Physics
Permanent URI for this collectionhttps://repository.chuka.ac.ke/handle/chuka/698
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Item PHYS 427: PHYSICS PRACTICALS(Chuka University, 2023-12-20) Chuka UniversityItem PHYS 391: ASTROPHYSICS(Chuka University, 2023-12-20) Chuka UniversityItem PHYS 362: THERMAL AND STATISTICAL PHYSICS(Chuka University, 2023-12-19) Chuka UniversityItem PHYS 342: ELECTRICITY AND MAGNETISM II(Chuka University, 2023-12-19) Chuka UniversityItem PHYS 317: MATHEMATICAL PHYSICS I(Chuka University, 2023-12-20) Chuka UniversityItem PHYS 161: HEAT AND THERMODYNAMICS(Chuka University, 2023-12-20) Chuka UniversityItem PHYS 121: PHYSICS PRACTICAL I(Chuka University, 2023-12-19) Chuka UniversityItem PHYS 121: PHYSICS PRACTICAL I(Chuka University, 2023-12-19) Chuka UniversityItem PHYS 112: PHYSICS A(Chuka University, 2023-12-19) Chuka UniversityItem GPHY 223: GEOPHYSICS PRACTICAL III(Chuka University, 2023-12-19) Chuka UniversityItem GPHY 111: INTRODUCTION TO GEOLOGY STREAMS: BSc. PHYSICS(Chuka University, 2024-12-13) Chuka UniversityItem GPHY 427: GEOPHYSICS PRACTICAL VII STREAMS: BSC (PHYS)(Chuka University, 2024-12-24) Chuka UniversityItem GPHY 353 – MINERALS ENGINEERING AND PROCESS CONTROL STREAMS: BSC(Chuka University, 2024-12-17) Chuka UniversityItem GPHY 352: GEOPHYSICAL DATA ANALYSIS AND INTERPRETATION STREAMS: BSC(Chuka University, 2024-12-17) Chuka UniversityItem GPHY 343: INTRODUCTORY GEOPHYSICS STREAMS: BSc(Chuka University, 2024-12-09) Chuka UniversityItem GPHY 334: MINERAL PROCESSING STREAMS: BSC(Chuka University, 2024-12-16) Chuka UniversityItem GPHY 121: GEOPHYSICS PRACTICAL I STREAMS: BSC(Chuka University, 2024-12-16) Chuka UniversityItem ACMT 413: RISK MODELLING(chuka university, 2024-12-11) chuka universityItem Forecasting Commodity Price Index of Food and Beverages in Kenya Using Seasonal Autoregressive Integrated Moving Average (SARIMA) Models.(2021) Wanjuki, T. M.; Muriithi, D. K.; Wagala, A.Price stability is the primary monetary policy objective in any economy since it protects the interests of both consumers and producers. As a result, forecasting is a common practice and a vital aspect of monetary policymaking. Future predictions guide monetary and fiscal policy tools that that be used to stabilize commodity prices. As a result, developing an accurate and precise forecasting model is critical. The current study fitted and forecasted the food and beverages price index (FBPI) in Kenya using seasonal autoregressive integrated moving average (SARIMA) models. Unlike other ARIMA models like the autoregressive (AR), Moving Average (MA), and non-seasonal ARMA models, the SARIMA model accounts for the seasonal component in a given time series data better forecasts. The study relied on secondary data obtained from the KNBS website on monthly food and beverage price index in Kenya from January 1991 to February 2020. R-statistical software was used to analyze the data. The parameter estimation was done using the Maximum Likelihood Estimation method. Competing SARIMA models were compared using the Mean Absolute Error (MAE), Mean Absolute Scaled Error (MASE),.and Mean Absolute Percentage Error (MAPE). A first-order differenced SARIMA (1,1,1) (0,1,1)12 minimized these model evaluation criteria (AIC = 1818.15, BIC =1833.40). The forecasting ability evaluation statistics MAE = 2.00%, MAPE = 1.62% and MASE= 0.87%. The 24-step ahead forecasts showed that the FPBI is unstable with an overall increasing trend. Therefore, the monetary policy committee ought to control inflation through monetary or fiscal policy, strengthening food security and trade liberalization.Item Ab initio Investigation of the Structural and Electronic Properties of Alkaline Earth Metal - TiO2 Natural Polymorphs(Hindawi, 2022) Mbae, J. K.; Muthui, Z. W.Titanium (IV) oxide (TiO2) has gained much attention due to its application in technologies such as optoelectronics, electronics, sensors, photocatalysts, and sustainable energy generation. However, its optical absorption falls in the ultraviolet part of the electromagnetic spectrum, resulting in a low absorption ratio of solar light. In addition, rapid electron-hole recombination limits its photocatalytic activity. To extend the application range of TiO2, the structural and chemical properties can be modified by adding various dopants to tune its electronic structure for applications within a wider range of the solar energy spectrum and ideally extend towards the visible region, which forms the dominant part of the solar energy spectrum. In this study, the structural and electronic properties of three polymorphs of TiO2 have been studied using density functional theory (DFT) as implemented in the Quantum ESPRESSO simulation package. The exchange-correlation potential has been treated with the generalised gradient approximation (GGA). Cationic substitution with non-toxic alkaline earth metal dopants Mg and Ca has been carried out with the aim of modifying the electronic structure of the polymorphs of TiO2. On 1–4% Mg and Ca cationic substitution, there is a slight expansion of the optimal unit cell volume and modulation of the band gap energy by raising the valence band maximum to higher energies. In addition, dopant inter and intra-band states are observed.