http://ir.mu.ac.ke:8080/jspui/handle/123456789/61 2026-08-25T11:17:39Z 2026-08-25T11:17:39Z Kipnoo, Rotich E.K Isoe, G.M. Kiboi, Boiyo c Kuja, S. Waswa, , D. Leitch, A.W.R. http://ir.mu.ac.ke:8080/jspui/handle/123456789/10462 2026-08-24T08:04:43Z 2020-03-01T00:00:00Z

All optical polarization-based and DSP-Assisted distributed fiber sensor for earth mass movements caused by environmental factors Kipnoo, Rotich E.K; Isoe, G.M.; Kiboi, Boiyo c; Kuja, S.; Waswa, , D.; Leitch, A.W.R. Fiber optic sensors for industrial, consumer, medical and military applications have been reported. Their working principle is majorly based on non-linear optics. For the first time to our knowledge, we propose a cost-effective real time monitoring polarization-based digital signal processing (DSP)-assisted sensor that relies on linear optics for application in earth mass movements due to environmental factors. A sensitivity of 0.075 kg−1 is achieved. This is realized on an average SOP speed of 0.83°/s yielding 598° angular drift on its polarization changes. A sensing performance comparison of single mode fiber (SMF) and large effective area fiber (LEAF) fiber is reported.

2020-03-01T00:00:00Z Naibei, Victor Chepkech Choge, Dismas Jena, James Waswa, David Boiyo, Duncan Kiboi http://ir.mu.ac.ke:8080/jspui/handle/123456789/10461 2026-08-24T07:41:08Z 2026-06-01T00:00:00Z

Tunable Phase Shifters for 6G Beamforming Networks Naibei, Victor Chepkech; Choge, Dismas; Jena, James; Waswa, David; Boiyo, Duncan Kiboi The deployment of 6G network requires multiple number of antennas at the base station with multiple signals that undergo constructive interference to create thinner beams with more energy so as to mitigate path loss. This will support higher data rates, lower latency levels, and improved energy efficiency. This paper proposes a phase-shifting technology for beamforming that focuses radio energy to a specific user equipment, thus maximizing spectral efficiency. We present a novel approach of phase-shifting technology by generating tunable microwave pulses using the slicing-level technique in an optoelectronic oscillator (OEO) setup. Two laser sources undergo intensity and phase modulation using a well-characterized Mach–Zehnder modulator and a phase modulator. Modulating signals in the range of 100 kHz–13.3 MHz are used to generate microwave waveforms. Repetition-rate-tunable pulses are generated from the microwave waveforms using the slicing-level technique. Photonic-assisted tunable pulses generated have a pulse width ranging from 0.6 ns to 7.5 μs and a duty cycle ranging from 17% to 96% optimized for phase shifting (𝜑) of signals, with potential for multiple antenna elements, which act as time delays aimed at creating constructive interference of the beams that form a concentrated beam of energy. This work successfully creates phase shifters ranging from 14° to 299° that can be used to steer antennas for 6G network by controlling pointing angles at the antenna array terminals, which creates a multiplex transmission line as a linear combination of signals.

2026-06-01T00:00:00Z Bishir, Sadiq Ramkat, Rose Chepchirchir Makatiani, Jacqueline Kubochi Njira, Njira Pili http://ir.mu.ac.ke:8080/jspui/handle/123456789/10448 2026-08-12T07:00:34Z 2026-07-01T00:00:00Z

Valorization of shrimp shell waste into functional chitosan: recent advances, analytical challenges, and future perspectives Bishir, Sadiq; Ramkat, Rose Chepchirchir; Makatiani, Jacqueline Kubochi; Njira, Njira Pili The increasing accumulation of shrimp shell waste from seafood processing presents both an environmental challenge and an opportunity for sustainable biomass valorization within the circular bioeconomy. Chitosan, a biodegradable and biocompatible polysaccharide obtained through chitin deacetylation, has emerged as a versatile biomaterial with broad applications in biomedicine, agriculture, environmental remediation, food packaging, and advanced functional materials. This review critically evaluates recent advances in the production of chitosan from shrimp shell waste, emphasizing extraction technologies, quality determinants, structural characterization, and analytical evaluation. Conventional chemical extraction is critically compared with emerging green approaches, including microwave-, ultrasonic-, autoclave-, enzymatic-, fermentation-, and deep eutectic solvent-assisted processes, highlighting their effects on yield, degree of deacetylation, molecular weight, scalability, and environmental sustainability. Current characterization and analytical methods are comparatively assessed, with particular emphasis on the complementary role of 3,5-dinitrosalicylic acid (DNSA)-based assays for reducing-end quantification during chitosan depolymerization. The review further discusses advances in functionalized chitosan derivatives, nanocomposites, industrial translation, and sustainable production strategies while identifying standardization of extraction and analytical protocols as a critical requirement for improving reproducibility and facilitating commercial-scale production. Collectively, this review provides an integrated perspective on current progress, remaining challenges, and future research priorities for developing high-quality chitosan from shrimp shell waste.

2026-07-01T00:00:00Z Sorowen, Ben Nyamwala, Fredrick Ambogo, D.O. http://ir.mu.ac.ke:8080/jspui/handle/123456789/10414 2026-07-28T06:51:36Z 2025-12-01T00:00:00Z

Construction of symmetric third order difference operators on a Hilbert space Sorowen, Ben; Nyamwala, Fredrick; Ambogo, D.O. We have constructed a symmetric third order difference equation and studied the absolutely continuous spectrum of the self adjoint subspace extension generated using the subspace and decomposition theories. In particular, we have shown that under some decay and growth conditions, the self-adjoint subspace extension exists with discrete spectrum on l2(N) while the absolutely continuous spectrum contained on half line of multiplicity one exists on l2(Z) if we use decomposition technique. We have given a number of examples to reinforce our results.

2025-12-01T00:00:00Z