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.
Aleksandr Ursolov, Yuriy Batrak and Wieslaw Tarelko
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.
Oleksandr Cherednichenko, Serhiy Serbin and Marek Dzida
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%.
River water pollution has been reported globally. In suggestion to adapt sustainability approach, this study carry out to tests the structural equation model between sustainable development and water resources management in the Malacca River basin (Malaysia). The model consists of six latent constructs (anthropogenic activities; law, regulation and policy; land and water ecosystem; Malacca River; river water pollution; sustainability) and twenty four items based on 400 questionnaires which were completed and returned by the local residents of Malacca state. Selected study area is within Malacca River basin. The result show the Malacca River is influenced by water law-regulation-policy (β = 0.546, p < 0.001), anthropogenic activities (β = 0.145, p < 0.001), river water pollution (β = 0.142, p < 0.001), land and water ecosystem (β = 0.105, p < 0.01), as well as sustainable approach (β = 0.127, p < 0.5). It was found that a sustainable approach and water law-regulation-policy have a direct influence on anthropogenic activities, river water pollution, as well as the land and water ecosystem. In conclusion, this study suggests developing an earlier approach of the model involved with water resources management and sustainable development.
Based on chemical analyses, the quality of ground waters for drinking, agricultural and industrial purposes was determined in Rafsanjan Plain-Iran. Samples for analyses were taken from 22 wells in 2012. Because of high water hardness and total dissolved solids content, water was found to be unsuitable for drinking purposes. Water quality for agriculture was determined with the use of the Wilcox method. Among the analysed water, 10.33% were attributed to C3-S1 class (high electrolytic conductivity and low sodium adsorption ratio), 59.5% to class C4-S1 (very high EC and low SAR) and 30.17% to class C4-S2 (very high EC and medium SAR). 89.67% of studied wells were unsuitable for agriculture. Because of corrosive water properties all but two wells on Rafsanjan Plain were undesirable for use in the industry. The results of qualitative analyses were presented in GIS and in databases to support making decision and management of groundwater on Rafsanjan Plain.
Mohammed Kadaoui, Abderrahime Bouali and Mourad Arabi
The physicochemical and bacteriological quality of groundwater was assessed to show the impact of the agriculture and human activities in the Triffa Plain located in North-East of Morocco. The current levels of contamination of the groundwater were estimated by analysing electrical conductivity, nitrate, nitrite, ammonia, orthophosphate, and indicators of faecal pollution content.
Water samples from 55 locations were collected during two period of time, the wet and the dry season of the year 2016. Result obtained indicated that most samples are highly contaminated. The electrical conductivity varied from 800 to 9 100 μS∙cm−1. Nitrate levels ranged from 25 to 216 mg·dm−3, with 78% of samples exceeding the critical level value set at 50 mg·dm−3. Nitrate concentrations are slightly higher during the wet period in 73% of studied cases. Nitrite rarely exceeded the normal rate fixed by World Health Organization and reached 0.90 mg·dm−3. Ammonia and orthophosphate contents do not exceed these norms.
The study revealed a wide contamination of groundwater by microbial agents such as, total coliforms, faecal coliforms and faecal streptococci, with content ranged from 0 to 14 000, 0 to 5 000 and 0 to 5 000 CFU·(100 cm3)−1 respectively, confirming the impact of septic tanks, wastewater discharge into rivers without treatment, and the use of animal waste on the ground water vulnerability.
Samplings and measurements were carried out according to the international standard ISO 13395, ISO 11732 and ISO 15681-2 for chemical compounds and ISO 9308-1 and ISO 7899-2 for microbiological numerations.
Ayobami A. Akanmu, Umar O. Salisu, Simeon O. Fasina and Samuel A. Okunubi
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.
Eligiusz Mieloszyk, Marcin Abramski and Anita Milewska
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.
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.
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:
The optimization of approach channel parameters,
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.