http://41.93.71.3:8080/xmlui/handle/123456789/7 2026-05-02T05:02:20Z 2026-05-02T05:02:20Z Mwita, L.C Geoffrey2, R.J. http://41.93.71.3:8080/xmlui/handle/123456789/194 2026-01-08T10:23:04Z 2020-07-01T00:00:00Z

Evaluation of Compressor Anti-Surge Control During Unexpected Shutdown Mwita, L.C; Geoffrey2, R.J. Abstract Compressors play significant roles in the oil and gas industries. Compressors’ operating points shift to the surge line during startup or emergency shutdown as the flow decreases. Surge causes a compressor to lose the ability to maintain peak head, causes the system to overheat, reduces discharge pressure, damages thrust bearing, and make the entire system unstable. This study aims to evaluate compressor anti-surge control in emergence shutdown using Aspen HYSYS. Aspen HYSYS Dynamics extends models into dynamic model enabling process verification control scheme, design, safety studies, relief valve sizing and rating, failure analysis, development of a startup, shutdown, and operational model changes. Extensive numerical and graphical results generated from dynamic models in Aspen HYSYS allow for in-depth analysis for each completed simulation. The study used dynamic simulation to confirm the recycling valve’s performance and computing surge control scaling of a boil-off gas compressor. The study investigated further if the anti-surge valve would open during operation, keeping the compressor from surging and testing compressor procedure during startup and shutdown. Simulation results show that when the inlet gas flow decreases, compressor speed increases and all anti-surge valves opened to keep the compressor away from a surge. Finally, the paper reveals compressor performance, such as efficiency, surge control line, compressor duty, control tuning parameters, and valve flow coefficient can be predicted using Aspen HYSYS. Thus, the use of Dynamic simulation is a great and efficient design tool for the centrifugal compressors system, and it is highly recommended. For the simulation result to reflect what happens in the plant, it is recommended to select an appropriate thermodynamic method. Improper selection of the thermodynamic model and plant data inconsistent will produce an absurd result. For oil and gas applications, it is advised to use the Peng-Robinson equation of state. It provides accurate results, an extensive applicability range in terms of temperature and pressure, and has a comprehensive binary interaction parameter database.

2020-07-01T00:00:00Z Muya1, *Francis Mganilwa2, Zacharia M.D. Mgaya 3, Prosper L. http://41.93.71.3:8080/xmlui/handle/123456789/193 2025-09-19T10:53:30Z 2023-01-01T00:00:00Z

Realizing the Benefits of Tanzania’s Standard Gauge Railway Flagship Project. A Marketing Mix Perspective Muya1, *Francis; Mganilwa2, Zacharia M.D.; Mgaya 3, Prosper L. The Government of Tanzania has invested heavily in Flagship Projects specifically the nation's transport infrastructures to ensure that every part of the country is accessible. These include road and railway infrastructures, especially the Standard Gauge Railway (SGR) which has been heavily invested in recently. Although many strategic options lead to the realization of the SGR project gains in terms of the number of passengers and freight carried, total operating cost, revenues, and high customer satisfaction, a marketing mix lens which involves the application of specific controllable marketing variables, leaves much to be desired. This study involved an intensive review of the literature and interviews with railway experts to determine and assess potential marketing mix benefits during the operations of the SGR project. Data were collected using an interview guide and analysed using the contents analysis technique. The study found that Tanzania Railways Corporation (TRC) must properly align the SGR service and overall corporations’ operations along the marketing mix elements of product, price, promotion, place, people, processes, and physical evidence for the realization of indirect benefits of SGR project. This can be possible through preparing marketing plans, communication, and marketing strategies to integrate the stated elements within the railway organizational setting.

2023-01-01T00:00:00Z Muya1, *Francis Mganilwa2, Zacharia M.D. Mgaya 3, Prosper L. http://41.93.71.3:8080/xmlui/handle/123456789/192 2025-09-19T10:52:53Z 2023-01-01T00:00:00Z

Realizing the Benefits of Tanzania’s Standard Gauge Railway Flagship Project. A Marketing Mix Perspective Muya1, *Francis; Mganilwa2, Zacharia M.D.; Mgaya 3, Prosper L. The Government of Tanzania has invested heavily in Flagship Projects specifically the nation's transport infrastructures to ensure that every part of the country is accessible. These include road and railway infrastructures, especially the Standard Gauge Railway (SGR) which has been heavily invested in recently. Although many strategic options lead to the realization of the SGR project gains in terms of the number of passengers and freight carried, total operating cost, revenues, and high customer satisfaction, a marketing mix lens which involves the application of specific controllable marketing variables, leaves much to be desired. This study involved an intensive review of the literature and interviews with railway experts to determine and assess potential marketing mix benefits during the operations of the SGR project. Data were collected using an interview guide and analysed using the contents analysis technique. The study found that Tanzania Railways Corporation (TRC) must properly align the SGR service and overall corporations’ operations along the marketing mix elements of product, price, promotion, place, people, processes, and physical evidence for the realization of indirect benefits of SGR project. This can be possible through preparing marketing plans, communication, and marketing strategies to integrate the stated elements within the railway organizational setting.

2023-01-01T00:00:00Z Msumanje, G.P1. http://41.93.71.3:8080/xmlui/handle/123456789/191 2025-09-19T09:47:02Z 2021-01-01T00:00:00Z

Public Transport Service Reliability in Dar es Salaam City, Tanzania: A Case of Bus Rapid Transit (BRT) Msumanje, G.P1. The main problems of BRT service users are delays and overcrowding at stations and in buses during peak hours. This situation causes low region productivity, accidents, insecurity, poor students’ academic performance and increased health risks. The objective of the study was to analyze the satisfaction of passengers with BRT service reliability. Case study design with mixed approach for data collection and analysis was adopted. A total of 138 respondents represented the relevant study population. The study revealed that more than 70% of the respondents showed dissatisfaction on schedule adherence caused by inadequate bus supply, ineffective ticketing systems, ineffective bus scheduling, bus breakdowns and accident, poor passenger information, weather conditions, drivers’ behavior and traffic interactions. It is recommended that the service provider (BRT) should supply sufficient buses, build staff capacity and implement Intelligent Transport Systems (ITS) for management of its service

2021-01-01T00:00:00Z