Applications of the first integral method to nonlinear evolution equations

In this paper, we establish travelling wave solutions for some nonlinear evolution equations. The first integral method is used to construct the travelling wave solutions of the modified Benjamin-Bona-Mahony and the coupled Klein-Gordon equations. The obtained results include periodic and solitary wave solutions. The first integral method presents a wider applicability to handling nonlinear wave equations.

A novel simulation method for positive corona current pulses

A novel two-dimensional （2D） simulation method of positive corona current pulses is proposed. A control-volume- based finite element method （CV-FEM） is used to solve continuity equations, and the Galerkin finite element method （FEM） is used to solve Poisson＇s equation. In the proposed method, photoionization is considered by adopting an exact Helmholtz photoionization model. Furthermore, fully implicit discretization and variable time step are used to ensure the time-efficiency of the present method. Finally, the method is applied to a positive rod-plane corona problem. The numerical results are in agreement with the experimental results, and the validity of the proposed method is verified.

Exact solutions of nonlinear fractional differential equations by (G'/G)-expansion method

In this paper, we use the fractional complex transform and the （G＇/G）-expansion method to study the nonlinear fractional differential equations and find the exact solutions. The fractional complex transform is proposed to convert a partial fractional differential equation with Jumarie＇s modified Riemann-Liouville derivative into its ordinary differential equation. It is shown that the considered transform and method are very efficient and powerful in solving wide classes of nonlinear fractional order equations.

Compact implicit integration factor methods for some complex-valued nonlinear equations

The compact implicit integration factor （cIIF） method is an efficient time discretization scheme for stiff nonlinear diffusion equations in two and three spatial dimensions. In the current work, we apply the cIIF method to some complex-valued nonlinear evolutionary equations such as the nonlinear SchrSdinger （NLS） equation and the complex Ginzburg-Landau （GL） equation. Detailed algorithm formulation and practical implementation of cIIF method are performed. The numerical results indicate that this method is very accurate and efficient.

Interval finite difference method for steady-state temperature field prediction with interval parameters

A new numerical technique named interval finite difference method is proposed for the steady-state temperature field prediction with uncertainties in both physical parameters and boundary conditions. Interval variables are used to quantitatively describe the uncertain parameters with limited information. Based on different Taylor and Neumann series, two kinds of parameter perturbation methods are presented to approximately yield the ranges of the uncertain temperature field. By comparing the results with traditional Monte Carlo simulation, a numerical example is given to demonstrate the feasibility and effectiveness of the proposed method for solving steady-state heat conduction problem with uncertain-but-bounded parameters.

Calculation methods of lubricant film pressure distribution of radial grooved thrust bearings

In order to calculate the pressure distribution of radial grooved thrust bearing, analytical and numerical methods were applied respectively. Grooved region and land region were linked by u- sing the mass conservations principle at the groove/land boundary in each method. The block-weight approach was implemented to deal with the non-coincidence of mesh and radial groove pattern in nu- merical method. It was observed that the numerical solutions had higher precision as mesh number exceed 70 x 70, and the relaxation iteration of differential scheme presented the fastest convergence speed when relaxation factor was close to 1.94.

A GENERALIZED GAUSS-TYPE QUADRATURE FORMULA AND ITS APPLICATIONS TO PSEUDOSPECTRAL METHOD

A generalized Gauss-type quadrature formula is introduced, which assists in selection of collocation points in pseudospectral method for differential equations with two-point derivative boundary conditions. Some results on the related Jacobi interpolation are established. A pseudospectral scheme is proposed for the Kuramoto-Sivashisky equation. A skew symmetric decomposition is used for dealing with the nonlinear convection term. The stability and convergence of the proposed scheme are proved. The error estimates are obtained. Numerical results show the efficiency of this approach.

Variational iteration method for solving compressible Euler equations

This paper applies the variational iteration method to obtain approximate analytic solutions of compressible Euler equations in gas dynamics. This method is based on the use of Lagrange multiplier for identification of optimal values of parameters in a functional. Using this method, a rapid convergent sequence is produced which converges to the exact solutions of the problem. Numerical results and comparison with other two numerical solutions verify that this method is very convenient and efficient.

Investigation of third-grade non-Newtonian blood flow in arteries under periodic body acceleration using multi-step differential transformation method

In this paper, a non-Newtonian third-grade blood in coronary and femoral arteries is simulated analytically and numerically. The blood is considered as the third- grade non-Newtonian fluid under the periodic body acceleration motion and the pulsatile pressure gradient. The hybrid multi-step differential transformation method （Hybrid-Ms- DTM） and the Crank-Nicholson method （CNM） are used to solve the partial differential equation （PDE）, and a good agreement between them is observed in the results. The effects of the some physical parameters such as the amplitude, the lead angle, and the body acceleration frequency on the velocity and shear stress profiles are considered. The results show that increasing the amplitude, Ag, and reducing the lead angle of body acceleration, 9, make higher velocity profiles on the center line of both arteries. Also, the maximum wall shear stress increases when Ag increases.

High order multiplication perturbation method for singular perturbation problems

This paper presents a high order multiplication perturbation method for sin- gularly perturbed two-point boundary value problems with the boundary layer at one end. By the theory of singular perturbations, the singularly perturbed two-point boundary value problems are first transformed into the singularly perturbed initial value problems. With the variable coefficient dimensional expanding, the non-homogeneous ordinary dif- ferential equations （ODEs） are transformed into the homogeneous ODEs, which are then solved by the high order multiplication perturbation method. Some linear and nonlinear numerical examples show that the proposed method has high precision.

Optimization of multibody systems based on the generalized-α projection method for DAEs

Efficient optimization strategy of multibody systems is developed in this paper. Aug- mented Lagrange method is used to transform constrained optimal problem into unconstrained form firstly. Then methods based on second order sensitivity are used to solve the unconstrained problem, where the sensitivity is solved by hybrid method. Generalized-α method and generalized-α projection method for the differential-algebraic equation, which shows more efficient properties with the lager time step, are presented to get state variables and adjoint variables during the optimization procedure. Numerical results validate the accuracy and efficiency of the methods is presented.

时频电磁技术在黄土塬覆盖区河道砂油藏分布预测中的应用

鄂尔多斯盆地西部黄土塬覆盖区的中生界侏罗系油藏成藏主控因素复杂,在未开展三维地震勘探的区域,仅利用二维地震资料进行钻探的成功率较低。为了提高钻井成功率,针对该区侏罗系河道砂油藏特点,采用时频电磁双侧、双源激发、多线接收的油气检测技术方案。在鄂尔多斯盆地西部ZB地区进行攻关试验,总结了适用于黄土塬覆盖区的时频电磁采集、处理、解释技术方案,即两项针对性采集方案设计和三项针对性处理、解释技术。利用GeoEast软件系统,基于深度学习开展时频电磁多参数智能油气预测。根据时频电磁解释成果,在时频电磁强异常区域部署并完钻Z6井,获得工业油气流,表明时频电磁预测结果与实钻结果吻合,证实了在黄土塬覆盖区利用时频电磁技术对侏罗系薄储层进行油气预测的可靠性。

案例教学法结合PBL模式在心内科教学中的应用与探索

目的探讨案例教学法结合问题为基础学习(Problem-Based Learning,PBL)模式在心内科教学中实践效果。方法选取2022年1月—2023年1月新疆医科大学第四附属医院70名心内科学生为研究对象,采取随机数表法分为两组,每组35名,对照组给予常规讲授法教学,研究组采用案例教学法联合PBL模式,定时记录学习效果。结果研究组理论考试、实践操作、病例分析能力、自主学习能力评分均高于对照组,差异有统计学意义(P均<0.05)。结论案例教学法结合PBL模式在心内科教学中具有较好的应用效果,能有效提高学生的学习能力与实践操作能力。

多模式融合教学法在骨科临床教学中的实施效果

目的探讨多模式融合教学法在骨科临床教学中的实施效果。方法选取2020年1月—2023年1月广西医科大学第一附属医院骨科参与临床教学的85名学员为研究对象,根据不同教学法将入选者进行分组,对照组42名学员接受传统教学法,研究组43名学员多模式融合教学法,比较两组的考核成绩、自主学习能力与自我效能、教学认可度、教学满意度。结果教学前,两组学员理论知识、病例分析、诊疗技能考核成绩比较,差异无统计学意义(P均>0.05)。教学后,研究组理论知识、病例分析、诊疗技能考核成绩评分别为(36.41±2.67)分、(26.17±2.15)分、(25.53±3.02)分,高于对照组的(34.76±2.52)分、(23.13±1.62)分、(23.45±2.37)分,差异有统计学意义(P均<0.05)。教学前,两组学员自主学习能力与自我效能评分比较,差异无统计学意义(P均>0.05)。教学后,研究组各项评分均高于对照组,差异有统计学意义(P<0.05)。教学后,研究组学员对各项教学指标的认可度、对教学模式各条目的满意度分均较对照组高,差异有统计学意义(P均<0.05)。结论多模式融合教学法有助于提升学员考核成绩,在骨科临床教学中效果显著,学员满意度高。

四川盆地南部中二叠统茅口组岩溶古地貌恢复及特征

岩溶古地貌是含油气盆地沉积微相类型、分布范围及储层发育的主控因素,恢复岩溶古地貌对指导油气勘探至关重要。基于钻井、测井及地震等资料,采用沉积速率法和地层厚度对比法对四川盆地南部地区中二叠统茅口组顶部不整合界面的剥蚀厚度进行了精确计算,并根据剥蚀厚度的地区差异及古地貌指示,对岩溶古地貌单元进行了进一步划分。研究结果表明:①四川盆地南部中二叠统茅口组顶部主要发育平行不整合,仅在局部地区形成角度不整合。早中二叠世,上扬子地台内部沉积稳定,构造运动较弱,沉积速率法与地层厚度对比法相对更适用于研究区的岩溶古地貌恢复。②研究区中二叠统茅口组顶部剥蚀厚度为0~120m,其中北部剥蚀最强烈,如LG1井区、W4井区代表了岩溶古地貌地势的最高位置,向东南方向剥蚀强度逐渐减弱,地势逐渐降低;剥蚀最薄弱地区位于LS1井东北部,代表了岩溶古地貌地势的最低位置,整体呈现北部高,南部低,东北部最低的地貌格局。③研究区茅口组古地貌特征控制了岩溶作用的发育强度,可划分为岩溶高地、岩溶斜坡、岩溶盆地等3个二级岩溶古地貌单元以及溶峰盆地、溶丘洼地、丘丛谷地、丘丛洼地、丘丛沟谷、峰林平原、残丘平原等7个三级古地貌单元,其中岩溶斜坡易形成良好的储集空间,为油气圈闭的形成奠定了良好的基础,是下一步有利勘探方向。

硅基聚合物耐高温衍生陶瓷涂层制备与应用研究进展

随着航空航天领域的不断发展,金属以及碳材料等高温结构部件的服役条件日益苛刻。通过恰当的工艺在高温结构部件表面制备硅基陶瓷涂层并赋予其特殊性能,可有效提高高温结构部件的使用寿命。近年来,聚合物前驱体转化陶瓷涂层逐渐成为一种无机涂层制备的新方法。该方法具有制备工艺简便、涂层功能拓展性强等特点,得到了研究者越来越多的关注。本文主要综述了硅基聚合物前驱体转化陶瓷涂层的研究进展。首先从聚合物陶瓷涂层的制备展开,简要介绍了硅基聚合物前驱体、填料种类以及涂覆工艺和裂解方式对涂层结构以及性能的影响。随后,重点讨论了聚合物前驱体转化陶瓷涂层在耐高温防护领域,包括抗氧化、环境障、热障涂层的应用进展。最后,指出了聚合物陶瓷涂层在涂层性能提升及缺陷控制等方面的问题,并对其发展方向进行了展望,例如通过在硅基前驱体中引入Hf,Zr,Ta等超高温元素,提高陶瓷涂层的耐温等级,以及发展高效的陶瓷化新技术,从而提高陶瓷转化效率及涂层适用性范围等。

基于隆起变形分析的基坑坑底抗隆起稳定可靠度分析

采用土体硬化(Hardening Soil)模型,在PLAXIS 2D中建立基坑开挖数值模型,在获取坑底特征点隆起变形数据的基础上构建坑底隆起变形超限失效模式对应的极限状态函数,为提高计算效率,应用响应面法代替有限元计算快速获取坑底特征点隆起变形值,结合蒙特卡罗模拟方法进行坑底抗隆起稳定性可靠度分析,分析结果表明:第三层土的卸载再加载模量E_(3)^(ur)以及有效内摩擦角φ’_(3)的变异性对坑底抗隆起稳定性影响显著;第一层土的有效黏聚力c’_(1)、有效内摩擦角φ’_(1)、割线模量E_(1)^(50)、切线模量E_(1)^(oed)以及第二层土的有效黏聚力c’_(2)的变异性对坑底抗隆起稳定性影响较小,但相对而言,第二层土的有效黏聚力c’_(2)对坑底抗隆起稳定性的影响较大;对于坑底土体为粉砂的深基坑来说,对坑内土体进行加固可以有效约束坑底隆起变形。

地下水超采综合治理效益评价

地下水超采综合治理是加强新时代生态文明建设、保障国家水安全的重大决策部署,是打基础、利长远的战略性工程。其治理效益关乎着治理工作推进的有效性,是衡量地下水超采综合治理水平的关键。为定量评价地下水超采区综合治理效益,以“八大准则”为框架,以18项必选指标、12项备选指标为基础,构建了基于“目标-准则-指标”的多层级地下水超采综合治理效益评价体系;结合层次分析法和熵权法确定指标权重,采用“单指标量化-多指标综合-多准则集成”的方法计算地下水超采综合治理效益指数(GGI),定量评价了地下水超采综合治理水平,并对河南省滑县、内黄县、汤阴县开展地下水超采综合治理效益评价实例研究。结果表明:滑县、内黄县、汤阴县的地下水超采综合治理效益指数的等级均为良好,主要制约因素为地下水水位变化幅度、地下水水质达标情况、水文化传承载体数量。基于该研究结果提出多渠道增加水源供给、优化农业种植结构、改造升级企业生产工艺、加大宣传和教育力度等改善措施。经实例验证,所提出的地下水超采综合治理效益评价体系能真实反映地下水超采综合治理的工作效果,可为地下水超采综合治理提供参考依据。

高含水油田剩余油研究方法、分布特征与发展趋势

为了提高高含水油田剩余油研究与评价效果,基于大量文献调研,梳理了剩余油的概念、影响因素,从剩余油微观分布、宏观分布和饱和度定量分析3个方面总结了剩余油研究方法及其适用条件,概括了水驱油藏、稠油油藏和化学驱油藏的剩余油分布特征,进一步提出了目前剩余油研究的难点和发展趋势。结果表明:剩余油的影响因素主要包括地质构造、沉积微相、储层非均质性和井网密度、井网模式、注采系统的完善程度、生产动态等;剩余油研究方法包括实验分析方法、数值模拟方法和矿场测试方法等,各种方法的研究目的和适用条件不同,测试结果反映不同位置、不同尺度下的剩余油饱和度分布;高含水油田剩余油分布总体呈现高度分散和相对富集的特征,剩余油微观分布呈现连续相和非连续相多种形式;剩余油研究发展趋势包括但不限于以下5方面:超大物理模型的构建、多尺度高分辨率成像系统集成、考虑不同驱替介质及物性时变与非连续相非线性渗流的数值模拟改进方法、多学科多方法矿场测试的综合应用及大数据人工智能的广泛应用。

北虫草液体菌种培养基优化及胞外多糖抗氧化性初探

针对北虫草人工栽培中菌丝液体发酵培养菌丝长速慢,产量不高的问题。研究引入了用于人工栽培的北虫草菌种(Cordyceps militaris),对其液体发酵培养基进行了优化并提取北虫草胞外多糖测定其抗氧化活性。结果表明,单因素筛选实验及Plackett-Burman分析表明最佳碳源、氮源、无机盐分别为蔗糖、酵母粉、磷酸二氢钾。爬坡试验进一步得出,当蔗糖浓度为25 g·L^(-1)、酵母粉为6 g·L^(-1)、磷酸二氢钾为2 g·L^(-1)时,北虫草生物量达到较大值2.113 g·L^(-1)。最后经中心组合试验设计和响应面法分析得出,最佳培养基配方为:蔗糖26.364 g·L^(-1)、酵母粉6.699 g·L^(-1)、磷酸二氢钾2.093 g·L^(-1),此时菌丝干重达到最大值为2.314 g·L^(-1)。验证实验表明结果准确,产量提升了107.34%。对胞外多糖提取物的DPPH自由基及ABTS自由基清除率,超氧阴离子自由基与脂质过氧化抑制率测定试验表明清除率与样品浓度呈正相关。