DETERMINATION OF COHESIVE ENERGY DENSITY OF UP RESIN BY THE SWELLING METHOD

Different types of solvents were chosen, and their solubleexpansion ability to unsaturated polyster- resin was determined. Theprinciple and method of deter- mining the cohesive energy density ofunsaturated polyster resin by using the swelling method are presentedin details.

Study of Mutual Improvement of Completed Weathered Phyllite and Red Clay Based on Neutralization Effects of Swelling and Shrinkage Deformation

Completely weathered phyllite(CWP)soil is a kind of special soil with high swell potential,while red clay is a special soil with high shrinkage.This means that these two kinds of special soils are usually not suitable for direct use as subgrade fill.To reduce the swell index of the CWP soil and the shrinkage of red clay at the same time,it was proposed to blend the CWP soil with red clay to improve their basic characteristics.A series of swell index tests and dry-wet cycle tests of the blended soils have been carried out at varying blending ratios,compaction coefficients and moisture contents.The test results show that the free swell index of the blended soil decreases with the increase of red clay,moisture content and compaction coefficient,respectively.The fissure density of the blended soil first decreases and then increases with the blending ratio,with the lowest being zero when the blending ratio is ranging from 20%to 40%.Through particle microscopic analysis and elemental composition analysis,it is found that the neutralization effect,the dilution effect of swell minerals,and the partition effect of coarse particles play an important role in restraining expansion and shrinkage deformation of the blended soil.Based on the liquid limit requirement of Chinese Railway Design Code(TB 10001-2016),the optimal blending ratio of red clay has been proposed to be 50%.Compared with the CWP soil,the free load swell index of the blended soil is reduced by 45.0%and the fissure density is reduced by 99.3%compared with that of red clay.Therefore,it is feasible to improve the CWP soil by blending it with red clay at an optimal ratio of 50%by using the neutralization effect of the expansion of CWP and shrinkage of red clay.

Application of Multi-Step Differential Transform Method on Flow of a Second-Grade Fluid over a Stretching or Shrinking Sheet

In this study, a reliable algorithm to develop approximate solutions for the problem of fluid flow over a stretching or shrinking sheet is proposed. It is depicted that the differential transform method (DTM) solutions are only valid for small values of the independent variable. The DTM solutions diverge for some differential equations that extremely have nonlinear behaviors or have boundary-conditions at infinity. For this reason the governing boundary-layer equations are solved by the Multi-step Differential Transform Method (MDTM). The main advantage of this method is that it can be applied directly to nonlinear differential equations without requiring linearization, discretization, or perturbation. It is a semi analytical-numerical technique that formulizes Taylor series in a very different manner. By applying the MDTM the interval of convergence for the series solution is increased. The MDTM is treated as an algorithm in a sequence of intervals for finding accurate approximate solutions for systems of differential equations. It is predicted that the MDTM can be applied to a wide range of engineering applications.

Adaptive multi-step piecewise interpolation reproducing kernel method for solving the nonlinear time-fractional partial differential equation arising from financial economics

This paper is aimed at solving the nonlinear time-fractional partial differential equation with two small parameters arising from option pricing model in financial economics.The traditional reproducing kernel(RK)method which deals with this problem is very troublesome.This paper proposes a new method by adaptive multi-step piecewise interpolation reproducing kernel(AMPIRK)method for the first time.This method has three obvious advantages which are as follows.Firstly,the piecewise number is reduced.Secondly,the calculation accuracy is improved.Finally,the waste time caused by too many fragments is avoided.Then four numerical examples show that this new method has a higher precision and it is a more timesaving numerical method than the others.The research in this paper provides a powerful mathematical tool for solving time-fractional option pricing model which will play an important role in financial economics.

Swelling Measurements of a Low Rank Coal in Supercritical CO₂

Coal swelling in the presence of water as well as CO2 is a well-known phenomenon, and these may affect the permeability of coal. Quantifying swelling effects is becoming an important issue to verify the suitability of particular coal seams for CO2-enhanced coal bed methane recovery projects. In this report, coal swelling experiments using a visualization method in the CO2 supercritical conditions were conducted on crushed coal samples. The measurement apparatus was designed specifically for the present swelling experiment using a visualization method. Crushed coal samples were used instead of block coal samples to shorten equilibrium time and to solve the problem of limited availability of core coal samples. Dry and wet coal samples were used in the experiments because there is relatively limited information about how the swelling of coal by CO2 is affected by water saturation. Moreover, some coal seams are saturated with water in initial reservoir conditions. The maximum volumetric swelling was around 3% at 10 MPa for dry samples and almost half that at the same pressure for wet samples. The wet samples showed lower volumetric swelling than dry ones because the wet coal samples were already swollen by water. Experimental results obtained for swelling were comparable with other reports. Our visualization method using crushed samples has advantages in terms of sample preparation and experimental execution compared with the other methods used to measure coal swelling using block samples.

Chaos control of gear system with elastomeric web based on multi-parameter multi-step method

This paper employs a multi-parameter multi-step chaos control method, which is built up on the OGY method, to stabilize desirable UPOs of a gear system with elastomeric web as a high-dimensional and non-hyperbolic chaotic system, and the analyses are carried out. Three types of relations between components of a certain control parameter combination are defined in a certain control process. Special emphasis is put on the comparison of control efficiencies of the multi-parameter multi-step method and single-parameter multi-step method. The numerical experiments show the ability to switch between different orbits and the method can be a good chaos control alternative since it provides a more effective UPOs stabilization of high-dimensional and non-hyperbolic chaotic systems than the single-parameter chaos control, and according to the relation between components of each parameter combination, the best combination for chaos control in a certain UPO stabilization process are obtained.

修正硫化效应法制定厚制品橡胶硫化时间

测试了混炼胶不同温度下的硫化曲线,研究了硫化温度对不同混炼胶交联程度的影响;以天然橡胶(NR)/顺丁橡胶(BR)硫化胶为研究对象,进一步测试了其不同硫化温度下的硫化曲线,进行硫化程度修正系数P和硫化温度系数K拟合,采用预埋热电偶法测试了厚制品橡胶中心处的升温曲线,采用修正以及传统硫化效应法分别进行二者工程硫化时间计算。结果表明,硫化温度对不同橡胶硫化程度会产生较大影响,采用修正硫化效应法硫化的厚制品与标准试片更加接近,而传统硫化效应法硫化程度偏低。

Numerical Simulation of Viscoelastic Extrudate Swell Through Elliptical Ring Die

The numerical simulation of extrudate swell is significant in extrusion processing.Precise prediction of extrudate swell is propitious to the control of melt flow and the quality of final products.A mathematical model of three-dimensional（3D）viscoelastic flow through elliptical ring die for polymer extrusion was investigated.The penalty function formulation of viscoelastic incompressible fluid was introduced to the finite element model to analyze 3D extrusion problem.The discrete elastic viscous split stress（DEVSS）and streamline-upwind PetrovGalerkin（SUPG）technology were used to obtain stable simulation results.Free surface was updated by updating the streamlines which needs less memory space.According to numerical simulation results,the effect of zero-shear viscosity and elongation parameter on extrudate swell was slight,but with the increase of volumetric flow rate and relax time the extrudate swell ratio increased markedly.Finally,the numerical simulation of extrudate swell flow for low-density polyethylene（LDPE）melts was investigated and the results agreed well with others’work.These conclusions provided quantitative basis for the forecasting extrudate swell ratio and the controlling of extrusion productivity shape.

POINCARE-LIGHTHILL-KUO METHOD AND SYMBOLIC COMPUTATION

This paper elucidates the effectiveness of combining the Poincare-Lighthill-Kuo method (PLK method, for short) and symbolic computation. Firstly, the idea and history of the PLK method are briefly introduced. Then, the difficulty of intermediate expression swell, often encountered in symbolic computation, is outlined. For overcoming the difficulty, a semi-inverse algorithm was proposed by the author, with which the lengthy ports of intermediate expressions are first frozen in the form of symbols till the Fnal stage of seeking perturbation solutions. Tn discuss the applications of the above algorithm, the related work of the author and his research group on nonlinear oscillations and waves is concisely reviewed. The computer-extended perturbation solution of the Duffing equation shows that the asymptotic solution obtained with the PLK method possesses the convergence radius of 1 and thus the range of validity of the solution is considerably enlarged. The studies on internal solitary waves in stratified fluid and on the head-on collision between two solitary waves in a hyperelastic rod indicate that by means of the presented methods, very complicated manipulation, unconceivable in hand calculation, can be conducted and thus result in higher-order evolution equations and asymptotic solutions. The examples illustrate that the algorithm helps to realize the symbolic computation on micro-commputers. Finally, it is concluded that,vith the aid of symbolic computation, the vitality of the PLK method is greatly. Strengthened and at least for the solutions to conservative systems of oscillations and waves, it is a powerful tool.

Forecasting available parking space with largest Lyapunov exponents method

The techniques to forecast available parking space(APS) are indispensable components for parking guidance systems(PGS). According to the data collected in Newcastle upon Tyne, England, the changing characteristics of APS were studied. Thereafter, aiming to build up a multi-step APS forecasting model that provides richer information than a conventional one-step model, the largest Lyapunov exponents(largest LEs) method was introduced into PGS. By experimental tests conducted using the same dataset, its prediction performance was compared with traditional wavelet neural network(WNN) method in both one-step and multi-step processes. Based on the results, a new multi-step forecasting model called WNN-LE method was proposed, where WNN, which enjoys a more accurate performance along with a better learning ability in short-term forecasting, was applied in the early forecast steps while the Lyapunov exponent prediction method in the latter steps precisely reflect the chaotic feature in latter forecast period. The MSE of APS forecasting for one hour time period can be reduced from 83.1 to 27.1(in a parking building with 492 berths) by using largest LEs method instead of WNN and further reduced to 19.0 by conducted the new method.

A laboratory study of directional spectrawith maximum likelihood mehod─ⅡDecaying swell

From measurements by a circular array consisting of 18 wave gauges in a large wave tank, directional spectra of swell in deep water are systematically investigated with maximum likelihood method. It is shown that the directional spreading of swell, qualitatively similar to that of developing wind wave which is narrowest in the region of Peak frequency and bxoadens with increasing or decreasing frequency, can be effectively described by cos2s(θ/2) introduced by Longuet-Higgins et al. (1963,Ocean Wave Spectra, 111~136). It is intriguing that bimodal distribution found in our experiments appers at the forward face instead of the rear face of a frequency spectrum in the cases of nonlinearity being very weak. Parameterized by nonlinearity, formulations which can be applied to swell as well as wind wave are proposed. It is concluded that nonlinear interaction plays a central role in controlling the development of directional angular spreading even for the swell.

Optimized Hybrid Block Adams Method for Solving First Order Ordinary Differential Equations

Multistep integration methods are being extensively used in the simulations of high dimensional systems due to their lower computational cost.The block methods were developed with the intent of obtaining numerical results on numerous points at a time and improving computational efficiency.Hybrid block methods for instance are specifically used in numerical integration of initial value problems.In this paper,an optimized hybrid block Adams block method is designed for the solutions of linear and nonlinear first-order initial value problems in ordinary differential equations(ODEs).In deriving themethod,the Lagrange interpolation polynomial was employed based on some data points to replace the differential equation function and it was integrated over a specified interval.Furthermore,the convergence properties along with the region of stability of the method were examined.It was concluded that the newly derived method is convergent,consistent,and zero-stable.The method was also found to be A-stable implying that it covers the whole of the left/negative half plane.From the numerical computations of absolute errors carried out using the newly derived method,it was found that the method performed better than the ones with which we compared our results with.Themethod also showed its superiority over the existing methods in terms of stability and convergence.

Die-Swell Performance of Colored Poly(m-phenylene isophthalamide)(PMIA)Fiber Prepared by Wet Spinning

The colored poly(m-phenylene isophthalamide)(PMIA)spinning solution was prepared by wet spinning and the die-swell of the colored PMIA spinning solution was done when it was extruded from a die in this experiment.The properties and structures of colored PMIA fibers were characterized by scanning electron microscopy(SEM).The colored PMIA spinning dopes were first commixed in a pressurizer and then spun into a coagulation bath.The effect of die swell on the colored PMIA solution was resulted from the viscoelastic properties of the colored PMIA solution in the spinning process.The results showed that the die-swell ratio of the colored PMIA solution increased linearly with increasing the pressure and die length/diameter ratio(L/D).At the same pressure and L/D,the die-swell ratio decreased with the increase of filter layers and temperature.Also,optimized spinning parameters of the dopedyed PMIA fiber were obtained.

基于DEM-FDM耦合的过渡段膨胀诱发钢轨上拱研究

研究目的:为分析涵洞过渡段地基膨胀引起的钢轨上拱响应,基于现场测试、室内膨胀试验数据,开展DEM-FDM耦合数值模拟,分析某涵洞附近路基土在膨胀范围为16 m,膨胀中心距离涵洞中心分别为0 m、5 m、10 m这三种工况下,不同膨胀率时基床填料的运动规律及钢轨的上拱响应。研究结论:(1)涵洞对于钢轨上拱位移的传递存在阻断作用,但会增大钢轨上拱的峰值,原位膨胀率下工况二的钢轨上拱峰值达到46 mm,当路基膨胀率为0.3%时钢轨上拱位移量达到无砟轨道钢轨可调节临界值(4mm);(2)过渡段钢轨上拱处同时产生轴向应力集中,其中原位膨胀率下工况二轴向应力峰值达到14.4 MPa;(3)对于膨胀区域位于涵洞下方的工况,钢轨轴向应力呈现出来的分布规律为钢轨上拱拱顶处为主拉应力状态,拱脚处为主压应力状态,因此一共包括三个压应力峰值点以及两个拉应力峰值点;(4)本文研究可为高铁涵洞过渡段路基膨胀病害解决方案的确定提供理论依据。

微悬浮法消光PVC糊树脂膨润度的测定方法

确定了微悬浮消光PVC糊树脂膨润度的测试方法:采用10 mL刻度试管,样品量为0.2440 g,加入四氢呋喃溶剂量为8 mL,水浴溶胀温度为60℃,水浴溶胀时间为2 h,室温放置溶胀时间为48 h。

溶胀法制备荧光微球研究进展

溶胀法作为一种可调控性强、操作简单、实用性高的制备荧光微球的方法而被广泛应用。本文综述了利用溶胀法制备荧光微球的研究进展,阐述了溶胀法制备荧光微球的基本原理和步骤。进一步综述了溶胀过程中影响微球性能的常见因素,例如聚合物基质、荧光物质、溶胀剂的种类等,总结了溶胀法调控优化荧光微球的改进策略,对溶胀法制备荧光微球的应用前景进行了展望。

考虑非饱和土基质吸力-回弹指数相关性的弹塑性本构模型及有限元实现

非饱和土压缩指数受基质吸力影响明显,回弹指数是土的临界状态本构模型中的重要变形参数。但在本构模型理论研究中,回弹指数随基质吸力的变化影响往往被忽略。为解决这一矛盾,以杭州地区重塑粉土为试样,使用GDS非饱和直剪系统的竖向加载功能,对试样进行50、100、200 kPa 3种定吸力条件下一维固结回弹试验,获取不同基质吸力非饱和回弹指数κ(s),并拟合得到κ(s)函数关系,对比已有试验研究,验证了拟合结果的合理性。进而将κ(s)表达式引入非饱和土扩展剑桥弹塑性本构模型,形成一种考虑回弹指数随基质吸力变化的非饱和土弹塑性本构模型。应用子增量步显示积分算法将该模型编辑成ABAQUS有限元UMAT子程序,最后基于ABAQUS有限元平台结合自编UMAT子程序进行固结回弹数值试验,模拟实际试验过程,对比两者试验结果,验证了该UMAT子程序的正确性。实现了一种考虑回弹指数随基质吸力变化的非饱和土弹塑性本构模型的数值化,为其进一步应用建立基础。

基于PFC^(3D)的膨胀岩湿胀变形研究

为研究不同过程含水率下膨胀岩的湿胀变形特性,以侧限无荷载膨胀试验和双电层理论为依据,通过PFC^(3D)软件建立计算模型,对万州地区的膨胀岩地基进行研究.结果表明:数值模拟与室内试验结果吻合较好,整个湿胀变形过程按时程特征可划分为变加速“蠕变”、匀变速上升和变减速“蠕变”3个阶段;增大膨胀岩内部的含水率后,首先会引起其内部黏土矿物颗粒的膨胀,当颗粒膨胀累计到一定阶段时会导致宏观层面上的湿胀变形;湿胀变形与湿胀变形速率的关系本质上反映的是膨胀应变与膨胀应力之间的“应力-应变”本构;膨胀岩湿胀变形速率与细胞吸水膨胀速率相似,即随内部含水率的增大而呈现“Λ”字形的变化趋势;K_(0)应力状态下的侧限膨胀试验不能充分释放膨胀岩的膨胀潜势,因此后期需要三轴应力状态下的膨胀试验来进行进一步研究.

泻火解毒法治疗原矛头蝮蛇咬伤的临床观察

目的观察泻火解毒法治疗原矛头蝮蛇咬伤的临床疗效。方法选择2022年7月1日至2023年8月1日在我院治疗的原矛头蝮蛇咬伤患者108例,按随机数字表法分为治疗组和对照组各54例。对照组给予常规治疗,治疗组在对照组的基础上给予口服蛇伤胶囊(泻火解毒法治疗毒蛇咬伤代表方)治疗,观察两组患者治疗后第1、3、5、7天时的患肢周径差、肿胀消退时间、治疗疗程及患肢疼痛评分。结果两组患者治疗后第1、3天时的患肢周径差比较,差异均无统计学意义(均P>0.05);治疗后第5、7天时,治疗组的患肢周径差明显低于对照组,差异均有统计学意义(均P<0.05)。治疗组的患肢肿胀消退时间、治疗疗程均短于对照组,差异有统计学意义(均P<0.05)。治疗第3、5、7天时,治疗组的患肢疼痛评分均明显低于对照组,差异均有统计学意义(均P<0.05)。结论泻火解毒法治疗原矛头蝮蛇咬伤的临床疗效好,值得推广应用。

Box-Behnken响应面法优选平痤滴丸制备工艺及药效研究

目的在平痤散中药处方基础上,研制平痤滴丸,并对比研究平痤散和平痤滴丸对痤疮的作用。方法以综合评分为评价指标,考察因素为药物与基质质量比、药液温度、冷凝温度,采用Box-Behnken响应面法,对平痤滴丸的制备工艺进行优化;考察平痤散和平痤滴丸对小鼠激素水平、皮脂腺斑组织的影响,对耳肿胀的抗炎作用、对金色葡萄球菌和痤疮丙酸杆菌的抑制作用。结果最优滴丸制备工艺料液比为5∶1,药液温度为80℃,冷凝温度为0℃;平痤滴丸组体内激素水平睾酮(T)值、雌二醇(E2)值、T/E2值、小鼠耳肿胀程度及抑菌作用,均与阳性药组差异无统计学意义(P>0.05),且优于平痤散组。结论平痤滴丸组治疗痤疮效果显著,优于平痤散组,能够有效调节小鼠体内激素水平、减轻小鼠耳肿胀程度、抑制痤疮致病菌。