Chloride migration in concrete with superabsorbent polymers

Superabsorbent polymers (SAP) can be used as a means for internal curing of concrete. In the present study, the development of transport properties of concrete with SAP is investigated. The chloride migration coefficient according to NT BUILD 492 is used as a measure of this. Twenty concrete mixtures are tested 7, 14, and 28 days after casting. The development of degree of hydration is followed for 20 corresponding paste mixtures.Both when SAP is added with extra water to compensate the SAP water absorption in fresh concrete and without extra water, the internal curing water held by SAP may contribute to increase the degree of hydration. No matter if SAP is added with or without extra water, it appears that the so-called gel space ratio can be used as a key parameter to link age and mixture proportions (water-to-cement ratio and SAP dosage) to the resulting chloride migration coefficient; the higher the volume of gel solid relative to the space available for it, the lower the chloride migration coefficient, because the pore system becomes more tortuous and the porosity becomes less.     

PETROLEUM MIGRATION, FAULTS AND OVERPRESSURE, PART I: CALIBRATING BASIN MODELLING USING PETROLEUM IN TRAPS — A REVIEW

This paper considers the principles of deciphering basin-scale hydrocarbon migration patterns using the geochemical information which is present in trapped petroleum. Petroleum accumulations in subsiding basins can be thought of as "data archives" within which stored information can help us to understand aspects of hydrocarbon formation and migration. This information can impart a time-resolved picture of hydrocarbon migration in a basin in response to processes associated with progressive burial, particularly in the context of the occurrence and periodic activity of faults.
This review, which includes a series of tentative models of migration-related processes in the extensional Halten Terrace area, offshore mid-Norway, illustrates how we can use information from the migrating mobile hydrocarbon phase to improve our knowledge of the static geological system. Of particular importance is the role of sub-seismic heterogeneities and faults in controlling migration processes. We focus on how the secondary migration process can be enhanced in a multi-source rock basin such as the Halten Terrace, thereby increasing prospectivity.     

针对不同地质目标的叠前时间偏移成像解释评价

随着计算机硬件和地震勘探成像技术的发展，叠前时间偏移正逐步替代常规的NMO加DMO加叠后时间偏移成为地震数据成像处理方法的主流。但对于不同的地质目标，叠前时间偏移的成像效果是否优于常规NMO加DMO加叠后时间偏移的成像效果呢？为此，从地震数据成像处理方法、处理流程和处理参数等方面进行了讨论，并基于某地区三维数据常规处理结果和叠前时间偏移处理结果，针对不同地质目标进行了剖析与评价。认为：叠前时间偏移成像的垂向分辨率较常规处理明显降低，但对于空间波阻抗变化明显的河流和断层，叠前时间偏移成像的空间分辨率要高于常规处理；对于小于1／4波长的叠置薄储层，叠前时间偏移成像的垂向和空间分辨率低于常规处理结果。     

炼油厂全流程优化建模方法研究

为了克服使用线性规划和单处理单元非线性规划进行生产优化的内在缺点，在建立原油单元、催化裂化、催化重整和汽油调合等4个重要处理单元详细模型的基础上，将单处理单元非线性过程模型集成到一个全流程优化非线性模型中。优化的目标函数是使炼油厂全厂利润最大。决策变量是那些显著影响全厂效益的变量，约束条件是单个处理单元约束条件的集合。对某炼油厂进行实例研究，结果表明该全流程模型能有效处理全厂优化问题，所得利润在线性规划的基础上提高4．5％。     

营尔凹陷下白垩统油气勘探应避开高压水层

营尔凹陷下白垩统(K₁₎存在下沟组和赤金堡组2套源岩，目前它们已到成熟阶段。凹陷东侧长沙岭构造在下白垩统下沟组和赤金堡组储层中也发现油藏，但主要分布在高压水层的顶部及下部，而高压水层段存在良好的储层，并未发现油气。文章根据高压水层段的储层荧光特征，通过储层烃与源岩的对比，分析了下白垩统高压水层对油气运移的影响。研究结果表明：高压水层段，储层荧光弱，储层抽提物特征既不同于赤赤金堡组源岩，也不同于下构组源岩，为就近捕获的产物；高压水层未发生大规模的油气运移，其形成时间早于油气运移的时间。建议该区油气勘探目标的选择应避开高压水层，选择凹陷附近的圈闭、高压水层以下的层位。     

多分量波场的矢量法叠前深度偏移技术

本文研究了二维各向同性介质中两分量记录的矢量法叠前深度偏移方法———叠前逆时深度偏移方法。首先从弹性波波动方程出发,在交错网格空间中推导了各向同性介质中弹性波逆时延拓的高阶有限差分格式;然后从程函方程出发,采用逆时差分格式求解地下各点的地震波走时。为确保算法满足地震波传播的因果性条件及其对复杂模型的适应性,用扩展波阵面算法追踪波前并搜索全局极小,以上述方法的计算结果作为弹性波逆时偏移的成像条件,实现二维多分量资料的叠前逆时深度偏移。模型试算和实际单炮记录试验表明,叠前逆时深度偏移方法考虑了地震波的矢量特征,是一种有效的矢量波场处理技术。     

氧化锌压敏电阻的老化机理

研究了ZnO压敏电阻的老化现象,提出了一种新的老化机理-线性链理论。该理论认为,在外电场作用下,压敏电阻势垒高度降低;当降低到一定值时,晶界可变电阻转化为线性晶界电阻,从而压敏链转化为线性链。线性链是稳定的,因而压敏电阻老化到一定程度后其电性能将不能完全恢复。     

论反射地震偏移成像

对反射地震偏移成像问题进行了分析、对比与探讨，并对各种偏移方法如叠后时间偏移、叠后深度偏移、叠前时间偏移、叠前深度偏移和它们之间在地质效果上的异同进行了讨论。认为，在当前的地面观测记录的质量条件下，叠后时间偏移和叠后深度偏移，叠前时间偏移和叠前深度偏移，都有各自的优势和不足。因此，它们都有应用价值，不是互相排斥，而是互相补充。今后的方向是发展和完善高分辨率和高保真度的偏移成像方法。在这方面还有许多问题要解决。     

Generation of Technology-Independent Retargetable Analog Blocks

This paper introduces a complete methodology for retargeting of analog cells to different sets of specifications. This methodology is technology-independent, thus allowing the migration, from one technology to another, of the circuit under retargeting. Careful integration of the device sizing and layout generation tasks via the incorporation of layout constraints during the sizing process allows to generate fully functional designs in a few minutes. The methodology is illustrated via the retargeting of a fully-differential Miller-compensated two-stage operational amplifier for a new set of specifications and two different technological processes.An erratum to this article can be found at     

建立速度模型的层析成像方法研究

针对目前叠前深度偏移速度模型建立中，全局反演的层析成像方法存在稳定性和走时拾取困难，以及局部反演的偏移速度分析大多存在假设条件过于苛刻等问题，通过分析，提出了利用地震同相辅的多种信息进行层析反演，并在反演中加入富有地质含义的倾角信息以增加反演过程的稳定性和收敛速度，利用类似于叠加速度谱的斜率速度谱来拾取地震同相轴的斜率，抛开了层位反演要求拾取同一同相轴这一实际应用难度很大的条件，使拾取方便，算法稳定。通过理论试算，证明了本方法的有效性。