Thermodynamic analysis of a novel fossil-fuel–free energy storage system with a trans-critical carbon dioxide cycle and heat pump

This paper presents and analyzes a novel fossil-fuel–free trans-critical energy storage system that uses CO2 as the working fluid in a closed loop shuttled between two saline aquifers or caverns at different depths: one a low-pressure reservoir and the other a high-pressure reservoir. Thermal energy storage and a heat pump are adopted to eliminate the need for external natural gas for heating the CO2 entering the energy recovery turbines. We carefully analyze the energy storage and recovery processes to reveal the actual efficiency of the system. We also highlight thermodynamic and sensitivity analyses of the performance of this fossil-fuel–free trans-critical energy storage system based on a steady-state mathematical method. It is found that the fossil-fuel–free trans-critical CO2 energy storage system has good comprehensive thermodynamic performance. The exergy efficiency, round-trip efficiency, and energy storage efficiency are 67.89%, 66%, and 58.41%, and the energy generated of per unit storage volume is 2.12 kW·h/m3, and the main contribution to exergy destruction is the turbine reheater, from which we can quantify how performance can be improved. Moreover, with a higher energy storage and recovery pressure and lower pressure in the low-pressure reservoir, this novel system shows promising performance

Synergy of flocculation and flotation for microalgae harvesting using aluminium electrolysis

Microalgae are often used as feedstock for renewable biofuel production and as pollutant up-takers for wastewater treatment; however, biomass harvesting still remains a challenge in field applications. In this study, electro-flocculation using aluminium electrolysis was tested as a method to collect Chlorella vulgaris. The electrolysis products were positively charged over a wide pH range below 9.5, which gave them a flocculation potential for negatively charged microalgae. As flocculants were in-situ generated and gradually released, microalgae flocs formed in a snowballing mode, resulting in the compaction of large flocs. When higher current density was applied, microalgae could be harvested more rapidly, although there was a trade-off between a higher energy use and more residual aluminium in the culture medium. Benefits of this flocculation method are two-fold: the phosphate decrease in post-harvesting could improve nutrient removal in microalgae based wastewater treatment, while the ammonium increase may favor microalgae recovery for medium recycling

Planar model system of the Phillips (Cr/SiO₂) catalyst based on a well-defined thin silicate film

The Phillips catalyst (Cr/SiO2) is successfully used in the large-scale production of polyethylene and has attracted a great interest in catalytic community over the last sixty years. However, the atomic structure of the active site(s) and the reaction mechanism remain controversial, in particular due to the structural complexity and surface heterogeneity of the amorphous silica. In this work, we used a well-defined, atomically flat silicate bilayer film grown on Ru(0001) as a support offering the opportunity to investigate mechanistic aspects at the atomic scale. To fabricate a planar Cr/SiO2 model system suitable for surface science studies, chromium was deposited using physical vapor deposition onto the hydroxylated silica film surface. Structural characterization and adsorption studies were performed by infrared reflection absorption spectroscopy (IRAS) and temperature programmed desorption (TPD). Hydroxyls groups seem to serve as anchoring cites to Cr ad-atoms. As monitored by IRAS, hydroxyls consumption correlated with the appearance of the new band at ~1007 cm-1 typical for Cr=O vibrations. In addition, CO titration experiments suggested also the presence of "naked" Cr, which transforms into mono- and di-oxo chromyl species and their aggregation upon oxidation treatments. TPD experiments of ethylene adsorption at low temperatures under UHV conditions showed the formation of butane as one of the main products. The resultant surfaces are thermally stable, at least, up to 400 K which allows to investigate ethylene polymerization further under more realistic conditions

Ferromagnetism in 2p Light Element-Doped II-oxide and III-nitride Semiconductors

II-oxide and III-nitride semiconductors doped by nonmagnetic 2p light elements are investigated as potential dilute magnetic semiconductors (DMS). Based on our first-principle calculations, nitrogen doped ZnO, carbon doped ZnO, and carbon doped AlN are predicted to be ferromagnetic. The ferromagnetism of such DMS materials can be attributed to a p-d exchange-like p-p coupling interaction which is derived from the similar symmetry and wave function between the impurity (p-like t_2) and valence (p) states. We also propose a co-doping mechanism, using beryllium and nitrogen as dopants in ZnO, to enhance the ferromagnetic coupling and to increase the solubility and activity

From Traditional to Modern : Domain Adaptation for Action Classification in Short Social Video Clips

Short internet video clips like vines present a significantly wild distribution compared to traditional video datasets. In this paper, we focus on the problem of unsupervised action classification in wild vines using traditional labeled datasets. To this end, we use a data augmentation based simple domain adaptation strategy. We utilise semantic word2vec space as a common subspace to embed video features from both, labeled source domain and unlablled target domain. Our method incrementally augments the labeled source with target samples and iteratively modifies the embedding function to bring the source and target distributions together. Additionally, we utilise a multi-modal representation that incorporates noisy semantic information available in form of hash-tags. We show the effectiveness of this simple adaptation technique on a test set of vines and achieve notable improvements in performance.Comment: 9 pages, GCPR, 201

Characteristic Aroma Compounds in Two New Vitis vinifera Cultivars (Table Grapes) and Impact of Vintage and Greenhouse Cultivation

‘Zaoheibao’ (a red tetraploid hybrid) and ‘Wuhecuibao’ (a white triploid hybrid) grapes have beenobtained from Guibao♀ (diploid, Vitis vinifera) × Zaomeigui♂ (diploid, V. vinifera) and Guibao♀ (diploid,V. vinifera) × Wuhebaijixin♂ (triploid, V. vinifera) respectively. Aroma characterisation of the twonew table grape cultivars was firstly done by the investigation of volatile compounds. The influence ofgreenhouse cultivation and vintage on berry aroma was studied as well. The results showed that linalool,decanal, β-damascenone, hexanal and (E)-2-hexenal were the main volatile compounds of the two cultivars,which meant that the floral, fruity and sweet odour were prominent, followed by the herbaceous aroma.Greenhouse cultivation enhanced herbaceous odour in both ‘Wuhecuibao’ and ‘Zaoheibao’ berries,and reduced the floral aroma, contributed mainly by β-damascenone, in ‘Wuhecuibao’, and the sweetaroma, represented mainly by linalool, in ‘Zaoheibao’. The concentrations of the main aroma compoundswere greatly affected by vintage and the intensity of sensorial perception was correspondingly changed,but varietal odour attributes were not significantly altered. These results will not only help promote thecultivation and popularisation of these cultivars, but also will provide valuable data for the use of thesecultivars in future breeding

Polymorphisms of the CAST gene in the Meishan and five other pig populations in China

The aim of the study was to characterize the polymorphism of the Calpastatin (CAST) gene identified with three restriction enzymes (TaqI, HinfI, MspI) in Meishan and five other pig populations, and to provide information on their potential in marker-assisted selection and conservation. Meishan pigs appeared to be monomorphic at loci CAST/HinfI and CAST/MspI. A high frequency of the favoured genotype, FF, in terms of meat quality was detected in Meishan pigs, a breed well known for high quality meat. However, the frequency of the genotype, FF, was very low in Sutai pigs, a breed developed from a Duroc (50%) × Meishan (50%) cross. This is probably partially due to the fact that genetic improvement in this breed was achieved through the use of traditional quantitative genetics. It is suggested that traditional selection techniques combined with the use of the polymorphisms discovered have an important potential to improve overall meat quality. Keywords: Polymorphism, CAST, Meishan, Sutai South African Journal of Animal Science Vol. 37 (1) 2007: pp. 27-3