Frank Agyen Dwomoh

The study evaluated the effects of cultivation under a canopy, concerning plant density, row spacing, and cultivation without a canopy, on the application rate and the uniformity coefficient with different catch-can heights. The experiment was conducted at the Fishery and Aquaculture Technology Farm in the Volta Region of Ghana. Catch-cans were arranged at the heights of 0.5, 1.0, 1.5, and 2.0 m, respectively, and the working pressure varied from 150~250 kPa. The average infiltration rate with the canopy and without it was 31.2 mm h ⁻¹ and 37.08 mm h ⁻¹ , respectively. Corn under the canopy significantly influenced (p-values 0.001) the infiltration depth before runoff. However, the effect of the cultivation without a canopy was insignificant (p = 0.05). The average application rates obtained under the canopy at the catch-can heights of 0.5, 1.0, 1.5, and 2.0 m were 56.6, 61.4, 68.0, and 52.0 m h ⁻¹ , respectively. The maximum and the average uniformity coefficient (Cu) values obtained under the canopy were 79% and 64%, respectively. The average sediment productions (gm ⁻² ) were 2.0, 2.53, 3.0, 3.63, 5.95 and 70.2, respectively, in the treatments of 40.1 mm·h ⁻¹ and duration (Dur) 80 min, 45.2 mm·h ⁻¹ and Dur 60 min, with 30.4 mm·h ⁻¹ and Dur 110 min, 28.4 mm·h ⁻¹ and Dur 120 min, and 59.2 mm·h ⁻¹ and Dur 40min.

The effect of oven wall chamber insulation on the Nusselt number and heat loss reduction in a specially fabricated direct-fired natural convection oven was studied. Fiber glass and aluminum-reinforced fiber were used as wall chamber insulation materials. Three sets of experiments, namely uninsulated and insulation with each of the two insulation materials were performed and a data acquisition system was used to continuously monitor temperature and environmental changes from the oven’s four sides, ambient, and inside using a heat temperature sensor (REX-C700-FK07-M-AN) and thermocouple (OM-HL-EH-TC). The temperature profiles, the Nusselt number, the Rayleigh number and the heat transfer coefficient were used to assess the heat transfer characteristics of the oven to ascertain the heat loss reduction potential of the insulation materials. Within the range of the Raleigh numbers studied, the average Nusselt number is highest for the uninsulated and higher for the insulated with aluminum-reinforced fiber and least for the insulated with fiberglass. The average percentage reduction in heat loss as a result of insulation was 3.8% and 16.7% for the fiber reinforced aluminum and fiberglass, respectively. Based on the findings, which are consistent with earlier related research, installing thermal insulation materials in oven walls could reduce heat loss, appreciably. The least-square correlation of the Nusselt numbers and the Rayleigh numbers resulted in high values of adjusted R-square values, which could be used for the optimization of natural convective heat transfer for uninsulated and insulated ovens.

The fluidic sprinkler was designed to have the prospect of a simple design, ease of construction, low energy consumption, and water saving. The present review focused on the fluidic sprinkler, compared the performance parameters of the fluidic sprinkler with the impact sprinkler, and highlighted the main challenges associated with the fluidic sprinkler. Even though the fluidic sprinkler compares quite well with the impact sprinkler, the review highlighted that the fluidic sprinkler appears to have more variability in application rate (0-1.5 mm/h) than the impact sprinkler (0-0.8 mm/h). The wetted radii were, on average, less than the impact sprinkler by 9.7, 9.3, 11.0, and 9.9% at 200, 250, 300, and 350 kPa operating pressures, respectively. Experiments on the fluidic sprinkler have mainly concentrated on the structural design of the fluidic component, water distribution profile, coefficient of uniformity, droplet size characterisation, and rotation uniformity, as well as the effect of different nozzle sizes on hydraulic performance under varying discharge and pressure conditions ranging from 100-500 kPa under indoor conditions. However, experimental studies on its performance in the field remain scanty. Statistical analysis of research papers published on the fluidic sprinkler indicates that less than 10% of the studies focused on the performance of the fluidic sprinkler on the field, and more than 90% on the design, structural and hydraulic performance under indoor conditions. Rotation stability of the fluidic sprinkler and testing with different sizes of the nozzle under low-pressure conditions on the field require further research to achieve energy and water saving through optimisation of the operating conditions.

A numerical model was developed to determine the water drop movement and mean droplet size diameter at any distance from a sprinkler as a function of nozzle size and pressure. Droplet size data from 4, 5, 6, and 7 mm nozzle sizes verified the model. Data for model prediction were generated throughout lab experiments. The results demonstrated that the correlation between the observed and predicted droplet size diameter values for all the nozzle sizes and pressures is quite good. Nozzle size and pressure had a major influence on droplet size. Higher pressure produced smaller droplets over the entire application profile. The wetted distance downwind from the sprinkler increased as wind velocity increased, for example at a constant working pressure of 300 kPa, at wind speeds of 3.5 m/s and 4.5 m/s, 20% and 32% of the total volume exceeded the wet radius respectively. Larger droplets (3.9–4.5 mm), accounting for 3.6% and 6.3% of the total number of distributed droplets, respectively. The model can also predict the droplet size distribution at any wind direction overall the irrigated pattern.

The fluidic sprinkler, a relatively new type of rotating sprinkler, has been the subject of quite a lot of research about its structural parameters, hydraulic characteristics, and water distribution profile, albeit under indoor conditions. The fluidic sprinkler’s performance in terms of water distribution profile and droplet size distribution pattern in wind has seen little investigation. To obtain information about its droplet size distribution in wind, the Thiess Clima Laser Precipitation Monitor was employed. Drop diameter, drop velocity, and the number of drops at varying distances from the fluidic sprinkler were measured in both wind and no wind at three operating pressures of 250, 300, and 350 kPa. The logistic model was adopted to fit a relationship between the drop diameter and the cumulative numeric frequency (CNF) and the cumulative volumetric frequency (CVF) values resulting in very high correlation coefficient (R²) values of above 0.99 for all conditions. At 250, 300, and 350 kPa, drops traveled 0.6, 1.0, and 1.3 m, respectively, farther in wind than in no wind along the direction of throw. Drops exhibited a spectrum of velocities and diameters at a given radial distance from the sprinkler. Up to two-thirds of the radius of throw, the proportion of drops with diameters ranging from 0.125 mm to 1.00 mm were above 80% at 300 and 350 kPa.

Modelling the behaviour of Pneumatic Artificial Muscle (PAM) has proven difficult due to its highly complicated structure, nonlinear nature of rubbery material, and air compressibility. To overcome these limitations, a FEM (Finite Element Method) model using Abaqus and CATIA is derived for the quantitative analysis on the impact of different factors on the pulling force of PAM. In the Abaqus a two parameter Mooney–Rivlin model is utilized to consider the hyper-elastic nature of flexible material. Then both Abaqus and CATIA are used in the parametric design of a 3-Dimensional model of PAM. Furthermore, the FEM model is employed to predict the static force exerted by PAM and the results show that the model is promising. The FEM model produces closer results to the test data for the typical PAM. Nonlinear behaviour of PAM is found to be obvious with an increase in both the contraction and the air pressure, different from the linear curves obtained by the fundamental geometrical model. Nonlinear changes in the PAM force are also observed in the numerical study on the effect of structural factors including initial braid angle, initial diameter, initial wall thickness, and flexible material. Besides, these phenomena can be explained by a connection between mechanical and morphological behaviour of PAMs with the FEM model. Generally, this modelling approach is more accurate compared to the fundamental theoretical model and more cost competitive compared to the empirical methods.