Journal of Sustainable Research in Engineeringhttp://localhost/xmlui/handle/123456789/21662024-03-29T06:54:21Z2024-03-29T06:54:21ZSWAT model parameter calibration and uncertainty analysis using the HydroPSO R package in Nzoia Basin, KenyaMusau, J.Sang, J.Gathenya, J.Luedeling, E.Home, P.http://localhost/xmlui/handle/123456789/22862016-10-03T11:47:33Z2016-10-03T00:00:00ZSWAT model parameter calibration and uncertainty analysis using the HydroPSO R package in Nzoia Basin, Kenya
Musau, J.; Sang, J.; Gathenya, J.; Luedeling, E.; Home, P.
The parameter uncertainty in hydrological modelling has been accorded much attention in the recent past. Parameter
uncertainty is a major source of overall model unreliability. In this study, the HydroPSO R package was used to assess parameter
identification and uncertainty for the Soil and Water Assessment Tool (SWAT) model applied in the upper reaches of Nzoia River
Basin. Fourteen parameters were selected based on previous studies and parameter sensitivity analysis using the Latin Hypercube
Sampling method. Based on the optimum parameter set, the simulated flow corresponded well with the observed flow with daily
Percent Bias (PBIAS), coefficient of determination (R2) and Nash–Sutcliffe efficiency (NSE) of -1.4, 0.73 and 0.72, respectively.
For monthly calibration, these values were -1.4, 0.78 and 0.77, respectively. The results of this study showuncertainty in parameter
identification. The posterior distributions of the parameter values were not normally distributed and the uncertainty ranges of the parameters varied widely. The low flows (Q5) were overestimated with a 13.8% bias while the Q50 and Q95 flows were
underestimated with -4.2% and -13.1% biases respectively. Further analysis indicated that the contribution of parameter uncertainty to stream flow simulation was substantial with 35% of the observed flow data falling within the 95% simulation confidence interval
for the calibration period. Different parameter sets gave the same correlation between the simulated and observed flows. A multiobjective analysis of the hydrological modeling uncertainties emanating from model selection, calibration procedure and
calibration data errors in the basin is therefore recommended.
2016-10-03T00:00:00ZSimulation of Saturation Efficiency and Cooling Capacity of an Unloaded Near Infrared Reflecting Charcoal Cooler for On-farm Storage of Mango fruitsKorir, Meshack K.Mutwiwa, UrbanusKituu, Gareth M.Sila, Daniel N.http://localhost/xmlui/handle/123456789/22852016-10-03T11:47:21Z2016-10-03T00:00:00ZSimulation of Saturation Efficiency and Cooling Capacity of an Unloaded Near Infrared Reflecting Charcoal Cooler for On-farm Storage of Mango fruits
Korir, Meshack K.; Mutwiwa, Urbanus; Kituu, Gareth M.; Sila, Daniel N.
Mango (Mangifera indica L.) fruit is a valuable fruit in Kenya due to its nutritive value and economic importance. However, at least 40 to 45% of mango fruit is lost during postharvest handling primarily due to inadequate storage facilities for mango fruits. In this study, saturation efficiency and cooling capacity of an unloaded improved evaporatively cooled store for onfarm storage of mango fruits were simulated. The cooler had a storage space of 0.75 m3 and its dimensions were 0.84 m x 0.84 m
x 1.5 m. The external surfaces of the cooler were sprayed with a near infrared reflecting (NIR) paint. The cooler was constructed from locally available materials including hardwood and charcoal. The charcoal was kept moist by water dripping by gravity from
horizontally laid pipes on the roof. The flow of water from an overhead tank approximately 2 m high to the cooler was monitored using a flow meter. The excess water which dripped was collected by gutters fixed at the lower ends of the charcoal walls and channeled to a water reservoir. A 12V pump was used to pump the water back to the overhead tank while a 12V fan located centrally on one of the sides directly opposite the door was used to draw air into the cooler. The pump and fan was powered by a 70Ah battery recharged by a 125 W solar panel. A computer model to simulate the saturation efficiency and cooling capacity of the cooler was developed on a java platform. The input parameters of the model were inlet air conditions, water conditions, air properties at selected ambient condition, and charcoal cooler characteristics. At varied inlet air velocities ranging from 3.0 m/s to 4.0 m/s at an interval of 0.2 m/s, the actual saturation efficiency of the cooler ranged from 68.9% to 66.9% while the predicted
ranged from 69.0% to 66.9%. The actual cooling capacity of the cooler ranged from 1055667 kJ/h to 136477 kJ/h while the predicted ranged from105726 kW/h to 136680 kW/h. The high coefficient of determination (R2=0.999) indicated a strong
correlation between the actual and predicted results. A root mean square error (RMSE) corresponding to the actual and predicted saturated efficiency was 0.028% while that corresponding to the actual and predicted cooling capacity was 118 kJ/h. At 95% level
of confidence, t test results showed no significant difference (tcalculated, 0.06; tcritical, 2.23) between the actual and predicted saturation efficiency. The t test results also indicated no significant difference (tcalculated, 0.01; tcritical, 2.23) between the actual and predicted cooling capacity.
2016-10-03T00:00:00ZStrain Rate Effects on the Tensile Behavior of Fiber Bundles Isolated from Nerve RootTamura, AtsutakaMurakami, JunjiSone, YutaKoide, Takaohttp://localhost/xmlui/handle/123456789/22842016-10-03T11:41:27Z2016-10-03T00:00:00ZStrain Rate Effects on the Tensile Behavior of Fiber Bundles Isolated from Nerve Root
Tamura, Atsutaka; Murakami, Junji; Sone, Yuta; Koide, Takao
Fresh porcine spinal cords (N = 5) were obtained at a local abattoir, and intact nerve roots were excised at cervical, thoracic, and lumbar levels using a surgical scalpel and fine forceps with a special caution. In total, 77 fiber bundles with a dimension of 30 mm in length and 0.5 mm in diameter were isolated from the excised nerve roots. By conducting a series of uniaxial stretching tests at three different velocities,
0.1, 1, and 10 mm/s, we revealed that mechanical properties of fiber bundles were relatively insensitive to strain rates under such a sub-impulsive loading condition. On average, elastic moduli, linear portion of stress–strain curve, resulted in 3.8, 3.3, and 4.5 MPa for 0.1, 1, and 10 mm/s, respectively. In addition, strain at failure was almost constant, ~0.15, irrespective of a 100-fold increase in the applied loading rate, while at the same time axial strains were distributed non-homogeneously along fiber direction. We also found that spinal level effect may exist in the spinal nerve roots, suggesting that we should pay more close attention even to an anatomical site where excised samples are obtained.
2016-10-03T00:00:00ZThe Performance of a Resistance-Capacitance Type Pulse Generation Circuit in Electrical Discharge MachiningKabini, KaranjaBojer, Sile KIkua, Bernard W.Kihiu, John M.Nyakoe, George N.Wamai, James W.http://localhost/xmlui/handle/123456789/22832016-10-03T10:00:30Z2016-09-30T00:00:00ZThe Performance of a Resistance-Capacitance Type Pulse Generation Circuit in Electrical Discharge Machining
Kabini, Karanja; Bojer, Sile K; Ikua, Bernard W.; Kihiu, John M.; Nyakoe, George N.; Wamai, James W.
The Electrical Discharge Machining (EDM) Process is complex in nature partly due to the mechanism of material removal, and, partly due to the presence of many machining parameters. This complexity of the EDM process has undermined its full potential drastically reducing its efficiency. In turn, this has led to relatively higher consumption of electrical energy, longer machining periods, higher rate of electrode wear and lower surface quality of the finished product. Various researchers have used varied approaches with the aim of optimizing the process. However, most of these researches have focused on optimization of one or at most two parameters and have used either fuzzy logic control techniques or modeling approaches. Others have used purely predictive and non-realtime approaches. All of these do not offer the advantage of realtime control of the process.
This paper focuses on experimental work carried out to establish the performance of Resistance-Capacitance (RC) pulse generation circuit in the EDM process.
This is part of an ongoing research who's aim is to study the EDM process with a view to designing a controller that is capable of improving the process' efficiency by optimizing all the machining parameters in realtime.
2016-09-30T00:00:00Z