Physics
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Item 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.Item Density Functional Study of Structural and Electronic Properties of Ca and Mg Doped Tio2(2022) Mbae, J. K.; Muthui, Z. W.The scarcity of affordable and environment-friendly sources of energy has led to emergence of photocatalysis to mitigate this problem. This is especially so if the photo catalysts are active in as much a wide region of the solar energy spectrum as possible. Environment-friendly, non-toxic and economical photocatalysts would find application in water treatment, providing another solution to the problem of clean water for domestic use. Of many materials available for photocatalysis is Titanium (IV) oxide (TiO2). It possesses many merits such as low cost, high photocatalytic activity, non-toxicity and high availability. However, drawbacks that limit its application include its optical absorption that falls in the ultraviolet part of the electromagnetic spectrum and rapid electron-hole recombination, which limits its photoquantum efficiency. To extend the optical absorption to a wider region of the solar energy spectrum, various dopants have been added to the oxide. In this study, the effect of doping rutile TiO2 with alkaline earth metals Ca and Mg is investigated using the Density Functional Theory (DFT) method as implemented in the Quantum ESPRESSO simulation package, treating the exchange correlation potential with the Generalised Gradient Approximation. The optimized cell parameters for pure rutile crystal system are 𝑎 = 𝑏 = 4.603Å 𝑐 = 2.992Å, with a volume of 63.393 (Å)3. On doping there is a slight expansion of the crystal structure and its volume slightly increases by 8.753 (Å)3 and 28.816 (Å)3 with Mg and Ca doping respectively. The calculated band gap of undoped rutile is 1.8 eV. Mg and Ca doping raises the valence band edge by 0.2 eV in both Ca and Mg doped rutile. Dopant inter band and intra band states are observed that would be useful in mitigating against charge recombination hence enhancing the efficiency of the photocatalysts. Isolated O 2p states are observed in the Projected Density of States (PDOS) of the doped systems which are normally attributed to enhanced optical absorption of photocatalysts in the visible region. Alkaline earth metal doping of TiO2 rutile modifies the structural and electronic properties of rutile TiO2 in a manner that would make it a more efficient photocatalyst. Co-doping with the alkaline metal dopants could be attempted to investigate the combined effect.Item An Application of Maximal Numerical Range on Norm of Basic Elementary Operator in Tensor Product(Scitech Research Organisation, 2022) Daniel, B.; Ndungu, K.; Musundi, S.Many researchers in operator theory have attempted to determine the relationship between the norm of basic elementary operator and the norms of its coefficient operators. Various results have been obtained using varied aTphpirsosatcuhdeys. In this paper, we attempt this problem by the use of the Stampfli’s maximal numerical range in a tensor product.Item PHYS 224: PHYSICS PRACTICAL IV(Chuka University, 2023-04-13) Chuka UniversityItem ECDE 0135: MATERIAL DEVELOPMENT IN ECDE(Chuka University, 2023-04-13) Chuka UniversityItem PHYS 113: PHYSICS II(Chuka University, 2023-04-13) Chuka UniversityItem PHYS 372 DIGITAL ELECTRONIC(2023) Chuka UniversityItem PHYS 111: GENERAL PHYSICS(Chuka University, 2023) Chuka UniversityItem PHYS 861: STATISTICAL MECHANICS(Chuka University, 2023-09-01) CHUKA UNIVERSITYItem PHYS 832: QUANTUM MECHANICS(Chuka University, 2023-09-01) CHUKA UNIVERSITYItem PHYS 495: AERONOMY AND PALEOMAGNETISM(Chuka University, 2023-04-19) CHUKA UNIVERSITY