Rheological property of low-damage,ideal packing,film-forming amphoteric/sulfonation polymer drilling fluids

Low-permeability dense reservoirs,including micro-fractured reservoirs,are commonly characterized by high content of clay substances,high original water saturation,high sensitivity to invasive fluids,high capillary pressure,complicated structure and anisotropic,high flow-resistance and micro pore throats etc,.Generally they also have lots of natural micro fractures,probably leading to stress sensibility.Main damaging factors in such reservoirs are water-sensibility and water-blocking caused by invasive fluids during drilling and production operations.Once damaged,formation permeability can rarely recovered.Numerous studies have shown that damaging extent of water-blocking ranges from 70% to 90%.Main damaging mechanisms and influencing factors of water-blocking were systematically analyzed.Also some feasible precaution or treating approaches of water-blocking were put forward.In a laboratory setting,a new multi-functional drilling fluid composed mainly of amphion polymer,sulfonation polymer,high effectively preventive water-blocking surfactants,ideal packing temporary bridging agents(TBA) and film-forming agents,etc.,were developed.New low-damage drilling fluids has many advantages,such as good rheological properties,excellent effectiveness of water-blocking prevention,good temporary plugging effect,low filtration and ultra-low permeability(API filtration≤5 mL,HTHP filtration≤10 mL,mud cake frictional coefficient≤0.14,permeability recovery>81%),can efficiently prevent or minimize damage,preserve natural formation and enhance comprehensive development-investment effect in TUHA Jurassic dense sandstone reservoir formation with low-permeability,the only one developing integrated condense gas field.Some references can be provided to similar reservoir formations.

Densely packed ultrafine SnO_(2) nanoparticles grown on carbon cloth for selective CO_(2) reduction to formate

Electrochemical reduction of CO_(2) to fuels and chemicals is a viable strategy for CO_(2) utilization and renewable energy storage.Developing free-standing electrodes from robust and scalable electrocatalysts becomes highly desirable.Here,dense SnO_(2) nanoparticles are uniformly grown on three-dimensional(3D)fiber network of carbon cloth(CC)by a facile dip-coating and calcination method.Importantly,Zn modification strategy is employed to restrain the growth of long-range order of SnO_(2) lattices and to produce rich grain boundaries.The hybrid architecture can act as a flexible electrode for CO_(2)-to-formate conversion,which delivers a high partial current of 18.8 m A cm-2 with a formate selectivity of 80%at a moderate cathodic potential of-0.947 V vs.RHE.The electrode exhibits remarkable stability over a 16 h continuous operation.The superior performance is attributed to the synergistic effect of ultrafine SnO_(2) nanoparticles with abundant active sites and 3D fiber network of the electrode for efficient mass transport and electron transfer.The sizeable electrodes hold promise for industrial applications.

1344吡啶羧酸配体构筑的Cu(Ⅱ)-MOFs及其染料吸附降解性能

为探究不同反应条件对MOFs微观结构和宏观性能的影响,在不同反应条件下,以硫酸铜(CuSO_(4)·5H_(2)O)和6-(吡啶-3′-基)间苯二甲酸(H_(2)L)为材料,制备了2种金属有机框架材料(MOFs){[Cu_(2)(L)_(2)·C _(2) H _(3) N]}n(1)和{[Cu(HL)_(2)]}n(2),并对合成的金属有机框架材料1和2进行了结构分析、TGA和FTIR表征以及对染料的吸附性能研究。单晶衍射数据分析表明:配合物1和2都属单斜晶系,P 21/c空间群。配合物1是一种基于双核轮桨次级构筑单元[Cu_(2)(COO)_(4)]构筑的三维紧密堆积化合物,配合物2由于配体部分质子化,结构中存在氢键[O_(3)—H…O_(4)],将二维层状网络结构连接成三维结构。配合物1是rtl拓扑类型的网络结构,拓扑符号为(42.610.83);配合物2是sql拓扑类型的网络结构,拓扑符号为(4^(4).6^(2))。2种配合物在相同时间间隔下对不同染料降解性能表明配合物2对水溶液中的孔雀石绿具有一定的化学吸附降解能力。

Chiral σ-ω Model Study of Hot Dense Nuclear Matter

The hot dense nuclear matter is studied in the chiral σ-ω model in theformalism of thermo-field dynamics.The binding energy,pressure and effective mass ofnucleon are calculated in the level of one-loop vaccum quantum fluctuation.The tem-perature effect is found very large at high temperature and the pressure can not reachsaturation as a function of nuclear density.

关于齐次Moran集的packing维数结果

该文构造了一类特殊的齐次Moran集,称为{m_k}-拟齐次Cantor集,并讨论了它们的packing维数.通过调整序列{m_k}_(k≥1)的值,构造性证明了齐次Moran集packing维数的介值定理.此外,还得到了齐次Moran集的packing维数取得最小值的一个充分条件.

Particle dynamics in dense shear granular flow

The particle dynamics in an annular shear granular flow is studied using the discrete element method, and the influences of packing fraction, shear rate and friction coefficient are analyzed. We demonstrate the existence of a critical packing fraction exists in the shear granular flow. When the packing fraction is lower than this critical value, the mean tangential velocity profile exhibits a rate-independent feature. However, when the packing fraction exceeds this critical value, the tangential velocity profile becomes rate-dependent and varies gradually from linear to nonlinear with increasing shear rate. Furthermore, we find a continuous transition from the unjammed state to the jammed state in a shear granular flow as the packing fraction increases. In this transforming process, the force distribution varies distinctly and the contact force network also exhibits different features.

Application Research of Dense Sintered Alumina in Iron Runner Castables

Three different kinds of corundum aggregates-tabular sintered alumina, dense sintered alumina, and fused dense corundum-were introduced into the silica fume .free or silica fume containing Al2O3 -SiC - C iron runner castables to investigate their influences on the flow ability, linear change on heating, bulk density, apparent porosity, cold strength, hot modulus of rupture, therm, al shock resistance, slag resistance, oxidation resistance as well as wear resistance of Al2O3 - SiC - C iron runner castables. The results show that （ 1 ） compared with the specimens with fused dense corundum, the specimens with dense sintered alumina have equivalent installation property, slag resistance and oxidation resistance, equivalent or even higher cold modulus of rupture, cold crushing strength and hot modulus of rupture, exhibiting better thermal shock resistance and cold wear resistance ; （2） adopting bimodal alumina micropowder LISAL22RABL as well as water reducers ZX2 and ZD2 can well reduce the water requirement of silica fume free castables, solving the problem of deteriorated flow ability resulted from the lack of silica fume; since the lack of silica fume avoids the formation of low melting point liquid, the hot modulus of rupture and the thermal shock resistance of the silica fume free castables are both better than those of the silica fume containing castables ; （3） the density of the castable specimens with dense sintered alumina is 4% -6% lower than that of the castable specimens with Jhsed dense corundum so the refractories consumption of one iron runner reduces by 5% by using the tastable with dense sintered alumina, which obviously reduces the cost of refractories.

An Improved Binary Wolf Pack Algorithm Based on Adaptive Step Length and Improved Update Strategy for 0-1 Knapsack Problems

Binary wolf pack algorithm (BWPA) is a kind of intelligence algorithm which can solve combination optimization problems in discrete spaces.Based on BWPA, an improved binary wolf pack algorithm (AIBWPA) can be proposed by adopting adaptive step length and improved update strategy of wolf pack. AIBWPA is applied to 10 classic 0-1 knapsack problems and compared with BWPA, DPSO, which proves that AIBWPA has higher optimization accuracy and better computational robustness. AIBWPA makes the parameters simple, protects the population diversity and enhances the global convergence.

基于紧密堆积理论的混凝土弹性模量与徐变控制

为降低连续刚构桥跨中下挠幅度,针对弹性模量与徐变2种影响因素,提出一种基于骨料紧密堆积理论的配合比优化控制方法,并对比原配合比研究了优化控制方法对不同龄期与环境下的弹性模量与徐变的影响;结合SEM(scanning electron microscope)与MIP(mercury intrusion porosimetry)试验,从混凝土微观层面分析优化机理,以CEB-FIP(1990)模型为基础,提出考虑弹性模量成熟度的修正模型.结果表明:优化控制方法对早龄期混凝土弹性模量具有明显的控制效果,但界面过渡区面积的增加限制了后期弹性模量的发展;相同条件下,优化后混凝土徐变系数较原配合比降低了12%~23%;环境对混凝土徐变影响与优化控制方法相比占主导作用,不同环境下混凝土徐变变化幅度在45%~60%;混凝土徐变随加载龄期延长而减小,且优化后混凝土在较小加载龄期时,徐变仍比较大加载龄期的原配合比混凝土徐变降低3%~13%;优化后混凝土早龄期内部孔隙与微裂缝数量减少,改善了混凝土内部结构;修正后的CEB-FIP(1990)模型对徐变预测精度更高.

Two-dimensional densely ordered packings of non-convex bending and assembled rods

The investigation of the problem of particle packing has provided basic insights into the structure,symmetry,and physical properties of condensed matter.Dense packings of non-spherical particles have many applications,both in research and industry.We report the two-dimensional dense packing patterns of bending and assembled rods,which are non-convexly deformed from simple objects and modeled as entangled particles.Monte Carlo simulations and further analytical constructions are carried out to explore possible densely packed structures.Two typical densely packed structures of C-bending rods are found,and their packing densities are identified as being functions of the aspect ratio and central angle.Six shapes of assembled rods,representing the combined deformations of rods,are employed in simulations with the packing structures classified into three types.The dense packing density of each packing pattern is derived as a function of different shape parameters.In contrast with the case of disordered packings,both the shape and order are verified to affect the packing density.

三峡-葛洲坝联合调度系统闸室编排快速算法

三峡—葛洲坝两坝联合调度系统是用于提高三峡—葛洲坝航道通航能力的一套系统。两坝联合调度的计划编排是一个与闸室编排相耦合的时间表问题。闸室编排可以用二维Packing模型来描述,是一个典型NP完全问题。提出一种基于分步降维思想的启发式快速编排算法,该算法把闸室编排二维Packing问题降到一维求解,有效解决三峡-葛洲坝联合调度的计划编排中与闸室编排相耦合的时间表问题。该算法在实际工程应用中取得了良好的效果,有效地提高了闸室面积利用率。

超高性能混凝土设计理论与磷石膏高质利用研究进展

从干堆积、湿堆积、化学堆积、复杂原料的等效堆积等方面综述了超高性能混凝土(UHPC)配合比设计理论从MAA模型发展至全尺度物理和化学协同堆积模型的过程,阐述了人工智能技术在提升理论设计精度中的重要应用,以及借助UHPC设计理论实现固废高质化利用和混凝土高性能协同提升的可行性,可为UHPC原材料的优化设计提供参考。

矿渣-水泥胶凝体系颗粒群匹配与其活性的关系研究

将矿渣粉磨后,以不同的比例与一定细度的水泥混合,配成一系列的矿渣-水泥胶凝粉体。以Fuller曲线得到的粉体颗粒群分布作为矿渣-水泥胶凝粉体的最佳紧密堆积颗粒群分布。利用水泥与矿渣激光粒度检测结果来计算矿渣-水泥胶凝粉体的颗粒群分布,运用灰色关联分析方法计算矿渣-水泥胶凝粉体与最紧密颗粒群堆积颗粒群分布的关联度,同时测定不同矿渣掺量下矿渣-水泥胶凝体系的不同龄期的活性指数。结果表明:矿渣-水泥胶凝粉体的实际颗粒群分布与最紧密堆积颗粒群分布关联度最高时,该胶凝体系的28d矿渣活性指数最为理想。

螺旋藻中β-胡萝卜素高效液相色谱测定方法的研究

采用高效液相色谱法直接测定螺旋藻中β-胡萝卜素组分的含量.色谱柱为YMC-pack ODS(4.6mm i.dx 150 mm,5μm),流动相为甲醇-乙腈-二氯甲烷(体积比60:30:10),在435nm波长处检测.研究结果表明:β-胡萝卜素的检测限为20ng,线性范围在4.60～36.80 mg/L,相关系数为0.9996,加样平均回收率为96.61%.方法准确、简便、快速,适用于螺旋藻及螺旋藻制品中β-胡萝卜素组分的检测.

Dense packing properties of mineral admixtures in cementitious material

The effect of ultra-fine fly ash （UFFA）, steel slag （SS） and silica fume （SF） on packing density of binary, ternary and quaternary cementitious materials was studied in this paper in terms of minimum water requirement of cement. The influence of mineral admixtures on the relative density of pastes with low water/hinder ratios was analyzed and the relationship between paste density and compressive strength of the corresponding hardened mortars was discussed. The results indicate that the incorporation of mineral admixtures can effectively improve the packing density ofcementitious materials; the increase in packing density of a composite with incorporation of two or three kinds of mineral admixtures is even more obvious than that with only one mineral admixture. Moreover, an optimal amount of mineral admixture imparts to the mixture maximum packing density. The dense packing effect of a mineral admixture can increase the packing density of the resulting cementitious material and also the density of paste with low water/binder ratio, which evidently enhances the compressive strength of the hardened mortar.

Strange Stars: Can Their Crust Reach the Neutron Drip Density?

The electrostatic potential of electrons near the surface of static strange stars at zero temperature is studied within the frame of the MIT bag model. We find that for QCD parameters within rather wide ranges, if the nuclear crust on the strange star is at a density leading to neutron drip, then the electrostatic potential will be insufficient to establish an outwardly directed electric field, which is crucial for the survival of such a crust. If a minimum gap width of 200 fm is brought in as a more stringent constraint, then our calculations will completely rule out the possibility of such crusts. Therefore, our results argue against the existence of neutron-drip crusts in nature.

Synthesis,Crystal Structure and Characterization of a New Mixed-valence Cu(Ⅰ)/Cu(Ⅱ) Complex [Cu(bipy)(Me_2dtc)CuI_2]_n

A new one-dimensional mixed-valence Cu（Ⅰ）/Cu（Ⅱ） complex [Cu（bipy）（Me2dtc）CuI2]n 1 （bipy = 2,2′-bipyridine and Me2dtc = N,N-dimethyldithiocarbamate） has been synthesized under solution condition, and characterized by elemental analysis, IR spectrum, single-crystal X-ray diffraction and magnetic property. The crystal belongs to the tetragonal system, space group P4122 with a = b = 11.6504（16）, c = 13.466（3） A, V = 1827.8（5） A^3, Z = 4, Dc = 2.389 g/cm^3, Mr = 657.27, λ（MoKa） = 0.71073 , μ = 5.931 mm·1, F（000） = 1236, the final R = 0.0483 and wR = 0.1245. A total of 2102 unique reflections were collected, of which 2009 with I 〉 2σ（I） were observed. 1 consists of polymeric [Cu^II2]nn^- anions and [Cu^II（bipy）（Me2dtc）]^＋ cations. It is interesting that the cations of 1 interact through π-π stacking interactions after rotating 90° to form one-dimensional chains parallel to the anion chains. The magnetic study indicates antiferromagnetic behavior for this complex.

复杂背景下遥感图像密集目标检测

遥感图像中的目标排列密集,常见的检测算法难以较好地区分密集目标,同时目标所处背景复杂,导致在模型生成的特征图中,存在高响应的背景噪声,容易带来错误的检测结果。针对上述问题,在CenterNet算法基础上,提出一种改进权重分配的目标检测算法。在计算热力图损失的过程中,设计一种改进权重分配策略,加大目标边缘区域回传的损失,促进网络对密集目标边缘的学习,减少算法将密集目标认定为单个目标的概率;在CenterNet网络结构中,添加语义分割模块,让网络模型学习每一个目标的分割图,通过分割图抑制特征图中高响应的背景噪声。在DOTA数据集上进行实验,改进算法均值平均精度(mAP)达到68.56%,优于其他方法,和原CenterNet算法相比,mAP提升了6.53个百分点。实验结果表明,改进的CenterNet算法能更好地适应复杂背景下的密集目标检测。

基于FLOW 3D的密排管桩防波堤透射系数研究

港内波高大小对泊稳条件影响重大。以海外某离岸式化工码头为工程背景,采用新型密排管桩防波堤为研究对象,探讨不同波浪工况下防波堤的透射性能。基于FLOW 3D的有限差分法,建立具有自由水面的三维数值波浪水池,通过与物理模型试验对比验证模型的准确性,分析在不同波陡、不同周期波浪条件下,不同管桩间缝宽的透射系数。结果表明:随波浪周期的增大,透射系数先增大后趋于平缓,当入射波浪周期大于一定范围时,防波堤对于波浪的掩护作用不再增强;在小周期波浪条件下,透射系数随桩间缝宽的增大而增大,当相对缝宽为0.05时,透射系数低于70%。研究结果可为实际工程应用提供指导。

基于最紧密堆积理论的自密实混凝土制备与性能研究

基于最紧密堆积理论,对砂石和胶凝材料进行了最紧密堆积设计,选用最佳配合比制备了高速铁路CRTSⅢ型板式无砟轨道自密实混凝土,并对其性能进行了测试。结果表明:当m2区砂∶m3区砂=6∶4,m5~10 mm石∶m5~10 mm石=4∶6,水泥、粉煤灰、矿粉质量比为7.0∶0.5∶2.5,水胶比为0.35,膨胀剂掺量为5%时,所制备的自密实混凝土性能良好,扩展度可达660~680 mm,T500为4~6 s,28 d抗压强度>40 MPa,56 d干燥收缩≤400×10-6,满足相关标准要求。