A New Elasticity and Finite Element Formulation for Different Young's Modulus When Tension and Compression Loadings

This paper presents a new elasticity and finite element formulation for different Young's modulus when tension and compression loadings in anisotropy media. The case studies, such as anisotropy and isotropy, were investigated. A numerical example was shown to find out the changes of neutral axis at the pure bending beams.

NANOINDENTATION OF THIN-FILM-SUBSTRATE SYSTEM DETERMINATION OF FILM HARDNESS AND YOUNG'S MODULUS

In the present paper,the hardness and Young's modulus of film-substrate systems are determined by means of nanoindentation experiments and modified models.Aluminum film and two kinds of substrates,i.e.glass and silicon,are studied.Nanoindentation XP Ⅱ and continuous stiffness mode are used during the experiments.In order to avoid the influence of the Oliver and Pharr method used in the experiments,the experiment data are analyzed with the constant Young's modulus assumption and the equal hardness assumption.The volume fraction model(CZ model)proposed by Fabes et al.(1992)is used and modified to analyze the measured hardness.The method proposed by Doerner and Nix(DN formula)(1986)is modified to analyze the measured Young's modulus.Two kinds of modified empirical formula are used to predict the present experiment results and those in the literature,which include the results of two kinds of systems,i.e.,a soft film on a hard substrate and a hard film on a soft substrate.In the modified CZ model,the indentation influence angle,(?), is considered as a relevant physical parameter,which embodies the effects of the indenter tip radius, pile-up or sink-in phenomena and deformation of film and substrate.

EFFECT OF DISPERSION OF MICA IN MATRIX ON YOUNG'S MODULUS OF MICA FILLED POLYETHYLENE

The correlation between Young's modulus of mica-filled high density polyethylene (HDPE), low density polyethylene(LDPE) and the state of dispersion of plasma-treated mica in the polymer matrices was studied. The modulus and the number average diameter of mica aggregates in matrix were determined with tensile testing and image analysis respectively. The interface structure of the filler/matrix and the bulk structure of matrix were examined through the dielectric spectrometry, differential scanning calorimetry (DSC) and dynamic viscoelastic spectrometry. The results show that the Young's modulus of the filial polyethylene depends to a great extent upon the state of dispersion of filler in matrix, but it is independent of the interface structure and bulk structure. The better the dispersion, the higher the Young's modulus.

Anomalies in Young's modulus behavior after annealing in polycrystalline SmS

In this paper,the dependencies of Young's modulus and attenuation decrement on samarium sulfide polycrystals(SmS)under various annealing temperatures are studied by the piezoelectric ultrasonic composite oscillator technique at a frequency of 100 kHz in the temperature range of 80-300 K.A decrease in Young's modulus with an increase of the annealing temperature due to the texturing of the material was revealed.At the same time,attenuation peaks were observed at temperatures about 90 and 125 K,presumably due to Niblett-Wilks and Bordoni relaxations.

WIDELY LINEAR RLS CONSTANT MODULUS ALGORITHM FOR COMPLEX-VALUED NONCIRCULAR SIGNALS

Based on the constant modulus criterion, a new Widely Linear(WL) blind equalizer and a novel widely linear recursive least square constant modulus algorithm are proposed to improve the blind equalization performance for complex-valued noncircular signals. The new algorithm takes advantage of the WL filtering theory by taking full use of second-order statistical information of the complex-valued noncircular signals. Therefore, the weight vector contains the complete second-order information of the real and imaginary parts to decrease the residual inter-symbol interference effectively. Theoretical analysis and simulation results show that the proposed scheme can significantly improve the equalization performance for complex-valued noncircular signals compared with traditional blind equalization algorithms.

Block-Based Steganographic Algorithm Using Modulus Function and Pixel-Value Differencing

The main purpose in developing the steganographic algorithms lies in achieving most of the steganographic objectives which comprise the embedding capacity, imperceptibility, security, robustness and complexity. In this paper, we propose a high quality steganographic algorithm using new block structure which makes a good use of both modulus function and pixel-value differencing, namely, MF-PVD. We have made many experiments with various test images from several galleries, such as USC-SIPI and UWATERLOO-LINK. The performance of our proposed algorithm is verified using three different performance metrics which include peak signal-to-noise ratio (PSNR), structural similarity index measure (SSIM), and embedding capacity (EC). Experimental results and comparisons with six pertinent state-of-art algorithms are given to prove the validation and efficiency of the proposed algorithm.

地基承载力特征值确定土变形模量的探讨

目前我国地基沉降计算主要采用土压缩模量来计算,再用经验系数对计算结果进行修正。这种方法对于一些结构性较强的硬土地基误差较大,主要原因是取样扰动影响。为此,探讨了变形模量与地基承载力特征值的理论联系,在笔者提出的确定变形模量经验方法基础上,总结出依据地基承载力特征值确定变形模量的方法,该方法具有理论依据,可便捷地通过岩土工程勘察报告中常提供的地基承载力特征值确定土的变形模量,能够更为准确计算地基沉降值。采用不同方法(压板试验法、压缩模量推求法、标贯击数法、承载力经验法、依据地基承载力特征值确定变形模量法)计算了若干试验案例,通过对不同方法结果的对比,初步验证了依据地基承载力特征值确定变形模量法是可行的。

不同因素对固体推进剂流变性能影响研究进展

针对推进剂药浆的流变性能受多种因素的影响,综述了固体推进剂用增塑剂、含能固体填料、工艺助剂、工艺参数等因素对于推进剂药浆流变性能影响的国内外研究现状,并分析总结了不同因素对固体推进剂药浆流变性能的影响规律及机理,对比了不同固体填料和粒度级配对药浆流变特性的影响。指出适当加入增塑剂可有效改善药浆的流变特性;选择合适的工艺助剂、工艺参数可大大改善药浆流变特性;固体填料表面越接近球形、越规则,粒径分布范围越宽,推进剂药浆黏度越小;对固体颗粒进行表面包覆、添加表面活性剂也有助于药浆流变性能的改善。提出了改善推进剂药浆流变性能的技术途径以及后期推进剂药浆流变性能的重点研究方向,以便更加全面研究药浆流变特性,设计出流变性能更好的固体推进剂药浆。附参考文献94篇。

固废粗集料平均弹性模量与混凝土弹性模量的相关性

试验研究了12种不同固废粗集料压碎值试验中σ-ε曲线与配制混凝土的静态弹性模量之间关系,进行了压碎值试验固废粗集料变形的离散元数值模拟,分析了国内外主要标准中公式计算固废粗集料混凝土弹性模量误差偏大的原因。研究结果表明:基于中国、美国和欧洲标准的普通密度固废粗集料混凝土弹性模量计算值分别高出实测值45.5%、15.8%和52.5%;固废粗集料在压碎值试验σ-ε曲线的线性区间主要发生弹性变形;建立的固废粗集料σ-ε曲线指数模型拟合度高,R^(2)均大于0.99;通过在传统的压碎值试验中引入粗集料平均弹性模量、含水系数等参数,回归建立了固废粗集料混凝土弹性模量半经验公式,R^(2)为0.867。利用已有文献数据对半经验公式的普适性进行了检验,高判定系数(R^(2)=0.895)实测值与预测值的比较表明模型具有有效性,为快速、可靠预测固废粗集料混凝土弹性模量提供了依据。

Photoacoustic elastography based on laser-excited shear wave

Elastography can be used as a diagnostic method for quantitative characterization of tissue hardness information and thus,differential changes in pathophysiological states of tissues.In this study,we propose a new method for shear wave elastography(SWE)based on laser-excited shear wave,called photoacoustic shear wave elastography(PASWE),which combines photoacoustic(PA)technology with ultrafast ultrasound imaging.By using a focused laser to excite shear waves and ultrafast ultrasonic imaging for detection,high-frequency excitation of shear waves and noncontact elastic imaging can be realized.The laser can stimulate the tissue with the light absorption characteristic to produce the thermal expansion,thus producing the shear wave.The frequency of shear wave induced by laser is higher and the frequency band is wider.By tracking the propagation of shear wave,Young’s modulus of tissue is reconstructed in the whole shear wave propagation region to further evaluate the elastic information of tissue.The feasibility of the method is verified by experiments.Compared with the experimental results of supersonic shear imaging(SSI),it is proved that the method can be used for quantitative elastic imaging of the phantoms.In addition,compared with the SSI method,this method can realize the noncontact excitation of the shear wave,and the frequency of the shear wave excited by the laser is higher than that of the acoustic radiation force(ARF),so the spatial resolution is higher.Compared to the traditional PA elastic imaging method,this method can obtain a larger imaging depth under the premise of ensuring the imaging resolution,and it has potential application value in the clinical diagnosis of diseases requiring noncontact quantitative elasticity.

不同弹性模量计算机辅助设计和计算机辅助制造桩核材料的应力分析

背景:桩核修复是牙体缺损修复的一种常规选择,然而不同桩核材料的修复效果存在差异。目的:利用有限元方法评估不同弹性模量桩核修复模型中桩核与牙根黏结剂部位的应力分布情况。方法:在三维建模软件中构建一个三维根管治疗过的上颌中切牙模型,进行全瓷冠修复,修复中的桩核材料分别使用纳米陶瓷树脂(弹性模量12.8 GPa)、复合树脂(弹性模量16 GPa)、混合陶瓷(弹性模量34.7 GPa)、玻璃陶瓷(弹性模量95 GPa)、钛合金(弹性模量112 GPa)和氧化锆(弹性模量209.3 GPa),将模型约束在皮质骨中,在中切牙牙冠舌侧1/3处加载与牙体长轴呈45°的100 N集中力,通过最大主应力分析修复模型中桩核、牙本质及桩与牙根黏结剂的应力分布。结果与结论:(1)当使用弹性模量较高的桩核材料时,修复模型中的桩核应力较集中;当使用弹性模量接近牙本质的桩核材料(纳米陶瓷树脂和复合树脂)时,桩核的应力分布较均匀;无论桩核材料如何,各修复模型中牙本质上的应力分布相似;使用弹性模量更高的桩核时,修复模型中桩与牙根黏结剂处显示出更多的应力集中。(2)纳米陶瓷树脂模型中桩核、牙根及桩与牙根黏结剂处的最大应力值分别为31.00,33.21,0.51 MPa,复合树脂模型中桩核、牙根及桩与牙根黏结剂处的最大应力值分别为36.84,33.14,0.59 MPa,混合陶瓷模型中桩核、牙根及桩与牙根黏结剂处的最大应力值分别为64.05,32.83,1.00 MPa,玻璃陶瓷模型中桩核、牙根及桩与牙根黏结剂处的最大应力值分别为112.30,32.69,1.73 MPa,钛合金模型中桩核、牙根及桩与牙根黏结剂处的最大应力值分别为120.00,32.17,1.86 MPa,氧化锆模型中桩核、牙根及桩与牙根黏结剂处的最大应力值分别为148.80,31.85,2.28 MPa。(3)桩核材料的弹性模量越高,进行桩核修复时桩核处的最大应力值越大,桩核材料弹性模量对修复模型中桩与牙根黏结剂处与牙本质的最大应力值无明显影响。

河北及周边地区岩石圈磁场变化模值的分析

为更好地开展地磁异常变化与地震的关系,通过对河北及周边地区2017—2021年流动地磁矢量资料,采用模值量化的计算方法,研究发生在测区范围内震级M_(L)≥4.0地震震中位置变化模值的分布特征。结果表明:H模和F模的图像分布形态极为相似。测区主要异常形态与测区地质构造对岩石圈磁场变化的控制作用不强。测区岩石圈磁场时间变化总体稳定,局部地区存在起伏波动变化。80%的震例均发生在H模和F模的低值区,且震中模值与模值测区均值的比值ρ的取值集中在0.2~0.9区间范围内,M_(L)和ρ不具备线性相关性。将标准模作为研究地区模值异常的参考阈值,得到H模和F模的参考异常阈值分别为3.10和3.54。采用改进的R值评估方法,得到基于模值测区均值的R为0.3。可见,基于模值异常的地震预测水平还很低,流动地磁的异常研判工作仍处于探索阶段。

实时剪切波弹性成像技术在深静脉血栓中的临床应用进展

近年来发现实时剪切波弹性成像(SWE)可以通过测得杨氏模量值,为诊断提供定性和定量信息。它具有安全、实时、低成本的特点,在肝纤维化、甲状腺和乳腺结节的诊断中取得了较好的临床应用,但在深静脉血栓(DVT)形成的临床分期方面的临床研究较少。因此,本文系统综述实时SWE在DVT中的应用进展,以期指导DVT分期的临床诊断和治疗。

C-TIRADS联合STE对C-TIRADS 4类结节良恶性的诊断价值

目的 分析C-TIRADS分类联合声触弹性成像(sound touch elastography,STE)在C-TIRADS 4类结节良恶性中的诊断价值。方法 回顾性分析2023年2—8月在本院行甲状腺细针穿刺活检(FNA)或手术的302例患者的临床资料(共309个C-TIRADS 4类结节)。用STE、C-TIRADS分类、C-TIRADS分类联合STE中“壳”参数(即校正C-TIRADS分类)分别对结节进行良恶性鉴别,以细胞或者术后病理诊断结果为准,采用Kappa一致性检验和绘制受试者工作特征曲线(receiver operating characteristic,ROC)并计算曲线下面积(area under curve,AUC),比较STE、C-TIRADS分类、校正C-TIRADS对C-TIRADS 4类结节良恶性的诊断效能。结果 病理结果显示,309个结节中93个为良性结节,216个为恶性结节。病理结果和C-TIRADS分类诊断结果的Kappa系数为0.488(P<0.05);病理结果和STE诊断结果的Kappa系数为0.479(P<0.05);病理结果和校正C-TIRADS诊断结果的Kappa系数为0.704(P<0.05)。ROC曲线结果显示,C-TIRADS分类诊断的AUC为0.709,敏感度、特异度及准确率分别为97.70%、44.10%和81.55%;STE诊断AUC为0.769,敏感度、特异度及准确率分别为73.10%、80.60%和75.51%;校正C-TIRADS分类诊断AUC为0.848,敏感度、特异度及准确率分别为92.10%、77.40%和72.64%。结论 C-TIRADS分类联合STE较单独使用STE、C-TIRADS分类在C-TIRADS 4类结节性质有更好的诊断价值,值得临床推广。

超声剪切波弹性成像结合血浆NRG4水平评估慢性乙型肝炎肝纤维化程度的价值

目的探究超声剪切波弹性成像(SWE)联合血浆神经调节蛋白4(NRG4)水平评估慢性乙型肝炎(CHB)肝纤维化程度的价值。方法2020年6月—2022年6月雅安市人民医院接诊的CHB肝纤维化患者116例,均进行肝脏穿刺病理活检,采用超声SWE检测肝脏杨氏模量值,Elisa法检测血浆NRG4水平。分析肝脏杨氏模量值及血浆NRG4水平与肝纤维化程度的相关性。绘制受试者工作特征曲线(ROC),并采用曲线下面积(AUC)评估杨氏模量值联合血浆NRG4水平对CHB肝纤维化程度的诊断效能。结果116例CHB肝纤维化患者中F1期33例(28.4%)、F2期38例(32.8%)、F3期26例(22.4%)、F4期19例(16.4%)。F1期、F2期、F3期、F4期患者的杨氏模量值分别为[(5.2±1.3)kPa、(6.3±1.2)kPa、(8.7±1.4)kPa、(11.9±1.6)kPa,P<0.05];F1期、F2期、F3期、F4期患者的血浆NRG4水平分别为(6.7±1.2)、(4.9±1.0)、(3.3±0.9)、(1.9±0.5)pg/mL(P<0.05)。Spearman相关性分析结果显示,杨氏模量值与肝纤维化程度呈正相关(r=0.673,P<0.05);血浆NRG4水平与肝纤维化程度呈负相关(r=-0.702,P<0.05)。ROC分析结果显示,杨氏模量值对CHB肝纤维化患者F1期、F2期、F3期及F4期诊断的AUC分别为0.85(95%CI:0.75~0.94)、0.83(95%CI:0.75~0.92)、0.86(95%CI:0.76~0.95)、0.92(95%CI:0.82~1.00)。血浆NRG4水平对CHB肝纤维化患者F1期、F2期、F3期及F4期诊断的AUC分别为0.86(95%CI:0.76~0.95)、0.82(95%CI:0.74~0.91)、0.88(95%CI:0.80~0.97)、0.92(95%CI:0.82~1.00)。杨氏模量值联合血浆NRG4水平对CHB肝纤维化患者F1期、F2期、F3期及F4期诊断的AUC分别为0.92(95%CI:0.84~0.99)、0.92(95%CI:0.85~0.98)、0.94(95%CI:0.88~1.00)、0.97(95%CI:0.91~1.00),杨氏模量值联合血浆NRG4诊断肝纤维化不同分期的AUC高于二者单一诊断(P<0.05)。结论杨氏模量值和血浆NRG4水平对CHB肝纤维化程度的诊断效果良好,且联合诊断价值更高。

基于连续检测的高速铁路路基压实质量控制方法

针对传统检测方法无法满足路基压实质量实时、全面控制要求的问题,开展了高速铁路路基碾压足尺模型连续检测试验,分析了路基压实过程中振动轮振动能量变化规律,建立了能量压实值与动态变形模量、地基系数和压实度的相关关系,对基于连续检测的路基压实程度、压实稳定性和压实均匀性进行分析。结果表明:振动轮振动能量随碾压遍数增大而增大,能量压实值与常规检测指标具有强相关性,可以作为高速铁路路基压实质量连续检测指标;采用考虑90%置信水平预测区间下限的压实质量连续控制值判断路基压实程度更符合路基实际压实状态;碾压区域内能量压实值平均增长率应小于2%,出现过压现象时应停止碾压;碾压结束后,各检测单元能量压实值应在碾压区域平均能量压实值的80%~120%范围内。

超声SWE联合MRI对非肿块型乳腺癌的诊断价值分析

目的分析超声实时剪切波弹性成像(shearwave elastography,SWE)联合MRI诊断非肿块型乳腺癌的临床价值。方法收集2021年8月至2023年12月108例非肿块型乳腺病变患者,根据病理结果分为恶性组33例和非恶性组75例。比较2组一般资料及超声SWE定量参数,分析超声SWE联合MRI对非肿块型乳腺癌的诊断价值。结果恶性组病灶弹性模量最大值、弹性模量最小值、弹性模量平均值及与周围组织弹性模量比值均较良性组大(P<0.01)。受试者工作特征曲线分析结果显示,超声SWE与MRI联合诊断非肿块型乳腺癌的曲线下面积、敏感度均较单独诊断高(P<0.01)。结论超声SWE联合MRI有利于提高对非肿块型乳腺癌的诊断敏感度,具有较好的诊断价值。

Value of elastography point quantification in improving the diagnostic accuracy of early diabetic kidney disease

BACKGROUND Diabetic kidney disease(DKD)is a common complication of diabetes.The patient’s prognosis is poor once DKD progresses to advanced stage.Accurate diagnosis and timely treatment of early DKD are important for improving patient’s prognosis and reducing mortality.AIM To explore the value of elastography point quantification(ElastPQ)in improving the accuracy of early DKD diagnosis.METHODS A total of 69 patients with type 2 diabetes were recruited from Naval Military Medical University Affiliated Gongli Hospital.Patients were divided into early DKD group and medium DKD group according to pathological results and urinary albumin excretion rate(UAER).Another 40 patients with simple diabetes were included as the diabetes group.The baseline data,laboratory diagnostic indicators,and ultrasound indicators for each patient were recorded.The differences of the indicators in the three groups were compared.Multivariate logistic regression was used to analyze the influencing factors of the development from simple diabetes into early DKD and from early DKD into medium DKD.Receiver operating characteristic analyses of potential indicators in identifying early DKD and medium DKD,and early DKD and simple diabetes were established.RESULTS Multivariate logistic regression analysis showed that UAER(P<0.001),renocortical Young's Modulus(YM)(P<0.001),and renal parenchymal thickness(P=0.013)were the independent influencing factors of the development from early DKD into medium DKD.Diabetes duration(P=0.041),UAER(P=0.034),and renocortical YM(P=0.017)were the independent influencing factors of the development from simple diabetes into early DKD.Receiver operating characteristic analysis indicated that UAER,renocortical YM,and renal parenchymal thickness were accurate in identifying early DKD and medium DKD[all area under curve(AUC)>0.9].The accuracy of UAER(AUC=0.744),diabetes duration(AUC=0.757),and renocortical YM(AUC=0.782)for the diagnosis of early DKD and simple diabetes were limited.However,the combined diagnosis of UAER,diabetes duration,and renocortical YM was accurate in identifying early DKD and simple diabetes(AUC=0.906),which was significantly higher than any of the three indicators(all P<0.05).CONCLUSION ElastPQ is of great value in the diagnosis of early DKD.When combined with the diabetes duration and UAER,it is expected to diagnose accurately early DKD.

Modulus-Based Matrix Splitting Iteration Methods for a Class of Stochastic Linear Complementarity Problem

For the expected value formulation of stochastic linear complementarity problem, we establish modulus-based matrix splitting iteration methods. The convergence of the new methods is discussed when the coefficient matrix is a positive definite matrix or a positive semi-definite matrix, respectively. The advantages of the new methods are that they can solve the large scale stochastic linear complementarity problem, and spend less computational time. Numerical results show that the new methods are efficient and suitable for solving the large scale problems.

Preliminary <i>k</i>-Values of Unbound Natural Quartzitic Gravels for Mechanistic-Empirical Pavement Design

The generalized constitutive model relating the resilient modulus (MR) of flexible pavement layer materials to stress state, adopted by the Mechanistic-Empirical Pavement Design Guide (MEPDG), contains a set of constants known as k-values (k1, k2, and k3) which are associated with the physical state of the layer materials. In Ghana, natural gravels constitute the predominant and sometimes the sole layer materials for most flexible pavements yet representative k-values of gravel materials, have not been determined to permit full application and implementation of the mechanistic-empirical design concept to pavements involving such materials. In this study, k-values characterising typical natural quartzitic gravels used for road construction in the country were derived by regression techniques from MR values determined using laboratory repeated load triaxial test. Using multiple linear regression technique, correlation relationships were then developed between the k-values and the physical properties of the gravels, namely, percentages of materials passing the 9.5 mm (P9.5) and 2.0 mm (P2.0) sieves, liquid limit (LL), maximum dry density (ρdmax), and optimum moisture content (wopt). The regression analysis returned k1 values which ranged between 441 and 958 with a mean of 516;k2 which varied between 0.0636 and 0.2168 with a mean value of 0.1216;and, k3 values which ranged between 0.1257 and 3.1590 with a mean value of 1.723. Contrary to what is mostly reported in literature, the analysis returned positive k3 values for all but one gravel material, suggesting stress hardening under octahedral shear stress for those materials. While an expanded sample base is required to fully characterize the whole gamut of natural gravels used in pavement construction in the country, this study on limited quartzitic gravel samples has given a good indication of strong linear correlations between the k-values and the index properties of the gravels, to permit estimates of the constants for such gravels be made where capability and opportunity for conducting resilient modulus tests do not exist.However, further work is recommended to fully characterise the exact nature of k3 values for quartzitic gravels in the country.