Heave compensation system of lifting pipeline for deep-sea mining based on combined action of vibration absorber and accumulator

ABSTRACT

A heave compensation system combined with a vibration absorber and accumulator is proposed, with regard to the requirement for poly-metallic nodule mining systems at an ocean depth of 6,000?m in China. The principle of the compensation system was analyzed, its main parameters were designed, and its mathematical model was established. The system performance was simulated and analyzed in MATLAB, and the frequency domain characteristics and compensation rate of the system with different volume accumulators, and with or without vibration absorbers, were compared. A simulation test of the compensation system was conducted. The proposed compensation system had a better compensation effect for a random wave interference under level-6 sea conditions, and the compensation rate being more than 72% with optimal system parameters.     

云南农村土木结构房屋有限元抗震分析

根据2007年6月3日宁洱6.4级地震现场调查结果,对破坏较严重的土坯房建立了地震分析模型。对不同的开间、进深及檐口高的房屋,输入了3类场地超越概率为63%及超越概率为3%的地震波进行了有限元抗震分析。结果表明:墙厚影响不大,墙高的影响较大,墙高增加,破坏性增加;因此建议在满足使用功能的前提下,不增加墙厚,而减少层高对抗震更为有利,最后提出了相应的抗震加固措施。     

2010年4月14日青海玉树7.1级地震序列中小地震辐射能量的估计

本文利用震后架设的4个流动台站和震源区周围3个固定台站记录到的青海玉树7.1级地震序列波形资料,资料时间截止到2010年5月19日.经过传播路径效应和场地响应校正后,估算了玉树地震序列中80个中小地震的辐射能量.比较了辐射能量估计中不同方法之间结果存在的差异性,首次考虑了由于仪器频带宽度的限制而造成的中小地震辐射能量的低估与补偿问题,得到以下主要结论:(1)分别采用Andrews方法、震源实际谱方法(区分能量补偿前和后二种情况)和根据理论模型并将积分上限外推到所计算地震拐角频率的10倍的方法(理论谱方法)计算出的中小地震辐射能量4种结果基本上位于同一个量级水平之上,表明结果具有一定的可靠性和稳定性.这其中,Andrews方法得到的辐射能量最低,理论谱方法得到的结果最高,而由实际谱方法得到的地震辐射能量介于两者之间.(2)由古登堡经验公式得到的地震辐射能量远高于上述4种方法计算出的结果,能够达到理论谱方法结果的4倍,而且随震级的增大,由它带来的辐射能量的高估趋势更加明显.(3)由于没有考虑地震能量的补偿,Andrews方法得到的地震辐射量明显偏低.用两种不同方法进行地震辐射能量补偿后得到的结果比较接近,但考虑到仪器频带上限值设定的复杂性,认为由理论谱方法计算中小地震的辐射能量更加合适.(4)经过能量补偿后地震辐射能量要高于未作能量补偿的结果,能量补偿带来的辐射能量增加的作用对于小地震更加明显.在本文研究范围之内,不同方法得到的折合能量均明显存在随地震矩的增大而增大的现象,反映出玉树余震序列中大震地震辐射效率高于小震.     

Compensatory mitigation in marine ecosystems: Which indicators for assessing the “no net loss” goal of ecosystem services and ecological functions?

Recent years have seen increasing interest in the concepts of compensation and ecosystem services. Regulation systems in the United States dealing with environmental protection (Superfund Act, Oil Pollution Act, National Environment Policy Act, Clean Water Act, Endangered Species Act, etc.) require those responsible for damage to ecosystem services to compensate for it “physically” and restore these services for the benefit of the entire population. This article, using simple indicators of compensation identified in the literature, attempts to analyze what types of ecological compensation are adopted, how performance is assessed, how standards on ecological equivalencies are adopted, and what are the costs of this compensation. To perform this analysis, compensatory measures carried out during the last ten years in the case of coastal and marine ecosystems in Florida have been addressed. The results show that: analysis criteria for the equivalencies between ecosystem services lost due to damage and ecosystem services gained due to compensatory measures are questionable; most compensation monitoring is for a relatively brief period of time and the data obtained during this period may be insufficient for assessing the net effect of the compensatory measure; the weaknesses regarding criteria for the equivalencies and the uncertainty about the relevant time-scale can be counter-balanced by increasing the area of compensation, a problematic solution at best.     

对生态补偿概念及两个研究层面的反思

对生态补偿的基本语义进行解析,提出了一种以损失性境遇与补偿关系域为基本元素的分析模式。强调生态补偿的研究与实践必须物质与价值层面并举,且以前者为指归。生态补偿在自然科学方面的深层机理与准则还有待深入研究,才能指导生态补偿在经济、法律等其他层面的正确认识与实践。指出生态效益价值计量与生态补偿没有实质性的联系;“生态效益补偿”是一个容易引起误解的观念或概念。补偿标准基本的考量在成本、包括机会成本一面,不在效益一面;既实现生产者剩余又实现消费者剩余,是合珲补偿的基本前撂。     

Making a home during crisis: Post‐tsunami recovery in a context of war,Sri Lanka

This paper provides insights into the dynamic linkages between the ongoing construction of houses for people displaced by war and disaster, conceptions of homemaking and processes of recovery and reconstruction in the post‐tsunami context in Sri Lanka. In so doing, it also uncovers the dilemmas and ambiguities that are embedded in the recovery process. A case from Eastern Province, Sri Lanka illustrates how recovery works in local areas are driven by various stakeholders from outside, whose negotiations and power, voices and preferences, both independently and collectively, define the scope for homemaking processes. Our findings recommend that debates of ‘building back better’ following such disasters should embody an understanding of houses as political, cultural, social and economic constructs, and be cognizant of the wider processes of homemaking.     

基于DSC模型的房屋开裂评估与监测分析

城市隧道下穿时,普遍存在着地表房屋变形超限、倾斜开裂等安全风险问题,而且当前针对房屋变形开裂的计算分析、风险评估研究,也严重滞后于实际工程的需要。通过综合分析、比选,以及单、三轴试验验证表明：DSC（disturbed state concept）本构模型能够较好地描述材料开裂后力学行为;采用该模型并结合厦门机场路隧道下穿建筑群的工程实践,对地表建筑群开裂进行定量评估,评估结果与现场房屋裂缝监测、变形监测结果一致性良好。同时,对照扰动变量与实际房屋开裂的对应关系,发现扰动变量可以作为房屋开裂的定量安全指标,进一步即可以建立房屋变形开裂的过程控制标准,从而使隧道下穿过程中每个关键施工部、每个时段,地表房屋变形开裂程度、开裂风险都可以进行量化评估。     

A method for absorption compensation based on adaptive molecular decomposition

In this paper, we present a new method for seismic stratigraphic absorption compensation based on the adaptive molecular decomposition. Using this method, we can remove most of the effects resulting from wavelets truncation and interference which usually exist in the common time-frequency absorption compensation method. Based on the assumption that the amplitude spectrum of the source wavelet is smooth, we first construct a set of adaptive Gabor frames based on the time-variant properties of the seismic signal to transform the signal into the time-frequency domain and then extract the slowly varying component (the wavelet’s time-varying amplitude spectrum) in each window in the time-frequency domain. Then we invert the absorption compensation filter parameters with an objective function defined using the correlation coefficients in each window to get the corresponding compensation filters. Finally, we use these filters to compensate the time-frequency spectrum in each window and then transform the time-frequency spectrum to the time domain to obtain the absorption-compensated signal. By using adaptive molecular decomposition, this method can adapt to isolated and overlapped seismic signals from the complex layers in the inhomogeneous viscoelastic medium. The viability of the method is verified by synthetic and real data sets.     

伺服阀对地震模拟振动台控制性能影响及控制参数自整定

振动台控制系统设计时对物理系统进行了两个基本假设:伺服阀线性、台面和负载刚性。这样得到的控制系统频带较窄、时滞大,还有可能出现控制系统不稳定。本文通过系统建模,主要分析了伺服阀对振动台控制性能的影响:伺服阀频率特性限制了其控制精度。设计了前馈补偿环节、控制系统参数自整定算法修正系统控制性能,实例仿真结果表明:修正后的算法扩宽了系统频带,提高了地震记录的再现精度。     

某工程地基软弱夹层的补强设计与检测

对于地基主要受力层范围内局部存在软弱夹层的复杂地质条件,通常的处理方法或挖除换填或采用复合地基,针对具体工程探讨了的不同补强处理设计和施工方法的适用性,利用以往的研究成果,提出了按沉降控制进行补强设计的新思路,并针对处理后的深层复合土层不便直观和开挖检验的难题,结合多道瞬态面波法检验补强加固效果,实现了预期的目的,为类似工程实践提供了有益的借鉴。