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Fabrication and Investigation of Novel Cu2O-doped CaCO3 Composites-based Thermochemical Energy Storage System for Concentrating Solar Power Application
Full text linkThe limited solar energy absorption capacity of CaCO3 hinders its efficacy in thermochemical energy storage (TCES) systems for concentrated solar power (CSP) facilities. This study aims to tackle this problem by introducing Cu2O as a dopant in CaCO3. Cu2O possesses a bandgap that is more conducive to solar absorption. This study examines the structural, optical, and thermal characteristics of CaCO3 doped with Cu2O to improve its effectiveness in TCES applications. Therefore, the current study investigates the sunlight absorption of CaCO3 material after doping Cu2O. Cu2O in CaCO3 is doped and its UV, FTIR, and XRD characteristics are analyzed. Furthermore, non-isothermal and isothermal calcination was conducted to determine the kinetics and lower the calcination temperature limit. The results reveal that Cu2O introduced no new phase in CaCO3, and XRD data confirmed it. UV data reveals that the Cu2O-doped CaCO3 has a bandgap of 5.01 eV, while pure CaCO3 has a bandgap of 5.30 eV. According to the kinetic analysis, Cu2O-doped CaCO3 follows the three-dimensional diffusion (D3) model. Its activation energy is 644.3 kJ/mol, while pure CaCO3 follows the D1 model, and its activation energy is calculated as 234.8 kJ/mol. The lowest calcination temperature limit for pure and Cu2O-doped CaCO3 samples is 750°C. Hence, the proposed material is recommended for use in thermal energy storage applications
Fractional Inequalities for Exponentially s-Convex Functions on Time Scales
Full text linkIn this paper, we present new integral inequalities involving exponentially s-convex functions in the second sense on time scales. By utilizing the delta Riemann-Liouville fractional integral and the fractional Taylor formula, we establish upper bounds for functions that are n-times rd-continuously Δ-differentiable with exponentially s-convex properties. Our results provide novel insights into the theory of time scales, bridging the gap between discrete and continuous calculus. The application of fractional calculus on time scales is explored, and several well-known inequalities are employed to derive the main findings. These results have potential implications for further studies in fractional dynamic calculus and other related fields.
AMS Subject Classification: 39A10, 39A11, 39A20
Sign-changing Solutions for Fourth Order Elliptic Equation with Concave-convex Nonlinearities
Full text linkIn this paper, we study the following fourth order elliptic equation:
Δ²u - Δu + V(x)u = κ(x)|u|q-2u + |u|p-2u in RN,
where Δ² := Δ(Δ) is the biharmonic operator, 4 > N, 1 < q < 2 < p < 2* := 2N / (N - 4). Assuming that V(x) satisfies a class of coercive conditions and the nonnegative weighted function κ(x) belongs to Lp / (p-q)(RN), we obtain the existence of one sign-changing solution with the help of constraint variational method and quantitative deformation lemma.
The novelty of this paper is that when the nonlinearity is the combination of concave and convex functions, we are able to obtain the existence of sign-changing solutions. Some recent results are improved and generalized significantly
A Study of an EOQ Model of Deteriorated Items with Pentagonal Dense Fuzzy Demand Rate
Full text linkIn this project work, we deal with an economic order quantity inventory model of deteriorating items under non-random uncertain demand. Here we consider the customers screen the fresh items during the selling period. After a certain period of time, the deteriorated items are sold at a discounted price. Firstly, we solve the crisp model, and then the model is converted into a fuzzy environment. Here we consider the pentagonal dense fuzzy, trapezoidal dense fuzzy, and triangular dense fuzzy for a comparative study. We have taken the numerical result using LINGO 18.0 software. Finally, sensitivity analysis and graphical illustration have been given to check the validity of the model
Distribution and Density of Common Woodpigeon (Columba palumbus) in Central Northern Bulgaria
Full text linkThe breeding density of the Woodpigeon was determined in square LH75 in the period from March to May 2023. For this purpose, a point counting method was used, and in addition, some characteristics of the habitats were taken into account. The breeding density of Woodpigeon in the present study was 16.42, 12.75 and 14.44 pairs/100ha, in March, April and May 2023 year, respectively. Breeding density decreases from March to May. Anova analysis showed statistically significant differences in the mean number of song pigeons by habitat and cropland types (F=8.11, p=0.005). The number of song Woodpigeons was significantly greater in open habitats with single large trees or small groups of large trees among grassland and meadows than in other breeding habitat types. Their number is relatively high in Silver lime forests, coniferous plantations, and in the fringe strip of all forest habitats. The number of song pigeons is also relatively high in cases where we have a lack of arable land in the fixed radius or in the presence of wheat. Their number in the fixed radius increased with increasing average tree height. The number of singing pigeons is positively correlated with tree height (R=0.49, F=2.132, p<0.0001). The latest data on the breeding density of the Woodpigeon are from the end of the last century in Bulgaria. This study presents first results on the breeding distribution and density of the species in an information-poor area
Enhancing Fruit Tree Yield Prediction with an Optimized Grey Neural Network Model Using the Fruit Fly Algorithm
Full text linkThis article first integrates data on fruit tree yield and related influencing factors in Fujian Province, covering two major categories of factors: social and natural. On this basis, this article calculated the correlation coefficients between fruit tree yield and various factors, verifying the rationality of indicator selection. Subsequently, this article used a combination of grey model GM (1,1), BP neural network model, and fruit fly algorithm to optimize the grey model and neural network for fruit tree yield prediction. In the end, based on the research results, it was found that the combination model of fruit fly algorithm optimized grey model and neural network has a better prediction effect on fruit tree yield, which is more suitable for us to deeply understand the changes in fruit tree yield. It can also be well trained for relatively random natural factors
Comparison Study of Cascaded Organic Rankine Cycles with Single and Dual Working Fluids for Waste Heat Recovery
Full text linkThis study compares thermodynamics, economics, and environmental performance of cascaded ORCs operated under a single and dual fluids. In the single fluid cascaded ORC, toluene, benzene, acetone and cyclopentane are run in high and low temperature cycles, whereas in dual fluid cascaded ORC, toluene, benzene, acetone and cyclopentane are run in high temperature cycle and R601a in the low temperature cycle. The analysis compares variations in expander inlet temperature and condensation temperature. Thermodynamic performance involved net power output (Pnet) and thermal efficiency (ηth), while economic indicators included net present value (NPV) and levelized cost of electricity (LCOE). In environmental performance, the annual reduction in carbon dioxide emission (CO2-eq) is assessed. The findings revealed that dual fluid cascaded ORC generated the highest Pnet of 1245.11 kW while single fluid cascaded ORC reached 1170.27 kW. The dual fluid cascaded ORC showed the significant increase in Pnet (%DPnet) for about 43% at the lowest expander inlet temperature (500 K). In terms of ηth, dual fluid cascaded ORC attained 37.23 % while single fluid cascaded ORC reached 33.25%. It is further found that acetone+R601a performed well in dual fluid cascaded ORC, resulting in the highest Pnet and allowing system’s NPV to turn positive sooner than other fluids. Furthermore, cyclopentane+R601a had the lowest LCOE of 0.0158 US$/kWh, which is 1.1% lower compared to the single fluid cascaded ORC and competitive in the Thai electricity market. In environmental saving, dual fluid cascaded ORC reduced about 144.96 tCO2-eq/year, and outperformed single fluid cascaded ORC by roughly 6.39%
Effects of Prototype Hydroxylated Water Treatment on Sanitizing Wastewater Spiked with Bacillus subtilis Spores
Full text linkA wastewater treatment study evaluated the effects of a prototype hydroxylated water treatment on water spiked with Bacillus subtilis spores. The study objectives were to determine the impact of water exposure time and humic acid water treatments on spore inactivation rates. This factorial study included seven water sample collection times and three humic acid concentrations with 21 water treatments. The prototype hydroxylated water treatment system reduced viable B. subtilis spore by 2.47 log10 after a 12-minute exposure without any quenching agents in the water. The average B. subtilis spore concentration for the control water samples was 4.86 x 105 CFU/ml. Adding humic acid at 0.5% (v/v) as a quenching agent reduced spore inactivation from 3 to 1 log10. Also, adding humic acid as a quenching agent reduced oxidation-reduction potential (ORP) from 600 to about 250 mV. Wastewater treatments based on hydroxylated water technologies can sanitize bio-contaminated water if the water is first filtered to remove most organic contaminants. Alternatively, hydroxylated water treatments should use extended water exposure times, beyond 12 minutes, to minimize the quenching effects of the organic matter in wastewater
Integrated Surveillance and Reservoir Characterization Evaluation for Preliminary Water Injection Optimization Strategy of Carbonate Reservoir
Full text linkThe RS field is a green oil field that is in development stage with a carbonate reservoir as the interest zone. A Zone is one of the reservoir zones of the field with the highest oil reserve and has been produced since October 2019. A water injection program has been applied through one injection well since November 2020. The significant pressure decline is an indicator that the injection program in A Zone is not optimum in maintaining the reservoir pressure. There is no dynamic model for reservoir performance forecasting. Therefore, a further detail and comprehensive analysis through monitoring surveillance and reservoir characterization is required. The objective is to optimize the pressure maintenance program and to increase the oil recovery of A Zone in RS field. This study consists of three steps of analysis: the evaluation of existing water injection (pressure maintenance) surveillance; reservoir characterization evaluation; and 1-D reservoir simulation study. Surveillance analysis includes production and injection performance analysis; pressure performance analysis; voidage replacement ratio (VRR) analysis; Hall’s Plot analysis and Chan’s Diagnostic Plot analysis. Reservoir characterization evaluation includes remaining reserve evaluation; drive mechanism analysis; reservoir displacement profile phase based on fractional flow analysis (Buckley-Leverett); quality and reservoir heterogeneity; and reservoir pressure condition analysis. Material balance modelling is used as an initial simulation for optimization of injection wells and production performance prediction. Based on production prediction model material balance, if produced with VRR = 1, until the end of the contract (October 2039), the A Zone reservoir is capable of producing oil with a flow rate of 3038.36 BOPD; capable of maintaining reservoir pressure up to 1679.28 psig; water cut reservoir reached 77.82%; and cumulative oil production is 31.14MMSTB or equivalent to 12.50% of recovery factor
Designing an Inclusive City with Chrono-Urbanism Principles
Full text linkA study was conducted in Tallasa District, the newly developing district in Makassar, Indonesia, to examine all public facilities accessible in the Chrono-Urbanism timeframe and promote social inclusion and equal participation. The study found that while the concept may not be sustainable in the long term, potential development could be achieved through adjustments in spatial planning connections and involving a wide range of age groups in neighborhood designs. The study used the principles of proximity, diversity, density, and digitalization to analyze the concept. The results showed that only the diversity criteria almost met the accessibility and inclusiveness aspects. Applying the Chrono-Urbanism theory may encounter difficulties in regions with large populations and distinctive geographical features such as Indonesia's archipelago. Diverse demographic characteristics, various transportation needs between different areas, and differences in economic and educational strata pose specific challenges. The complexities in managing urban spaces and ensuring proximity and accessibility become more pronounced in densely populated areas and require considerations to accommodate the unique circumstances of each region like Tallasa District in Makassar