Assessment of the Elastic-Wave Well Treatment in Oil-Bearing Clastic and Carbonate Reservoirs

A set of techniques for well treatment aimed to enhance oil recovery are considered in the present study.These are based on the application of elastic waves of various types(dilation-wave,vibro-wave,or other acoustically induced effects).In such a context,a new technique is proposed to predict the effectiveness of the elastic-wave well treatment using the rank distribution according to Zipf’s law.It is revealed that,when the results of elastic wave well treatments are analyzed,groups of wells exploiting various geological deposits can differ in terms of their slope coefficients and free members.As the slope coefficient increases,the average increase in the well oil production rate(after the well treatment)becomes larger.An equation is obtained accordingly for estimating the slope coefficient in the Zipf’s equation from the frequency of the elastic wave.The obtained results demonstrate the applicability of the Zipf’s law in the analysis of the technological efficiency of elastic-wave well treatment methods.

Exploiting Virtual Elasticity of Manufacturing Systems to Respect OTD—Part 2: Post-Optimality Conditions for the Cases of Ergodic and Non-Ergodic Order Rate with Deterministic Product-Mix

Respecting the on-time delivery (OTD) for manufacturing orders is mandatory. However, for non-JIT Batch & Queue Push-manufacturing systems, the compliance of OTD is not intrinsically guaranteed. As an OTD related manufacturing theory is largely missing it is crucial to understand and formalize the necessary conditions of OTD compliance for complex production environments for maximum exploitation of the production capacity. This paper evaluates the conditions of post-optimality while being OTD compliant for production systems, which are characterized by stochastic order rate and a deterministic product-mix. Instead of applying discrete event simulation to explore the real case-by-case order scheduling optimization for OTD compliance, a Cartesian approach is followed. This enables to define theoretically the solution space of order backlog for OTD, which contributes to developing further manufacturing theory. At the base stands the recently defined new concept of virtual manufacturing elasticity by reducing lead-time to increase virtually production capacity. The result has led to defining additional two corollaries to the OTD theorem, which sets up basic OTD theory. Apart from defining the post-optimal requirements to guarantee for orders at least a weak solution for OTD compliance, this paper reveals that for a deterministic product-mix a non-ergodic order arrival rate can be rescheduled into an ergodic order input rate to the shopfloor if the virtual elasticity T is large enough, hence the importance of having fast and flexible production lines.

Precise calculation of average strain and average strain rate considering roll elastic flattening

Considering roll elastic flattening, new equations were proposed to calculate the average strain ε and average strain rate ε- in the hot strip rolling process. By comparing the proposed equations with currently used equations ,it was observed that the strain rate of thick strip and strain are not sensitive to roll elastic flattening. However,for thin strip, a noticeable calculated difference in the strain rate occurred when roll elastic flattening was considered.

ON CRACK-TIP STRAIA ENERGY RELEASE RATE IN NON-PRINCIPAL DIRECTIONS OF ELASTICITY FOR SIMPLE LAYER PLATE OF COMPOSITE MATERIALS

In this paper, the fracture problem in non-principal directions of elasticity for a simple layer plate of linear-elastic orthotropic composite materials is studied. The formulae of transformation between characteristic roots, coefficients of elastic compliances in non-principal directions of elasticity and corresponding parameters in principal directions of elasticity are derived. Then, the computing formulae of strain energy release rate under skew-symmetric loading in terms of engineering parameters for principal directions of elasticity are obtained by substituting crack-tip stresses and displacements into the basic formula of the strain energy release rate.

Elastic analysis of a mode Ⅱ crack in an icosahedral quasicrystal

Based on the displacement potential functions, the elastic analysis of a mode Ⅱ crack in an icosahedral quasicrystal is performed by using the Fourier transform and dual integral equation theory. By the solution, the analytic expressions for the displacement field and stress field are obtained. The asymptotic behaviours of the phonon and phason stress fields around the crack tip indicate that the stresses near the crack tip exhibit a square root singularity. The most important physical quantities of fracture theory, crack stress intensity factor and energy release rate, are evaluated in an explicit version.

Analysis of a permeable interface crack in elastic dielectric/piezoelectric bimaterials

A permeable interface crack between elastic dielectric material and piezoelectric material is studied based on the extended Stroh＇s formalism. Motivated by strong engineering demands to design new composite materials, the authors perform numerical analysis of interface crack tip singularities and the crack tip energy release rates for 35 types of dissimilar bimaterials, respectively, which are constructed by five kinds of elastic dielectric materials： Epoxy, Polymer, Al2O3, SiC, and Si3N4 and seven kinds of practical piezoelectric ceramics： PZT-4, BaTiO3, PZT-5H, PZT-6B, PZT-TA, P-7, and PZT-PIC 151, respectively. The elastic dielectric material with much smaller permittivity than commercial piezoelectric ceramics is treated as a special transversely isotropic piezoelectric material with extremely small piezoelectricity. The present investigation shows that the structure of the singular field near the permeable interface crack tip consists of three singularities： r^-1/2±iε and r^-1/2, which is quite different from that in the impermeable interface crack. It can be concluded that different far field loading cases have significant influence on the near-tip fracture behaviors of the permeable interface crack. Based on the present theoretical treatment and numerical analysis, the electric field induced crack growth is well explained, which provides a better understanding of the failure mechanism induced from interface crack growth in elastic dielectric/piezoelectric bimaterials.

RESTUDY OF THEORIES FOR ELASTIC SOLIDS WITH MICROSTRUCTURE

The dynamical theories of elastic solids with microstructure are restudied and the reason why so many notations have been introduced for derivation of basic equations for such theories is given. In view of the existing problems in those theories the rather general principle of power and energy rate is postulated and the equations of motion, the balance equations of energy rate and energy and the boundary conditions for local and nonlocal theories are naturally derived with help of that principle and the generalized Piola's theorem. These basic equations and the boundary conditions together with the initial conditions may be. used to solve the mixed problems of the dynamical theory of elastic solids with microstructure.

非线性反问题的elastic-net正则化

研究非线性不适定算子方程F(x)=y的求解问题,提出基于非线性算子方程的elastic-net正则化.研究elastic-net正则化性质,即正则化解的存在性,稳定性,收敛性和收敛速度.

Exploiting Virtual Elasticity of Production Systems for Respecting OTD-Part 1: Post-Optimality Conditions for Ergodic Order Arrivals in Fixed Capacity Regimes

Respecting the on-time-delivery (OTD) for manufacturing orders is mandatory. This depends, however, on the probability distribution of incoming order rate. The case of non-equal distribution, such as aggregated arrivals, may compromise the observance of on-time supplies for some orders. The purpose of this paper is to evaluate the conditions of post-optimality for stochastic order rate governed production systems in order to observe OTD. Instead of a heuristic or a simulative exploration, a Cartesian-based approach is applied to developing the necessary and sufficient mathematical condition to solve the problem statement. The research result demonstrates that increasing speed of throughput reveals a latent capacity, which allows arrival orders above capacity limits to be backlog-buffered and rescheduled for OTD, exploiting the virtual manufacturing elasticity inherent to all production systems to increase OTD reliability of non JIT-based production systems.

Exploiting Virtual Elasticity of Production Systems to Respect OTD—Part 3: Basic Considerations for Modelling CPPS Characterized by Non-Ergodic Order Entry and Non-Deterministic Product-Mix for Fully Flexible Addressable Workstations

The recently experienced hype concerning the so-called “4th Industrial Revolution” of production systems has prompted several papers of various subtopics regarding Cyber-Phdysical Production Systems (CPPS). However, important aspects such as the modelling of CPPS to understand the theory regarding the performance of highly non-ergodic and non-deterministic flexible manufacturing systems in terms of Exit Rate (ER), Manufacturing Lead Time (MLT), and On-Time Delivery (OTD) have not yet been examined systematically and even less modeled analytically. To develop the topic, in this paper, the prerequisites for modelling such systems are defined in order to be able to derive an explicit and dedicated production mathematics-based understanding of CPPS and its dynamics: switching from explorative simulation to rational modelling of the manufacturing “physics” led to an own and specific manufacturing theory. The findings have led to enouncing, among others, the Theorem of Non-Ergodicity as well as the Batch Cycle Time Deviation Function giving important insights to model digital twin-based CPPS for complying with the mandatory OTD.

Elasticity Ratio of Resource Consumption and the Resource Consumption

Today the resources are becoming scarcer, which should not be regarded as unexhausted any more. Correspondingly, the production would be constrained by the scarcity of resources clearly. Then the economic researchers would pay much more at-tention to reducing the consumption of natural resources in the future. Therefore this paper brings foreword the conception of elasticity ratio of resource consumption based on the concept of elasticity and analyzes the relationship between the parameters. For the certain relationships between the elasticity ratio of resource consumption and resource consumption, this paper will try to re-veal, to keep economy growing while resource consumption reduc-ing, what conditions should be met as to the relationships among resource productivity, its growth rate, energy saving efficiency, economic growth rate and elasticity ratio of resource consumption. This paper proves the relationship between the China's energy consumption and economy growth using statistic data from 1978 to

机车用钛合金弹簧的设计与制备

钛合金弹簧替代钢制弹簧应用于机车悬架弹簧可以减重40%~60%,而且钛合金弹簧具有良好的耐蚀性和阻尼特性,不仅能够抵御恶劣环境的腐蚀,增加机车的行驶里程,还能增强机车的操控性和乘架的舒适性。通过赛车用悬架弹簧实例,详细介绍TB9钛合金弹簧的设计方法和制备过程。计算得到钛合金悬架弹簧的螺旋角为9.45°,已经超出弹簧设计国家标准范围,因此对公式进行了修正。此外,还研究了温度对TB9钛合金弹簧刚度的影响。研究发现,随着温度的上升,TB9钛合金弹簧的刚度逐渐下降。

气井定产量和变产量弹性二相法的通式及应用

对于受封闭边界控制的气体流动,当气井完成试气和关井取得原始地层压力之后,若以某稳定产量开井生产,测试的井底流压的压降曲线,根据压力动态的变化特征,可划分为非稳态阶段、过渡阶段和拟稳态阶段。其中的拟稳态阶段,称为弹性二相法阶段。在弹性二相法阶段的井控范围内,井底流压呈等速下降。本文基于陈元千提出的压力一次方、压力平方和拟压力表示的定产量弹性二相法,以及基于Blasingame提出的压力一次方表示的变产量弹性二相法,分别建立了气井定产量和变产量弹性二相法的通式。通过实例的应用表明,两个通式是实用有效的。

高应变率下不同初始相变温度NiTi合金的力学响应

为获得高应变率下不同初始相变温度NiTi合金的屈服应力等基本物理特性和力学响应规律,采用10^(−3)s^(−1)应变率下准静态压缩与拉伸、10^(5)s^(−1)应变率下准等熵压缩及10^(7)s^(−1)应变率下冲击加载实现跨量级的不同应变率加载,高应变率加载实验中通过控制样品初始温度实现不同初始相态NiTi合金的力学响应测量。结果显示,初始马氏体相和初始奥氏体相NiTi合金的准静态加载应力-应变曲线中均出现2次模量变化,初始马氏体相中的模量变化由晶体重定向和马氏体相塑性变形引起,初始奥氏体相中的模量变化由马氏体相变和相变后塑性变形引起。准等熵加载下,初始马氏体相NiTi合金的Lagrangian声速随粒子速度增大而增大,未观察到间断等非线性变化;而初始奥氏体相中声速曲线存在间断,声速由初始横波值间断减小至体波声速后再随粒子速度线性增大。冲击实验中,初始马氏体相NiTi合金后自由面速度约34 m/s处出现双波结构,而将样品初始温度升至402 K后再冲击加载,则在约100 m/s处出现双波结构,二者速度曲线拐点分别由马氏体相弹塑性屈服和奥氏体相塑性屈服引起;在初始奥氏体相NiTi合金冲击实验中,在样品后自由面速度达到220~260 m/s时才出现显著的奥氏体相弹塑性转变。随着应变率从约105 s^(−1)升高至10^(7) s^(−1),相同组分奥氏体相NiTi合金的弹性极限由约2 GPa增大至约4 GPa,10^(7) s^(−1)应变率下,随着初始样品温度升至402 K,弹性极限降至1.7 GPa,表明NiTi合金的弹性极限存在显著的温度和应变率效应。

盐冻耦合环境下再生砖粉ECC的耐久性研究

利用再生砖粉取代工程水泥基复合材料(ECC)中的石英砂,制备再生砖粉ECC,采用混凝土快速冻融试验,研究了氯盐、硫酸盐及复合盐(氯盐+硫酸盐)溶液侵蚀作用下再生砖粉ECC的质量损失率和相对动弹性模量变化规律,建立了ECC在盐冻侵蚀环境下的损伤模型,并对其耐久性进行评价。结果表明:冻融循环300次后,再生砖粉ECC在清水、氯盐、硫酸盐及复合盐四种介质中的质量损失率分别为2.884%、4.984%、1.955%和6.891%,相对动弹性模量分别下降了6.468%、16.300%、24.303%和39.861%;再生砖粉ECC在单一盐冻情况下的抗冻等级大于F300,在复合盐冻情况下的抗冻等级大于F250,具有良好的抗盐冻性能;建立的冻融损伤模型可较好地反映ECC在不同冻融介质下的损伤度Dn与冻融循环次数的关系,可以为严寒地区的结构耐久性设计提供有效参考。

快压缩P_(1)波在饱和冻土与弹性基岩分界面上的能量传输特性

基于弹性波在冻结饱和多孔介质与单相弹性介质中的传播理论,选取了饱和冻土中传播速度最大的快压缩P 1波入射在饱和冻土与弹性基岩分界面上的能量传输问题。根据分界面上的边界条件,推导出了快压缩P 1波从饱和冻土介质入射到弹性基岩分界面上透反射振幅比和能量率的解析表达式。研究了快压缩P_(1)波入射在饱和冻土与弹性基岩分界面上的能量与入射角度,入射频率,温度(含冰量),孔隙率,胶结参数以及接触参数的关系。研究结果表明:当入射角度为0°时仅存在压缩波,达到临界角后透射P波消失;各种波在达到临界角时出现不同程度的脉冲,其中反射P_(1)波最为显著;随着胶结参数,孔隙率,接触参数的增大,临界角越早出现;入射频率仅对反射P_(2),P_(3)和S_(2)波的能量反射率影响较大;当温度和含冰量较低或较高时,均不利于反射S_(2)波的能量产生。

Processing Modflow模拟地面沉降中有关参数取值的研究

本文以天津多个群井抽水试验和基坑工程降水为例,结合多年来实际工程的实测数据,利用Processing Modflow模拟软件,将降水条件下地下水三维非稳定渗流数学模型与地面沉降数学模型相耦合,对基坑降水引起的各地层参数进行反演分析并识别和验证数学模型。在此基础上,对有限差分法中有关地面沉降参数,即土体骨架成分的弹性储水率和非弹性储水率的取值做进一步分析,确定了天津市平原区抽降地下水引起的地面沉降中相关参数的取值规律及变化范围。

弹性基体软固结磨料磨具的材料去除机理

基于弹性磨具的磨抛工艺为硬脆材料超精密加工效率与加工质量的兼顾平衡提供了新的解决思路,但其磨抛过程的材料去除机理尚未明确。为研究弹性磨抛过程中的材料去除行为,以硅橡胶作为磨具基体材料,混合微米级金刚石磨料制备弹性基体软固结磨料磨具,利用有限元仿真分析方法研究弹性基体软固结磨粒的受力状态,结合接触力学与运动学分析建立考虑单颗磨粒磨损行为与有效磨粒数量的材料去除模型,通过石英玻璃试件的弹性磨抛加工试验验证预测模型的准确性。结果表明:石英玻璃试件的材料去除率随着磨抛压力、主轴转速、磨具偏角的增大而显著增加,而磨料粒径对其影响程度较小;当工艺参数组合为磨料粒径100μm、磨抛压力7 N、主轴转速1500 r/min、磨具偏角20°时,经60 min磨抛后,工件已加工表面粗糙度由1.069μm降至0.089μm,材料去除率为8.893×10^(8)μm^(3)/min;该试验条件下,建立的材料去除模型预测准确度相比Preston经典模型提高36.7%。研究成果可为实现硬脆材料的确定性材料去除提供技术支持和理论依据。

超声弹性成像评估足月妊娠宫颈预测临产时间的研究

目的探讨超声弹性成像评估足月妊娠宫颈预测临产时间的临床价值。方法回顾性选取2021年11月至2022年12月在大连医科大学附属第二医院产科病房住院的符合纳入标准的足月妊娠孕妇85例。采用统计学方法分析足月后,经阴道超声评估宫颈各参数(宫颈的长度、相同面积下宫颈内口与宫颈外口的应变率及两者的比值)的时间与孕妇临产时间之间的时间差定义为距离临产时间(TOL),将85例孕妇分为TOL<7 d组(n=27)和TOL≥7 d(n=58)。记录85例孕妇的基本资料,宫颈的长度、相同面积下宫颈内口与宫颈外口弹性应变率及两者的比值,分析TOL的影响因素;比较TOL<7 d组与TOL≥7 d组的宫颈长度、宫颈位置、相同面积下宫颈内、外口弹性应变率及两者的比值,分析TOL<7 d组与TOL≥7 d组的影响因素;并对TOL≥7 d组内的宫颈长度、宫颈位置、相同面积下宫颈内、外口弹性应变率及两者的比值进行Logistic回归分析。结果足月妊娠后,受检孕妇TOL四分位组基本特征比较可得,无论是TOL≥7 d组,还是TOL<7 d组,孕妇的孕周(P=0.001)和宫颈长度(P=0.023)是预测临产时间的相关因素;宫颈内口弹性应变率、宫颈外口弹性应变率以及两者的比值预测临产时间差异无统计学意义(P>0.05)。TOL<7 d组宫颈长度为(24.10±5.48)mm,明显小于TOL≥7 d组[(28.30±4.80)mm],宫颈内口弹性应变率为0.22±0.06,明显大于TOL≥7 d组(0.19±0.04),差异均有统计学意义(P<0.05),但TOL<7 d组与TOL≥7 d组的年龄、孕周、身高、体重指数、宫颈外口弹性应变率及宫颈外口与宫颈内口弹性应变率比值比较,差异均无统计学意义(P>0.05)。TOL≥7 d组Logistic回归分析结果显示,孕周小、宫颈外口弹性应变率大,宫颈外口与宫颈内口弹性应变率比值大,更是TOL>10 d的危险因素(P<0.05)。结论孕周和宫颈长度对于TOL有影响;TOL≥7 d者宫颈外口与内口变化率比值越大,宫颈内口弹性应变率较小,即宫颈内口较硬,宫颈外口弹性应变率较大者越容易发生延迟。TOL<7 d者宫颈长度更短,宫颈内口更软。因此,足月妊娠后宫颈弹性成像联合孕妇的孕周、宫颈长度预测临产时间更加准确。

基于多指标下POM纤维对EPS轻型混凝土性能的影响

为探究聚甲醛(POM)纤维对聚苯乙烯(EPS)轻型混凝土性能的综合影响,避免以往单纯依赖力学性能指标评价的不足,比选后基于长度为12 mm的POM纤维研究了不同性能评价指标下POM纤维的最优掺量。结果表明:基于基本的力学性能及相对动弹性模量变化绝对值,掺量为0.9%时,POM纤维对EPS轻型混凝土的增强效果最优,冻融损伤最低;基于吸水性及流变性能指标,掺量同样为0.9%时浆体稠度及抗吸水能力最佳;基于干缩性能,则掺量为1.2%时,浆体抗干缩效果最优;基于冻融后相对弹性模量变化率,则掺量为0.6%时相对弹性模量衰减率最低;研究揭示了POM纤维增强EPS轻型混凝土的复杂性和多样性,进一步通过微观分析,辅证了POM纤维增强增韧EPS轻型混凝土的机理。