无公害刺参稳产健康养殖新技术

本文针对目前刺参养殖中存在的问题,简单明了叙述刺参无公害健康养殖一系列新技术和新方法,对推动海参养殖业持续、稳定、健康发展,起到积极作用和效果。     

Equilibrium constants of triethanolamine in major seawater salts

Acid–base equilibrium constants of triethanolamine (TEA) have been determined by potentiometric titrations with a glass electrode, at 25 °C. Ionic strength was kept constant with only one electrolyte (using one of these salts: NaCl, KCl, MgCl₂ or CaCl₂), with binary mixtures of MgCl₂ and CaCl₂, and finally, in a solution with a composition approximately similar to that of natural seawater without sulfate. Equilibrium constants have been expressed in function of ionic strength by means of Pitzer equations and interaction parameters proposed in this theory have been obtained. It has been found that acid–base behaviour of TEA depends greatly on the salt used: basicity of TEA is decreased by CaCl₂, while it is increased by the other electrolytes used in this work.     

SoFISHticated policy – social perspectives on the fish conflict in the Northeast Atlantic

Ecosystem changes currently question the traditional allocation of fishing rights and quotas in the fishery of Northeast Atlantic mackerel and Norwegian spring-spawning herring in the Northeast Atlantic. Variability in the distribution of these highly migratory species escalated in a political conflict between member states of the European Union, Iceland, the Faroe Islands and Norway, which is a driving force for unsustainable fishery. The aim of this paper is to investigate this conflict by outlining the social understandings of diverse stakeholders by using the Q methodology. The method reduced the complexity of numerous opinions, detected four distinct perspectives and simultaneously categorised the participating stakeholders. Although the perspectives differ in various elements, the protection of economic interests seems to dominate over the quest for sustainability. The call of all stakeholders in this study to clarify the fishing rights in the Northeast Atlantic reveals a clear deficiency of the current international fishery management in handling abrupt ecological changes and the necessity to acknowledge this as a complex adaptive system.     

考虑各向异性的原状软黏土微观结构变化机制研究

采用电镜扫描仪（SEM）对在复杂应力路径作用下剪切前后的黏土样进行微观观察,并从剪切前后孔隙排列、孔隙形态、孔隙尺度变化特征3方面分析宏观试验原状软黏土归一化抗剪强度各向异性的微观本质。试验表明：剪切前后孔隙排列无序,孔隙排列方向变化很小,对黏土宏观性质影响很小;当中主应力参数b=0时,剪切过程中孔隙形态的变化对剪切后黏土归一化抗剪强度表现出的各向异性贡献较大;当b =0.5时,剪切过程中孔隙尺度的变化对剪切后黏土归一化抗剪强度表现出的各向异性贡献较大。因此,当中主应力参数不同时,影响剪切后黏土归一化抗剪强度各向异性的土的微观变化因素不同。     

双向耦合循环剪切条件下超固结饱和海洋黏土孔压与强度特性研究

针对长江口地区的重塑饱和海洋黏土,进行了一系列均等固结条件下的应力控制式轴向-扭转双向耦合循环剪切试验,着重探讨了循环荷载分量比R与超固结比OCR对孔压与动强度特性的影响。试验结果表明,随着R的减小,波动孔压幅值逐渐降低,而残余孔压先降低后升高,R = 1时残余孔压最小。在循环耦合剪切作用过程中,对应相同循环次数,随着OCR的增大,累积孔压变小,而波动孔压幅值却在增大。对应相同循环次数比N/Nf,随着OCR增大,残余孔隙水压力比ur / urmax减小。经归一化处理后ur / urmax-N/Nf关系曲线对于正常固结与超固结饱和黏土可分别用不同的表达式来表达。随着R的降低,破坏循环次数先增大后减小,R = 1时最大。随着OCR的增大,饱和黏土的强度变化减小     

暴雨作用下排土场平台–边坡系统土壤侵蚀过程模拟研究

为了探究冻融循环作用对土体结构和力学性质的影响机理,以内蒙古元宝山露天煤矿内排土场典型黏土为研究对象,采用室内冻融循环试验和MatDEM数值模拟,进行土体内部温度场、水分场和应力场的模拟分析。结果表明：排土场土料经过冻融循环后发生冻缩现象;低围压时应力−应变曲线呈现应变软化型,发生剪切破坏,围压升高后向应变硬化型转变,发生剪胀破坏;抗剪强度的劣化受前3次冻融作用的影响最为显著,在第3次达到最低值;温度的传递过程可划分为温度快速下降、缓慢相变过程、继续降温、温度稳定4个阶段;水分运移主要在温度传递的前2个阶段发生,且第二阶段的水分运移量居多;颗粒受冻融作用后整体半径缩小、分散性增大;温度和水分运移引起的颗粒胀缩、冰−水相变、冷生结构的形成等,导致颗粒的大小、位置、连接状态和颗粒间的应力等反复变化,共同驱动土体产生不可逆的结构性损伤,进而造成强度劣化。水分运移不仅为冷生构造的生长提供水源条件,还产生溶蚀、冲刷破坏,与水的相变共同成为冻融循环作用导致土体发生结构调整和应力场变化的主要原因。通过离散元法模拟冻融循环,有助于了解土体内部的力学特征和强度劣化机理,为冻区露天煤矿内排土场边坡及其他工程建设的稳定性研究提供参考。

     

基于强度参数演化行为的岩石峰后应力-应变关系研究

基于岩石材料峰后强度参数的演化行为,结合强度准则,提出了建立峰后应力-应变关系的一般方法。在此基础上,基于摩尔-库仑强度准则,以最大主应变 作为应变软化参数,假设黏聚力 ,内摩擦角 为主应变 的分段线性函数条件下,给出了岩石材料的峰后应力-应变关系式的求法。在数值算例中,利用提出的方法,给出了大理岩在不同围压下的应力-应变曲线,算例显示,利用这一方法求得的峰后应力-应变关系曲线变化趋势与试验数据基本一致,表明该方法在研究峰后应力-应变关系上具有一定的合理性。     

Reliability of mooring lines and piles for a permanently manned vessel in a tropical cyclone environment

The factors of safety for stationkeeping systems in current standards (ISO, API) are not derived or validated using reliability analyses. As the oil and gas exploration and production is breaking new boundaries, deploying new floating systems and moving into regions with harsher environments, it is of paramount importance to understand what level of reliability these new marine structures are achieving. This paper presents a reliability analysis of the mooring system of a Floating LNG (FLNG) vessel permanently moored and permanently manned offshore North West Australia in a tropical cyclone environment. The reliability analysis addresses both the mooring chain and the pile foundation. The analysis accounts for the long term characteristics of the environment, including the short term variability, in response to a given sea state and the variability and uncertainty in strength of the mooring chain and the pile. The stationkeeping system was analysed using detailed time domain simulations, capturing system non-linearities and low frequency oscillations as well as wave frequency responses and, thereby, reducing modelling uncertainties to a minimum.It is found that for the conditions modelled, neither the chain nor the pile meet a target reliability of 10⁻⁴/annum using the factors of safety commonly used in design following current ISO and API standards. New factors of safety are proposed to achieve this target reliability. For the pile design, one complicating factor is that current design standards do not explicitly define the exceedance probability that should be associated with the characteristic value of the undrained shear strength to be used in the design. It is demonstrated that the required factor of safety is crucially dependent on the definition of this characteristic value and on the level and the type of uncertainty in the soil strength profile. A recommendation is made regarding the definition of this characteristic value and the associated factor of safety. Furthermore, it is found that designing the mooring system to an environmental condition with a return period of 10,000 yr (as an Abnormal Limit State event), and setting the factor of safety to unity, meets the target reliability of 10⁻⁴/annum for the pile, if the characteristic undrained shear strength is a lower bound, defined in this paper by the 10th percentile value. For the chain however, this target reliability is not achieved.