| 1. |
- Jiang, L., et al.
(författare)
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Experimental investigation on BOF slag oxidation in air
- 2019
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Ingår i: Ironmaking & steelmaking. - : Taylor and Francis Ltd.. - 0301-9233 .- 1743-2812. ; 46:8, s. 747-754
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Tidskriftsartikel (refereegranskat)abstract
- Basic oxygen furnace (BOF) slag contains a significant amount of iron-containing species, which is considered to be iron resources and therefore need to be recovered. In this work, the oxidation behaviour of BOF slag under air (at selected oxidation temperatures and holding time) was investigated to explore the potential of transforming non-magnetic wustite in the BOF slag into magnetic spinel, which may subsequently be recovered by magnetic separation. The experimental results show that the iron-containing spices in the BOF slag can be oxidised into magnetic spinel phases in the investigated temperature range of 1000–1150°C and thereafter be recovered by magnetic separation. The formation of these phases is closely related to the oxidation temperatures and holding time: a higher oxidation temperature and longer holding time lead to a larger amount of formed magnetic species; however, the amount of formed magnetic species decreases at elevated temperature (>1050°C) and with extended holding time (>40 min).
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| 2. |
- Jiang, Zhiheng, et al.
(författare)
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Use of software-defined radio receivers in two-way satellite time and frequency transfers for UTC computation
- 2018
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Ingår i: Metrologia. - : IOP Publishing. - 0026-1394 .- 1681-7575. ; 55:5, s. 685-698
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Tidskriftsartikel (refereegranskat)abstract
- Two-way satellite time and frequency transfer (TWSTFT) is a primary technique for the generation of coordinated universal time (UTC). About 20 timing laboratories around the world continuously operate TWSTFT using satellite time and ranging equipment (SATRE19) modems for remote time and frequency comparisons in this context. The precision of the SATRE TWSTFT as observed today is limited by an apparent daily variation pattern (diurnal) in the TWSTFT results. The observed peak-to-peak variation have been found as high as 2 ns in some cases. Investigations into the origins of the diurnals have so far provided no complete understanding about the cause of the diurnals. One major contributor to the diurnals, however, could be related to properties of the receive part in the modem. In 2014 and 2015, it was demonstrated that bypassing the receive part and the use of software-defined radio (SDR) receivers in TWSTFT ground stations (SDR TWSTFT) instead could considerably reduce both the diurnals and the measurement noise. In 2016, the International Bureau of Weights and Measures (BIPM) and the Consultative Committee for Time and Frequency (CCTF) working group (WG) on TWSTFT launched a pilot study on the application of SDR receivers in the TWSTFT network for UTC computation. The first results of the pilot study were reported to the CCTF WG on TWSTFT annual meeting in May 2017, demonstrating that SDR TWSTFT shows superior performance compared to that of SATRE TWSTFT for practically all links between participating stations. In particular, for continental TWSTFT links, in which the strongest diurnals appear, the use of SDR TWSTFT results in a significant suppression of the diurnals by a factor of between two and three. For the very long inter-continental links, e.g. the Europe-to-USA links where the diurnals are less pronounced, SDR TWSTFT achieved a smaller but still significant gain of 30%. These findings are supported by an evaluation of some of the links with an alternate technique based on GPS signals (GPS IPPP) as reported in this paper. Stimulated by these results, the WG on TWSTFT prepared a recommendation for the 21st CCTF meeting, which proposed the introduction of SDR TWSTFT in UTC generation. With CCTF approval of the recommendation, a roadmap was developed for the implementation of SDR TWSTFT in UTC generation. In accordance with the roadmap, most of the stations that participated in the pilot study have updated the SDR TWSTFT settings to facilitate the use of SDR TWSTFT data in UTC generation. In addition, the BIPM conducted a final evaluation to validate the long-term stability of SDR TWSTFT links, made test runs using the BIPM standard software for the calculation of UTC, now including SDR TWSTFT data, and started to calculate SDR TWSTFT time links as backup from October 2017. The use of SDR TWSTFT in UTC generation will begin in 2018.
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| 3. |
- Yao, Y., et al.
(författare)
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Numerical study on fire behavior and temperature distribution in a blind roadway with different sealing situations
- 2023
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media Deutschland GmbH. - 0944-1344 .- 1614-7499. ; 30, s. 36967-36978
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Tidskriftsartikel (refereegranskat)abstract
- Blind roadways have only one portal which connects with other types of mine roadways. Sealing the fire area in a blind roadway is an effective method of disaster relief in a mine. To understand the effect of sealing ratio and sealing distance on fire behavior, Fire Dynamics Simulator (FDS 6.6) was used to study blind roadway fires with different fire scenarios. Results indicate that the smoke flow velocity increases significantly with the increase of sealing distance. The fire in the blind roadway is ventilation-controlled. When the sealing ratio reaches 80%, the fire self-extinguishes completely. Otherwise, the fire experiences an extinguishing-reburning cycle periodically. Besides, an empirical model is proposed to predict the downstream temperature distribution beneath the ceiling in the region from fire source to sealing position. The predictions by the proposed model comply well with the simulation and experimental results from our and others’ studies. This study provides new insights into the sealing strategies in blind roadway fires, and the outcomes of the current study are of guiding significance for the fire rescue in the blind roadways or similar structures. © 2022, The Author(s)
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