Papers by Thaddeus C H I D I E B E R E Nwaoha
Journal of Structural Integrity and Maintenance, 2019
Majority of the world cargoes is transported through the sea, and failure of the ship structure i... more Majority of the world cargoes is transported through the sea, and failure of the ship structure is a major concern and thus needs to be avoided due to its catastrophic nature in terms of system loss. In view of this, ship structural safety is assessed regularly so as to prevent their failures and implement cost-effective improvement measures that ensure optimal operations, especially in the realm of uncertainty. In this research, a methodology for safety assessment and optimization of ship structures using discrete fuzzy set theory as an artificial intelligence method and Technique for Order Preference by Similarity to the Ideal Solution as a multi-criteria decision-making method is developed. The two algorithms are integrated in a logical manner to achieve ship structural safety optimization under uncertainty.
Proceedings of 98th IASTEM International Conference, Ottawa, Canada, 2017
Managing outbound supply of manufacturing products in a multi-echelon systems is noticeably more ... more Managing outbound supply of manufacturing products in a multi-echelon systems is noticeably more complex than managing them in a single-echelon system. Unfortunately, engineering managers rely on local heuristics while making allocation decision. Rule of thumb strategies does not guarantee optimal solution. In this study, an algorithm for effective transshipment has been developed. The model was tested using information from a bottling plant in Nigeria. It was observed that the source distribute products to downstream location at a high cost, not meeting the demand at required outbound neighbourhood. At the end of the analysis, the results obtained showed that the developed model eliminated several deficiencies since all depots got a fraction of the products demanded at all destinations in a cost effective manner. It is concluded that the model is effective for reducing or minimizing distribution expenses while fulfilling demand at all destinations.
FUW Trends in Science & Technology Journal, 2019
The huge cost associated with rehabilitating workers suffering from epidemiological conditions as... more The huge cost associated with rehabilitating workers suffering from epidemiological conditions as a result of performing daily repetitive tasks that involves awkward postures in lifting low lying heavy loads in our workplace has been on the increase, as shown by records available in our health institutions. To address this problem in our workplaces, it becomes imperative that a simple device that can automatically lift and lower heavy objects powered by solar energy was conceived, designed and developed using available local materials and technology. This device was designed in such a way as to reduce the man-machine interface to the least minimum. Test carried out using the developed five tone solar powered hydraulic screw jack showed that the device can lift or lower heavy loads within its design limit to or from a height of four hundred 400 mm) in less than two minutes 2 min). It is our view that this cost effective lifting device be commercialized to eliminate these ugly health challenges among our workforce, thus encouraging more youths to become engaged as lifters in our industrial settings. This will in turn create employment among the youths, improve the already low standard of living and increase our national gross domestic product as a nation.
FUW Trends in Science & Technology Journal, 2019
Comprehensive Maritime Formal Safety Assessment (MFSA) methodology is applied in marine diesel en... more Comprehensive Maritime Formal Safety Assessment (MFSA) methodology is applied in marine diesel engine of a ship that is used in offshore environment to improve engine performance by reduction, prevention and mitigation of risk associated with its operation. The research focused on risk of crankcase explosion of the diesel engine, high pressure fuel line bursting, turbo charger explosion, suffocation from asphyxiating gases, burns, exposure to noise, vibration and explosions and fires in the exhaust manifold, which are estimated using expert engineering judgement. Possible ways of risk reduction and prevention that can ensure best output of the marine diesel engine are revealed, together with cost implications. Most preferred ways for the risk reduction and operational efficiency of marine diesel engine is recommended.
JOURNAL OF STRUCTURAL INTEGRITY AND MAINTENANCE, 2019
Majority of the world cargoes is transported through the sea, and failure of the ship structure i... more Majority of the world cargoes is transported through the sea, and failure of the ship structure is a major concern and thus needs to be avoided due to its catastrophic nature in terms of system loss. In view of this, ship structural safety is assessed regularly so as to prevent their failures and implement cost-effective improvement measures that ensure optimal operations, especially in the realm of uncertainty. In this research, a methodology for safety assessment and optimization of ship
structures using discrete fuzzy set theory as an artificial intelligence method and Technique for Order Preference by Similarity to the Ideal Solution as a multi-criteria decision-making method is developed. The two algorithms are integrated in a logical manner to achieve ship structural safety optimization under uncertainty.
Journal of Multidisciplinary Engineering Science and Technology, 2016
All over the world, there is an urgent need for effective fluid control equipment, such needs can... more All over the world, there is an urgent need for effective fluid control equipment, such needs can be found in foods, drugs, beverages, power generation, and oil and gas industries. Some of the existing equipment for this purpose has certain limitations for effective control of fluid at high pressure condition. Thus, there is a need for design modification to solve the prevailing problem. This paper majorly addressed the case peculiar to the oil and gas industries, where fluid control failure has cost millions of dollars, hazardous environmental effect and also decline in nation's economy, taking Niger Delta oil spillage as a case study. In this work, computer aided design method (CADM) was utilized to design and perform stress analysis of a high pressure gate valve used on a typical oil and gas wellhead of working pressure up to 15,000 psi. (103.4 MPa). The critical components in the gate valve are the body and gate (disc). Conversional design adopts calculations from analytical method, but in this work, finite element analysis (FEA) was used to determine stresses and deformations distribution on critical components of the high pressure gate valve (HPGV) as they are the main pressure retaining boundaries in the valve. The results obtained from the two methods indicated reasonable convergence after validation. The stress analysis conducted was based on von mises failure criterion which is most suitable for ductile materials. The results obtained from both analytical design calculation and that of finite element analysis indicates reasonable agreements by measuring their percentage performance variance. Therefore, the findings of this research work attests to reliability of the designed HPGV valves in meeting engineering design assessments, and in turn can be optimally advanced in the manufacture of high pressure gate valves.
International Journal of Scientific Research in Information Systems and Engineering, 2016
The overall aim of this research is to develop an efficient accident causative model for job haza... more The overall aim of this research is to develop an efficient accident causative model for job hazards prevalent in an oil and gas facility operating onshore and offshore conurbation and estimate future accident expenditure in the system. A questionnaire survey was used based on the findings from the interviews and focus group discussions. Markovian model was developed using QM for Windows software. The possible types of the accident for a company operation onshore and offshore environment were investigated. It was found that oil and gas workers were exposed to different hazards despite the existing legislations enacted to impact on the provision of occupational health and safety in the industry. The accident types investigated include Road, Marine, helicopter, workplace, medical, attack, community invasion, and fire. Road transportation can be seen to be the most prevalent source of an accident followed by a workplace hazard. From the model developed using Markov analysis, it is evident that 99.8% of workers in the Trivial state (S3) would transit to Terminal state (S1); it was also noticed from the F matrix that it would take an average period of 4 years and eight months for this transition. However, it was observed that 99.8% of workers in Major state (S2) would transmit to a terminal state (S1) at an average period of 2 years as shown in the F matrix. It is therefore recommended that road leading to the inbound and outbound facilities of the company should be in an excellent condition; offshore workers must receive adequate training on survival at sea and helicopter underwater escape. Site workers must also be properly kitted with personal protective equipment to prevent workplace hazard.
Journal of Sustainable Technology, 2015
Use of engineering judgement in design and production of quality product is inevitable. Thus, des... more Use of engineering judgement in design and production of quality product is inevitable. Thus, design optimization is important in development of efficient engineering products. Failure to
identify important design criteria and estimate their associated significance in design and development of an engineering system can result to design, manufacturing, assembly and operating errors.
Therefore, vital design criteria of an engineering product need to be identified and their various level of importance (i.e. weights) revealed using powerful engineering tool. To address this challenge, an Analytical Hierarchy Process (AHP) methodology was employed. The technique was adopted in weight estimation of the wheelchair design criteria such as manufacturing cost (MC), availability of material (AM), reliability (R), nature of environment to be used (NEU), efficiency (E) and anthropometry (A). Experts judgement were employed in the pairwise comparison of the criteria to facilitate the revealing of the criterion with higher weight and the one with lower weight using the mechanism of
the AHP technique. A criterion with higher weight is more important than the one with lower weight and vice versa. The illustrative case study revealed that the AHP technique is a viable tool for weight estimation of the wheelchair design criteria.
West African Journal of Industrial & Academic Research , 2015
A review of the West African ocean current energy generating potential is carried out. The peculi... more A review of the West African ocean current energy generating potential is carried out. The peculiarity of the West African ocean characteristic is discussed and the challenges noted. Based on this review, it is found that ocean current represents an alternative source of renewable energy in West Africa in a streamed regular supply. The ocean weather condition is mild and offers good benefit to marine operations with respect to renewable energy conversion system installations offshore. In the perspective of the authors, it is believed that engineering and scientific investments are necessary in order to harness the ocean current renewable source in West Africa. Suggested techniques include-Application of momentum diffusion technology to the ocean current flow system; Design of ocean current generating system whose efficiency relies more on volume flow rather than fast running fluid velocities; Investigation into reported increased velocities suspected to be due to hydrodynamic influence of discharging upland rivers into the ocean water systems. A success of such confirmation will lead to the use of conventional generating system in such locations.It is largely hoped that aggressive interests in the subject area will open wide opportunities in the ocean current renewable energy source to supplement the intense energy demand of this part of the continent.
Journal of Mechanical and Energy Engineering,, 2019
Hydrostatic parameters of a ship are very important in ship design. The importance of
the paramet... more Hydrostatic parameters of a ship are very important in ship design. The importance of
the parameters compared to one another need to be revealed in realm of uncertainty, so as to
avoid design error. In view of this, a fuzzy-analytical hierarchical process (Fuzzy-AHP) method is
utilized in addressing the subject under investigation. The fuzzy logic is used to address
uncertainty in pairwise comparison exercise, so as to facilitate the estimation of order of
importance of hydrostatic parameters. In this research, the engineering judgements of three
designers in analysis of importance of hydrostatic parameters are aggregated and processed using
the Fuzzy-AHP methodology. The result produced in the study showed that hydrostatic
parameters are importance in order of moments of inertia of vessels (MIV), mass displacement
(MD), tons per centimeter immersion (TPCI), coefficients of form (CF), centers of buoyancy
(CB), metacentric heights of vessels (MHV), ship waterplane area (SWA), longitudinal center of
floatation (LCF), volume displacement (VD) and wetted surface area (WSA) with weight values
of 0.218, 0.095, 0.078, 0.083, 0.074, 0.1, 0.46, 0.108, 0.209 and 0.028 respectively.
Scientific Journal of Maritime Research, 2018
This paper suggests Fuzzy-logic-rule base method to assess the performance status of a wharf in o... more This paper suggests Fuzzy-logic-rule base method to assess the performance status of a wharf in order
to classify it. The method proposed is predicated upon its ability to analyse processes and operations
based on subjective judgement with little or no statistical data available. The study also shows that
fuzzy-logic rule base is a veritable tool to qualitatively and quantitatively assess the status of a wharf
offering ferry service. Using the model developed in this study, the performance status of Yenagoa
wharf has been determined to be orange, having a (WPS) overall of 4.8. The status of the wharf has been
in good agreement with the perception of stakeholders that the Yenagoa wharf needs restructuring
to curb the frequent crisis occurring among stakeholders. The model also indicated those areas of the
wharf’s operations needing attention. The study indicates that even though major components that
determine the quality and profitability of the wharf’s ferry service are high in value, the overall status
of the wharf may not be necessarily high. As such, the study method can be used to control the growing
ill-feeling between boat operators and passengers while harmonizing all stakeholders (operators,
passengers, and regulators etc) to work together to improve the status of the wharf.
International Journal of Integrated Engineering, 2018
Sea harvester is a vital marine vessel needed in sea safety and cleanliness. Reliability and safe... more Sea harvester is a vital marine vessel needed in sea safety and cleanliness. Reliability and safety of the
operations of the vessel need to be ensured via identification of hazards/failures that tends to affect the system and
prevent them from occurring and also mitigate their consequences. In this research, a traditional hybrid
methodology is employed in ensuring the reliability and safety of a sea harvester. The methodology is a logical
combination of preliminary hazard analysis (PHA), risk matrix approach (RMA) and event tree analysis (ETA).
Fire, flood, machinery failure and capsize that pose to affect optimal operations of a sea harvester are identified
using a PHA method. RMA is incorporated in application of the PHA method to estimate the risks associated with
them. Due the fact that risks associated with fire, flood, machinery failure and capsize are classified as very high,
identifying preventing measures becomes necessary. Furthermore, systems which by means of their operability and
non-operability can mitigate fire, flood, machinery failure, capsize and grounding consequences are captured using
an ETA method. Therefore, the traditional hybrid methodology developed is successfully applied in design for safety, construction and operation of a sea harvester.
Journal of Marine Science and Application, 2016
This study discusses the analysis of various modeling approaches and maintenance techniques appli... more This study discusses the analysis of various modeling approaches and maintenance techniques applicable to the Liquefied Natural Gas (LNG) carrier operations in the maritime environment. Various novel modeling techniques are discussed; including genetic algorithms, fuzzy logic and evidential reasoning. We also identify the usefulness of these algorithms in the LNG carrier industry in the areas of risk assessment and maintenance modeling.
Proc IMechE Part M: J Engineering for the Maritime Environment, 2016
Fault tree analysis is a known methodology used for analysing engineering systems. The approach i... more Fault tree analysis is a known methodology used for analysing engineering systems. The approach is usually conducted
using known failure data. Given that most maritime operations are conducted in a challenging and uncertain environment,
their failure data are usually unavailable requiring a flexible and yet robust algorithm for the analysis of the systems.
This research therefore seeks to analyse hazards of ships during ship and port interface operations as a result of manoeuvring
by incorporating fuzzy fault tree analysis method to optimise the performance effectiveness of the system.
Fuzzy set theory provides the needed flexibility to represent vague information from the analysis process. The methodology
is structured in such a manner that diverse sets of data can be integrated and synthesised for analysing the system.
It is envisaged that the proposed method could avail safety specialist with a simple and a step-by-step framework
for evaluating maritime hazards in seaport operations in a concise way.
International Journal of Maritime Engineering, 2016
Safety Critical Maritime Infrastructure (SCMI) systems are vulnerable to diverse risks in their c... more Safety Critical Maritime Infrastructure (SCMI) systems are vulnerable to diverse risks in their challenging field of operations due to their interactions and interdependence. In addition, the multiplicity of stakeholders in these systems and the complex operational scenarios are often associated with a high level of uncertainty because they usually operate in a dynamic environment in which the boundaries of safety are pushed, leading to the disruption of operations. Therefore, the safety of these systems is very important to ensuring resilience of their operations. This research is focus on the background analysis of SCMI systems. This includes operational processes of SCMI systems, security threats and estimates of economic damage to the system, resilience engineering literature relevant to maritime operations; regulatory overview including risk governance of the systems, lessons learnt from major accidents and a concluding remark is drawn.
Proc IMechE Part M: J Engineering for the Maritime Environment, 2016
Prediction of fuel consumption rate level of a vessel per voyage posed to be a challenge under un... more Prediction of fuel consumption rate level of a vessel per voyage posed to be a challenge under uncertainties. In such uncertain conditions, revealing of fuel consumption rate levels of the fleet of vessels is deemed imperative to ensure effective and efficient operations of the vessels per voyage. Therefore, development of uncertainty treatment model is necessary in this research. A combined algorithm that is made up of fuzzy rule base and utility theory methods is incorporated in the investigation of the fuel consumption rate levels of marine vessels. The mechanism of the algorithm is used to capture and combine all the important parameters that determine the fuel consumption rate level of each marine vessel. The workability of the model is demonstrated. The produced results revealed that the combined algorithm can support estimation of the fuel consumption rate levels of marine vessels and show which vessel is better than the other. Based on the results of this article, the management and crew of a marine vessel are equipped with the necessary decision support tool to optimize, implement and manage improvements on the performance characteristics and fuel consumption rate of their marine vessels during voyages.
Ships and Offshore Structures, 2014
Liquefied natural gas (LNG) transfer arms have been in regular operations due to rapid increase i... more Liquefied natural gas (LNG) transfer arms have been in regular operations due to rapid increase in the demand of an LNG. The LNG transfer arms are used in loading and unloading of the LNG to ships and onshore tanks. Best safety practises need to be put in place for effective operations of the transfer arms. The cost of carrying out such exercise must be considered for industrial benefit. Therefore, an investigation of the cost of implementation of safety improvement measures (SIMs) for optimal operations of an LNG transfer arm need to be carried out under uncertainty. Such SIMs can be used in protection of the environment and ship crew members. A model that is made of a hybridised algorithm such as fuzzy logic and evidential reasoning (ER) is employed for the exercise. The model is used to capture all the necessary information that is needed in addressing uncertainties associated with the costs of application of the SIMs. The mechanisms of the ER algorithm such as aggregation of multiple ideas to a single level are incorporated into intelligent decision system software to facilitate identification of a SIM that can optimise the LNG transfer arm operations in a cost effective manner.
Proc. IMechE Vol. 225 Part M: J. Engineering for the Maritime Environment, 2011
In this research, the safety/risk level of a liquefied natural gas (LNG) carrier system is invest... more In this research, the safety/risk level of a liquefied natural gas (LNG) carrier system is investigated through the application of a fuzzy evidential reasoning (FER) method to uncertainty treatment of its failure modes. A fuzzy set manipulation formula with multiple parameters such as consequence severity, failure consequence probability, and failure likelihood is used to assess the safety/risk levels of failure modes of the system. Such failure estimations are synthesized to evaluate the whole system's safety/risk level using an evidential reasoning (ER) approach. Risk control options (RCOs) are developed for reduction/control of high-risk level of the system. The best RCO, which is the one with the highest preference degree, is used to improve the safety level of the system.
Proc. IMechE Vol. 225 Part E: J. Process Mechanical Engineering, 2010
The concept of genetic algorithm (GA) is used to model the cost of maintenance and repair of a li... more The concept of genetic algorithm (GA) is used to model the cost of maintenance and repair of a liquefied natural gas (LNG) containment system and its transfer arm, after assessing the total risk of the systems using the probabilistic risk assessment technique. The failure frequency data of the basic events of the fault tree developed to model the LNG containment system and transfer arm, which is implemented and evaluated to estimate the failure frequencies of the systems, are derived from a careful literature search. A total risk formula is developed, which is dependent on hazard severity weight, failure frequencies, and the time and cost of maintenance and repair of the LNG carrier systems. The formula serves as the objective function, while new total cost allocated for the maintenance and repair of the LNG carrier systems as a whole is the constraint with the boundaries of presenting initial/unit cost of maintenance and repair of each containment system and transfer arm. Optimization is carried out on the objective function and its constraint for the identification of new cost of maintaining and repairing the containment system and transfer arm independently with the powerful tool of GA using Matlab version 7.7 software for improvement of the system's safety level.
Ship and Offshore Structures, 2016
The failure-based implications of a cavitating propulsion system on the operations of the ship ar... more The failure-based implications of a cavitating propulsion system on the operations of the ship are analysed; in line with cost distribution plan and impact of adopted preventive and corrective measures under uncertainty. Therefore, a methodology comprised of discrete fuzzy logic, evidential reasoning and utility theory is developed, for the purpose of addressing cavitation prevention and reduction on ships in a cost-effective manner. The framework is capable of reducing the frequency of failure occurrence of ship propeller due to cavitation and/or mitigates their possible consequences through improvement of the design standards and operational practices.
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Papers by Thaddeus C H I D I E B E R E Nwaoha
structures using discrete fuzzy set theory as an artificial intelligence method and Technique for Order Preference by Similarity to the Ideal Solution as a multi-criteria decision-making method is developed. The two algorithms are integrated in a logical manner to achieve ship structural safety optimization under uncertainty.
identify important design criteria and estimate their associated significance in design and development of an engineering system can result to design, manufacturing, assembly and operating errors.
Therefore, vital design criteria of an engineering product need to be identified and their various level of importance (i.e. weights) revealed using powerful engineering tool. To address this challenge, an Analytical Hierarchy Process (AHP) methodology was employed. The technique was adopted in weight estimation of the wheelchair design criteria such as manufacturing cost (MC), availability of material (AM), reliability (R), nature of environment to be used (NEU), efficiency (E) and anthropometry (A). Experts judgement were employed in the pairwise comparison of the criteria to facilitate the revealing of the criterion with higher weight and the one with lower weight using the mechanism of
the AHP technique. A criterion with higher weight is more important than the one with lower weight and vice versa. The illustrative case study revealed that the AHP technique is a viable tool for weight estimation of the wheelchair design criteria.
the parameters compared to one another need to be revealed in realm of uncertainty, so as to
avoid design error. In view of this, a fuzzy-analytical hierarchical process (Fuzzy-AHP) method is
utilized in addressing the subject under investigation. The fuzzy logic is used to address
uncertainty in pairwise comparison exercise, so as to facilitate the estimation of order of
importance of hydrostatic parameters. In this research, the engineering judgements of three
designers in analysis of importance of hydrostatic parameters are aggregated and processed using
the Fuzzy-AHP methodology. The result produced in the study showed that hydrostatic
parameters are importance in order of moments of inertia of vessels (MIV), mass displacement
(MD), tons per centimeter immersion (TPCI), coefficients of form (CF), centers of buoyancy
(CB), metacentric heights of vessels (MHV), ship waterplane area (SWA), longitudinal center of
floatation (LCF), volume displacement (VD) and wetted surface area (WSA) with weight values
of 0.218, 0.095, 0.078, 0.083, 0.074, 0.1, 0.46, 0.108, 0.209 and 0.028 respectively.
to classify it. The method proposed is predicated upon its ability to analyse processes and operations
based on subjective judgement with little or no statistical data available. The study also shows that
fuzzy-logic rule base is a veritable tool to qualitatively and quantitatively assess the status of a wharf
offering ferry service. Using the model developed in this study, the performance status of Yenagoa
wharf has been determined to be orange, having a (WPS) overall of 4.8. The status of the wharf has been
in good agreement with the perception of stakeholders that the Yenagoa wharf needs restructuring
to curb the frequent crisis occurring among stakeholders. The model also indicated those areas of the
wharf’s operations needing attention. The study indicates that even though major components that
determine the quality and profitability of the wharf’s ferry service are high in value, the overall status
of the wharf may not be necessarily high. As such, the study method can be used to control the growing
ill-feeling between boat operators and passengers while harmonizing all stakeholders (operators,
passengers, and regulators etc) to work together to improve the status of the wharf.
operations of the vessel need to be ensured via identification of hazards/failures that tends to affect the system and
prevent them from occurring and also mitigate their consequences. In this research, a traditional hybrid
methodology is employed in ensuring the reliability and safety of a sea harvester. The methodology is a logical
combination of preliminary hazard analysis (PHA), risk matrix approach (RMA) and event tree analysis (ETA).
Fire, flood, machinery failure and capsize that pose to affect optimal operations of a sea harvester are identified
using a PHA method. RMA is incorporated in application of the PHA method to estimate the risks associated with
them. Due the fact that risks associated with fire, flood, machinery failure and capsize are classified as very high,
identifying preventing measures becomes necessary. Furthermore, systems which by means of their operability and
non-operability can mitigate fire, flood, machinery failure, capsize and grounding consequences are captured using
an ETA method. Therefore, the traditional hybrid methodology developed is successfully applied in design for safety, construction and operation of a sea harvester.
using known failure data. Given that most maritime operations are conducted in a challenging and uncertain environment,
their failure data are usually unavailable requiring a flexible and yet robust algorithm for the analysis of the systems.
This research therefore seeks to analyse hazards of ships during ship and port interface operations as a result of manoeuvring
by incorporating fuzzy fault tree analysis method to optimise the performance effectiveness of the system.
Fuzzy set theory provides the needed flexibility to represent vague information from the analysis process. The methodology
is structured in such a manner that diverse sets of data can be integrated and synthesised for analysing the system.
It is envisaged that the proposed method could avail safety specialist with a simple and a step-by-step framework
for evaluating maritime hazards in seaport operations in a concise way.