An inevitable consequence of the development of the offshore petroleum industry is the eventual obsolescence of large offshore structures. Proper methods for removal of decommissioned offshore platforms are becoming a...An inevitable consequence of the development of the offshore petroleum industry is the eventual obsolescence of large offshore structures. Proper methods for removal of decommissioned offshore platforms are becoming an important topic that the oil and gas industry must pay increasing attention to. While removing sections from a decommissioned jacket platform, the stability of the remaining parts is critical The jacket danger indices D ~ and Ds defined in this paper are very useful for analyzing the safety of any procedure planned for disassembling a jacket platform. The safest piles cutting sequence can be determined easily by comparing every column of Do and Ds or simply analyzing the figures of every row ofD o and D,.展开更多
This paper proposes the finite element simplified fatigue analysis method for fatigue evaluation of the composite non-tubular joint structure of an offshore jacket subjected to wave loads. The skirt pile sleeve of the...This paper proposes the finite element simplified fatigue analysis method for fatigue evaluation of the composite non-tubular joint structure of an offshore jacket subjected to wave loads. The skirt pile sleeve of the offshore jacket, which had been in service, was taken as an example of the non-tubular joint structure. SACS software was used for global analysis of multi-directional wave loads for the jacket platform, and ALGOR software was used to build a finite element model, perform finite element analysis, post-process stress results for acquiring the stress range, and perform fatigue evaluation. The analysis results indicate that the extreme stress range is within the allowable stress range and meets the requirements of DNV code. That means the simplified fatigue analysis method is effective and can be used in fatigue design for the non-tubular joint structure of an offshore jacket.展开更多
The development of damage detection techniques for offshore jacket structures is vital to prevent catastrophic events. This paper applies a frequency response based method for the purpose of structural health monitori...The development of damage detection techniques for offshore jacket structures is vital to prevent catastrophic events. This paper applies a frequency response based method for the purpose of structural health monitoring. In efforts to fulfill this task, concept of the minimum rank perturbation theory has been utilized. The present article introduces a promising methodology to select frequency points effectively. To achieve this goal, modal strain energy ratio of each member was evaluated at different natural frequencies of structure in order to identify the sensitive frequency domain for damage detection. The proposed methodology opens up the possibility of much greater detection efficiency. In addition, the performance of the proposed method was evaluated in relation to multiple damages. The aforementioned points are illustrated using the numerical study of a two dimensional jacket platform, and the results proved to be satisfactory utilizing the proposed methodology.展开更多
Magnetorheological （MR） dampers have been proposed to control the vibration of offshore platforms in this paper. The semi-active control strategy based on fuzzy control algorithm was adopted to determine the optimal...Magnetorheological （MR） dampers have been proposed to control the vibration of offshore platforms in this paper. The semi-active control strategy based on fuzzy control algorithm was adopted to determine the optimal output control force based on the responses of jacket platforms. A typical jacket platform in Mexico Gulf was selected as the numerical example to investigate the effectiveness of the proposed control method. Furthermore, a model experiment was performed to validate the results of the numerical simulation. The experimental model of the jacket platform was designed based on dynamical similarity criterion by the scale of 1：50. Both of the numerical and experimental results show that the semi-active control system with the MR damper can reduce vibrations of jacket platforms effectively and at the same time the control effect is stable.展开更多
Based on the self-excited vibration theory of ice, the vibration control technology of jacket platform is studied in this paper. The magnetorheological suspensions (MR) unit is chosen as the damper, the control object...Based on the self-excited vibration theory of ice, the vibration control technology of jacket platform is studied in this paper. The magnetorheological suspensions (MR) unit is chosen as the damper, the control objective function for vibration excited by ice is determined by instantaneous optimal control (IOC) method, and genetic algorithm (GA) is used to select the optimal control force. For the jacket platform of 40 m in height and a 3-floor deck, the vibration responses induced by ice have been calculated before and after control considering the different thickness and speed of ice. It is shown that the control method presented in this paper can reduce the vibration response by 30%, and it is feasible to adopt MR absorber and GA in the control of vibration induced by ice.展开更多
The objective of this study is to experimentally investigate the effectiveness of Tuned Liquid Dampers (TLDs) for suppressing the dynamic response of a platform structure subjected to wave loading and to explore the a...The objective of this study is to experimentally investigate the effectiveness of Tuned Liquid Dampers (TLDs) for suppressing the dynamic response of a platform structure subjected to wave loading and to explore the applicability of TLDs for suppressing the structural vibration of fixed offshore platforms. The experimental model is scaled according to a full size platform by matching its dynamic properties. Rectangular and circular TLDs of various sizes and water depths are examined. The experiments were performed in a 2-D wave flume. The effectiveness of TLDs is evaluated based on their response reduction. By observing the performance and the behavior of TLDs through laboratory experiments, the effects of a number of parameters including container shape, container size, number of dampers, frequency ratio, mass ratio, and incident wave characteristics are investigated.展开更多
Based on the information system characteristics of mine, proposed network architecture design of the mine property. And in this framework based on the design of three-dimensional virtual mine described the application...Based on the information system characteristics of mine, proposed network architecture design of the mine property. And in this framework based on the design of three-dimensional virtual mine described the application of intelligent management platform. Three-dimensional virtual underground mine that shows the situation, the core application is through remote monitoring system of information exchange between devices （material object communication）. Internet of things in the framework of mining three-dimensional virtual reconstruction of mine. On coal mine safety in the production process of human, machine and environment, control elements and their harmony and unity. 3D virtual mine management platform integrates personnel positioning, dust control, gas monitoring, roof pressure monitoring, fan-line monitoring and other subsystems. Platform through the underground mine sensing equipment to conduct various types of monitoring data integration, through the transport layer device to transmit the information to the application layer intelligence processing software platform, the system automatically handles the operational status of each subsystem and the need for safe production under the proper introduction of human factors deal with special event. 3D virtual mine management platform to mining, excavation, transport, ventilation and other safety information quickly and accurately transmitted to the ground operation control center. Underground for the first time on the linkage between systems in case of emergencies, to provide safety for management decision support.展开更多
Because of the high requirement of quality,vile working environment and great difficulty of automatic welding,MMAW is usually adopted for the welding of the platform jacket and the pile pipe.Its low efficiency and har...Because of the high requirement of quality,vile working environment and great difficulty of automatic welding,MMAW is usually adopted for the welding of the platform jacket and the pile pipe.Its low efficiency and hard working is one of the choke points for construction progress. In this article,an up-to-date technology for platform pile pipe welding was introduced. Cored with FCW-S and combined with the characters and requirements of platform construction,the special automatic horizontal welding equipment and process were developed. Further more,the offshore application were introduced too.展开更多
The article analyzes the current situation of city infrastructure construction in China, elaborated needs if our country city infrastructure construction projects in various stages of information management, a framewo...The article analyzes the current situation of city infrastructure construction in China, elaborated needs if our country city infrastructure construction projects in various stages of information management, a framework of information platform are presented for city infrastructure projects of our construction comprehensive control, and efficient management city infrastructure construction project, and provide collaboration platform for the party in the infrastructure construction projects.展开更多
基金Supported by the Open Foundation of the State Key Lab for Ocean Engineering of Shanghai Jiao Tong University under Grant No.0602
文摘An inevitable consequence of the development of the offshore petroleum industry is the eventual obsolescence of large offshore structures. Proper methods for removal of decommissioned offshore platforms are becoming an important topic that the oil and gas industry must pay increasing attention to. While removing sections from a decommissioned jacket platform, the stability of the remaining parts is critical The jacket danger indices D ~ and Ds defined in this paper are very useful for analyzing the safety of any procedure planned for disassembling a jacket platform. The safest piles cutting sequence can be determined easily by comparing every column of Do and Ds or simply analyzing the figures of every row ofD o and D,.
文摘This paper proposes the finite element simplified fatigue analysis method for fatigue evaluation of the composite non-tubular joint structure of an offshore jacket subjected to wave loads. The skirt pile sleeve of the offshore jacket, which had been in service, was taken as an example of the non-tubular joint structure. SACS software was used for global analysis of multi-directional wave loads for the jacket platform, and ALGOR software was used to build a finite element model, perform finite element analysis, post-process stress results for acquiring the stress range, and perform fatigue evaluation. The analysis results indicate that the extreme stress range is within the allowable stress range and meets the requirements of DNV code. That means the simplified fatigue analysis method is effective and can be used in fatigue design for the non-tubular joint structure of an offshore jacket.
基金Financial Support by the Pars Oil and Gas Company(Grant No. 88-065)
文摘The development of damage detection techniques for offshore jacket structures is vital to prevent catastrophic events. This paper applies a frequency response based method for the purpose of structural health monitoring. In efforts to fulfill this task, concept of the minimum rank perturbation theory has been utilized. The present article introduces a promising methodology to select frequency points effectively. To achieve this goal, modal strain energy ratio of each member was evaluated at different natural frequencies of structure in order to identify the sensitive frequency domain for damage detection. The proposed methodology opens up the possibility of much greater detection efficiency. In addition, the performance of the proposed method was evaluated in relation to multiple damages. The aforementioned points are illustrated using the numerical study of a two dimensional jacket platform, and the results proved to be satisfactory utilizing the proposed methodology.
基金Supported by the National Natural Science Foundation of China （NSFC-5060900）.
文摘Magnetorheological （MR） dampers have been proposed to control the vibration of offshore platforms in this paper. The semi-active control strategy based on fuzzy control algorithm was adopted to determine the optimal output control force based on the responses of jacket platforms. A typical jacket platform in Mexico Gulf was selected as the numerical example to investigate the effectiveness of the proposed control method. Furthermore, a model experiment was performed to validate the results of the numerical simulation. The experimental model of the jacket platform was designed based on dynamical similarity criterion by the scale of 1：50. Both of the numerical and experimental results show that the semi-active control system with the MR damper can reduce vibrations of jacket platforms effectively and at the same time the control effect is stable.
文摘Based on the self-excited vibration theory of ice, the vibration control technology of jacket platform is studied in this paper. The magnetorheological suspensions (MR) unit is chosen as the damper, the control objective function for vibration excited by ice is determined by instantaneous optimal control (IOC) method, and genetic algorithm (GA) is used to select the optimal control force. For the jacket platform of 40 m in height and a 3-floor deck, the vibration responses induced by ice have been calculated before and after control considering the different thickness and speed of ice. It is shown that the control method presented in this paper can reduce the vibration response by 30%, and it is feasible to adopt MR absorber and GA in the control of vibration induced by ice.
基金financially supported partially by the National Natural Science Foundation of China(No.G50179014)Ph.D.Education Fund from Education Ministry of China.
文摘The objective of this study is to experimentally investigate the effectiveness of Tuned Liquid Dampers (TLDs) for suppressing the dynamic response of a platform structure subjected to wave loading and to explore the applicability of TLDs for suppressing the structural vibration of fixed offshore platforms. The experimental model is scaled according to a full size platform by matching its dynamic properties. Rectangular and circular TLDs of various sizes and water depths are examined. The experiments were performed in a 2-D wave flume. The effectiveness of TLDs is evaluated based on their response reduction. By observing the performance and the behavior of TLDs through laboratory experiments, the effects of a number of parameters including container shape, container size, number of dampers, frequency ratio, mass ratio, and incident wave characteristics are investigated.
文摘Based on the information system characteristics of mine, proposed network architecture design of the mine property. And in this framework based on the design of three-dimensional virtual mine described the application of intelligent management platform. Three-dimensional virtual underground mine that shows the situation, the core application is through remote monitoring system of information exchange between devices （material object communication）. Internet of things in the framework of mining three-dimensional virtual reconstruction of mine. On coal mine safety in the production process of human, machine and environment, control elements and their harmony and unity. 3D virtual mine management platform integrates personnel positioning, dust control, gas monitoring, roof pressure monitoring, fan-line monitoring and other subsystems. Platform through the underground mine sensing equipment to conduct various types of monitoring data integration, through the transport layer device to transmit the information to the application layer intelligence processing software platform, the system automatically handles the operational status of each subsystem and the need for safe production under the proper introduction of human factors deal with special event. 3D virtual mine management platform to mining, excavation, transport, ventilation and other safety information quickly and accurately transmitted to the ground operation control center. Underground for the first time on the linkage between systems in case of emergencies, to provide safety for management decision support.
文摘Because of the high requirement of quality,vile working environment and great difficulty of automatic welding,MMAW is usually adopted for the welding of the platform jacket and the pile pipe.Its low efficiency and hard working is one of the choke points for construction progress. In this article,an up-to-date technology for platform pile pipe welding was introduced. Cored with FCW-S and combined with the characters and requirements of platform construction,the special automatic horizontal welding equipment and process were developed. Further more,the offshore application were introduced too.
文摘The article analyzes the current situation of city infrastructure construction in China, elaborated needs if our country city infrastructure construction projects in various stages of information management, a framework of information platform are presented for city infrastructure projects of our construction comprehensive control, and efficient management city infrastructure construction project, and provide collaboration platform for the party in the infrastructure construction projects.
