325,482 research outputs found
Coupling chemical looping air separation with the Allam cycle – A thermodynamic analysis
No full textThe Allam cycle is a class of oxy-fuel combustion power cycles using supercritical CO2 (s-CO2) as the thermal fluid to achieve power generation with inherent capture of CO2. Compared to other conventional CO2 capture techniques, the Allam cycle stands out owing to its high fuel-to-electricity conversion efficiency (55–59%), the elimination of the Rankine cycle and reduced physical footprint. A key source of energy penalty of Allam cycle comes from the air separation unit (ASU), which supplies pure oxygen via an energy intensive cryogenic process. This paper presents a thermodynamic analysis of a novel supercritical CO2-based power generation scheme, in which a natural gas fuelled Allam cycle is integrated with a chemical looping air separation (CLAS) system, which supplies oxygen to the combustor. The modelling results show that the Allam-chemical looping air separation (Allam-CLAS) process can achieve 56.04% net electrical efficiency with a 100% CO2 capture rate, when a Co3O4-based oxygen carrier is used. This is 6% higher than the Allam cycle coupled to a cryogenic ASU. The exergetic efficiency of the Allam-CLAS system driven by the Co3O4-CoO redox cycle is 57.13%, also more favourable than a conventional Allam-ASU system (with reported exergetic efficiency of 53.4%). This newly proposed Allam-CLAS power cycle presents a highly efficient, and simple solution to generate zero-carbon electricity from natural gas.Nanyang Technological UniversityThe authors wish to acknowledge financial support by Nanyang Technological University
Transeius audeae Kreiter, Allam & Tixier, new species
No full textTranseius audeae Kreiter, Allam & Tixier, new species Specimens examined: Holotype: female, at Meknès on Vitis vinifera. June, 16, 2001. Deposited in the Montpellier SupAgro—INRA Acarology collection. Description of the adult female (n = 1) (Figs 17–21) Diagnosis. Dorsal shield smooth with anterolateral striae. All setae smooth. Measurements of the following setae different from other species of the genus Transeius: s 4 = 55, S 2 = 50 and Z 5 = 78. Peritremes extend to j 1. Sternal shield with three pairs of setae, posterior margin slightly concave. Ventri-anal shield striated and squareshaped. Three pairs of pre-anal setae and a pair of round pores. Calyx of spermatheca pocular tubular. Fixed digit of chelicera with two teeth; movable unidentate. Genu II with eight setae. Three macrosetae on leg IV (Ge IV 47, tibia, STI IV 35 and basitarsus, ST IV 70). Dorsum (Fig. 17) . Dorsal shield mostly smooth with anterolateral striae, with six solenostomes (gd 1, gd 2, gd 4, gd 6, gd 8 and gd 9) and eight poroids, 385 long and 200 wide, 17 pairs of dorsal setae and two pairs of sub-lateral setae: j 1 25, j 3 43, j 4 10, j 5 10, j 6 10, J 2 10, J 5 10, z 2 30, z 4 40, z 5 5, Z 1 13, Z 4 63, Z 5 78, s 4 55, S 2 50, S 4 12, S 5 12, r 3 34, R 1 22. All setae smooth. Peritreme extending to j 1 (Fig. 17). Venter (Fig. 18) . Sternal and genital shields smooth, ventri-anal shield reticulated. Sternal shield with three pairs of setae and two pairs of lyrifissures; one pair of sternal setae on small metasternal plate and with a pair of lyrifissures; posterior margin slightly concave. Distances between ST 1 – ST 3 63, ST 2 – ST 2 72, ST 5 –ST 5 72. Two pairs of metapodal plates 25 long, 6 wide for the largest and 18 long and 2 wide for the smallest. Ventri-anal shield with three pairs of pre-anal setae, JV 1, JV 2, and ZV 2, and one pair pre-anal pores present. Membrane surrounding ventri-anal shield with four pairs of setae ZV 1, ZV 3, JV 4 and JV 5; square ventri-anal shield 118 long, 100 wide at anterior corners, and 100 wide at level of anus. JV 5 67. A pair of lyrifissures near JV 5. Legs (Fig. 19) . Leg IV with three macrosetae on genu, Ge IV 47, tibia, STI IV 35 and basitarsus, ST IV 70. Length of leg I: 340, II: 250, III: 250, IV: 355. Chaetotactic formula of Ge II: eight setae; 1 2 / 1, 2 / 1 1 and Ge III: seven setae, 1 2 / 2, 2 /0 1. Chelicera (Fig. 20) . Fixed digit 37 long with two teeth; and movable digit 34 long with one tooth. Pilus dentilis visible. Spermatheca (Fig. 21) . Pocular tubular (Denmark et al., 1999), with a cervix elongate 20 long and 6 wide, with a neck at the basis of the cervix and visible minor and major ducts. Remarks. Transeius audeae ressemble to T. fragilis (Kolodochka & Bodarenko) but S 2 length is 36 µm for this latter species and 50 µm in T. audeae. The shapes of the spermatheca and of the ventri-anal shield are also totally different. It also resembles T. soniae Zannou, Moraes & Oliveira but differs largely in the length of s 4, S 2, Z 5 (T. soniae: s 4 = 90, S 2 = 63, Z 5 = 99; T. audeae: s 4 = 55, S 2 = 50 and Z 5 = 78) and in the shape of the spermatheca and ventri-anal shield. It also looks like T. sosninae (Wainstein) but differs in the length of S 2 (32 in T. sosninae and 50 in T. audeae), and the shapes of spermatheca and ventri-anal shields are totally different. It finally resembles to T. avetianae (Arutunjan & Ohandjanian) which is the closest species but again measurements of s 4, S 2 and Z 5 are very different (T. avetianae: s 4 = 63, S 2 = 60, Z 5 = 85; T. audeae: s 4 = 55, S 2 = 50 and Z 5 = 78). Furthermore, shapes of spermatheca and ventri-anal shield are very different and pores are more close to JV 2 (so more central than lateral) in T. avetianae than in the new species. This species was so different and was found in a so specific location and on a specific plant without any other Transeius species that it was decided to describe it, despite the fact that we have only one female. It cannot constitute a variant of an already known and described species. Etymology. The name “ audeae ” refers to the daughter of Serge Kreiter, Aude Kreiter.Published as part of Tixier, Marie-Stephane, Allam, Latifa, Douin, Martial & Kreiter, Serge, 2016, Phytoseiidae (Acari: Mesostigmata) of Morocco: new records, descriptions of five new species, re-descriptions of two species, and key for identification, pp. 501-551 in Zootaxa 4067 (5) on pages 532-533, DOI: 10.11646/zootaxa.4067.5.1, http://zenodo.org/record/27063
Analyzing cell-to-cell heterogeneities and cell configurations in parallel-connected battery modules using physics-based modeling
No full textIn parallel-connected cells, cell-to-cell (CtC) heterogeneities can lead to current and thermal gradients that may adversely impact the battery performance and aging. Sources of CtC heterogeneity include manufacturing process tolerances, poor module configurations, and inadequate thermal management. Understanding which CtC heterogeneity sources most significantly impact battery performance is crucial, as it can provide valuable insights. In this study, we use an experimentally validated electrochemical battery model to simulate hundreds of battery configurations, each consisting of four cells in parallel. We conduct a statistical analysis to evaluate the relative importance of key cell-level parameters, interconnection resistance, cell spacing, and location on performance and aging. The analysis reveals that heterogeneities in electrode active material volume fractions primarily impact module capacity, energy, and cell current, leading to substantial thermal gradients. However, to fully capture the output behavior, interconnection resistance, state of charge gradients and the effect of the temperature on parameter values must also be considered. Additionally, module design configurations, particularly cell location, exacerbate thermal gradients, accelerating long-term module degradation. This study also offers insights into optimizing cell arrangement during module design to reduce thermal gradients and enhance overall battery performance and longevity. Simulation results with four cells indicate a reduction of 51.8% in thermal gradients, leading to a 5.2% decrease in long-term energy loss
Thermodynamic analysis of the Allam cycle and its pressure sensitivity
No full textThe Allam cycle is a novel system which operates the oxy-combustor at a high pressure under supercritical conditions, uses a single gas turbine, circulates carbon dioxide as the working fluid in a semiclosed-loop and utilizes low-pressure-ratio recuperated Brayton cycle. These properties of the Allam Cycle enable to reach high efficiencies. This system was simulated using Chemcad software for a methane feed flow rate of 1 kmol/s. The pressure at the inlet of turbine was taken as 285 bar. The net power generation rate was estimated considering the generation in the turbine and the usage in the compressors for circulating carbon dioxide and for oxygen and natural gas feeds. The calculations using energy balance for the process gave 388 MW net power output, whilst Chemcad software gave 392 MW. The thermal energy recovered by lowering the temperature of the flue gas before condensing its water content was also considered in the overall efficiency of the system. The net power cycle efficiency was determined as 48.89%. The second law analysis of the cycle was also made. Entropy generation rate, S-gen, was determined as 965.79 kW/K and exergy destroyed, psi(destroyed), was found as 287.81 MW from entropy balance for the process. The exergy balance for the process was also made and the results were compared with the findings from the entropy balance. The second law efficiency of the process was found as 62.54%
Developmental defects of enamel in childhood cancer survivors: A systematic review and meta-analysis.
No full textAIM
The present systematic review and meta-analysis (Prospero registration number: CRD42023472016) aims to assess the prevalence of developmental defects of enamel (DDEs), qualitatively and/or quantitatively, in childhood cancer survivors (CCS) and evaluate, when possible, these data in comparison with those found in healthy children.
METHODS
Three electronic databases (PubMed, Embase, Scopus) were searched from January 2003 to January 2024 for studies reporting on DDEs in children with a mean age not exceeding 16 years at the time of the study who underwent antineoplastic therapy. The ROBINS-I and the Joanna Briggs Institute (JBI) tools were used to assess the risk of bias. Included studies with comparable outcomes underwent random effects models meta-analysis using Stata®18.
CONCLUSION
CCS showed a higher prevalence of DDEs, both qualitative and quantitative, compared to healthy children. The meta- analysis showed higher odds of developing qualitative defects over quantitative defects in CCS. Conclusions regarding the association between the type of therapy administered, age of therapy initiation, and prevalence of DDEs could not be drawn due to insufficient data. A lack of a standardized method of detecting enamel defects posed a challenge in the qualitative and quantitative analysis
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Potential Role of Fertilizer Sources and Soil Tillage Practices to Mitigate Soil CO2 Emissions in Mediterranean Potato Production Systems
No full textAgricultural practices should be approached with environmental-friendly strategies, able to restore soil organic matter and reduce the greenhouse gas emissions. The main objective of this study is to evaluate the environmental benefits, in terms of CO2 emissions and carbon balance, of some agricultural practices for potato cultivation. A randomized complete block design was adopted where the treatments were: (a) tillage systems (plowing; subsoiler and spading); (b) fertilizer sources (mineral and organic). All treatments were replicated three times. Potato yield and its carbon content, soil CO2 emissions, temperature, and volumetric water content were measured. The CO2 emissions were higher in organic than in mineral fertilizer (0.60 and vs. 0.77 g m−2 h−1, respectively), while they were low in spading compared to the other soil tillage (0.64 vs. 0.72 g m−2 h−1, respectively). Carbon input was the highest in plowing and organic fertilizer 4.76 and 5.59 Mg C ha−1, respectively. The input/output ratio of carbon varied according to the main treatments. The findings suggest that spading tillage and organic fertilizer might result in environmental and agronomical benefits, further research should be performed to evaluate to possibility to extend the results to other environments and crops
Interactive sections of an internet-based intervention increase patient empowerment: a randomized controlled study with chronic back pain patients
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