Efficient integration of the carbon capture and storage (CCS) process in power generation plants can help reduce global CO
2
emissions. Hydrate technology has emerged as one of the most promising ...technologies for the separation and sequestration of CO
2
. This paper compares the process energy consumption of different CO
2
capture techniques, gas transportation, and sequestration methods integrated into a pre-combustion power plant. Process modeling of a conceptualized hydrate technology-based CCS process is simulated using a coupled TRNSYS simulation software and engineering equation solver. The performance in efficiency, energy consumption, and potential energy penalty is evaluated and analyzed for three study cases. Furthermore, the energy requirement for transporting and sequestrating CO
2
in hydrate as hydrate slurry is evaluated and compared to supercritical transportation and sequestration. The results obtained show that the energy consumption of hydrate-based gas separation amounts to 70 % of the total energy consumption for hydrate-based CO
2
capture, transportation, and sequestration.
ABSTRACTSeabed sediment mapping with acoustical data and ground-truth samples is a growing field in marine science. In recent years, multi-classifier ensemble models have gained prominence for ...classification problems by combining several base classifiers. However, traditional ensemble methods do not consider the confidence scores of base classifiers, leading to suboptimal fusion when there are conflicting predictions. The current study introduces a novel optimization strategy that enhances the ensemble’s accuracy by constructing an ideal ensemble predicted probability matrix based on the fusion of predicted probabilities of the base classifiers, to improve seabed sediment mapping. The proposed approach not only addresses the limitations of traditional ensemble methods but also significantly increases the ensemble’s performance. The proposed approach demonstrates significant accuracy improvements. On the under-sampled dataset, it achieves 73.5% improvement compared to individual classifiers (random forest, decision tree, support vector machine), surpassing their respective accuracies. On the standard dataset, the ensemble model attains an accuracy of 79.1%, surpassing individual classifiers. Employing over-sampling techniques further elevates accuracy to 94.9%, exceeding the individual classifier performances. The proposed method is evaluated on acoustical data obtained from the Irish Sea. The proposed method outperforms base classifiers in terms of accuracy, F1 score, and the Kappa coefficient.
The underwater ancient town of Chunan is of great importance in archaeology and tourism. Hence, the efficient mapping and monitoring of the topographical changes in this town are essential. An ...attractive choice for the efficient mapping of underwater archaeology is the multibeam echo sounder system (MBES). The MBES has several advantages including noncontact survey, high precision, and low cost. In this study, the topographical changes of the ancient town under Qiandao Lake were quantitatively assessed on the basis of time-series MBES data collected in 2002 and 2015. First, the iterative closest point (ICP) algorithm was applied to eliminate the coordinate deviations between two point sets. Second, the robust estimation method was used to analyse the characterisations of the terrain variations of the town on the basis of the differences between the two matched point sets. Obvious topographical changes ranging from −0.89 m to 0.88 m were observed in a number of local areas in the town. On the global scale, the mean absolute value of the depth change in the town was merely 0.12 m, which indicated a weak global deformation pattern. The experiment proved the effectiveness of applying MBES data to analyse the deformation of the ancient town. The results are beneficial to the study of underwater ancient towns and the development of protection strategies.
A vigorous root system in barley promotes water uptake from the soil under water-limited conditions. We investigated three spring barley genotypes with varying water stress responses using rhizoboxes ...at the seedling stage. The genotypes comprised two elite German cultivars, Barke and Scarlett, and a near-isogenic line, NIL 143. The isogenic line harbors the wild allele pyrroline-5-carboxylate synthase1-P5cs1. Root growth in rhizoboxes under reduced water availability conditions caused a significant reduction in total root length, rooting depth, root maximum width, and root length density. On average, root growth was reduced by more than 20% due to water stress. Differences in organ proline concentrations were observed for all genotypes, with shoots grown under water stress exhibiting at least a 30% higher concentration than the roots. Drought induced higher leaf and root proline concentrations in NIL 143 compared with any of the other genotypes. Under reduced water availability conditions, NIL 143 showed less severe symptoms of drought, higher lateral root length, rooting depth, maximum root width, root length density, and convex hull area compared with Barke and Scarlett. Within the same comparison, under water stress, NIL 143 had a higher proportion of lateral roots (+30%), which were also placed at deeper substrate horizons. NIL 143 had a less negative plant water potential and higher relative leaf water content and stomatal conductance compared with the other genotypes under water stress. Under these conditions, this genotype also maintained an enhanced net photosynthetic rate and exhibited considerable fine root growth (diameter class 0.05–0.35 mm). These results show that water stress induces increased shoot and root proline accumulation in the NIL 143 barley genotype at the seedling stage and that this effect is associated with increased lateral root growth.
The classification of seabed sediments is an essential aspect of marine spatial planning and management. Multibeam echo sounders (MBESs) have been widely used for efficient and reliable sediment ...classification. However, feature optimization is a complex and difficult task that requires considerable effort and domain expertise. In addition, selecting the optimal number of features and avoiding redundancy can pose challenges and ultimately lead to suboptimal classification performance. To address these limitations, this paper proposes a new approach to classifying seabed sediments by combining the parametric uniform manifold approximation and projection (PUMAP) feature optimization method with a convolutional neural network (CNN). MBES data are used to generate the main textures and bathymetric features, which are then transmitted via the CNN network. PUMAP is used to construct a representative graph from the extracted features and optimize the graph in a low-dimensional space using the weight of an autoencoder. The proposed approach was tested with MBES data from an Irish Sea survey. The results show that the proposed approach outperforms conventional sediment classification methods, with total accuracy of 97.20%, an F1 score of 97.31%, and a kappa of 0.9638.
In the search for alternatives to wood fuel, to meet the bio-energy requirement of an ever-increasing global population, the International Network for Bamboo and Rattan has supported farmers in many ...tropical countries to establish plantations of Beema bamboo (a tissue-cultured clone from Bambusa vulgaris) and Oxytenanthera abyssinica for bio-energy production. The quality of these species as solid biofuels is unknown due to the absence of data on their physico-thermal and emission characteristics. Using the American Standard for Testing and Materials and other internationally accepted standards, their ultimate and proximate analysis, and physico-thermal and emission properties were evaluated. Beema bamboo and O. abyssinica have high Hydrogen, organic and fixed Carbon contents and low quantities of ash, moisture content, volatile matter, Oxygen, Nitrogen and Sulphur. This will contribute to their heating values and low oxide emissions. Based on their High Heating Values (Beema bamboo = 23.22 MJ/kg; O. abyssinica = 23.26 MJ/kg), the species will be suitable for high energy-using applications. The Particulate Matter and Carbon Monoxide concentrations (Beema bamboo: 90 ug/m3 and 2.83 ppm respectively; O. abyssinica: 77.33 ug/m3 and 3.20 ppm respectively) are lower than the threshold (35000 ug/m3 and 9 ppm respectively) approved by the United States Environmental Protection Agency. These properties make the species good raw materials for solid biofuel which is safe for indoor use. Their use will contribute to reducing pressure on tropical forests for wood fuel and the health hazards associated with fossil fuel use.
The morphological aspects of urban growth on wetlands in Africa are under-researched. Using the Densu Delta Ramsar site in Accra, Ghana, as a case study, this paper analyses the morphological ...patterns and drivers of urban growth and its impact on wetlands. Data were obtained through remote-sensing, ground truthing, and limited key informant interviews. The analysis combined land use/land cover, building coverage and spatial autoregressive and ordinary least square regression techniques with the aid of ArcGIS version 10.8.2, QGIS version 3.34 and STATA version 17 software. The findings reveal that urban growth at the Ramsar site follows discernible spatial patterns consistent with the spreading pancake, village magnet, and ribbon development models. However, the primary force behind these patterns is growing demand for land to meet housing needs, aided by the failure of state institutions to perform their land use control and wetland protection functions. To achieve sustainable urban development, there is an urgent need to ensure effective wetland management by enforcing existing land use, development control, and wetland protection measures. This calls for the strengthening, resourcing, and closer collaboration of the relationships between the various state agencies responsible for urban planning and wetland management. There is also the need to engage and sensitise political leaders to increase their commitment to implementing wetland protection and pro-environmental policies.
Voluntary counselling and testing for Human Immunodeficiency Virus (HIV) and Acquired Immune Deficiency Syndrome (AIDS) has always been one of the key policy interventions in the management and ...control of HIV/AIDS transmission. However, the prevalence of HIV testing among reproductive women in the Gambia remains low despite near universal information about HIV and Sexually Transmitted Infections (STIs) in the Gambia. Understanding factors influencing HIV testing uptake provides empirical data for the development of targeted evidenced-based strategies aimed at enhancing HIV testing uptake. Therefore, this study examined the factors associated with HIV testing among reproductive women aged 15−49 years in the Gambia. Data on weighted sample of 11,865 women from the 2019−2020 Gambia Demographic and Health Survey were analyzed in this study. Chi square, bivariate and multivariate logistic regression models were fitted and analysis conducted through Complex Samples Analysis in Statistical Package for Social Sciences (SPSS). Level of significance was set at p < 0.05 and 95% CI. Further analysis was conducted to determine the variability in HIV testing among women stratified by rural and urban centers. Prevalence of HIV testing among reproductive women was 42.1% (95% CI = 40.1−44.2%) in the Gambia. Women aged 20−24 years and 25−29 years (aOR = 3.10, 95% CI = 2.51−3.83) and (aOR = 4.52, 95% CI = 3.61−5.54) were more likely to test for HIV than those aged 15−19 years, respectively. Married women (aOR = 5.90, 95% CI = 4.84−7.02) were more likely to test for HIV compared to those who were not in any union. Respondents with higher education in urban centers (aOR = 2.65, 95% CI = 2.08−3.86) were likely to test for HIV compared to those in rural areas. HIV testing in the Gambia among reproductive women is low. Age, marital status, wealth index, place of residence, educational level, recent sexual activity, previous history of risky sexual behaviors, and history of an STI were associated with HIV testing. Health interventions targeted at increasing HIV testing uptake should factor in these.
The paper studies the dynamics of a full delay-logistic population model incorporated with a proportionate harvesting function. The study discusses the stability of the model in comparison with the ...well-known Hutchinson logistic growth equation with harvesting function using the rate of harvesting as a bifurcation parameter to determine sustainable harvesting rate even at a bigger time delay of τ=3.00. In all cases, the Hutchinson equation with harvesting was forced to converge to equilibrium using an additional and a different time delay parameter, a deficiency previous researchers have failed to address when the Hutchinson model is used for this purpose. The population fluctuations are catered for with this model making the estimated maximum sustainable growth and harvest reflect realities as this model drastically reduces time-delay associated oscillations compared to the well-known Hutchinson delayed logistic models. The numerical simulations were be done using the MatLab Software.
PDF
