Dissipative particle dynamics simulation of wettability alternation phenomena in the chemical flooding process

Wettability alternation phenomena is considered one of the most important enhanced oil recovery （EOR） mechanisms in the chemical flooding process and induced by the adsorption of surfactant on the rock surface. These phenomena are studied by a mesoscopic method named as dissipative particle dynamics （DPD）. Both the alteration phenomena of water-wet to oil-wet and that of oil-wet to water-wet are simulated based on reasonable definition of interaction parameters between beads. The wetting hysteresis phenomenon and the process of oil-drops detachment from rock surfaces with different wettability are simulated by adding long-range external forces on the fluid particles. The simulation results show that, the oil drop is liable to spread on the oil-wetting surface and move in the form of liquid film flow, whereas it is likely to move as a whole on the waterwetting surface. There are the same phenomena occuring in wettability-alternated cases. The results also show that DPD method provides a feasible approach to the problems of seepage flow with physicochemical phenomena and can be used to study the mechanism of EOR of chemical flooding.

2015 IWA Alternative Water Resources Conference Nanjing,China(May 26-28,2015)

The IWA Alternative Water Resources（AWR）Conference is organized by the International Water Association,Hohai University,the IWA China Chapter of the AWR Cluster,and the Seawater Desalination and AWR Utilization Research Center of Hohai University.

Novel miR-490-3p/hnRNPA1-b/PKM2 axis mediates the Warburg effect and proliferation of colon cancer cells via the PI3K/AKT pathway

BACKGROUND Heterogeneous ribonucleoprotein A1(hnRNPA1)has been reported to enhance the Warburg effect and promote colon cancer(CC)cell proliferation,but the role and mechanism of the miR-490-3p/hnRNPA1-b/PKM2 axis in CC have not yet been elucidated.AIM To investigate the role and mechanism of a novel miR-490-3p/hnRNPA1-b/PKM2 axis in enhancing the Warburg effect and promoting CC cell proliferation through the PI3K/AKT pathway.METHODS Paraffin-embedded pathological sections from 220 CC patients were collected and subjected to immunohistochemical analysis to determine the expression of hnRNPA1-b.The relationship between the expression values and the clinicopathological features of the patients was investigated.Differences in mRNA expression were analyzed using quantitative real-time polymerase chain reaction,while differences in protein expression were analyzed using western blot.Cell proliferation was evaluated using the cell counting kit-8 and 5-ethynyl-2’-deoxyuridine assays,and cell cycle and apoptosis were detected using flow cytometric assays.The targeted binding of miR-490-3p to hnRNPA1-b was validated using a dual luciferase reporter assay.The Warburg effect was evaluated by glucose uptake and lactic acid production assays.RESULTS The expression of hnRNPA1-b was significantly increased in CC tissues and cells compared to normal controls(P<0.05).Immunohistochemical results demonstrated significant variations in the expression of the hnRNPA1-b antigen in different stages of CC,including stage I,II-III,and IV.Furthermore,the clinicopathologic characterization revealed a significant correlation between hnRNPA1-b expression and clinical stage as well as T classification.HnRNPA1-b was found to enhance the Warburg effect through the PI3K/AKT pathway,thereby promoting proliferation of HCT116 and SW620 cells.However,the proliferation of HCT116 and SW620 cells was inhibited when miR-490-3p targeted and bound to hnRNPA1-b,effectively blocking the Warburg effect.CONCLUSION These findings suggest that the novel miR-490-3p/hnRNPA1-b/PKM2 axis could provide a new strategy for the diagnosis and treatment of CC.

Ionic Conduction and Fuel Cell Performance of Ba0.98Ce0.8Tm0.2O3-α Ceramic

The perovskite-type oxide solid solution Ba0.98Ce0.8Tm0.2O3-α was prepared by high temperature solid-state reaction and its single phase character was confirmed by X-ray diffraction. The conduction property of the sample was investigated by alternating current impedance spectroscopy and gas concentration cell methods under different gases atmospheres in the temperature range of 500-900 ℃. The performance of the hydrogen-air fuel cell using the sample as solid electrolyte was measured. In wet hydrogen, the sample is a pure protonic conductor with the protonic transport number of 1 in the range of 500-600 ℃, a mixed conductor of proton and electron with the protonic transport number of 0.945-0.933 above 600 ℃. In wet air, the sample is a mixed conductor of proton, oxide ion, and electronic hole. The protonic transport numbers are 0.010-0.021, and the oxide ionic transport numbers are 0.471-0.382. In hydrogen-air fuel cell, the sample is a mixed conductor of proton, oxide ion and electron, the ionic transport numbers are 0.942 0.885. The fuel cell using Ba0.98Ce0.8Tm0.2O3-α as solid electrolyte can work stably. At 900 ℃, the maximum power output density is 110,2 mW/cm2, which is higher than that of our previous cell using Ba0.98Ce0.8Tm0.2O3-α （x〈≤1, RE=Y, Eu, Ho） as solid electrolyte.

Effects of alternating current interference on corrosion of X60 pipeline steel

With rapid economic development in China, demand for energy and transportation is growing. Due to the limitations of factors such as terrain and traffic, a large number of buried oil and gas pipelines are parallel to high- voltage transmission lines and electrified railways over long distances. Alternating pipelines is very serious in laboratory experiments were current （AC） corrosion of such cases. In this work, carried out with an electrochemical method in a simulated soil solution at various AC current densities from 0 to 200 A]m2 and AC frequencies from 10 to 200 Hz. Experimental results indicated that with an increase in the AC current density, the corrosion po- tential of an X60 steel electrode shifted negatively, the anodic current density increased significantly, and the corrosion rate increased. Moreover, with an increase in the AC frequency, the corrosion potential of the X60 electrode shifted positively and the anodic current density decreased, which led to a decrease in the corrosion rate. Furthermore, the morphology of X60 electrodes indicated that uniform corrosion occurred at a low AC current density; while corrosion pits were found on the X60 electrode surface at a high AC current density, and deep corrosion pits seriously damaged the pipelines and might lead to leakage.

Dynamic Weapon Target Assignment Based on Intuitionistic Fuzzy Entropy of Discrete Particle Swarm

Aiming at the problems of convergence-slow and convergence-free of Discrete Particle Swarm Optimization Algorithm(DPSO) in solving large scale or complicated discrete problem, this article proposes Intuitionistic Fuzzy Entropy of Discrete Particle Swarm Optimization(IFDPSO) and makes it applied to Dynamic Weapon Target Assignment(WTA). First, the strategy of choosing intuitionistic fuzzy parameters of particle swarm is defined, making intuitionistic fuzzy entropy as a basic parameter for measure and velocity mutation. Second, through analyzing the defects of DPSO, an adjusting parameter for balancing two cognition, velocity mutation mechanism and position mutation strategy are designed, and then two sets of improved and derivative algorithms for IFDPSO are put forward, which ensures the IFDPSO possibly search as much as possible sub-optimal positions and its neighborhood and the algorithm ability of searching global optimal value in solving large scale 0-1 knapsack problem is intensified. Third, focusing on the problem of WTA, some parameters including dynamic parameter for shifting firepower and constraints are designed to solve the problems of weapon target assignment. In addition, WTA Optimization Model with time and resource constraints is finally set up, which also intensifies the algorithm ability of searching global and local best value in the solution of WTA problem. Finally, the superiority of IFDPSO is proved by several simulation experiments. Particularly, IFDPSO, IFDPSO1~IFDPSO3 are respectively effective in solving large scale, medium scale or strict constraint problems such as 0-1 knapsack problem and WTA problem.

Synthesis of novel biodegradable poly(ethylene glycol) analogue:Water-soluble aliphatic polyester with pendant oligo(ethylene glycol) chains

A novel poly（ethylene glycol） （PEG） analogue composed of aliphatic polyester backbone and pendant oligo（ethylene glycol） short chains is reported. The PEG analogue is a copolymer synthesized by ring-opening alternating copolymerization of succinic anhydride with 2-（（2-（2-metho xyethoxy）ethoxy）methyl）oxirane. The structure of the copolymer was confirmed by ^1H NMR spectrum. The effects of the monomer feed ratio on the copolymerization were studied and the polymerization mechanism was given. The PEG analogue disclosed is water-soluble and expected to have promising applications in biomedical fields as a substitute of PEG due to the existence of degradable ester bond in the backbone.

Numerical Study on Plume Interaction Above An AlternatingDiffuser in Stagnant Water

The plume interaction above an alternating diffuser in stagnant water is studied with 3D Reynolds-averaged NavierStokes equations （RANS） combined with a buoyancy-extended κ-ε model. The steady three-dimensional turbulent flow and temperature fields are computed by use of the finite volume method on a non-uniform high resolution orthogonal grid. The numerical predictions demonstrate a generic flow pattern for different turbulent heated jet discharges： the buoyant jets on each side of the diffuser first merge to form an essentially two-dimensional plume which bends back toward the diffuser centerline due to a low pressure cavity. In general, an under-pressure exists in the cavity until the plumes merge; the pressure increases to slightly positive afterwards. Two-dimensionality of the scalar and flow field is attained much later than the point of zero pressure. The position of merging point is governed by mainly four parameters - the discharge densimetfic Froude number, the port diameter and space, and the horizontal distance between alternating jet nozzles. A formula from numerical simulations is obtained through regression analysis and it is used to predict the position of plume merging point. The predicted temperature fields are comparable to previous experiments.

Waveform inversion and analysis of an unusual earthquake swarm in the Boshan mining area, Shandong Province, China

Moment tensor solutions were retrieved for the earthquake swarm that occurred during November and December 2010 in the Boshan mining area, Shandong Province, China. The results showed that the double-couple components in the source mechanisms were higher at the beginning of the swarm and consisted mainly of shear faulting controlled by tectonic stress. The subsequent events had significant non-double-couple components, indicating tensile faulting. The double-couple components predominately presented as normal faulting and the P axes were orientated almost vertically. The slip vectors of the swarm events were relatively stable. With reference to the tectonic features near the epicenter, we concluded that the swarm was a result of subordinate fault motion related to the Wangmu Mountain fault and that high-pressure pore fluids played a crucial role in the activity of the earthquake swarm.

Entropy Analysis of Vapor-Compression Refrigeration System by Using the Second Law of Thermodynamics

By means of the Second Law of Thermodynamics,thispaper gives out the entropy analysis method for vapor-comperession refrigeration system.The thermal irrevers-ibility of the system charged with R12 and its hopeful al-ternative refrlgerant R134a have been studied respective-ly.On the basis of all the research results of this paper,the measure used to save energy for vapor-compressionrefrigeration system has been put out.

某型复杂工程机械变速箱体复合工艺约束机加工线平衡研究

为解决机加工生产线平衡问题所包含的加工任务刀具需求、机床类型需求、加工方位约束、“紧密”型和“或”型约束等复杂条件,建立了机加工生产线平衡数学模型,并采用含多重筛选机制的粒子群算法进行了求解。首先,建立了满足此复杂实际约束条件的机加工生产线平衡问题数学模型;然后,采用粒子的位置坐标作为粒子群搜索的权重信息,进行了加工任务、集中任务的选取,并设计了多重筛选机制构造启发式任务集生成规则;采用此规则对待分配加工任务进行了多重筛选,以得到可供直接分配的加工任务集合,粒子群算法(PSO)从此集合中依次选取了加工任务,构成了完整的解,并形成了具体的任务分配方案;最后,为提高程序的实用性和可视性,设计了加工任务的甘特图生成模块,通过对某复杂工程机械变速箱体零件的实际案例研究,将简化后的任务信息代入算法进行了求解。研究结果表明:该方法实现了多组平衡率高于90%的优化结果,在节拍时间为1120 s时,得到94.66%的较高平衡率,排产方案表格内容与甘特图显示一致;算法推演结果满足设定的多种复合约束条件,通过与人工排产对比说明了该算法的有效性并具有较好的经济性、实用性;对柔性生产案例进行探讨,证明该算法运算结果具备一定的生产柔性。

独立微电网微源多目标分层优化配置方法研究

微电源的优化配置是微电网设计规划阶段的重点,是实现微电网整个生命周期安全可靠经济运行的基础。文中提出了以负荷支撑最大和系统总成本最低为多目标的独立微电网微电源优化配置方法。提出微电源配置要以保证电能质量及供电可靠性为前提,进而提出了相应的微电网组网规则,并验证了组网规则是微电源配置中必须遵守的规则之一;提出了将储能作为系统源储荷平衡的桥梁,以实现对不可控微源的补充作用;还分析了系统备用度对微电源配置的影响,为微电网后续的扩展奠定基础。文中分别对2类微电源进行分析,采用分层优化方法进行求解,以提高优化速度及结果的准确性。第1层利用HOMER软件得出含不同类型微电源的系统生命周期成本最低的配置方案,从中筛选出满足组网规则的配置组合;第2层以第1层优化结果为初解,以负荷缺电率最低为目标应用粒子群算法求解,得到系统的最优配置方案。与纯运用粒子群算法相比,提出的方法能以更快的收敛速度实现微源容量配置的最优经济性和高供电可靠性。

考虑换件维修代价的测试优化选择

测试优化选择是测试性设计工作的基础,保证选择的测试对被测系统具有较好的故障检测率和故障隔离率是测试优化选择的重要约束。从装备换件维修的角度,通过对故障模糊组分析,可知换件维修代价对测试选择结果具有重要影响。基于相关性矩阵,在分析装备换件维修对测试选择的影响基础上,以测试代价和维修代价最小为优化目标,以故障检测率、故障隔离率为约束,建立了考虑换件维修代价的数学模型,并采用混沌二进制粒子群算法求解。仿真实例结果表明,考虑换件维修代价的测试优化选择模型更加符合工程实际,选择结果更加准确和可靠。

交替捕食的粒子群优化算法及其粒子轨迹收敛性分析

为避免算法陷入局部极值,在捕食者–猎物协同进化机制基础上,提出了一种交替捕食的粒子群优化算法(APPSO).对该算法迭代过程进行了分析,给出并证明了粒子运动轨迹收敛的充分条件.为使粒子运动轨迹可靠收敛,构建了一种参数设置方法.通过迭代矩阵谱半径计算、SQRT序列采样,对该算法的粒子轨迹收敛速度进行了分析.基准测试函数仿真结果表明,交替捕食的PSO算法具有较佳的搜索性能.

改进交替方向乘子法求解冷水机组负荷分配群智能优化问题

群智能控制系统中的多台冷水机组负荷优化分配问题是一个多块优化问题,传统分布式方法难以获得其收敛解.文中将交替方向乘子法(ADMM)引入冷水机组负荷分配群智能优化问题中,并通过一种有效的高斯罚函数(GPF)更新策略改进了交替方向乘子法收敛特性.同时,建立了一种基于ADMM–GPF–GBS双层分布式计算框架的冷水机组负荷优化分配模型,该模型仅利用相邻节点间的局部信息传递,即可求解得出最优运行策略.最后,通过两个典型算例对比分析了所提优化方法的有效性,并在实际硬件系统中进一步对该算法进行应用与验证.结果表明,所提算法适用于群智能控制系统下的多台冷水机组系统,且具有比传统分布式算法更好的寻优能力和收敛性,可以取得显著的节能效果.

基于小生境鱼群算法的有限元模型修正多解问题研究

传统模型的修正技术采用智能算法找到一组全局最优解,能使有限元模型的计算结果与结构实际响应更加接近。实际上由于传感器数量有限,测量数据不充分及仪器识别存在误差,局部最优解可能比全局最优解更能代表结构的实际参数。因此,引入小生境技术及反向学习策略,提出了一种改进的小生境鱼群算法,并在算法运行后期采用模拟退火算法执行局部细化寻优,克服了人工鱼群算法难以找到多个函数峰值、对初值敏感、后期收敛慢且精度不高的弊端;然后,通过数值仿真分析验证其可行性;最后,将其应用在一座缩尺斜拉桥模型的修正上。为避免大量调用有限元模型,采用响应面作为代理模型,通过拉丁超立方产生试验数据,对各因素进行显著性检验,剔除无关因素后检验拟合精度。研究发现:模型修正后产生了使缩尺斜拉桥模态的计算值与实测值误差减小的1组全局最优解与7组局部最优解,从而使得决策人员可根据工程经验,从多组解中做出选择,减少了对实际结构参数误判的可能。

基于静气弹性能的风力机翼型设计

引入翼型静气弹性能,即气动扭矩对扭转位移的敏感性和扭转位移诱发平移位移的能力,敏感性和能力越低,静气弹性能越好。结合改进的粒子群算法和基于通用集成理论的翼型参数化表达方法,兼顾气动性能和静气弹性能建立优化模型,对现有常用薄翼型NACA 64618进行替代优化设计,新翼型的部分气动性能和静气弹性能都有所提高。就NREL 5 MW参考风力机叶片,用新翼型替换NACA 64618并对额定工况进行仿真,仿真过程中对风速施加一个正弦脉冲,结果表明替换的叶片对脉冲的敏感性低于原叶片,且扭转位移更接近于零,可证明新翼型对叶片的扭转发散有一定抑制作用。

基于磁感应的油藏裂缝内地下无线传感网络定位

针对在油藏裂缝中地下无线传感网络节点定位问题,提出一种基于可变方向增强拉格朗日方法和粒子群优化相结合的定位算法。锚节点布置在井筒固定位置,传感器节点随压裂过程进入裂缝具有位置随机分布特性,节点间采用三线圈磁感应方式通信。推导了基于接收信号磁感应强度的节点间距离估计公式,据此获得全部节点与锚节点及与其邻居节点的距离集合。然后将定位问题转化为半定规划问题,并采用可变方向增强拉格朗日方法求解上述凸优化问题获得初步定位,再将其作为粒子群优化算法的初始值,在上述初始值小邻域内局部搜索获得最优解作为最终定位。仿真结果表明该算法相对定位误差低于0.6,且定位精度受测量噪声变化影响较小。

水电规划环境影响评价替代方案优选研究

针对水电开发规划环境影响评价,将多目标规划理论引入水电规划替代方案筛选研究,构建了基于景观多样性变化率、淹没土地面积、移民数量等环境约束的多目标替代方案优选模型,引入灰色关联系数作为粒子群算法的适应值函数,提出了多目标粒子群求解算法。通过模型应用,得到黄河黑山峡河段水电规划多个相对优化方案。模型应用及求解表明,多目标规划理论用于替代方案优化,突破了以往单方案或两个方案评价的片面性。

智能斜极面交流接触器动态优化设计与分析

采用ANSYS电磁场分析软件与基于遗传算法的人工鱼群优化算法对智能平极面交流接触器进行以快速分断、提高零电流分断准确性与稳定性为目标的动态优化计算,并验证了优化算法的正确性。考虑到斜极面交流电磁系统的优越性,对平极面交流接触器与斜极面交流接触器静态特性进行比较分析,提出了智能斜极面交流接触器的结构方案。根据上述优化算法,对智能斜极面交流接触器进行了智能动态优化设计。优化结果表明:智能斜极面交流接触器与智能平极面交流接触器相比,其用铜量减小45%,用铁量减小23%,而且具有更好的动态特性、更高的零电流分断准确性与稳定性。