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Analysis and Experiments of Embedded Gripping Mechanism Used in Large-scale Tools Holding Up Pile Foundation in Ocean

Abstract

With the rapid development of the marine economy and continuous improvement of the industry, the scale of the offshore engineering is increasing. This raises interest in studying, theoretically and experimentally, gripping and bearing mechanisms for large-scale holding and lifting tools used in foundation pile installations. In this paper, the embedded gripping mechanism is studied based on the theory of elastic-plastic mechanics. The embedded and bearing performance of the tooth is simulated and the influence factors are studied. In addition, the device used in the simplified embedded experiment on the tooth of the embedded block is designed. The relationship between embedded depth, load, and tooth profile angle is identified and validated. Meanwhile, the embedded performance of linear and ring type teeth is compared experimentally in order to select the suitable type of tooth for various situations. This comparison makes the basis for designing an upending gripper for the marine pile foundation, which can realize the operation of holding the pile to prevent its falling.

Open access
Application of the Optimization Methods to the Search of Marine Propulsion Shafting Global Equilibrium in Running Condition

Abstract

Full-film hydrodynamic lubrication of marine propulsion shafting journal bearings in running condition is discussed. Considerable computational difficulties in non-linear determining the quasi-static equilibrium of the shafting are highlighted. To overcome this problem the approach using two optimization methods (the particle swarm method and the interior point method) in combination with the specially developed relaxation technique is proposed. The developed algorithm allows to calculate marine propulsion shafting bending with taking into account lubrication in all journal bearings and exact form of journal inside bearings, compared to results of most of the publications which consider lubrication only in the aft most stern tube bearing and assume rest of bearings to be represented by points. The calculation results of typical shafting design with four bearings are provided. The significance of taking into account lubrication in all bearings is shown, specifically more exact values of bearings’ reactions, shafting deflections, minimum film thickness and maximum hydrodynamic pressure in the stern tube bearing in case of considering lubrication in all bearings.

Open access
Application of Thermo-chemical Technologies for Conversion of Associated Gas in Diesel-Gas Turbine Installations for Oil and Gas Floating Units

Abstract

The paper considers the issue of thermo-chemical recovery of engine’s waste heat and its further use for steam conversion of the associated gas for oil and gas floating units. The characteristics of the associated gas are presented, and problems of its application in dual-fuel medium-speed internal combustion engines are discussed. Various variants of combined diesel-gas turbine power plant with thermo-chemical heat recovery are analyzed. The heat of the gas turbine engine exhaust gas is utilized in a thermo-chemical reactor and a steam generator. The engines operate on synthesis gas, which is obtained as a result of steam conversion of the associated gas. Criteria for evaluating the effectiveness of the developed schemes are proposed. The results of mathematical modeling of processes in a 14.1 MW diesel-gas turbine power plant with waste heat recovery are presented. The effect of the steam/associated gas ratio on the efficiency criteria is analyzed. The obtained results indicate relatively high effectiveness of the scheme with separate high and low pressure thermo-chemical reactors for producing fuel gas for both gas turbine and internal combustion engines. The calculated efficiency of such a power plant for considered input parameters is 45.6%.

Open access
An assessment of the local empowerment and environmental management programme (LEEMP) for poverty alleviation in Oyo State, Nigeria

Abstract

Efforts to liberate the populace, most especially rural communities, from the shackles of poverty, have been ongoing through several approaches since the independent era in Nigeria. The most recent is the Local Empowerment and Environmental Management Programme (LEEMP) which is tailored to undertake projects capable of alleviating poverty. This study assessed the LEEMP projects in Itesiwaju Local Government Area of Oyo State in Nigeria. Data collection methods were through a questionnaire survey and an interview. A random sampling technique was employed to sample 152 residents from the study population of 30,400 and the results were analysed using both descriptive and inferential statistics. A binary logistics regression was used to determine the influence of the LEEMP projects on the socio-economic status of residents. The findings revealed that: LEEMP projects were mostly the initiatives of both the community and LEEMP officials (72%); over 80% of the respondents observed that community involvement was mainly about land provision and the labour force, justifying over 70% active involvement of the community in the project execution and maintenance. Inferentially, the prediction model was able to classify 83% of the cases correctly, indicating that the predictors contribute significantly to prediction power of the logistic regression model (p<0.000). The Pseudo R-Square of Cox & Snell’s R-square (28%) and Nagelkerke’s R (42%) also show that the model was relevant in predicting the influence of the LEEMP projects on the residents’ socio-economic status. However, age (p=0.000), household size (p=0.019), average monthly income (p=0.033), and educational status (p=0.038) predictors best contributed to the model prediction. The study, however, recommended among others, that the LEEMP projects should be extended extensively within the country accompanied by an injection of adequate funding and a project monitoring mechanism for continuous functionality and sustainability.

Open access
CFGFRPT Piles with a Circular Cross-Section and their Application in Offshore Structures

Abstract

The possibilities of using concrete piles in a polymer composite reinforced with glass fibres in offshore facilities were shown. Laboratory tests of CFGFRPT type piles compressed axially and in eccentric compression for the analysis of CFGFRPT piles were used. Methods of analysis of dynamic systems for mathematical modelling of the displacement of the hammer in the pile driving process were applied. The possibilities of combining CFGFRPT piles, including the creation of hybrid piles were also presented. For example, concrete piles can be combined with concrete piles in a polymer composite reinforced with glass fibres with different fibre beam angles. The possibilities of using such hybrid piles in offshore facilities were indicated.

Open access
A Concept Design of Diesel – Hydraulic Propulsion System for Passenger Ship Intended for Inland Shallow Water Navigation

Abstract

This paper presents an analysis of environmental and technical conditions necessary for working out a possibly most favourable propulsion system for a two – segment passenger ship intended for navigation between Berlin and Kaliningrad. There are presented various types of propulsion systems for small ships as well as analyzed their possible applications and consequences. In this work there were taken into account system’s reliability, efficiency, dimensions, mass and costs of manufacturing, assembling and possible replacing the system components as well as an impact on maneuverability and natural environment. With taking into account the above mentioned criteria it was finally found that the diesel-hydraulic system fitted with two azimuthal ducted solid propellers is the most favourable. There are also presented a schematic propulsion and control diagram, three-dimensional arrangement drawing of system components as well as assembly drawing of the designed azimuthal propulsion system.

Open access
Conditions of Safe Ship Operation in Seaports – Optimization of Port Waterway Parameters

Abstract

A seaport is presented in this article as a system composed of various types of waterways. The author has defined relationships between port waterway system elements and conditions of safe operation of ships in port. Relationships were determined between the conditions of safe operation of ships and the parameters of the following port waterways: anchorage, fairways (approach and inner channels, port entrances), turning area and port basin. The identified relationships between port waterway system and conditions of safe ship operation provided a basis for formulating the objective function of waterway parameter optimization during port design. In practice, these relations were used to determine the parameters of the Outer Container Terminal being built in Świnoujście, where two optimization problems were to be solved:

  1. The optimization of approach channel parameters,
  2. The optimization of parameters of the port entrance, turning area and port basin.
The Outer Container Terminal in Świnoujście is expected to handle ocean-going ships with a length overall Lo = 400 m, and its projected capacity is estimated at 1.5 million TEU per year, a figure that can be doubled in the future.

Open access
Diagnostic Model of Crankshaft Seals

Abstract

The paper presents a research stand being a diagnostic model of radial lip seals used, among others, on crankshafts of piston combustion engines in order to identify the correctness of their operation. The possibility of determining the technical condition of lip seals on the basis of the proposed coefficient of correctness of operation has been described. The basic features of seals influencing their correctness of operation were also described, along with examples of determining the durability limits of lip seals. A modified version of the friction node of the T-02 four-ball apparatus is presented. It allows to check the correctness of sealing lips operation as well as to test the compatibility between the steel shaft, sealing lip and sealed lubricating oil. It was shown that the test results con-firmed the usefulness of the hypothesis that the quality of oil affects the durability of sealing lips and their coefficient of correctness. Additionally, attention was paid to the possibility of analyzing the pumping effect affecting the transition of the seal-shaft system from the state of partial suitability S2 to the state of full suitability S1 or to the state of unfitness S3, and because the change in the state of such a system is random, it requires a probabilistic analysis.

Open access
Dynamic Characteristic Study of Riser with Complex Pre-stress Distribution

Abstract

In this study, the dynamic characteristic problem of riser structure with complex pre-stress distribution is investigated. At first, the differential equation of the riser structure with complex pre-stress distribution is derived. The analytical expression of the free vibration of a riser structure with complex pre-stress distribution is discussed by using the orthogonal property of the trigonometric series. A top-tensioned riser (TTR) for example, the influences of the amplitude and direction of complex pre-stress on natural frequency and mode shape characteristics are compared. This study provides a new method for addressing the riser structure response problem with complex loading.

Open access
The Energy Efficiency Gap in Turkish Maritime Transportation

Abstract

The Turkish Merchant Shipping Industry has recently witnessed an increasing awareness of the importance to minimize environmental pollution and fuel oil consumption. Together with certain non-governmental organizations and media concerns about environmental protection, the International Maritime Organization (IMO) has been strict on controlling undesirable effects on the environment and, consequently, forcing shipping companies to minimize their emissions. Besides, today’s highly advanced technology companies over the world have developed various innovative systems that can be utilized to minimize carbon emission, thus giving assurance to relevant investors that their investments are most likely to turn out well with a considerable financial gain in the short or long term. Despite all such favorable developments, in a general look, shipping companies seem reluctant in making use of technologies providing efficiency in energy consumption. This reluctance has eventually brought about the term “Energy Efficiency Gap”. This research conducts a questionnaire, created by Acciaro et al. [1], among the shipping companies in Turkey. 20 respondent companies, who represent 26 percent of the Turkish owned merchant marine fleet of over 1000 gross tonnage in terms of deadweight cargo capacity, participated in the research. The Pearson correlation analysis was used, and interpretations were made according to the obtained statistical values. The aim of the research was to identify reasons and points restraining the use of new technologies regarding energy efficiency, as well as to develop proposals for the innovators in this field about how to overcome this handicap concerning technical and managerial aspects of gaining energy efficiency.

Open access