An explanation of the mechanism of generation and acceleration of jets in outer space is given on the basis of experiments in the physics of electrical discharge. The presence of two arms in the spiral Galaxy gives gr...An explanation of the mechanism of generation and acceleration of jets in outer space is given on the basis of experiments in the physics of electrical discharge. The presence of two arms in the spiral Galaxy gives grounds to assume that they have excess charges of the opposite sign. At the moment when the electric field strength between the tips of the arms becomes sufficient, an electrical breakdown occurs, which is accompanied by the movement of the current-plasma leader in the jumper between the tips of the arms. In the head part of the leader there is a flat electric domain of a strong field, which, during its inception, emits intense transverse electromagnetic waves in a direction perpendicular to the direction of the leader’s motion and to the plane of the accretion disk. The electric domain periodically appears and collapses due to the entry of neutral particles. Transverse electromagnetic waves capture charged particles from the discharge region and accelerate them in the direction of wave propagation. The crossed fields of an electromagnetic wave perform the functions of a multistage accelerator. The acceleration of the particles of the plasma produced in the discharge to relativistic energy values in the region of narrow vortex jets occurs under the action of forces caused by the components of the electromagnetic wave fields and the pressure gradient. The charged particles of a vortex jet acquire a significant rotational moment under the action of the Lorentz force. Explanations of the generation of microwave, bremsstrahlung and optical radiation from the region of the jumper between the arms of the Galaxy in the absence of electrical breakdown are also given.展开更多
The study focuses on the flexible jumper issue of Subsurface Tension Leg Production （STLP） system concept, which is considered as a competing alternative system to support well completion devices and rigid risers in...The study focuses on the flexible jumper issue of Subsurface Tension Leg Production （STLP） system concept, which is considered as a competing alternative system to support well completion devices and rigid risers in ultra-deep water for offshore petroleum production. The paper presents analytical and numerical approaches for the optimum design and global analysis of the flexible jumper. Criteria using catenary concept are developed to define the critical length for optimum design. Based on the criteria, detailed hydrodynamic analyses including quasi-static analysis, modal analysis, and dynamic analysis are performed. Modal analysis with respect to the quasi-static analysis shows that the existence of resonant modes requires special consideration. The results of dynamic analysis confirm the effectiveness of the de-coupled effect from the jumper on STLP system. The approaches developed in the study also have wide application prospect in reference to the optimum design and analysis of any Hybrid Riser （HR） concept.展开更多
The purpose of this paper is to present a design procedure for subsea rigid jumper system including strength and fatigue analysis. Special attention gives to a methodology based on DNV-RP-F105 to evaluate jumper fatig...The purpose of this paper is to present a design procedure for subsea rigid jumper system including strength and fatigue analysis. Special attention gives to a methodology based on DNV-RP-F105 to evaluate jumper fatigue damage caused by vortex induced vibration (VIV). Jumper strength analysis is to determine the jumper con-figuration which can accommodate various load conditions and all possible span lengths driven by installation tole-rances of connected subsea structures. Fatigue analysis includes two parts:thermal fatigue and VIV fatigue. This paper presents the procedure of VIV fatigue damage calculation. An example is given to illustrate above methodologies.展开更多
A subsea flowline jumper （FJ） is a basic connected component for the wet oil tree, subsea pipeline and riser base, and it plays an irreplaceable role in the subsea production system. During the installation of FJ, c...A subsea flowline jumper （FJ） is a basic connected component for the wet oil tree, subsea pipeline and riser base, and it plays an irreplaceable role in the subsea production system. During the installation of FJ, collisions often happen between FJ and other equipment, which may cause serious damage. Besides, as the operating water depth increases, the demand for the installation equipments, such as the crane and winch, will increase. The research of deepwater FJ installation in China is still in the primary stage, thus an installation method for the deepwater FJ is proposed in this paper. Finite element models of a typical M-shaped FJ installation system are built to simulate the installation procedures. Analysis results show that the installation steps designed are feasible and valid for the deepwater FJ. In order to ensure the safety of the installation process, the collision-sensitive analysis for the FJ is conducted, and results show that it is necessary to set the pick up speed at a proper value, in order to avoid collision in the installation process. Besides, the mechanical characteristics of FJ during the installation are investigated under a range of environmental conditions and it is found that the maximum stress of the FJ always happens at its central position. The basic requirements for the installation equipment are also obtained through the analysis of the main installation steps.展开更多
Background: Jumper’s knee is relatively common among rugby players, and treatment of this condition is known to be difficult. Intratendinous revision surgery has shown poor results. New research on innervation patter...Background: Jumper’s knee is relatively common among rugby players, and treatment of this condition is known to be difficult. Intratendinous revision surgery has shown poor results. New research on innervation patterns, and a new US+DP-guided treatment method targeting the regions with vessels and nerves outside the tendon has shown promising results in patients with Jumper’s knee. Material: This study includes 12 patellar tendons from 9 professional rugby players (mean age 26 years) with a long duration (range 12 - 72 months) of pain from the proximal patellar tendon. For 3 tendons there was previously intratendinous revision surgery with a poor result. Method: Treatment with Ultrasound (US) and Doppler (DP)-guided arthroscopic shaving + open scraping, followed by immediate weight bearing and gradually increased loading up to full loading after 6 - 8 weeks, was performed. Results: For 9 tendons there was a good clinical result, and all returned to full professional rugby within 4 - 6 months. The mean VISA score increased from 49 to 78 (p < 0.05). Follow-ups (range 10 - 30 months) show remaining good results. For 3 tendons, all have had previous intratendinous revision surgery, the clinical results were poor and they couldn’t return to rugby. Conclusions: The short-term results in this relatively small material indicate that US+DP-guided arthroscopic shaving + open scraping is a good treatment method for professional rugby players with chronic painful Jumper’s knee.展开更多
文摘An explanation of the mechanism of generation and acceleration of jets in outer space is given on the basis of experiments in the physics of electrical discharge. The presence of two arms in the spiral Galaxy gives grounds to assume that they have excess charges of the opposite sign. At the moment when the electric field strength between the tips of the arms becomes sufficient, an electrical breakdown occurs, which is accompanied by the movement of the current-plasma leader in the jumper between the tips of the arms. In the head part of the leader there is a flat electric domain of a strong field, which, during its inception, emits intense transverse electromagnetic waves in a direction perpendicular to the direction of the leader’s motion and to the plane of the accretion disk. The electric domain periodically appears and collapses due to the entry of neutral particles. Transverse electromagnetic waves capture charged particles from the discharge region and accelerate them in the direction of wave propagation. The crossed fields of an electromagnetic wave perform the functions of a multistage accelerator. The acceleration of the particles of the plasma produced in the discharge to relativistic energy values in the region of narrow vortex jets occurs under the action of forces caused by the components of the electromagnetic wave fields and the pressure gradient. The charged particles of a vortex jet acquire a significant rotational moment under the action of the Lorentz force. Explanations of the generation of microwave, bremsstrahlung and optical radiation from the region of the jumper between the arms of the Galaxy in the absence of electrical breakdown are also given.
基金financially supported by the National Natural Science Foundation of China(Grant No.51221961)
文摘The study focuses on the flexible jumper issue of Subsurface Tension Leg Production （STLP） system concept, which is considered as a competing alternative system to support well completion devices and rigid risers in ultra-deep water for offshore petroleum production. The paper presents analytical and numerical approaches for the optimum design and global analysis of the flexible jumper. Criteria using catenary concept are developed to define the critical length for optimum design. Based on the criteria, detailed hydrodynamic analyses including quasi-static analysis, modal analysis, and dynamic analysis are performed. Modal analysis with respect to the quasi-static analysis shows that the existence of resonant modes requires special consideration. The results of dynamic analysis confirm the effectiveness of the de-coupled effect from the jumper on STLP system. The approaches developed in the study also have wide application prospect in reference to the optimum design and analysis of any Hybrid Riser （HR） concept.
文摘The purpose of this paper is to present a design procedure for subsea rigid jumper system including strength and fatigue analysis. Special attention gives to a methodology based on DNV-RP-F105 to evaluate jumper fatigue damage caused by vortex induced vibration (VIV). Jumper strength analysis is to determine the jumper con-figuration which can accommodate various load conditions and all possible span lengths driven by installation tole-rances of connected subsea structures. Fatigue analysis includes two parts:thermal fatigue and VIV fatigue. This paper presents the procedure of VIV fatigue damage calculation. An example is given to illustrate above methodologies.
基金Supported by the Numerical Simulation and Experimental Investigation of FPSO and Offloading System(2011ZX05030-006-002)
文摘A subsea flowline jumper （FJ） is a basic connected component for the wet oil tree, subsea pipeline and riser base, and it plays an irreplaceable role in the subsea production system. During the installation of FJ, collisions often happen between FJ and other equipment, which may cause serious damage. Besides, as the operating water depth increases, the demand for the installation equipments, such as the crane and winch, will increase. The research of deepwater FJ installation in China is still in the primary stage, thus an installation method for the deepwater FJ is proposed in this paper. Finite element models of a typical M-shaped FJ installation system are built to simulate the installation procedures. Analysis results show that the installation steps designed are feasible and valid for the deepwater FJ. In order to ensure the safety of the installation process, the collision-sensitive analysis for the FJ is conducted, and results show that it is necessary to set the pick up speed at a proper value, in order to avoid collision in the installation process. Besides, the mechanical characteristics of FJ during the installation are investigated under a range of environmental conditions and it is found that the maximum stress of the FJ always happens at its central position. The basic requirements for the installation equipment are also obtained through the analysis of the main installation steps.
文摘Background: Jumper’s knee is relatively common among rugby players, and treatment of this condition is known to be difficult. Intratendinous revision surgery has shown poor results. New research on innervation patterns, and a new US+DP-guided treatment method targeting the regions with vessels and nerves outside the tendon has shown promising results in patients with Jumper’s knee. Material: This study includes 12 patellar tendons from 9 professional rugby players (mean age 26 years) with a long duration (range 12 - 72 months) of pain from the proximal patellar tendon. For 3 tendons there was previously intratendinous revision surgery with a poor result. Method: Treatment with Ultrasound (US) and Doppler (DP)-guided arthroscopic shaving + open scraping, followed by immediate weight bearing and gradually increased loading up to full loading after 6 - 8 weeks, was performed. Results: For 9 tendons there was a good clinical result, and all returned to full professional rugby within 4 - 6 months. The mean VISA score increased from 49 to 78 (p < 0.05). Follow-ups (range 10 - 30 months) show remaining good results. For 3 tendons, all have had previous intratendinous revision surgery, the clinical results were poor and they couldn’t return to rugby. Conclusions: The short-term results in this relatively small material indicate that US+DP-guided arthroscopic shaving + open scraping is a good treatment method for professional rugby players with chronic painful Jumper’s knee.
