When the free standing riser(FSR)is in service in the ocean,its mechanical properties are affected by various factors,including complex ocean current forces,buoyancy of the buoyancy can,and torque caused by the deflec...When the free standing riser(FSR)is in service in the ocean,its mechanical properties are affected by various factors,including complex ocean current forces,buoyancy of the buoyancy can,and torque caused by the deflection of the upper floating body.These loads have a great influence on the deformation and internal force of the FSR.The static performance of FSR is investigated in this research under various working conditions.The finite element model of FSR is established based on the co-rotational method.The arc length approach is used to solve the model.The load is exerted in increments.The current load on the riser changes with the configuration of the riser.The accuracy of the numerical method is verified by Abaqus software.The calculation time is also compared.Then,the effects of uniform current,actual current and floating body yaw motion on FSR are studied by parameter analysis.Additionally,the influence of the FSR on the ocean current after the failure of part of the buoyancy can chamber is analyzed.The results show that the numerical model based on the co-rotational method can effectively simulate the large rotation and torsion behavior of FSR.This method has high computational efficiency and precision,and this method can quickly improve the efficiency of numerical calculation of static analysis of deep-water riser.The proposed technology may serve as an alternative to the existing proprietary commercial software,which uses a complex graphical user interface.展开更多
Evaluation of abandonment and recovery operation of steel lazy-wave riser in deepwater is presented in this paper.The calculation procedure includes two single continuous SLWR and cable segments, which are coupled tog...Evaluation of abandonment and recovery operation of steel lazy-wave riser in deepwater is presented in this paper.The calculation procedure includes two single continuous SLWR and cable segments, which are coupled together to form the overall mathematical model. Then the equilibrium equations of SLWR and cable are established based on minimum total potential energy principle. The coupled equations are discretized by the finite difference method and solved by Newton-Raphson technique in an iterative manner. The present method is validated by well-established commercial code OrcaFlex. Recovery methods by considering different ratios of vessel’s moving velocity to cable’s recovery velocity are evaluated to optimize the abandonment and recovery operation. In order to keep the tension more stable during the recovery process, the rate ratio before leaving the seabed is increased, and the rate ratio after leaving the seabed is reduced.展开更多
目的探讨银离子敷料联合负压引流治疗感染性伤口的有效性。方法检索Cochrane Library、PubMed、Embase、Web of Science、中国生物医学文献服务系统、中国知网、万方数据平台、维普中文期刊服务平台等数据库中关于银离子敷料联合负压引...目的探讨银离子敷料联合负压引流治疗感染性伤口的有效性。方法检索Cochrane Library、PubMed、Embase、Web of Science、中国生物医学文献服务系统、中国知网、万方数据平台、维普中文期刊服务平台等数据库中关于银离子敷料联合负压引流治疗感染性伤口的随机对照研究,由2名研究人员进行资料提取和文献质量评价,并使用RevMan 5.4软件进行Meta分析。结果共纳入9篇文献,总样本量为690例,其中试验组采用银离子敷料联合负压引流疗法,对照组采用银离子敷料、负压引流疗法或常规换药中一种方式进行治疗。Meta分析结果:试验组能降低压疮愈合计分量表评分[MD=-1.44,95%CI(-2.49,-0.39),Z=2.70,P=0.007]、细菌阳性率[OR=0.37,95%CI(0.27,0.50),Z=6.16,P<0.001],缩短伤口愈合时间[MD=-6.70,95%CI(-9.00,-4.40),Z=5.71,P<0.001],提高伤口痊愈率[OR=3.32,95%CI(1.72,6.40),Z=3.58,P<0.001]。结论银离子敷料联合负压引流治疗能有效促进感染性伤口的愈合。展开更多
[目的]对虾养殖环境中乳酸菌进行筛选并对其发酵工艺进行研究。[方法]首先利用含碳酸钙的MRS固体培养基从虾养殖环境中的海水和底泥中筛选出有溶钙圈的菌株M5;接着根据16S r DNA基因序列系统发育树分析对菌株M5进行鉴定,最后在单因子实...[目的]对虾养殖环境中乳酸菌进行筛选并对其发酵工艺进行研究。[方法]首先利用含碳酸钙的MRS固体培养基从虾养殖环境中的海水和底泥中筛选出有溶钙圈的菌株M5;接着根据16S r DNA基因序列系统发育树分析对菌株M5进行鉴定,最后在单因子实验的基础上,通过正交试验对发酵工艺进行优化。[结果]初步鉴定菌株M5为粪肠球菌,该菌株的最佳发酵工艺为:甘蔗糖蜜浓度为5%,蛋白胨浓度为0.75%,硫酸铵0.5%,磷酸氢二钾的浓度为0.5%,发酵温度为30℃,发酵时间为48 h。在以上工艺下,发酵液中乳酸菌的活菌数高达4.97×108CFU/m L。[结论]本研究对对虾养殖所用乳酸菌的发酵生产具有一定的参考价值。展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52271299).
文摘When the free standing riser(FSR)is in service in the ocean,its mechanical properties are affected by various factors,including complex ocean current forces,buoyancy of the buoyancy can,and torque caused by the deflection of the upper floating body.These loads have a great influence on the deformation and internal force of the FSR.The static performance of FSR is investigated in this research under various working conditions.The finite element model of FSR is established based on the co-rotational method.The arc length approach is used to solve the model.The load is exerted in increments.The current load on the riser changes with the configuration of the riser.The accuracy of the numerical method is verified by Abaqus software.The calculation time is also compared.Then,the effects of uniform current,actual current and floating body yaw motion on FSR are studied by parameter analysis.Additionally,the influence of the FSR on the ocean current after the failure of part of the buoyancy can chamber is analyzed.The results show that the numerical model based on the co-rotational method can effectively simulate the large rotation and torsion behavior of FSR.This method has high computational efficiency and precision,and this method can quickly improve the efficiency of numerical calculation of static analysis of deep-water riser.The proposed technology may serve as an alternative to the existing proprietary commercial software,which uses a complex graphical user interface.
基金financially supported by the National Natural Science Foundation of China (Grant No.52271299)the Science Foundation of China University of Petroleum,Beijing (Grant No.2462020YXZZ046)。
文摘Evaluation of abandonment and recovery operation of steel lazy-wave riser in deepwater is presented in this paper.The calculation procedure includes two single continuous SLWR and cable segments, which are coupled together to form the overall mathematical model. Then the equilibrium equations of SLWR and cable are established based on minimum total potential energy principle. The coupled equations are discretized by the finite difference method and solved by Newton-Raphson technique in an iterative manner. The present method is validated by well-established commercial code OrcaFlex. Recovery methods by considering different ratios of vessel’s moving velocity to cable’s recovery velocity are evaluated to optimize the abandonment and recovery operation. In order to keep the tension more stable during the recovery process, the rate ratio before leaving the seabed is increased, and the rate ratio after leaving the seabed is reduced.
文摘目的探讨银离子敷料联合负压引流治疗感染性伤口的有效性。方法检索Cochrane Library、PubMed、Embase、Web of Science、中国生物医学文献服务系统、中国知网、万方数据平台、维普中文期刊服务平台等数据库中关于银离子敷料联合负压引流治疗感染性伤口的随机对照研究,由2名研究人员进行资料提取和文献质量评价,并使用RevMan 5.4软件进行Meta分析。结果共纳入9篇文献,总样本量为690例,其中试验组采用银离子敷料联合负压引流疗法,对照组采用银离子敷料、负压引流疗法或常规换药中一种方式进行治疗。Meta分析结果:试验组能降低压疮愈合计分量表评分[MD=-1.44,95%CI(-2.49,-0.39),Z=2.70,P=0.007]、细菌阳性率[OR=0.37,95%CI(0.27,0.50),Z=6.16,P<0.001],缩短伤口愈合时间[MD=-6.70,95%CI(-9.00,-4.40),Z=5.71,P<0.001],提高伤口痊愈率[OR=3.32,95%CI(1.72,6.40),Z=3.58,P<0.001]。结论银离子敷料联合负压引流治疗能有效促进感染性伤口的愈合。
文摘[目的]对虾养殖环境中乳酸菌进行筛选并对其发酵工艺进行研究。[方法]首先利用含碳酸钙的MRS固体培养基从虾养殖环境中的海水和底泥中筛选出有溶钙圈的菌株M5;接着根据16S r DNA基因序列系统发育树分析对菌株M5进行鉴定,最后在单因子实验的基础上,通过正交试验对发酵工艺进行优化。[结果]初步鉴定菌株M5为粪肠球菌,该菌株的最佳发酵工艺为:甘蔗糖蜜浓度为5%,蛋白胨浓度为0.75%,硫酸铵0.5%,磷酸氢二钾的浓度为0.5%,发酵温度为30℃,发酵时间为48 h。在以上工艺下,发酵液中乳酸菌的活菌数高达4.97×108CFU/m L。[结论]本研究对对虾养殖所用乳酸菌的发酵生产具有一定的参考价值。
