffic consisting of CAVs and human-driven vehicles (HDVs) to optimize the overall traffic efficiency and safety in congested traffic scenarios at the traffic flow level instead of platoon levels. The macro level employs an optimization model based on fundamental diagrams and shock wave theories to make optimal coordination decisions, including optimal minimum merging platoon size to trigger merging coordination and optimal coordination speed, based on macroscopic traffic state in mainline and ramp (i.e., traffic volume and penetration rates of CAVs). Furthermore, the micro level determines the real platoon size in each merging cycle as per random arrival patterns and designs the coordinated trajectories of the mainline facilitating vehicle and ramp platoon. A receding horizon scheme is implemented to accommodate human drivers’ stochastics as well. The developed bi-level strategy is tested in terms of improving efficiency and safety in a simulation-based case study under various traffic volumes and CAV penetration rates. The results show the proposed coordination addresses the uncertainties in mixed traffic as expected and substantially improves ramp merging operation in terms of merging efficiency and traffic robustness, and reducing collision risk and emissions, especially under high traffic volume conditions.
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