A Multi-Symplectic Compact Method for the Two-Component Camassa-Holm Equation with Singular Solutions

The two-component Camassa–Holm equation includes many intriguing phenomena. We propose a multi-symplectic compact method to solve the two-component Camassa–Holm equation. Based on its multi-symplectic formulation, the proposed method is derived by the sixth-order compact finite difference method in spatial discretization and the symplectic implicit midpoint scheme in temporal discretization. Numerical experiments finely describe the velocity and density variables in the two-component integrable system and distinctly display the evolvement of the singular solutions. Moreover, the proposed method shows good conservative properties during long-time numerical simulation.

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.

New Method of Total Ionizing Dose Compact Modeling in Partially Depleted Silicon-on-Insulator MOSFETs

On the basis of a detailed discussion of the development of total ionizing dose （TID） effect model, a new commercial-model-independent TID modeling approach for partially depleted silicon-on-insulator metal-oxide- semiconductor field effect transistors is developed. An exponential approximation is proposed to simplify the trap charge calculation. Irradiation experiments with 60Co gamma rays for IO and core devices are performed to validate the simulation results. An excellent agreement of measurement with the simulation results is observed.

COMPACT FINITE DIFFERENCE-FOURIER SPECTRAL METHOD FOR THREE-DIMENSIONAL INCOMPRESSIBLE NAVIER-STOKES EQUATIONS

A new compact finite difference-Fourier spectral hybrid method for solving the three dimensional incompressible Navier-Stokes equations is developed in the present paper. The fifth-order upwind compact finite difference schemes for the nonlinear convection terms in the physical space, and the sixth-order center compact schemes for the derivatives in spectral space are described, respectively. The fourth-order compact schemes in a single nine-point cell for solving the Helmholtz equations satisfied by the velocities and pressure in spectral space is derived and its preconditioned conjugate gradient iteration method is studied. The treatment of pressure boundary conditions and the three dimensional non-reflecting outflow boundary conditions are presented. Application to the vortex dislocation evolution in a three dimensional wake is also reported.

Application of Compactness Detection to Complicated Concrete-Filled Steel Tube by Ultrasonic Method

An example of using ultrasonic method to detect the compactness of complicated concrete-filled steel tube in certain high-rise building was discussed in this study.Because of the particularity of the complicated concrete-filled steel tubular column,the plane detection method and embedded sounding pipe method were adopted in the process of effectively detecting the column.According to the results of the plane detection method and embedded sounding pipe method,the cementing status of steel tube and concrete can be concluded,which cannot be judged by the hammering method in the rectangular steel tube-reinforced concrete.

A Compact Difference Method for Viscoelastic Plate Vibration Equation

In this paper, a fourth-order viscoelastic plate vibration equation is transformed into a set of two second-order differential equations by introducing an intermediate variable. A three-layer compact difference scheme for the initial-boundary value problem of the viscoelastic plate vibration equation is established. Then the stability and convergence of the difference scheme are analyzed by the energy method, and the convergence order is <img src="Edit_0a250b60-7c3c-4caf-8013-5e302d6477ab.png" alt="" />. Finally, some numerical examples are given of which results verify the accuracy and validity of the scheme.

Warm Compaction Process of P/M Steels by Orthogonal Testing Method

为了用 die 完成 P/M 钢的更高的密度，围在温暖的压缩过程压缩方法或粉末润滑剂的润滑油，温暖的压缩样品的绿密度上的不同过程参数的影响被学习。根据直角的测试方法，作者系统地学习不同压缩压力的影响，润滑油的状况；在温暖的压缩过程的样品的绿密度上的压缩温度，；提出温暖的压缩实验的最佳的进程参数。它被发现那，一个高压缩压力(≥ 7 00 MPa ) ，死墙润滑油与内部润滑剂的小数量结合了，；由润滑油的不同状况的恰当的压缩温度，是在温暖的压缩的最佳的参数过程。

Efficiency and Effectiveness Method versus ε-NTU Method with Application in Finned Flat Tube Compact Heat Exchanger with Water-Ethylene Glycol as Nanofluid Base of Iron Oxide Nanoparticles

This work aims to establish comparisons between two models used for the performance of heat exchangers. The chosen system, in this case, consists of a heat exchanger used in automotive radiators flat finned tube type. Water and ethylene glycol compound as base fluid and volume fractions of iron oxide nanoparticles (Fe3O4) are used as a refrigerant. The quantities determined in this work are the nanofluid exit temperature, the air exit temperature, the absolute error between the models for heat transfer rate, and Effectiveness. The quantities that constitute parameters, independent variables, are the airflow, represented by the Reynolds number, and the iron oxide volume fraction. Ethylene Glycol 50% compound has slightly better thermal performance than pure water and reduces the reactive effect of water on the environment, increasing the average life of the equipment. The absolute relative error between the models is less than 20% and presents maximum values with the increase of the nanoparticle volume fraction and growth in the Reynolds number for the air.

Research of PDC Bit Compact Die With FEM and Optimum Method

In mould design, it is necessary for a designer to ensure that the cylinder has enough intensity in both the prestressed and synthesis states. An individual layer cylindrical mould cannot withstand a very high pressure needed in polycrystalline diamond composite (PDC) production. So, multi-layer prepressure combination assemble moulds are often used. The analysis conducted here is to study the interaction of cylindrical layers and to explain how to obtain enough load capability with the lowest requirement of material performance. The ratio of the pressure cylinder radius of synthetic diamond is 3.27, which is close to the optimal value and can be used as structure size in a design for PDC bit compact die. There is a linear relationship between the internal and external pressures under a special tangent stress on the inner wall of the pressure cylinder. So, when two of the three parameters (the internal pressure, external pressure, and the requirement value of the tangent stress on the inner wall of the pressure cylinder) are given, the third can be obtained. The sleeve acts as a bridge?between the pressure cylinder and the steel belts. The optimum model developed in this paper can be used in PDC bit compact die design and other similar prestressed cold extrusion die design.

High Order Compact Difference Scheme and Multigrid Method for 2D Elliptic Problems with Variable Coefficients and Interior/Boundary Layers on Nonuniform Grids

In this paper, a high order compact difference scheme and a multigrid method are proposed for solving two-dimensional (2D) elliptic problems with variable coefficients and interior/boundary layers on nonuniform grids. Firstly, the original equation is transformed from the physical domain (with a nonuniform mesh) to the computational domain (with a uniform mesh) by using a coordinate transformation. Then, a fourth order compact difference scheme is proposed to solve the transformed elliptic equation on uniform girds. After that, a multigrid method is employed to solve the linear algebraic system arising from the difference equation. At last, the numerical experiments on some elliptic problems with interior/boundary layers are conducted to show high accuracy and high efficiency of the present method.

高放废物处置缓冲材料砌块养护方法研究

在高放废物地质处置库中,作为阻滞核素迁移的关键环节,缓冲材料通常以高压实砌块形式放置于废物罐周围。为了保证砌块的工程性能,缓冲材料砌块在制备、储存、运输和安装等各阶段均应进行环境湿度控制,以减少环境湿度对砌块性能的劣化影响。以高庙子膨润土压实试样为研究对象,开展了裸样、覆膜、覆膜+密封等不同包装方式,在0~100%相对湿度环境下的长期养护性能测试。试验结果表明:针对含水率介于13%~15%之间的膨润土压实试样,当环境湿度在80%~92%养护时,试样的质量变化均不超过1%;其中在92%的环境湿度下,试样的质量变化不超过0.3%,为最优养护环境。采用覆膜+密封包装方式,可大幅拓宽环境湿度范围,试样在不同相对湿度下的质量变化大幅减少,当相对湿度超过57%后,试样的质量变化比均不超过1%。其中在相对湿度为92%的养护环境下,试样的质量变化比最小,仅为0.032%。研究结果可为解决米级尺度高放废物地质处置缓冲材料大型砌块长期存储这一难题提供基础参数和技术支撑。

On the Behavior of Combination High-Order Compact Approximations with Preconditioned Methods in the Diffusion-Convection Equation

In this paper, a family of high-order compact finite difference methods in combination preconditioned methods are used for solution of the Diffusion-Convection equation. We developed numerical methods by replacing the time and space derivatives by compact finite-difference approximations. The system of resulting nonlinear finite difference equations are solved by preconditioned Krylov subspace methods. Numerical results are given to verify the behavior of high-order compact approximations in combination preconditioned methods for stability, convergence. Also, the accuracy and efficiency of the proposed scheme are considered.

考虑侧向刚柔边界约束的黄土填方路基沉降计算方法

提出一种新的考虑刚柔边界约束和侧向变形的黄土填方路基沉降计算方法。基于自主研发的三向加载设备和室内压缩试验,分析不同竖向加载方式和不同侧向约束对土体竖向及侧向变形的影响,提出考虑土体压实度和围压的边界影响系数,建立压实黄土侧向应变模型,给出考虑刚柔边界条件和侧向变形的黄土路基沉降计算方法。研究结果表明:边界影响系数与路基压实度和围压都呈正相关,且刚柔约束边界对黄土压缩性指标的影响程度最高能达到40%。提出的竖向和三向边界影响系数综合考虑了路基压实度、侧向围压以及边界条件的影响。利用工程实例验证了新模型计算方法的准确性和实用性,提高了传统分层总和法的精度。

High accuracy compact finite difference methods and their applications

Numerical simulation of complex flow fields with multi-scale structures is one of the most important and challenging branches of computational fluid dynamics. From linear analysis and numerical experiments it has been discovered that the higher-order accurate method can give reliable and efficient computational results, as well as better resolution of the complex flow fields with multi-scale structures. Compact finite difference schemes, which feature higher-order accuracy and spectral-like resolution with smaller stencils and easier application of boundary conditions, has attracted more and more interest and attention.

套筒强夯长短桩复合地基承载特性研究

【目的】随着大型海洋工程项目不断发展,对水下软土地基处理提出了新的挑战,水下挤密砂桩和水下水泥搅拌桩复合地基等传统方法具有定位难、制桩难、桩体质量差等问题,始终制约着其在海洋工程中的应用和发展。【方法】借鉴陆上孔内深层强夯施工方法,因地制宜地提出水下套筒强夯复合地基成桩技术,该技术使用套筒阻隔海水进入桩孔,具有定位准、加固深和强度高等优点,通过模型试验的方法对该技术进行研究。【结果】结果表明,在强夯碎石桩与传统碎石桩相结合的工况下,地基极限承载力提高50%以上,等长度群桩复合地基极限承载力比长短桩复合地基提升18%;在全部采用强夯碎石桩的工况下,地基极限承载力提高170%以上,等长度群桩复合地基极限承载力比长短桩复合地基提升3.7%。【结论】全部采用强夯碎石桩的复合地基比强夯碎石桩与传统碎石桩组合而成的复合地基承载力提高更多,在提高承载力方面,采用套筒强夯长短桩复合地基更加经济有效。

气动振杆密实法加固湿陷性黄土的模型试验研究

气动振杆密实法是湿陷性黄土地基处理的一项全新技术。采用自行研制的气动振杆密实模型试验装置,进行了单一激振力、气体射流协同激振力两种条件下的模型试验,评价了土体加固效果,研究了振杆贯入过程中土体水平向土压力、土颗粒垂直振动速度和土体中气体压力值的变化规律。试验发现,处理后各深度土层的密度均有明显提高,湿陷系数降低;增设气体射流后,100 mm深度以下土层密度进一步提高,水平向土压力最大提高20.4%,同时放大了振杆密实法引起的土体振动响应。研究揭示了气体射流在土体加固过程中的作用机理,探讨了气动振杆密实法加固湿陷性黄土机理,为推广气动振杆密实法处理湿陷性黄土地基技术的应用提供了理论依据。

基于PFEM法的黄土地基振杆密实过程大变形分析

采用粒子有限元方法(PFEM)及结构性土的本构模型,对振杆密实法加固砂质黄土地基的大变形过程进行了数值模拟研究,分析了振杆贯入过程中周围土体的位移场、应力场、速度场以及塑性体应变等分布规律,揭示了砂质黄土地基深层振动密实机理.结果表明:现场实测和数值模拟获得的地面垂直振动速度峰值变化趋势较为一致,验证了粒子有限元方法的可靠性;垂直激振的振杆能够同时引起土体垂直方向和水平方向上位移场、应力场和速度场的变化;在距振源水平距离5R(R为振杆半径)范围内,土颗粒以半梭形向外扩展并趋于密实,同时水平应力大幅增加并产生预压效果;以塑性体应变作为加固范围的评价标准,结果表明土体径向加固范围随振杆贯入深度增加而略有增大,最大径向加固范围约为3.2R,且振杆底端以下1R~2R范围亦有密实效果.

不同一次性根管治疗在不可逆性牙髓炎患者中的应用研究

目的探讨不同一次性根管治疗对不可逆性牙髓炎患者疼痛程度及止痛干预的影响。方法选择2020年7月至2023年1月湖南中医药大学第一附属医院收治的100例不可逆性牙髓炎患者,按照随机数表法分为三组,其中33例接受热牙胶垂直加压(TSCC)填充治疗,34例接受冷牙胶自由压实(CFFC)治疗,33例接受冷牙胶侧方加压(CLC)治疗。比较三组患者疼痛程度、止痛干预相关指标、术后填充质量及炎症因子水平。结果术后2、6 h三组患者视觉模拟评分法(VAS)评分均降低,其中CFFC组VAS评分低于CLC组、TSCC组,差异有统计学意义(P<0.05);术后3 d,CFFC组用药剂量、频次少于其他两组,起效时间短于其他两组,差异有统计学意义(P<0.05);治疗后三组患者适充率比较,差异有统计学意义(P<0.05);治疗后CFFC组适充率为91.18%,显著高于其他两组,差异有统计学意义(P<0.05);术后三组炎症因子水平均下降(P<0.05),其中CFFC组白细胞介素-6、白细胞介素-1β、C反应蛋白水平明显低于其他两组,差异有统计学意义(P<0.05)。结论不可逆性牙髓炎患者实施TSCC及CFFC治疗后疼痛明显减轻且术后填充质量优秀,其中CFFC技术在缩短止痛干预起效时间及减少止痛药物摄入方面效果良好,可降低患者炎症因子水平。

智能化振杆密实法加固海陆交互相液化地基试验研究

长江三角洲地区广泛分布着海陆交互相液化地基,具有粉土、粉砂、淤泥质粉质黏土互层的工程地质特点。随着我国高速公路建设快速发展,对此类海陆交互相液化地基的处理已迫在眉睫。本文依托洋通高速公路工程项目,采用具有自主知识产权的智能化振杆密实法施工技术对海陆交互相液化地基进行了加固处理,通过室内试验、原位测试和填筑期沉降监测等方法,综合评价了该技术处理海陆相交互相液化地基的加固效果,并与碎石桩法的处理效果进行对比。研究结果表明:智能化振杆密实法处理后,试验场地土体密度、内摩擦角、压缩模量等均得到明显提高,含水量和孔隙比明显降低;处理范围内土层的锥尖阻力、侧摩阻力和标准贯入试验锤击数较处理前提高了80%以上,测试波速则提升了15%,预测工后沉降为10.36 mm,满足了高速公路建设要求。振杆密实法工程费用相比碎石桩法可节约38.0%,且施工过程自动化、可视化程度高,具有显著的经济效益与应用前景。

高填方路基强夯补强效果试验分析

文中以四川某高速公路改扩建项目为例,开展高填方路基强夯补强试验研究,并利用瑞利波法分析了补强前后高填方路基的密实度与瑞利波速的关系。结果表明,波速与压实度呈现近似线性增加的关系,波速每增加1 m/s,路基压实度增加0.19%。瑞利波监测法与现场灌砂法所有测量点位的压实度相差范围为3.5%左右,两种方法下的波速与压实度曲线相对一致。夯击后的夯击点密实深度显著提升,提升幅度在11.7%~18.7%,提升土体压实度可以有效提升路基土的施工质量。研究成果证明了瑞利波法测试土体压实度具有一定的可靠性,且采用的强夯方案有效提升了路基土的压实度,证实了高填方路基补强效果的可靠性。