Increment In Efficiency Research Articles

PRECISION LIVESTOCK FARMING TECHOLOGIES AND ITS COST ANALYSIS ON POULTRY PRODUCTION IN OYO METROPOLIS, OYO STATE

This study aimed at investigating the impact of precision livestock farming technologies (PLF) on workforce skills and employability in poultry husbandry sector in Oyo metropolis. A sample of twelve (12) farms was selected through simple random sampling techniques from Atiba, Oyo west, Oyo East and Afijio Local Government Areas was used for the study. A questionnaire instrument developed by the researcher was used for data collection on demographic information, familiarity, training and education, impact on workforce skills and employability, efficiency and productivity and challenges and barriers in adoption of PLF. The findings revealed that mostly male, adults, educated with 5 years of experiences were participated in the study. The farmers were familiars, trained and educated on the uses of PLF periodically and impact PLF was felt of workforce skill with increase in employability of personal that enhanced efficiency and productivity of the poultry sector. However, challenges and barriers were also documented. Meanwhile, the cost of monthly electricity bills, the cost of importing those equipment used in PLF Technologies, cost of repairing equipment, cost of operating equipment and couple with cost of installation of all the equipment were said to be on the higher side and at long run affect the cost of production. Based on the results, the following recommendations were made: the adoption of PLF should be more for increment in workforce skill, employability, efficiency and productivity of poultry products. Government can assist in subsidies of the equipment importation, stable stability of electricity to assist the adoption of PLF technologies in this study area.

Sr3Zr2Cu4Q9 (Q = S and Se): two novel layered quaternary mixed transition metal chalcogenides.

Depending on their bandgaps, mixed metal layered chalcogenides are potential candidates for thermoelectric and photovoltaic applications. Herein, we reported the exploratory synthesis of Sr-Zr-Cu-Q (Q = S/Se) systems, resulting in the identification of two novel quaternary chalcogenides: Sr3Zr2Cu4S9 and Sr3Zr2Cu4Se9. These isoelectronic compounds (Sr3Zr2Cu4Q9) crystallized in two different structural types. The Sr3Zr2Cu4S9 structure (space group: P1̄) adopted the Ba3Zr2Cu4S9 structure type with eighteen unique atomic sites: 3 × Sr, 2 × Zr, 4 × Cu, and 9 × S. In contrast, the Sr3Zr2Cu4Se9 structure (P1̄) represented a unique structure type with nineteen unique atomic positions including one additional Cu site compared to the Sr3Zr2Cu4S9 structure. The sulfide structure was stoichiometric, whereas the selenide structure was found to be non-stoichiometric with three partially occupied Cu positions. The Sr3Zr2Cu4Q9 structures consisted of layers with the Sr2+ cations occupying the interstitial spaces. In both structures, the Zr atoms occupied distorted octahedral positions. A striking difference between the two structures resulted from the distinct bonding interactions between the Cu and Q atoms. The optical bandgap of polycrystalline Sr3Zr2Cu4S9 was 1.7(1) eV. Interestingly, resistivity measurements of polycrystalline Sr3Zr2Cu4Se9 revealed metallic/degenerate semiconducting behavior at low temperatures. The photovoltaic performance of semiconducting Sr3Zr2Cu4S9 demonstrated ∼24% increment in power conversion efficiency when incorporated into a TiO2/CdS photoanode due to its narrower bandgap, which increased the light-harvesting ability of the cell. We also explored the theoretical electronic structures, COHP, and Bader charges of the Sr3Zr2Cu4Q9 structures using DFT calculations.

Ca2+/Si4+ Modification of the (Gd,Lu)AG Garnet for Enhanced Broadband Cr3+ Luminescence of High Thermal Stability.

Near-infrared (NIR)-emitting phosphors with high quantum efficiency and thermal stability are crucial to NIR pc-LEDs. Garnet-structured (GdLuCa)(Al4-zSiCrz)O12 (z = 0.01-0.2) and (Gd2-xLuCax)(Al4.95-xSixCr0.05)O12 (x = 0.2-1.0) new phosphors with promising NIR luminescence under blue light excitation were designed and fabricated by a solid-state reaction in this work. It was analyzed that the Ca2+, Cr3+, and Si4+ ions would replace Gd3+ in [GdO8], Al1 in [Al1O6], and Al2 in [Al2O4], respectively, and the optimal Cr3+ content is z = 0.05, above which concentration quenching would occur via an electric dipole-dipole interaction. Increasing Ca2+/Si4+ substitution up to x = 1.0 led to luminescence enhancement by a factor of up to 1.85 and internal/external quantum efficiency (%) increment from ∼25.9/10.7 to 63.4/27.5, and all of the phosphors showed excellent thermal stability (I423K/I298K ≥ 87.6%). The luminescence properties of Cr3+ were discussed in detail through systematic investigation of the effects of Cr3+ and Ca2+/Si4+ contents on the crystal structure, local coordination, and crystal field. With the NIR pc-LED device integrated from the optimal phosphor (x = 1.0) and a blue LED chip, electroluminescence manifested potential applications in night vision and medical diagnosis.

Novel Burst-Mode Control for Medium-to-Light Load Operation of Dual-Active-Bridge Converters, Achieving Minimum Backflow Power, Zero-Voltage-Switching, and DC Bias Suppression

The dual-active-bridge (DAB) converter is widely used in many applications such as solid-state transformers, multi-port converters, and on-board chargers. Nevertheless, its efficiency degrades significantly under light-load conditions due to high switching and conduction losses. Since a detailed analysis for burst-mode design has not been presented in the literature, effective burst-mode control for the light-load condition is proposed in this paper. In the proposed burst-mode, the regular duty cycle and the burst duty cycle are optimally coordinated to achieve the zero-voltage-switching (ZVS) condition and the minimum backflow power at the same time. Moreover, DC bias current is effectively eliminated in the proposed burst-mode. The switching loss and conduction loss are simultaneously minimized in the proposed burst-mode control. Therefore, the light-load efficiency is significantly improved. The detailed analysis and design procedure are also presented for both buck- and boost-mode operations to deal with widely varying output voltage ranges. The control mode switching condition is determined for achieving the ZVS condition for the whole load condition; thus, the proposed burst-mode control flowchart is presented. A 4 kW DAB converter prototype is built to verify the proposed method and the experiment results show about a 2% increment in efficiency of the proposed method compared to the conventional burst-mode method.

Nanobiohybrid Extracellular Vesicle Nanoreactor with Improving Metabolical Activity for Biocatalytic Therapy.

Extracellular vesicles (EVs) hosting enzymatic activities that function as independent metabolic units are attractive natural biocatalytic platforms. However, directly using these metabolically active nanoreactors for effective biocatalytic applications remains challenging, mainly due to their constrained catalytic capabilities. Here, we construct an EV-templated nanobiohybrid system by engineering an EV surface with a photoresponsive zeolitic imidazolate framework (ZIF). The deposition of ZIF nanostructures on EVs not only contributes to improved biocatalytic stability but also enables interfacial coupling between photoexcited electrons from the ZIF and the enzymatic reaction of metabolically active EVs. Nearly 300% of biomass conversion efficiency increment could be achieved by EVs derived from macrophages. This enhanced biocatalysis, high catalytic stability, and low cytotoxicity endowed the EV@ZIF nanosystem with robust biosynthesis and antimicrobial activity. When evaluated in a mouse periodontitis model, we show that the autologous biocatalytic EV@ZIF demonstrated efficient therapeutic capability by killing bacteria and inhibiting inflammation. This nanoengineering strategy will benefit the future optimization of metabolically active EV nanoreactors as biocatalysts for a broad range of therapeutics.

Enhanced Photovoltaic Efficiency through 3D-Printed COC/Al₂O₃ Anti-Reflective Coversheets

In the past few years, there has been a considerable growth in the utilization of solar cells to produce electrical power to fulfil the growing worldwide energy demands. An optical loss is a crucial factor that impacts the performance of the photovoltaic conversion process. This loss occurs when incoming sunlight is reflected back on the outer layer of the photovoltaic cells. The application of antireflective materials on the photovoltaic substrates can enhance the absorption of sunlight and minimize the reflection. Currently, there is no ideal anti-reflective coating for solar cells that can allow the transmission of sunlight without any reflection. In this research, a transparent cyclic-olefin-copolymer (COC) was used to fabricate anti-reflection (AR) coversheet by fused deposition modelling process (3D printing). Further, the aluminium oxide Al2O3 powder was added at the proportions of 1wt%, 2wt%, 3wt%, and 4wt% to the COC polymer to increase the anti-reflection characteristics. The structural, morphological, mechanical (tear strength), electrical and temperature characteristics were studied. The performance of COC with aluminium oxide (COCA) coversheets was evaluated, and the findings revealed a considerable increment in power conversion efficiency (PCE) of 17.21% (sunlight exposure) and 18.34% (neodymium light) for COCA3 coversheets. As seen, the COCA3 sample exhibit lower electrical resistance of 3.88 ×10-3 Ω cm, carrier concentration (36.91×1020 cm-3) and higher hall mobility (13.67 cm2/Vs). The findings from the investigations demonstrated that the utilization of COC with Al2O3 powder (COCA) can be a suitable antireflective coversheet material for boosting the performance of polycrystalline silicon photovoltaic cells.

Modelling and optimization of combined supercritical carbon dioxide Brayton cycle and organic Rankine cycle for electricity and hydrogen production

Hydrogen as a clean fuel, is key energy carrier for sustainable development, and its production via water electrolysis is most desirable for its carbon free nature. Nuclear power provides good opportunity to satisfy the huge energy demand associated with the process, in addition to electrical power generation. Modelling an efficient and cost effective nuclear based power and Hydrogen cogeneration system and optimizing it to enhance its performance is the core academic problem addressed in the present study. It proposes a power plant cycle aided by a nuclear reactor, providing 300 MW thermal power input. Supercritical CO2 Brayton cycle is used as the main cycle, instead of traditional Helium Brayton cycle or steam Rankine cycle. To increase the cycle efficiency, by reducing the compression work and by reducing the cold source loss, main compression intercooling and waste heat recovery by an Organic Rankine Cycle (ORC) is introduced together with recompression Brayton cycle arrangement. The power coming from recovered waste heat goes to a Proton Exchange Membrane Electrolyzer (PEME), which facilitates the production of Hydrogen by splitting water via electrolysis. Additional attention is given to ORC fluid selection by employing and comparing the performance of widely acknowledged R245fa together with its more eco friendly replacements, R1233Zd(E) and R1234Ze(Z). The evaluation of the system performance is conducted through the lenses of Energy, Exergy, and Economics. Essential parameters are scrutinized to gauge their impact on two pivotal objectives. Overall Exergy Efficiency(ηex) takes care of the thermodynamic performance and the economic aspect is scrutinized by Levelized Cost of Energy (LCOEn). Notably, by employing R245fa as the ORC working fluid, the system attains peak Energy efficiency of 42.13% and Exergy efficiency of 58.32%, and a minimum LCOEn of 0.063 USD/kWh. Of all the components associated with the system nuclear reactor tops the chart for maximum exergy destroyed(40.8% of total) as well as maximum investment cost(65.7% of total). Pump contributes least to exergy destruction(0.03% of the total) and heat exchangers hold least share(1.1% of total) for investment cost. Furthermore, a multiobjective optimization exercise is executed to fine-tune the system’s operational parameters. This optimization results in a 3.12% increase in Overall Exergy Efficiency and a 9.79% decrease in LCOEn compared to the base operating condition with R245fa used as the ORC fluid. The ηex & LCOEn in best possible operating condition are 58.25% & 0.0645 USD/kWh using R245fa as ORC fluid, 58.23% & 0.0645 USD/kWh using R1233Zd(E) as ORC fluid and 58.22% & 0.0644 USD/kWh using R1234Ze(Z) as ORC fluid. If same amount of electrical Power is supplied to PEME for both with and without ORC configuration, having an ORC is advantageous both in terms of superior Exergy Efficiency and lower LCOEn. The proposed configuration is also economically more lucrative with higher Net Present Value(NPV) and Benefit to Cost Ratio(BCR). For example, when PEME power input for both the cases is 10 MW, proposed system has NPV = 201.79 Million USD & BCR = 1.70 compared to NPV = 164.03 Million USD & BCR = 1.58 for without ORC configuration. Even if in without ORC configuration, no electrical power is supplied to the electrolyzer, adding an ORC to produce Hydrogen will still achieve maximum 1.57% Exergy Efficiency increment, compared to only electrical power production by sCO2 Brayton cycle. It is seen that in base condition, the NPV is still superior for the proposed configuration (203.03 to 189.32 Million USD), and the BCR dips only slightly from 1.72 to 1.71.

Influence of guide groove structure on in-flow drag reduction in spiral axial gas-liquid mixing pumps

Abstract With the onset of the fossil energy crisis, demand for oil has skyrocketed, and the spiral axial flow gas-liquid mixing pump has emerged as the primary piece of equipment for deep-sea oil extraction. However, at high gas content, the problems of separation of mixed media from hydraulic components, gas-liquid separation and gas phase aggregation are faced. The difficulties of gas-phase aggregation and bubble trajectory in the impeller channel have received much attention, while the problem of increased medium flow resistance induced by flow separation has received less attention. The spiral axial gas-liquid mixing pump is numerically calculated using the Eulerian multiphase flow model and the SST k- turbulence model in this work. The pump is designed with the design flow rate Q = 100 m3/h, rotational speed n = 4500 rmin, and head H = 30m by arranging guide slots with different relative depths and different number of slots to reduce the dissipative vortices, thus reducing the flow resistance in the 1/5 region behind the suction surface. The findings reveal that when the relative depth of the slots is 1/7 and the number of guide slots arranged is 5, the highest drag reduction rate in this location is 69.6% under the design flow condition. When the relative depth of the guide channel is1/7 and the number of guide channels is 3, the performance of the mixing pump is improved most, with an efficiency increment of 1.9% and a head increment of 4.2%, which can provide technical support for the flow resistance reduction of gas-liquid mixing pumps.

AI-Driven Strategies for Enhancing Non-Profit Organizational Impact

Throughout the last couple of years, Artificial Intelligence (AI) has come under consideration as a revolutionizer of numerous sectors in which the non-profit sector is involved is not an exception. AI intervention can be applied to the non-profit techniques in a way that this paper seeks to explain the extent of the success that can be realized. It discusses AI’s role in the non-profit organizations and pinpoints technologies like data analysis, AI-based fundraising solutions, program assessment, and chatbots to engage the donors. The paper also reviews general issues associated with the application of AI solutions including inadequate funds, dearth of specialists in AI and data privacy issues, and come up with measures to mitigate these challenges. It also elaborates on the evaluation indicators of the degree of AI impact in non-profits such as, efficiency increment indicators, fundraising indicators, changes in the programs, and indicators of stakeholders. The conclusions are that it is possible to achieve the positive impact on the function of distinctive non-profit organizations through the successful application of AI.

Associations between obstructive sleep apnea and sleep characteristics with chronic kidney disease in rural Pennsylvania

Study objectivesTo examine the association between moderate-severe obstructive sleep apnea (msOSA) and sleep characteristics with chronic kidney disease (CKD) in a population of rural and urban adults in Pennsylvania. MethodsA cross-sectional study of 23,643 adults who underwent polysomnography (PSG) at a rural healthcare system in Pennsylvania between 2009 and 2019. Serum creatinine was abstracted from electronic health records to calculate estimated glomerular filtration rate (eGFR). CKD was defined as an eGFR <60 mL/min/1.73 m2. msOSA was defined as an apnea-hypoxia index (AHI) ≥15 events/hour. Poisson regression was performed to estimate the prevalence ratio (PR) of CKD for various sleep measures while adjusting for age, sex, race, smoking (never, former, current), body mass index, diabetes, and hypertension at time of PSG. ResultsIn this clinically-referred sample comprised of over one-third (35 %) rural individuals, the prevalence of CKD and msOSA was 9.4 % and 32.1 %, respectively. Patients with CKD had more severe OSA based on AHI and intermittent hypoxia profile and presented worse sleep quality across all studied measures. Having OSA was associated with a 13 % higher prevalence of CKD (95%CI: 1.04, 1.22). In addition, for every 5 % increment in sleep efficiency, the prevalence of CKD was 3 % lower (PR = 0.97, 95%CI: 0.96, 0.98). Significant associations that were in the expected direction were observed across most sleep characteristics in adjusted models. ConclusionsModerate-severe OSA, nocturnal hypoxemia, and disruptions to normal sleep duration, continuity, and architecture are associated with increased CKD prevalence in Pennsylvania adults. Management of OSA and/or sleep disturbances may be an opportunity to improve CKD outcomes. The unique health disparities among vulnerable rural populations are deserving of future study.

Fuel properties, performance, and emissions of water-emulsified diesel fuel in an IDI diesel engine

This paper aims to verify the possibility of utilising water-in-diesel emulsions (WiDE) as an alternative drop-in fuel for diesel engines. An 8% WiDE was produced to be tested in a four-stroke, indirect injection (IDI) diesel engine and compared to EN590 diesel fuel. An eddy current brake and an exhaust gas analyser were utilised to measure different engine parameters such as torque, fuel consumption, and emissions at different engine loads. The results show that the engine running on emulsified fuel leads to a reduction in torque and power, an increase in the specific fuel consumption, and slightly better thermal efficiency. The highest percentual increment of thermal efficiency for WiDE is obtained at 100% engine load, 5.68% higher compared to diesel. The emissions of nitric oxide (NO) and carbon dioxide (CO2) are reduced, but carbon monoxide (CO) and hydrocarbons (HC) emissions are increased, compared to traditional diesel fuel. The most substantial decrease in NO and CO2 levels was achieved at 75% engine load with 33.86% and 25.08% respectively, compared to diesel.

Self-Cleaning Hydrophobic Coating Composed of Micro/Nano-Imprinted Polydimethylsiloxane with Enhanced Light In-Coupling Capabilities.

In this study, we have optimized optically transparent polydimethylsiloxane (PDMS) hydrophobic coating on glass substrates that exhibit self-cleaning as well as enhanced light in-coupling capabilities. Micro/nano textures on the surface of PDMS were introduced through micro/nanoimprinting to achieve light trapping as well as self-cleaning abilities. Comprehensive studies show that the periodic arrangement of the micro/nanopatterned features has enabled enhanced inward transmission of light in the visible range along with superior hydrophobicity. The water contact angle (WCA) measurements on these coatings demonstrated a superior capacity for self-cleaning with a WCA of about 117°. Subsequently, when these transparent and hydrophobic coatings were deposited on commercial silicon solar cells, they showed a 15.8% increment in efficiency due to enhanced light in-coupling with a nanopatterned PDMS coating.

Investigation of rotating detonation gas turbine cycle with different combustor passage areas

Application of rotating detonation combustion can significantly enhance gas turbine performance, but the limited flow capacity caused by normally aspirated characteristic of rotating detonation combustor (RDC) severely constrains the operating range of gas turbine. In this paper, the detailed investigation was carried out for the influence of RDC passage area on cycle characteristic parameters for a 25MW single shaft gas turbine. The results demonstrated that changes of RDC passage area had a significant impact on operating range of rotating detonation gas turbine. As RDC passage area increased, operating range of gas turbine moved to the higher power, with the slight increases for cycle efficiency, cycle efficiency increment and net power increment compared to traditional gas turbine at identical net power. For the process when RDC passage area decreased from 0.0272 m2 to 0.0240 m2, the lower working limit of rotating detonation gas turbine decreased to 53.3 % of rated power, in which equivalence ratio of RDC replaced turbine efficiency as the greatest influence factor on cycle efficiency increment.

Mitigating the disparities in carbon emission efficiency enhancement in China's coal resource-based cities

Enhancing carbon emission efficiency in coal resource-based cities (CRBCs) is pivotal for energy conservation and carbon reduction, but the combined pressures of technical efficiency and technological innovation may drive a sharp disparity in the sustainability of carbon emission efficiency enhancement across such cities. Here, we develop a “Static-Dynamic-Synergistic” progressive assessment framework, to systematically assess the carbon emission efficiency of 51 CRBCs in China from 2000 to 2020. We found that the carbon emission efficiency of CRBCs exhibited a fluctuating upward trajectory, with the average efficiency rising from 0.40 to 0.64. The enhancement of carbon emission efficiency in CRBCs has shifted from relying solely on efficiency change (EC) to incorporating both EC and technology change (TC). TC, EC, and the Carbon Emission Efficiency Improvement Synergy Index (CEEISI) exert a substantial positive influence on the increment of carbon emission efficiency. While the CEEISI of maturity CRBCs has increased by 2.22 % over the past 15 years, varying declines are observed for other types of CRBCs. CRBCs should formulate adaptive policies based on the stage of city development, fostering socio-economic-ecological transformation, synergistically improve technical efficiency and technological innovation, thereby achieving sustainable enhancement in carbon emission efficiency.

Exclusive optimization techniques for Cesium based perovskite solar cell for the efficiency increment

Exclusive optimization techniques for Cesium based perovskite solar cell for the efficiency increment

Efficiency increment of CFD modeling by using ANFIS artificial intelligence for thermal-based separation modeling

This study presents a comprehensive analysis of predicting the temperature in a vacuum membrane distillation (VMD) process. The simulation was carried out via computational fluid dynamics (CFD) as well as machine learning. CFD was performed for obtaining temperature distribution in the feed solution, and the calculated temperature was used for training several machine learning models. The dataset comprises over 13,000 observations, which provide a rich source for modeling complex relationships. Three sophisticated regression models were employed: Adaptive Neuro-Fuzzy Inference System (ANFIS), Kernel Ridge Regression (KRR), and Multi-Layer Perceptron (MLP). ANFIS was chosen for its hybrid nature, combining neural networks and fuzzy logic, effectively capturing intricate non-linear relationships in data. ANFIS performance in fitting the data was compared with the other models. Hyper-parameter optimization for these models was conducted using the Tabu Search algorithm to ensure optimal performance. The ANFIS model demonstrated superior performance with an R2 score of 0.9964513 on the training set and 0.9964507 on the test set, alongside a MSE of 0.037655 and a MAE of 0.168272. The robustness of ANFIS was further confirmed by a 3-fold cross-validation mean R2 score of 0.9964579 and a standard deviation of 3.3619616e−05.

Iron (Fe) and zinc (Zn) coated urea application enhances nitrogen (N) status and bulb yield of onion (A. cepa) through prolonged urea-N stay in alkaline calcareous soil

Onion (A. cepa) is an important horticulture crop which is sensitive to nutrient limitations worldwide. Urea hydrolysis to ammonia (NH3) and carbon dioxide (CO2), due to soil urease activity, causes urea-N loss. Comparative to several commercial products, the potential use of micronutrient coated urea to reduce urea hydrolysis based NH3-volatilization losses is novel to-date. In this study, boron (B), iron (Fe), zinc (Zn) and copper (Cu) were coated on urea at their full or half recommended rates as (B)-half, (Fe)-half, (Zn)-half, (Cu)-half, (B)-full, (Fe)-full, (Zn)-full, (Cu)-full, (B+Fe)-half, (B+Zn)-half, (B+Cu)-half, (Fe+Zn)-half, (Fe+Cu)-half, (Zn+Cu)-half, (B+Fe)-full, (B+Zn)-full, (B+Cu)-full, (Fe+Zn)-full, (Fe+Cu)-full and (Zn+Cu)-full having gum-only coated urea as an internal control. Parallel to these, p-Phenylenediamine (PPD-0.2 %, 0.4 %, 0.6 %, 0.8 % and 1.0 %) and hydroquinone (HQ-0.5 %, 1.0 % and 2 %) coated urea treatments were also used with acetone-only coated urea as an internal control. Whereas the uncoated urea treatment was taken as an overall control. In pot experiment, the soil residual urea concentrations were increased by 2, 0.5, 1.85, 2.69 and 3.15 folds at 8 days after incubation (DAI), by 5.6, 1.89, 5.97, 0.54 and 6.23 folds at 12 DAI and by 119, 123, 155, 84 and 87 folds at 16 DAI under (B)-full, (B+Zn)-full, (Fe+Zn)-full, PPD-0.8 % and PPD-1.0 % coated urea treatments, respectively, as compared to uncoated urea. Among these five coating combinations, 54.26 % and 44.82 % bulb yield increments were observed under (Fe+Zn)-full and PPD-1 % coated urea, respectively, in comparison to uncoated urea in field experiment. However, the 33.33 % increment in nitrogen agronomic efficiency (NAE) and subsequent economic gains proved (Fe+Zn)-full coated urea application as a solution to address N losses in alkaline calcareous soils.

Performance Improvement of a Straight-Bladed Darrieus Hydrokinetic Turbine through Enhanced Winglet Designs

The global climate and energy crisis have underscored the importance of sustainability in energy systems and their efficiency. In the case of vertical axis turbines (VATs) for hydrokinetic applications, the increment in efficiency is a topic of interest. Using winglets as passive flow control devices has the potential to improve the power coefficient of straight-bladed (SB) Darrieus turbines highly due to their impact in the dynamics of the flow close to the tip blade and the general impact in the hydrodynamic performance of each blade. The aim of the present work is to study the influence of the geometric parameters of a symmetric winglet in the performance of an SB-VAT for hydrokinetic applications via numerical simulations based on Computational Fluid Dynamics (CFD). Several simulations were performed in Star CCM+ v2206 varying the cant and sweep angles of the designed winglet. Numerical results show that a cant angle of 45° in combination with a sweep angle of 60° achieved the highest power coefficient with an increment around 20% with respect to the model without winglets. Furthermore, the vortical flow structures that form around straight and winglet blades are examined. This involves assessing the distribution of pressure and skin friction coefficients at different blade azimuthal positions during a turbine revolution. In general, the predicted increment in performance is related to the influence of the winglets in the strength of the tip vortices and in the delay in the flow separation.

Technical Note: Swing golden angle - A navigator-interleaved golden angle trajectory with eddy current suppression - Application in free-running cardiac MRI.

Golden angle (GA) radial trajectory is advantageous for dynamic magnetic resonance imaging (MRI). Recently, several advanced algorithms have been developed based on navigator-interleaved GA trajectory to realize free-running cardiac MRI. However, navigator-interleaved GA trajectory suffers from the eddy-current effect, which reduces the image quality. This work aims to integrate the navigator-interleaved GA trajectory with clinical cardiac MRI acquisition, with the minimum eddy-current artifacts. The ultimate goal is to realize a high-quality free-running cardiac imaging technique. In this paper, we propose a new "swing golden angle" (swingGA) radial profile order. SwingGA samples the k-space by rotating back and forth at the generalized golden ratio interval, with smoothly interleaved navigator readouts. The sampling efficiency and angle increment distributions were investigated by numerical simulations. Static phantom imaging experiments were conducted to evaluate the eddy current effect, compared with cartesian, golden angle radial (GA), and tiny golden angle (tGA) trajectories. Furthermore, 12 heart-healthy subjects (aged 21-25years) were recruited for free-running cardiac imaging with different sampling trajectories. Dynamic images were reconstructed by a low-rank subspace-constrained algorithm. The image quality was evaluated by signal-to-noise-ratio and spectrum analysis in the heart region, and compared with traditional clinical cardiac MRI images. SwingGA pattern achieves the highest sampling efficiency (mSE>0.925) and the minimum azimuthal angle increment (mAD<1.05). SwingGA can effectively suppress eddy currents in static phantom images, with the lowest normalized root mean square error (nRMSE) values among radial trajectories. For the in-vivo cardiac images, swingGA enjoys the highest SNR both in the blood pool and myocardium, and contains the minimum level of high-frequency artifacts. The free-running cardiac images have good consistency with traditional clinical cardiac MRI, and the swingGA sampling pattern achieves the best image quality among all sampling patterns. The proposed swingGA sampling pattern can effectively improve the sampling efficiency and reduce the eddy currents for the navigator-interleaved GA sequence. SwingGA is a promising sampling pattern for free-running cardiac MRI.

Evaluating effects of selected water conservation techniques and manure on sorghum yields and rainwater use efficiency in dry region of Zimbabwe

Sorghum production in semi-arid areas of Zimbabwe is constrained by low and erratic rainfall, low fertility and soil moisture stress. Sorghum grain yields ranges from 0.2 to 0.4 t ha−1 in sandy-to-sandy loam soils respectively. The objective of the study was to assess cattle manure and rainwater harvesting techniques in improving sorghum grain yield in a semi-arid region of Zimbabwe. The experiment used a randomised complete block design with rainwater harvesting technique as a main treatment factor at three levels. Sub-plot factor was cattle manure at five levels (0, 2.5, 5, 10 and 15 t ha−1) and two sorghum varieties (Macia and SV1) as sub-sub plot factor. Sorghum grain yields were improved significantly (p < 0.05) for both varieties using tied contours. Increasing application rates of cattle manure, showed significant increase (p < 0.05) in sorghum grain yield over the control (0 t ha−1). Tied contour had higher grain yield (1.15 t ha−1) with the use of Macia variety. Stover yield was highly influenced by rainwater harvesting method of tied contour (p < 0.05) compared with infiltration pit and standard contour. Increase in application levels of cattle manure show significant (p < 0.05) increase in stover yields. Tied contour had the highest (3.11 kg ha−1 mm−1) rainwater use efficiency which show significant differences (p < 0.05) from infiltration pits and standard contour. Interaction of tied contour and different rates of cattle manure showed significant increments in rainwater use efficiency with increases in manure application rates. Tied contours, 15 t ha−1 cattle manure and Macia variety are potential strategy to achieve climate smart agriculture and improve food security in semi-arid areas. Sorghum production in marginalised areas can be productive with adoption of tested techniques.