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Propulsion Shaft and Gearbox Failure in Marine Vessels: A Duration Model Analysis
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作者 d. e. onwuegbuchunam I. C. Ogwude +2 位作者 C. C. Igboanusi K. O. Okeke N. N. Azian 《Journal of Transportation Technologies》 2020年第4期291-305,共15页
The need to mitigate downtime in<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">marine vessels arising </span><span style="... The need to mitigate downtime in<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">marine vessels arising </span><span style="font-family:Verdana;">from propulsion system failures has led ship operating companies to devote enormous resources for</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">research based solutions. This paper applied duration models to determine</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">failure probabilities of shaft and gearbox systems in service boats. Using dockyard’s event history data on boat</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">repairs and maintenance, we applied Kaplan Meier hazard and survival curves to analyse</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">probability of failure</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">of shaft and gearbox</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">systems in supply, crew and tug boats. We found that average time to shaft and gearbox failure was 8.33, 5.23 and 5.21 months for tug, supply and crew boats respectively. The hazard plots however, showed that supply boats had higher probability of failure than crew boats and then tug boats in that order. Further analysis using Cox regression model showed that </span><span style="font-family:Verdana;">t</span><span style="font-family:Verdana;">he boats’ shaft and gearbox system failures were significantly affected by level of lubrication oil, stress corrosion cracking and impacts on the propul</span><span style="font-family:Verdana;">sion system’s components. The paper proposes that</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">design of maintenan</span><span style="font-family:;" "=""><span style="font-family:Verdana;">ce </span><span style="font-family:Verdana;">schedules for service boats should take the following into consideration: </span><span style="font-family:Verdana;">1)</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">estimated survival limits or failure times of propulsion system’s shaft and gearboxes</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> 2) significant risk factors that affect failure mode of</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">the propulsion system components.</span> 展开更多
关键词 Shaft and Gearbox Failure Propulsion System Hazard Rates Survival Analysis Service Boats
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Performance Evaluation of Motor Insurance Companies: Panel Data Evidence from Nigeria
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作者 G. U. Ugwuanyim d. e. onwuegbuchunam +1 位作者 d. C. Bartholomew C. C. Anikpe 《Journal of Transportation Technologies》 2021年第3期325-334,共10页
This paper evaluated performance of motor insurance companies in Nigeria. The objectives were to determine the following: 1) significant effects of claims settlements on motor insurance firms’ earned premium;2) diffe... This paper evaluated performance of motor insurance companies in Nigeria. The objectives were to determine the following: 1) significant effects of claims settlements on motor insurance firms’ earned premium;2) differences in managerial/technological capabilities among the companies and 3) effects of policy (or time effect) on insurance firms’ output within the study </span><span style="font-family:Verdana;">period. Panel data obtained for this study comprised operational data on</span><span style="font-family:Verdana;"> premium earned and direct claims settlement by these companies over a period </span><span style="font-family:Verdana;">of six (6) years. Using panel data statistical models, we found that direct</span><span style="font-family:Verdana;"> claims settlement negatively affected insurance companies’ earned premium. Also, </span><span style="font-family:Verdana;">significant differences in technological and managerial capabilities were </span><span style="font-family:Verdana;">found to exist among the companies, though only one company exhibited this heterogeneity. Besides, there were no policy impacts (or time effect) on vehicle insurance firms’ output in the study period. Policy implications of the results were discussed. 展开更多
关键词 Motor Insurance Premium Earned Claims Settlement Managerial and Tech-nological Performance Fixed Effects Regression
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Information &Communication Technology(ICT) Adoption in Nigerian Ports Terminal Operations
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作者 d. e. onwuegbuchunam M. O. Aponjolosun A. W. Ogunsakin 《Journal of Transportation Technologies》 2021年第3期311-324,共14页
Most ports around the globe have adopted ICT in a bid to improve their operational performance and remain competitive in the industry. However,</span></span><span><span><span style="fon... Most ports around the globe have adopted ICT in a bid to improve their operational performance and remain competitive in the industry. However,</span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> ports in developing economies still grapple with challenges associated with manual terminal operation. This paper evaluated the level of application</span><span style="font-family:Verdana;"> and integration of Information and Communication Technologies (ICT) and fac</span><span style="font-family:Verdana;">tors limiting their use in terminal operations in Nigerian seaports. The data for the study were obtained from copies of structured Likert scaled questionnaire administered to a random sample of terminal operators, stevedores, </span><span style="font-family:Verdana;">shipping companies’ agents, Customs licensed Clearing and Forwarding</span><span style="font-family:Verdana;"> agents (C&F) operating in Apapa and Tincan Island ports in Nigeria. Specifically, opinion of these respondents was sought on extent of ICT application, inte</span><span style="font-family:Verdana;">gration and perceived constraints to ICT use in port terminal operations.</span><span style="font-family:Verdana;"> Based on our findings using statistical model tests of proportion, the respondents stated that significant level of ICT procedures and processes have been adopted in port terminal operations. In terms of ICT applications, we found that electronic data and communication exchange applications were available in the terminals for use by the respondents. There are also in place ICT applications for warehouses and storage facilities management and e-payment </span><span style="font-family:Verdana;">systems. However, significant constraining factors were found to be: low ICT</span><span style="font-family:Verdana;"> investment budgetary allocation, lack of e-skilled manpower and poor equipment maintenance culture. Other limiting factors were lack of integrated ICT facilities operated by other port stakeholders and absence of Port Community Systems network (PCS) linking all other relevant interests connected to terminal operations. Policy implications of our findings were discussed. 展开更多
关键词 ICT Adoption Single Electronic Window ICT Application and Integration ICT Constraints Nigerian Ports
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Determinants of Inter-port Competition: A Case of Coastal Ports in West Africa 被引量:1
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作者 V. Omoke d. e. onwuegbuchunam 《Journal of Shipping and Ocean Engineering》 2018年第2期43-53,共11页
Ports operating in the same geographical range face significant competition among them. In such setting, less competitive ports may continually lose patronage of shippers (indigenous to them) to adjacent ones with b... Ports operating in the same geographical range face significant competition among them. In such setting, less competitive ports may continually lose patronage of shippers (indigenous to them) to adjacent ones with better attributes. The extent of and determinants of inter-port competition in the West Africa's coast are of interest to port administrators/operators who risk losing significant portion of their domestic generated cargo traffic to competing neighbouring ports. In this paper, we explore the question of what port specific attributes serve as competitive basis for West Africa's coastal ports operating in proximity to the other. Through a survey, users of these ports were asked to identify port specific attributes which they consider when deciding which port to use for shipments making. To enrich our empirical model, data collected from the survey were augmented with secondary data (on the identified attributes) obtained from the respective ports. Statistical evidence from data analysis suggests that ports operating in proximity in the West Africa's coast compete on the basis of attributes that minimise costs for port users, viz: ships' pre-berthiig time, ship turnround time, crane efficiency and availability of cargo spaces (proxied by frequency of ship calls). Policy implications of the findings were discussed. 展开更多
关键词 Port throughput inter-port competition ship turnround time ship calls frequency crane efficiency
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ISPS Code's Compliance and Operational Performance in Nigeria Seaports: Port Users Perspective
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作者 d. e. onwuegbuchunam M. O. Aponjolosun A. A. Oludare 《Journal of Shipping and Ocean Engineering》 2018年第2期54-62,共9页
In this paper, we developed performance assessment criteria to evaluate effects of compliance to ISPS Code's requirements on port/terminal operation in Nigeria. The primary data for the study were obtained from copie... In this paper, we developed performance assessment criteria to evaluate effects of compliance to ISPS Code's requirements on port/terminal operation in Nigeria. The primary data for the study were obtained from copies ofsurvey questionnaires administered to random sample of port users stratified by areas of specialisation. Hypotheses governing this study were based on the premise that additional port facilities provided and security measures adopted in compliance to ISPS code's requirements would have positive spillover effects on port operations. Evidence from data analysis indicated that compliance to ISPS code had positive effects on performance of operational performance of Nigeria ports. Similar effects were also observed inport users' satisfaction and profitability. The paper contributes by providing decision support framework for ports and terminals. monitoring and gauging outcomes of ISPS code administration in 展开更多
关键词 ISPS code port performance turnround time cargo throughputs vessel throughputs
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Sensitivity Analysis on the Negative Degree of Difficulty Geometric Programming Problem
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作者 H. O. Amuji N. P. Olewuezi +1 位作者 d. e. onwuegbuchunam C. Igboanusi 《American Journal of Operations Research》 2020年第1期13-23,共11页
The range of optimal values in cost optimization models provides management with options for decision making. However, it can be quite challenging to achieve feasible range of optimality in Geometric programming (Gp) ... The range of optimal values in cost optimization models provides management with options for decision making. However, it can be quite challenging to achieve feasible range of optimality in Geometric programming (Gp) models having negative degrees of difficulty. In this paper, we conduct sensitivity analysis on the optimal solution of Geometric programming problem with negative degree of difficulty. Using imprest data, we determine the optimal objective function, dual decision variables, primal decision variables;the range of values, the cost coefficient and RHS constraint must lie for the solution to stay optimal. From the analysis, we established that incremental sensitivity analysis has the functional form . 展开更多
关键词 NEGATIVE DEGREE of DIFFICULTY Sensitivity Analysis Primal DECISION VARIABLES Dual DECISION VARIABLES Global Optimal Solution
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