| 1081. |
- Sun, Q., et al.
(författare)
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Selection of appropriate biogas upgrading technology-a review of biogas cleaning, upgrading and utilisation
- 2015
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 51, s. 521-532
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Tidskriftsartikel (refereegranskat)abstract
- Biogas is experiencing a period of rapid development and biogas upgrading is attracting increasing attention. Consequently, the market for biogas upgrading is facing significant challenges in terms of energy consumption and operating costs. Selection of upgrading technology is site-specific, case-sensitive and dependent on the biogas utilisation requirements and local circumstances. Therefore, matching the technology selected for use to specific requirements is significantly important. This paper systematically reviews the state-of-the-art of biogas cleaning and upgrading technologies, including product purity and impurities, methane recovery and loss, upgrading efficiency and the investment and operating costs. In addition, the potential utilisation of biogas and the corresponding requirements on gas quality are investigated in depth. Based on the results of comparisons between the technical features of upgrading technologies, the specific requirements for different gas utilizations and the relevant investment and operating costs, recommendations are made regarding appropriate technology. CO2
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| 1082. |
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| 1083. |
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| 1084. |
- Sun, T., et al.
(författare)
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Spatial reuse based resource allocation in device-to-device communications
- 2016
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Ingår i: Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering. - Cham : Springer International Publishing. - 1867-8211 .- 1867-822X. - 9783319470627 ; 169, s. 131-143
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Konferensbidrag (refereegranskat)abstract
- Device-to-Device (D2D) communications have attracted more concern recently, since it provides a supplemental paradigm of short range communications for the current cellular networks. In D2D communications information bits are directly transmitted between devices without traversing base station (BS). As a result, D2D communications can potentially facilitate the improvement of the network capacity, extension of the network coverage, enhancement of the spectrum efficiency, and the energy efficiency as well. It also works well for couple of new applications, such as information exchange between devices in Internet of Things (IoT) and low delay video content sharing. From the perspective of resource allocation in D2D communications, multiple D2D users (DUs) may reuse the same resource of cellular users (CUs). Thus, we put our focus on the spatial reuse resource allocation in this paper. We formulate the spatial reuse problem which aims to maximize the system throughput while maintaining the desirable signal-noise-interference-ratio (SINR) at receivers. Accordingly, a greedy based user set selection algorithm is proposed to filter the candidate DU set to further reduce the computation complexity. Simulation results show that the cellular network can achieve a higher throughput by using our proposed scheme.
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| 1085. |
- Sun, Vivian Z., et al.
(författare)
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Overview and Results From the Mars 2020 Perseverance Rover's First Science Campaign on the Jezero Crater Floor
- 2023
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Ingår i: Journal of Geophysical Research: Planets. - : John Wiley and Sons Inc. - 2169-9097 .- 2169-9100. ; 128:6
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Tidskriftsartikel (refereegranskat)abstract
- The Mars 2020 Perseverance rover landed in Jezero crater on 18 February 2021. After a 100-sol period of commissioning and the Ingenuity Helicopter technology demonstration, Perseverance began its first science campaign to explore the enigmatic Jezero crater floor, whose igneous or sedimentary origins have been much debated in the scientific community. This paper describes the campaign plan developed to explore the crater floor's Máaz and Séítah formations and summarizes the results of the campaign between sols 100–379. By the end of the campaign, Perseverance had traversed more than 5 km, created seven abrasion patches, and sealed nine samples and a witness tube. Analysis of remote and proximity science observations show that the Máaz and Séítah formations are igneous in origin and composed of five and two geologic members, respectively. The Séítah formation represents the olivine-rich cumulate formed from differentiation of a slowly cooling melt or magma body, and the Máaz formation likely represents a separate series of lava flows emplaced after Séítah. The Máaz and Séítah rocks also preserve evidence of multiple episodes of aqueous alteration in secondary minerals like carbonate, Fe/Mg phyllosilicates, sulfates, and perchlorate, and surficial coatings. Post-emplacement processes tilted the rocks near the Máaz-Séítah contact and substantial erosion modified the crater floor rocks to their present-day expressions. Results from this crater floor campaign, including those obtained upon return of the collected samples, will help to build the geologic history of events that occurred in Jezero crater and provide time constraints on the formation of the Jezero delta.
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| 1086. |
- Sun, W. J., et al.
(författare)
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A Comparative Study of the Proton Properties of Magnetospheric Substorms at Earth and Mercury in the Near Magnetotail
- 2018
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Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 45:16, s. 7933-7941
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Tidskriftsartikel (refereegranskat)abstract
- The variations of plasma sheet proton properties during magnetospheric substorms at Earth and Mercury are comparatively studied. This study utilizes kappa distributions to interpret proton properties at both planets. Proton number densities are found to be around an order of magnitude higher, temperatures several times smaller, and kappa values broader at Mercury than at Earth. Protons become denser and cooler during the growth phase, and are depleted and heated after the dipolarizations in both magnetospheres. The changes of kappa at Earth are generally small (<20%), indicating that spectrum-preserving processes, like adiabatic betatron acceleration, play an important role there, while variations of kappa at Mercury are large (>60%), indicating the importance of spectrum-altering processes there, such as acceleration due to nonadiabatic cross-tail particle motions and wave-particle interactions. This comparative study reveals important intrinsic properties on the energization of protons in both magnetospheres. Plain Language Summary Earth and Mercury are the only two planets possessing global intrinsic magnetic fields among the four inner planets, which are Mercury, Venus, Earth, and Mars, within the solar system. The interactions between the intrinsic magnetic fields and the continual flow of high-speed solar wind from the Sun form similar magnetospheres at the two planets, although the scale of the magnetosphere is much smaller at Mercury than at Earth. Magnetospheric substorms, a result of solar wind-magnetosphere coupling, occur in both magnetospheres. Comparative study of a similar process between different planets is meaningful as it can help us in understanding the specific process further as well as help us in understanding the intrinsic properties of the magnetospheres. This research paper characterizes the proton properties of magnetospheric substorms of both planets, revealing that different mechanisms control the behavior of protons during the magnetospheric substorms of the two planets.
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| 1087. |
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| 1088. |
- Sun, Y. D., et al.
(författare)
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Perturbations in the carbon cycle during the carnian humid episode : Carbonate carbon isotope records from southwestern China and Northern Oman
- 2018
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Ingår i: Journal of the Geological Society. - : Geological Society of London. - 0016-7649 .- 2041-479X. ; 176:1, s. 167-177
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Tidskriftsartikel (refereegranskat)abstract
- The Carnian Humid Episode is an interval of prominent climatic changes in the Late Triassic. We studied the carbon isotope (δ13C) geochemistry of carbonates from sections in southwestern China and northern Oman. δ13C records from the Yongyue section (western Guizhou, South China) show a progressive positive shift from 1.4 to 2.8‰ in the early to middle Julian 1 substage. This positive trend is followed by a swift negative shift of c. 4.2‰ from 2.8 to −1.4‰ in the Julian 2 substage. δ13C from the Wadi Mayhah section (northern Oman) shows a positive shift from 2.2 to 2.8‰ in the Julian 1 substage, followed by a negative shift of c. 3.2‰ from 2.8 to −0.3‰ in the Julian 2 substage. The δ13C records from the two study sections generally correlate well with each other as well as with published records, pointing to a considerable input of isotopically light carbon starting in the late Julian 1 substage. Such a large amount of light carbon probably derived from direct degassing and the sediment–sill contact metamorphism of the Panthalassan Wrangellia Large Igneous Province and contemporary Tethyan volcanism. The voluminous volcanogenic greenhouse gases probably contributed to the warming pulse in the middle Carnian. Thus the dry–wet climatic transition during the Carnian Humid Episode is best interpreted as a warm climate-driven intensification of the activities of the atmospheric circulation and hydrological cycle.
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| 1089. |
- Sun, Y., et al.
(författare)
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Integrated biomass gasification using the waste heat from hot slags : Control of syngas and polluting gas releases
- 2016
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Ingår i: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 114, s. 165-176
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the thermodynamics of a novel strategy, i.e., biomass/CO2 gasification integrated with heat recovery from hot slags in the steel industry, were systemically investigated. Both the target syngas yield and the polluting gas release were considered where the effect of gasifying conditions including temperature, pressure and CO2 reacted was analyzed and then the roles of hot slags were further clarified. The results indicated that there existed an optimum temperature for the maximization of H2 production. Compared to blast furnace slags, steel slags remarkably increased the CO yield at 600–1400 °C due to the existence of iron oxides and decreased the S-containing gas releases at 400–700 °C, indicating potential desulfurizing ability. The identification of biomass/CO2 gasification thermodynamics in presence of slags could thus provide important clues not only for the deep understanding of biomass gasification but also for the industrial application of this emerging strategy from the viewpoint of syngas optimization and pollution control.
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| 1090. |
- Sun, Y., et al.
(författare)
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Integrating biomass pyrolysis with waste heat recovery from hot slags via extending the C-loops : Product yields and roles of slags
- 2018
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Ingår i: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 149, s. 792-803
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Tidskriftsartikel (refereegranskat)abstract
- The present study characterized a novel route, biomass pyrolysis using the waste heat in high temperature slags via extending the C-loops in the agricultural sector and metallurgy. The equilibrium yields of valuable syngas and biochar were clarified systemically here, in addition to the polluting gases. The results proved that compared to steel slags (SS), blast furnace slags (BFS) only had a limited influence at low temperatures (<700 °C). With respect to SS, there was a transition temperature range in which their roles varied remarkably, i.e., an increase of iron oxide content in SS continuously enhanced the CO yield over 700 °C, whereas a varying basicity mainly affected the pyrolysis results below 700 °C. Regarding the polluting gases, the overall effect of hot slags was quite limited, indicating that no great environmental impacts would be brought in this combined system.
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