Fully Coupled Time-Domain Simulation of Dynamic Positioning Semi-Submersible Platform Using Dynamic Surface Control

A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning(DP) system. In the control force design, a dynamic model of reference linear drift frequency in the horizontal plane is introduced. The dynamic surface control(DSC) is used to design a control strategy for the DP. Compared with the traditional back-stepping methods, the dynamic surface control combined with radial basis function(RBF) neural networks(NNs) can avoid differentiating intermediate variables repeatedly in every design step due to the introduction of a first order filter. Low frequency motions obtained from total motions by a low pass filter are chosen to be the inputs for the RBF NNs which are used to approximate the low frequency wave force. Considering the propellers' wear and tear, the effect of filtering frequencies for the control force is discussed. Based on power consumptions and positioning requirements, the NN centers are determined. Moreover, the RBF NNs used to approximate the total wave force are built to monitor the disturbances. With the DP assistance, the results of fully coupled dynamic response simulations are given to illustrate the effectiveness of the proposed control strategy.

低速侧向冲击下钢丝-CFRP复合杆的力学性能

针对传统CFRP杆横向抗冲击性能较差的问题,对4种不同钢丝体积含量和防护类型的钢丝-CFRP复合杆进行了摆锤冲击试验,并采用扫描电镜分析了其损伤形貌特征.结果表明:通过在CFRP杆中复合高强钢丝,可以显著提高杆材的横向抗冲击性能,其冲击吸收功与钢丝体积含量呈正相关,相较于CFRP杆,钢丝体积含量为30.3%的钢丝-CFRP复合杆的平均吸收功提高了41.97%;增加PVC套管的壁厚和内径能够明显提高钢丝-CFRP复合杆的抗冲击性能;钢丝-CFRP复合杆损伤形态为碳纤维因锤头冲击作用产生挤压损伤,形成许多较短的纤维,钢丝部分发生弯折变形但并未完全断裂,钢丝部分弯折变形可能吸收了部分冲击能量.

外置可更换耗能器的预制拼装自复位桥墩抗震性能试验研究

基于抗震韧性设计理念,结合装配式结构技术,发展了具有外置可更换耗能器的自复位预制拼装桥墩结构。开展了两组自复位预制拼装桥墩模型结构的拟静力往复加载试验研究。介绍了往复加载过程中自复位预制拼装桥墩的受力行为及损伤过程,分析了其力-位移滞回曲线、骨架曲线、耗能能力、预应力筋张拉力变化、残余位移、接缝开口、墩底受压区高度等抗震性能。结果表明:外置耗能部件具有良好的可更换性和耗能能力,更换前后桥墩的抗震性能基本一致。自复位桥墩力-位移滞回曲线呈现出明显的"旗帜"型形态,残余位移较小,具有良好的自复位能力。随墩顶水平位移增加,墩柱内轴向预应力筋张拉力基本呈线性增加,更换耗能器后预应力筋的预应力损失减小。墩底外包钢管有效地抑制了局部混凝土压溃,钢管没有出现局部外鼓等损伤破坏。

大位移摩擦摆底层和多层隔震韧性结构

结构韧性性能的目标是:在极罕遇地震作用时,结构不发生严重破坏;地震结束后,结构能恢复预期状态,进而恢复建筑功能的性能。隔震是结构韧性性能实现的关键技术,然而,结构隔震层位移响应超过允许值,引发隔震支座破坏,导致其减震性能失效,成为制约该类结构韧性性能目标实现的关键难题。本文以结构层作为滑动面,主体结构整体或滑动面之间的部分结构作为滑动块,提出大位移摩擦摆新型结构,通过隔震层的不同位置以及数量,构建大位移摩擦摆底层和多层隔震结构体系。分别建立该统一分析模型、探明其减震机理证明其良好减震性能,实现韧性结构性能目标。开展结构设计实现和韧性性能评价研究,表明了主体结构、非结构构件和大位移摩擦摆(支座和结构层)等地震损伤和恢复能力。本研究为韧性结构发展提供了结构新体系和关键发展方向。

利用汽车行驶风测试建筑风压系数的跑车试验方法研究

参照风洞试验和现场实测的试验方法,结合车辆行驶能产生风的特点,提出了一种理想道路条件下利用汽车行驶风测试建筑风压系数的跑车试验方法。采用理论推导和现场试验的方法,构建了跑车试验的基本理论,设计和组装了跑车试验的物理试验平台,搭建了软件测试系统,研究了测试数据的处理方法,运用该方法对CAARC标准模型典型测点的平均风压系数进行测试。研究了不同车速对平均风压系数的影响,并分析了同一车速多次重复测试平均风压系数结果的差异。研究结果表明:提出的跑车试验理论公式正确,构建的软硬件系统合理,标准模型测点的平均风压系数跑车试验测试结果与相关文献的风洞试验结果吻合很好,同一车速下多次重复测试结果偏差很小,不同车速影响平均风压系数程度小,验证了该方法在理想道路条件下的可行性。

伴MLL基因异常白血病的检测及其临床意义

目的研究伴混合谱系白血病(MLL)基因异常白血病的发病率及临床特征。方法回顾性分析单中心近五年来所有住院急性白血病患者的临床资料,采用多重逆转录聚合酶链式反应(RT-PCR)的方法筛选出MLL基因异常的患者,收集临床和预后资料进行分析。结果 2013年1月至2018年1月间我院收治的初发急性白血病223例(ALL 72例,AML 151例),其中MLL相关白血病患者资料完整的16例(ALL 3例,AML 13例)。MLL相关白血病占ALL的4.2%,AML的8.6%。16例患者经过2个疗程诱导化疗后达到完全缓解的只有7例(CR率43.8%)。11例患者进行了造血干细胞移植(HSCT),其中7例为单倍型移植,3例为同胞全相合移植,另外1例为脐血移植。16例患者随访4～51个月,中位随访时间17个月,期间9例患者死亡。16例患者的生存分析结果显示,这组患者的3年总生存率(OS)仅约40%,无进展生存率(PFS)约为30%。结论伴MLL基因异常的白血病对传统化疗反应不良,易复发,已成为疾病预后不良的标志,异基因移植有可能改善其预后。

岩浆侵入煤层中锑的赋存特征——以淮北卧龙湖矿为例

为探讨岩浆蚀变作用对煤层中锑赋存特征的影响,系统采集安徽淮北煤田卧龙湖煤矿岩浆侵入煤层侵入岩和全煤层样品共12个,利用原子荧光光谱法(AFS)测定样品中Sb含量,并对煤质参数进行分析。结果表明:卧龙湖煤矿岩浆侵入区煤表现为超低挥发分,中等灰分,特低硫的特点,煤中的硫主要以有机硫和黄铁矿硫存在。受岩浆热液影响,煤中灰分增加,挥发分减少;岩浆蚀变煤层中锑明显富集,算术平均值达到10.48mg/kg,且侵入岩上方煤中Sb的平均含量明显增高,煤岩接触带位置Sb的含量达到最高值(13.93 mg/kg);岩浆蚀变煤中的锑主要以无机结合态形式存在(相关系数r为0.74),有机硫与煤中Sb呈显著负相关(相关系数r为–0.60)。岩浆侵入作用导致卧龙湖煤矿煤的煤质特征及煤层中锑的赋存方式受到不同程度的影响,研究结果可为特殊地质作用下煤中锑的环境地球化学特征提供参考。

顾桥采煤沉陷积水区重金属分布与迁移特征

为了探讨上覆水-间隙水-沉积物层面微量元素的分布特征与潜在迁移趋势,系统采集淮南矿区顾桥采煤沉陷积水区上覆水和沉积物样品各10个,通过高速离心获得相应间隙水样品。利用电感耦合等离子体质谱(ICP-MS)及原子荧光光谱法(AFS)测试分析了各样品中As、Cd、Cr、Cu、Mn、Ni、Sb、Zn含量,并采用重金属污染指数法和地累积指数法评价上覆水体及沉积物中重金属污染程度。结果表明,(1)总体而言,顾桥采煤沉陷积水区上覆水水质较好,符合鱼类养殖的水质标准;间隙水中Cr、Cd和Zn的质量浓度分别达到193.11、2.14和176.18μg·L^(-1)。水质基准法生物毒性评价结果显示,间隙水中Cr、Cd和Zn对水生生物具有潜在生物毒性;沉积物中As、Cd、Cu、Cr、Ni的含量均值超过淮南土壤背景值和中国沉积物综合平均值,其中Cd平均质量分数高达1.114mg·kg^(-1),明显富集。(2)从垂直分布来看,水体中重金属的分布趋势表现为:沉积物>间隙水>上覆水。(3)分配系数结果表明,Cd、Zn、Sb易从沉积物中迁移进入上覆水中,具有较高的潜在环境危害。相关性分析结果显示,上覆水体中As与Mn、Cu与Cd具有相同污染源;间隙水中多种重金属之间的相关性较好,部分重金属具有同源性,沉积物中Ni与Zn、Mn的来源相似。(4)地累积指数结果表明,沉积物中Cd为偏重度污染,Cr为轻度污染,重金属总体污染程度为:Cd>Cr>Sb>Cu>As>Ni=Mn>Zn,顾桥采煤沉陷积水区水体沉积物中重金属Cd、Cr具有潜在生态危害,应引起管理者重视。

单倍型异基因造血干细胞移植治疗难治急性型成人T细胞白血病-淋巴瘤1例并文献复习

目的:探讨成人T细胞白血病-淋巴瘤(adult T cell leukemia-lymphoma,ATL)的临床特征及治疗。方法:回顾分析我院1例ATL的临床病理特征、治疗转归,并进行相关文献复习。结果:患者女性,44岁,祖籍福建,以皮疹、腹胀及水肿为首发表现,影像学检查提示全身多发代谢增高肿大淋巴结、脾大,腋窝淋巴结、腹壁皮肤活检提示外周T细胞淋巴瘤;经预治疗及多次化疗后效果欠佳,行HTLV I-RNA检测为阳性,诊断ATL急性型明确,后选择其子作为供者行单倍型异基因造血干细胞移植,移植后随访15个月至2022年04月仍存活。结论:由于北方地区HTLV-1感染率较低,遇到化疗效果欠佳的外周T细胞淋巴瘤时需考虑到ATL可能,尽早行相关病毒学检测以尽快明确诊断。单倍型异基因造血干细胞移植可以为ATL患者改善长期预后带来希望。

Design approaches for active,semi-active and passive control systems based on analysis of characteristics of active control force

In this paper, the characteristics of forces in active control systems connected to adjacent levels of a building are analyzed. The following characteristics are observed： （1） active control can provide significantly superior supplemental damping to a building, but causes a small frequency shift; （2） the linear quadratic regulator （LQR）-based control force is composed of an elastic restoring force component and a damping force component, where the damping force is almost identical to the total control force, however, the elastic restoring force is very small; and （3） the active control forces prevent mction most of the time during the entire control process. These three characteristics imply that active control systems connected to adjacent levels of a building behave like passive damping devices with adjustable parameters, namely damping characteristics in an active control, which is the mechanism used by semi-active control devices to reach similar performance as active control systems. Two indices are defined to quantify the damping characteristics of control forces in active control systems. These two indices can also be used to quantify the capacity of semi-active control to achieve the perfonrlance of active control. Based on the above observations, two principles are founded for optimization of parameters of semi-active control devices and passive dampers. The first is that the maximum output force of a semi-active or passive device to be designed is identical to an active device, called ＂design principle＂. The other is the response equivalent principle, which states that the response of a building with semi-active or passive devices is the same as with active devices when the same maximum output force is applied. The design procedure for semi-active control devices and passive dampers is described in detail. Finally, numerical simulations of two benchmark problems is conducted to demonstrate the damping characteristics of active control and investigate the capacity of semi-active control to achieve the same performance as active control.

Use of Different Mooring Models on Global Response Analysis of an Innovative Deep Draft Platform

The global responses of an innovative deep draft platform are investigated using catenary, semi-taut, and taut mooring models, respectively. The three mooring systems have the same arrangements and similar static restoring force characteristics. The dynamic coupling effects between the platform and the mooring systems are calculated in the time domain. Free-decay and 3-h simulations are conducted under 1-year and 100-year return period environmental conditions in the South China Sea. The mooring damping contributions, the response characteristics, and the mooring line tensions are investigated.

Conceptual Design of a Deep Draft Semi-Submersible Platform with a Moveable Heave-Plate

Based on the principle of turned mass damper(TMD) systems,the conceptual design of semi-submersible platform with a moveable heave-plate(MHS) has been put forward.The heave motion response amplitude operator(RAO) and viscous damping of the MHS platform are calculated by iteration,and the coupling stiffness between the MHS hull and the heave-plate is optimized to decrease the maximum heave motion response of the MHS hull under 10-year survival conditions in the South China Sea.The nu-merical results indicate that the heave motion RAO of the MHS hull can be decreased in the range of predominant wave frequencies,which may provide some reference to the heave motion control of offshore platforms.

Dynamic Performance of a Semi-Submersible Platform Subject to Wind and Waves

By applying experimental and numerical simulations, the motion performance of a semi-submersible platform with mooring positoning system under combined actions of wind and waves is studied. The numerical simulation is conducted by the method of nonlinear time domain coupled analysis, and the mooring forces are calculated by the piecewise extrapolating method. The scale in the model experiment is 1:100, and the mooring system of the model is designed with the method of equivalent water-depth truncation by comparing the numerical and the experimental results, the platform motion and mooring forces subject to wind and waves are investigated. The results indicate that the numerically simulated mooring forces agree well with the experimental results in static equivalent field, but show some difference in dynamic equivalent field; the numerically simulated platform motions coincide well with the experimental results. The maximum motion of the platform under operating conditions is 20.5 m. It means that the horizontal displacement is 2% less than the water depth, which satisfies the operating requirements.

A macro-level global seismic damage model considering higher modes

For modal pushover analysis procedures, the model proposed by Ghobarah et al. （called the G model hereafter, 1999） has been extended to account for the contributions of transient higher modes to global seismic damage of structures excited by strong ground motions. The proposed model has physically and perfectly bridged the G model and the final softening model proposed by DiPasquale and Cakmak （1988）. Modal damage indexes corresponding to all considered vibration modes are combined by the CQC rule or the SRSS rule. Incremental dynamic analysis （IDA） is performed on three example RC frames to validate the proposed model, and a comprehensive comparison is carried out. The demonstration indicates that the proposed model is easy to implement and reflects the influence of the transition in transient vibration periods and modes on structural damage evolution. Some limitations associated with the proposed model are also addressed. Further experimental validations are needed to improve the model in the future.

Hydroelastic Analysis of a Very Large Floating Structure Edged with a Pair of Submerged Horizontal Plates

This paper is concerned with the hydroelastic problem of a very large pontoon-type floating structure(VLFS) edged with a pair of submerged horizontal plates, which is a combination of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. For the hydroelastic analysis, the fluid is assumed to be ideal and its motion is irrotational so that a velocity potential exists. The VLFS is modeled as an elastic plate according to the classical thin plate theory. The fluid-structure interaction problem is separated into conventional hydrodynamics and structure dynamics by using modal expansion method in the frequency-domain. It involves, firstly, the deflection of the VLFS, which is expressed by a superposition of modal functions and corresponding modal amplitudes. Then the boundary element method is used to solve the integral equations of diffraction and radiation on the body surface for the velocity potential, whereas the vibration equation is solved by the Galerkin's method for modal amplitudes, and then the deflection is obtained by the sum of multiplying modal functions with modal amplitudes. This study examines the effects of the width and location of the non-perforated horizontal plates on the hydroelastic response of the VLFS, then the performance of perforated plates is investigated to reduce the motion near the fore-end of the VLFS. Considering the advantages and disadvantages of submerged plates without and with cylindrical holes, we propose a simple anti-motion device, which is a combination of a pair of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. The effectiveness of this device in reducing the deformation and bending moment of the VLFS has been confirmed, and is compared with the results in cases without and with the submerged horizontal plates by the analysis in this paper.

Numerical Study on Global Motion of Truss Spar in Frequency and Time Domains for the Liwan 3-1 Area

Using frequency and time domain analysis, the authors analyzed the hydrodynamics and motion behavior of a Truss Spar platform at a water depth of 1500 m in the Liwan 3-1 area of the South China Sea. Firstly, the seakeeping ability is acquired in the frequency domain by calculating the hull's hydrodynamics and comparing with a semi-submersible platform. The random wave analysis for 100-year, 10-year and 1-year return periods in Liwan 3-1 distinctly shows lower heave but larger surge and pitch re-sponses of the Truss Spar than those of a semi-submersible. Secondly, 3-hour motions of the Truss Spar are predicted and compared in the time domain under 100-year return period conditions in Liwan 3-1 and the Gulf of Mexico. Thirdly, the hull/mooring line cou-pled and uncoupled models are compared. Finally, the responses of the Truss Spar under 10-year and 1-year return period conditions are assessed. The results reveal that the mooring line damping reflected by the coupled model distinctly decreases the low frequency motion. The maximum heave response for 100-year return period waves is 1.23m and below 0.1m for the case of 1-year return period.

Fatigue damage characterization of carbon fiber reinforced polymer bridge cables:Wavelet transform analysis for clustering acoustic emission data

Carbon fiber reinforced polymer(CFRP)has many remarkable merits.It is lightweight and has great rigidity and high intensity. High-durability cable produced from CFRP as reinforcement material is widely used in bridge construction projects.However, there is a dearth of studies regarding damage types and mechanism under fatigue load of CFRP bridge cables.In this paper,we adopt acoustic emission(AE)technology to monitor fatigue damage and failure of the CFRP bridge cables,specifically by monitoring the bridge cable’s fatigue test process and using wavelet transformation to analyze data.Results show that damage on the CFRP cable is divided into three stages.Based on wavelet singularity theory,in each stage of AE,the burst signal is obtained and its time-frequency distribution is achieved through wavelet analysis.According to the analysis results,failure modes in each phase and type of acoustic emission source are easy to determine.The characteristics of waveform,types of damages, and frequency distribution of CFRP bridge cable in different damage phases are collected.Research shows that the method used to determine the types of fatigue damage on the CFRP cable is feasible according to the range of distribution characteristic parameters for acoustic emission signal and type of waveform.

Calculation Method of Wave Forces on Large Round-Ended Caisson Foundation

This paper presents an analytical formula for estimating the longitudinal wave forces on a large roundended caisson foundation. The establishment of the formula is based on the superposition of the theoretical formula of wave forces on a large circular cylinder and the empirical formula of wave forces on a large rectangular cylinder. With the formula transformed into an inertial force form, a specific inertia coefficient with an exact expression is extracted from the formula. The numerical calculations of the wave forces on round-ended cylinders are carried out by the boundary-element method. The undetermined coefficients in the expression of the inertial coefficient are determined by the numerical results. It is obvious that the numerical values can be well expressed by the computation values from the established formula. By a model experiment carried out in laboratory wave flume, the correctness of the analytical formula is further verified by the measured wave forces on a test model of a round-ended bridge caisson foundation. The comparison shows that the experimental forces can be approximately estimated by this simple calculation method.

Wave Forces and Moments on a Gravity Pier Foundation

In order to understand the wave forces and moments on a gravity pier foundation which consists of an upper column and a bottom gravity base,a model experiment with a scale of 1:60 has been conducted in a laboratory flume.A corresponding numerical calculation by using the boundary element method has been carried out to provide a comparative analysis.It is shown by the comparisons that the numerical wave forces and moments agree well with the experimentai results.It is proved that the wave forces and moments acting on the foundation are completely in their inertia dominative areas for wave loads.With the diffraction effects considered into the inertia item,appropriate inertia coefficients are assessed by the experimentai results for the inertia item of the Morison equation.The formula of the inertia item can be used to estimate wave forces and moments on such gravity foundations.

FLAG序贯马利兰／环磷酰胺预处理方案对异基因造血干细胞移植治疗难治／复发性急性髓系白血病疗效影响的临床观察

目的 观察采用FLAG（氟达拉滨联合大剂量阿糖胞苷及重组人粒细胞集落刺激因子）序贯马利兰/环磷酰胺（Bu/Cy）预处理方案进行异基因造血干细胞移植对于难治/复发性急性髓系白血病（AML）的疗效及安全性。方法 对2012年2月至2017年6月北京大学第一医院21例应用FLAG序贯Bu/Cy预处理方案进行异基因造血干细胞移植的难治/复发性AML患者资料进行回顾性分析，观察移植相关合并症及疗效情况。结果 预处理过程中21例患者均未出现肝静脉闭塞病及Ⅲ级以上出血性膀胱炎。76.2%（16/21）患者预处理过程中出现发热，发生败血症4例，除1例因感染中毒性休克在植入前死亡外，其余患者经抗感染治疗后均好转。20例患者获得中性粒细胞植活，中性粒细胞〉0.5×109/L的中位时间是13（10~21）d；17例患者获得血小板植活，血小板计数〉20×109/L的中位时间是18（9~25）d。发生急性移植物抗宿主病8例，累积发生率为39.5%，其中3例为Ⅲ~Ⅳ度急性移植物抗宿主病。移植后存活超过100 d的19例患者中，4例出现局限性慢性移植物抗宿主病。21例患者的中位生存时间为15（0.5~67）个月，移植相关死亡率为28.7%。4例患者在移植后3~8个月出现复发，1年累积复发率为21.4%。1年和3年的总体生存率分别为60.7%和54.6%。Log-rank分析显示，移植前骨髓内原始细胞≥20%或存在髓外病变、血小板植入不良和Ⅲ~Ⅳ度急性移植物抗宿主病显著降低患者移植后的总体生存率（P〈0.05）。结论 采用FLAG序贯Bu/Cy预处理方案的异基因造血干细胞移植具有可接受的移植相关风险，能够降低难治/复发性AML患者的复发率，提高其生存率。