Modelling of Hydropower Reservoir Variables for Energy Generation: Neural Network Approach

Efficient management of hydropower reservoir can only be realized when there is sufficient understanding of interactions existing between reservoir variables and energy generation. Reservoir inflow, storage, reservoir elevation, turbine release, net generating had, plant use coefficient, tail race level and evaporation losses are the major hydropower reservoir variables affecting the energy generation. Thus, this paper presents the modelling of reservoir variables of two hydropower dams along the River Niger (Kainji and Jebba dams) in Nigeria for energy generation using multilayer perceptron neural network. Total monthly historical data of Kainji and Jebba hydropower reservoirs’ variables and energy generated were collected from Power Holding Company of Nigeria respectively for a period of (1970-2011) and (1984-2011) for the network training. These data were divided into training, testing and holdout data set. The neural network summary yielded a good forecast for Kainji and Jebba hydropower reservoirs with correlation coefficients of 0.89 and 0.77 respectively. These values of the correlation coefficient showed that the networks are reliable for modeling energy generation as a function of reservoir variables for future energy prediction.Key words: Hydropower, reservoir variables, neural network, energy generation, coefficient of correlatio

Local interactions under switching costs

We study the impact of switching costs on the long-run outcome in 2×2 coordination games played in the circular city model of local interactions. For low levels of switching costs, the predictions are in line with the previous literature and the risk-dominant convention is the unique long-run equilibrium. For intermediate levels of switching costs, the set of long-run equilibria still contain the risk-dominant convention but may also contain conventions that are not risk dominant. The set of long-run equilibria may further be non-monotonic in the level of switching costs, i.e., as switching costs increase the prediction that the risk-dominant convention is the unique long-run equilibrium and the prediction that both conventions are long-run equilibria alternate. Finally, for high levels of switching costs, also non-monomorphic states will be included in the set of long-run equilibria

Hypoxia-regulated carbonic anhydrase IX expression is associated with poor survival in patients with invasive breast cancer.

Tumour hypoxia is a microenvironmental factor related to poor response to radiation, chemotherapy, genetic instability, selection for resistance to apoptosis, and increased risk of invasion and metastasis. Hypoxia-regulated carbonic anhydrase IX (CA IX) has been studied in various tumour sites and its expression has been correlated with the clinical outcome. The purpose of this study was to investigate the correlation of CA IX expression with outcome in patients with invasive breast cancer. We conducted a retrospective study examining the effects of carbonic anhydrase IX (CA IX) on survival in patients with breast cancer. To facilitate the screening of multiple tissue blocks from each patient, tissue microarrays were prepared containing between two and five representative samples of tumour per patient. Immunohistochemistry was used to examine expression of CA IX in patients with breast cancer. The study includes a cohort of 144 unselected patients with early invasive breast cancer who underwent surgery, and had CA IX expression and follow-up data available for analysis. At the time of analysis, there were 28 deaths and median follow-up of 48 months with 96% of patients having at least 2 years of follow-up. CA IX was negative for 107 patients (17 deaths) and positive for 37 patients (11 deaths). Kaplan-Meier survival curves show that survival was superior in the CA IX-negative group with a 2-year survival of 97% for negatives and 83% for positives (log-rank test P=0.01). Allowing for potential prognostic variables in a Cox regression analysis, CA IX remained a significant independent predictor of survival (P=0.035). This study showed in both univariate and multivariate analysis that survival is significantly inferior in patients with tumour expressing CA IX. Prospective studies are underway to investigate this correlation in clinical trial setting

Perturbation and numerical study of double-diffusive dissipative reactive convective flow in an open vertical duct containing a non-darcy porous medium with robin boundary conditions

A mathematical model for thermosolutal convection flow in an open two-dimensional vertical channel containing a porous medium saturated with reactive Newtonian fluid is developed and studied. Robin boundary conditions are prescribed, and a first-order homogenous chemical reaction is considered. The Darcy–Forchheimer model is used to simulate both the first- and second-order porous mediums’ drag effects. For the general non-Darcy-case, a numerical solution is presented using the Runge–Kutta quadrature and a shooting method. The influences of thermal (0≤λ1≤15) and solute Grashof numbers (0≤λ2≤20) , Biot numbers (1≤Bi1≤10,Bi2=10) , Brinkman number (0≤Br≤0.5) , first-order chemical reaction parameter (2≤α≤8) , porous medium parameter (2≤σ≤8) and Forchheimer (inertial drag) parameter (0≤I≤12) on the evolutions of velocity, temperature and concentration (species) distributions are visualized graphically. Nusselt number and skin friction at the walls are also computed for specific values of selected parameters. The study is relevant to the analysis of geothermal energy systems with chemical reaction

Initial study of invasive approach of electrical capacitance tomography for identifying non-conducting medium in steel pipe application

The paper aims to investigate the possibility of an invasive method for electrical capacitance tomography system for steel pipe application. This work presents the development process for modeling an ECT (Electrical Capacitance Tomography) sensor using COMSOL Multiphysics. COMSOL Multiphysics software is implemented as the main tool to model the ECT system. The 12 electrodes are modeled in 2-dimensional and it is based on the invasive approach. The ECT system is developed to obtain the electrical potential distribution between electrodes when an electric field is applied. Besides, it also obtains the permittivity distribution inside the closed pipe. This invasive approach is applied for the steel pipe that cannot be used with common ECT. Several positions of bubble air as the obstacle in the oil medium are tested. As a result, the sensor readings performance inside the region of interest is analyzed. Simultaneously, the tomograms are also obtained and analyzed using MATLAB software. A linear back-projection algorithm is implemented to reconstruct the image of the region of interest. Thus, the possibility of the ECT system applied for steel pipe can be observed and compared when there is a change of readings between the full oil and the existing obstacle inside the steel pipe. Besides, the tomograms for each condition tested can be observed. In short, the invasive approach for ECT is seen to be possible to apply for oil-gas application in steel pipe. The LBP algorithm with the average MSSIM value around 0.3 was able to detect the oil-gas regime inside the steel pipe

Initial study of invasive approach of electrical capacitance tomography for identifying non-conducting medium in steel pipe application

The paper aims to investigate the possibility of an invasive method for electrical capacitance tomography system for steel pipe application. This work presents the development process for modeling an ECT (Electrical Capacitance Tomography) sensor using COMSOL Multiphysics. COMSOL Multiphysics software is implemented as the main tool to model the ECT system. The 12 electrodes are modeled in 2-dimensional and it is based on the invasive approach. The ECT system is developed to obtain the electrical potential distribution between electrodes when an electric field is applied. Besides, it also obtains the permittivity distribution inside the closed pipe. This invasive approach is applied for the steel pipe that cannot be used with common ECT. Several positions of bubble air as the obstacle in the oil medium are tested. As a result, the sensor readings performance inside the region of interest is analyzed. Simultaneously, the tomograms are also obtained and analyzed using MATLAB software. A linear back-projection algorithm is implemented to reconstruct the image of the region of interest. Thus, the possibility of the ECT system applied for steel pipe can be observed and compared when there is a change of readings between the full oil and the existing obstacle inside the steel pipe. Besides, the tomograms for each condition tested can be observed. In short, the invasive approach for ECT is seen to be possible to apply for oil-gas application in steel pipe. The LBP algorithm with the average MSSIM value around 0.3 was able to detect the oil-gas regime inside the steel pipe

A review of the current treatment methods for posthaemorrhagic hydrocephalus of infants

Posthaemorrhagic hydrocephalus (PHH) is a major problem for premature infants, generally requiring lifelong care. It results from small blood clots inducing scarring within CSF channels impeding CSF circulation. Transforming growth factor – beta is released into CSF and cytokines stimulate deposition of extracellular matrix proteins which potentially obstruct CSF pathways. Prolonged raised pressures and free radical damage incur poor neurodevelopmental outcomes. The most common treatment involves permanent ventricular shunting with all its risks and consequences