针入度误差对老化沥青低温感温性指标的影响

为了验证不同老化程度沥青结合料的针入度测量误差与针入度指数PI和当量脆点T1.2间的关系,选取3种常用重交基质沥青进行TFOT和不同时长的PAV老化,测定不同老化程度沥青结合料在不同温度的针入度,得到针入度温度指数ALgPen、K、针入度指数PI和当量脆点T1.2;通过试验得出:针入度较小的测量误差会引起针入度指数PI和当量脆点T1.2较大的变异,这种变异可以掩盖沥青结合料的老化程度,导致PI和T1.2无法区分不同老化程度沥青结合料的低温抗裂性能.因此,现行规范使用的针入度指数PI和当量脆点T1.2不适合用于评价不同老化程度沥青结合料的低温抗裂性能.     

包装废PE改性沥青旋转薄膜烘箱老化试验

以回收的包装废聚乙烯(PE)代替普通聚合物改性剂,对石油沥青进行改性,并采用旋转薄膜烘箱加热老化试验(RTFOT)对沥青的老化过程进行研究。结果表明,老化后基质沥青与改性沥青的软化点、135℃黏度升高,而针入度降低,其性能变化趋势基本相似,但随着改性剂量的增加,老化幅度变小。改性后分散于沥青中的包装废PE在老化过程中一方面发生自身降解影响沥青体系的性能,另一方面包装废PE通过吸收基质沥青中轻质油分发生溶胀,从而减少了沥青在热老化过程中游离基的产生,降低了由于轻质组分氧化对基质沥青性能的影响,改善了由于其自身老化对沥青体系的影响,最终导致改性后沥青老化性能改善。     

煅烧高岭土对沥青老化性能影响的试验研究

为改善沥青路面路用性能,延长使用寿命,研究煅烧高岭土(CK)改性沥青的抗老化性能。通过旋转薄膜烘箱(RTFOT)、压力老化容器(PAV)、动态剪切流变仪(DSR)和傅里叶红外光谱(FT-IR)分析CK对沥青老化性能的影响以及沥青老化前后的化学官能团变化。结果表明：随着CK掺量的增加,沥青软化点和粘度逐渐升高,针入度和延度有所降低,同时CK使沥青具有较高的复剪切模量,当CK掺量为15%时,抗车辙性能最优;CK显著降低了基质沥青软化点指数(SPI)、粘度指数(VAI)和复剪切模量指数(CMAI),大幅提高了针入度保留率(PRR)和相位角指数(PAI);FT-IR试验表明,CK抑制了基质沥青热氧老化时羰基指数(I_C=O)和亚砜基指数(I_S=O)的产生,从而有效地改善了沥青的抗老化性能。     

热老化作用下石墨烯橡胶复合改性沥青性能研究

为了研究石墨烯橡胶复合改性沥青的老化性能,利用旋转薄膜烘箱(RTFOT)及压力老化箱(PAV)对石墨烯橡胶复合改性沥青试样进行短期老化及长期老化的室内模拟。采用橡胶沥青及基质沥青作为对比试验,将老化前后沥青试样的常规性能和微观性能进行对比分析。试验结果表明:石墨烯橡胶复合改性沥青在不同程度老化后,残留针入度比,软化点差及黏度老化指数相较于橡胶沥青及基质沥青显示出较强的抗老化性能。在微观试验中,石墨烯橡胶复合改性沥青亚砜基指数较小,耐老化性能得到明显改善,在荧光显微镜扫描中,石墨烯的添加在橡胶沥青中形成网状结构,并在老化后相较橡胶沥青较为稳定。     

KSHD温拌剂对新疆岩沥青改性沥青老化动力特性的影响

为探究KSHD温拌剂对新疆岩沥青改性沥青(XRA)老化动力特性的影响,本研究通过短期老化试验及布氏黏度试验,研究了XRA与温拌岩改性沥青表观黏度在不同老化时间和老化温度下的变化规律,并建立了以表观黏度为参数的老化动力学模型,求得老化反应速率常数、活化能等相关参数。结果表明:温拌岩沥青改性沥青(WRA)的表观黏度受老化时间和温度的影响小于XRA;老化温度超过163℃或老化时间超过10h,两种沥青表观黏度由常数增长进入快速增长阶段;对常、快速反应阶段进行独立分析可优化所建立的老化动力学方程,优化后两种沥青表观黏度的预测值与试验值的平均误差在5%以内,且建立的老化动力学方程能够准确地预测老化过程中两种沥青表观黏度值的变化。     

不同改性沥青温度敏感性

为评价不同改性沥青(SBS改性沥青(SMA)、橡胶粉改性沥青(RPMA)、复合改性沥青(CMA))老化前后的温度敏感性,利用动态剪切流变仪对以上3种改性沥青老化前后的试样进行动态剪切流变实验,并取老化前后温度扫描数据利用粘温指数VTS的不同算法在不同温标下对改性沥青的粘度-温度曲线进行拟合,针对不同沥青从线性相关系数的角度分析了各自最适用的温标及算法;在适用的温标下利用粘温指数VTS评价了不同改性沥青老化前后的温度敏感性,并利用电子显微镜扫描实验,从沥青的微观结构特征分析了不同改性沥青温度敏感性存在差异的原因。结果表明,在开式温标及兰金式温标下拟合出的VTS可以更好地评价不同改性沥青的温度敏感性;组分及蜡含量的变化对改性沥青温度敏感性影响最大,胶体结构与大分子分子量的影响次之;老化作用使改性沥青温度敏感性降低,RPMA在老化前后温度敏感性最低。     

硅烷偶联剂修饰高岭土对沥青物理和老化性能的影响

为改善沥青的物理和老化性能,本文采用γ-(2,3环氧丙氧)丙基三甲氧基硅烷(KH560)对高岭土进行了表面修饰,通过熔融共混法分别制备了高岭土和表面修饰高岭土改性沥青,并对其进行了薄膜加热试验(TFOT)和压力老化容器试验(PAV),测试了高岭土和表面修饰高岭土改性沥青老化前后的物理性能,并利用傅里叶变换红外光谱(FTIR)和X射线衍射(XRD)对高岭土和表面修饰高岭土及其改性沥青老化前后的结构进行了表征。FTIR和XRD分析表明,KH560成功接枝到高岭土表面,但未改变高岭土的晶体结构。相比未修饰高岭土,表面修饰高岭土对沥青软化点和黏度的提高幅度更大,对沥青低温延度的不利影响减弱,TFOT和PAV老化对沥青性能的负面影响降低,并有效抑制了沥青老化后羰基指数的增加,显著改善了沥青的抗热氧老化性能。随着表面修饰高岭土掺量的增加,沥青物理性能和抗老化性能的提升越来越明显。     

电位滴定法在沥青研究中的应用及展望

沥青的组成影响沥青路面的性能.环境和荷载使沥青组分的含量和结构发生变化,导致沥青老化、变硬变脆且粘结性降低,从而降低沥青路面的使用寿命.沥青老化分析技术的发展对研究沥青材料的老化、沥青的改性和老化沥青的再生具有重要意义.当前,应用广泛的傅里叶红外光谱法、凝胶渗透色谱法、原子力显微镜法及荧光显微镜法等在沥青的老化研究中均存在一定局限性,因此,发展一种新的研究方法至关重要.电位滴定法利用已知物质的量浓度的滴定剂对待测溶液中未知浓度的物质进行滴定,溶液中离子浓度变化程度的不同导致指示电极电位显示不同的电势.滴定终点前后,待测物质浓度发生明显改变,电位发生突跃,可根据电位突变时滴定剂的消耗量计算待测物质含量.对于给定的化学官能团,电极电位的变化是唯一的,并且与其浓度成比例.在沥青的检测中,该方法测试结果不受温度、沥青黑色背景、液体接界电位等因素的干扰,因此测试结果具有较高的准确性,适用于沥青组分研究.本文综合国内外研究成果,从监控沥青的老化过程及指导老化沥青的再生角度,综述了电位滴定法在沥青酸碱组分检测与分类中的应用、沥青组分与性能的关系、含水量和硫含量以及苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)改性沥青中SBS含量检测方面的研究进展及其它电化学方法在沥青老化前后的物质检测中的研究现状.通过电位滴定法将沥青老化前后组分的变化与沥青的性能及老化沥青再生机理研究相结合,为沥青路面的耐久性研究提供科学依据.     

基于红外光谱的短期老化SBS改性沥青再生微观机理

为探究不同再生剂类型和掺量对短期老化SBS改性沥青再生微观组成的影响,通过旋转薄膜烘箱(RTFOT)对SBS改性沥青进行短期老化,对其添加普通(西卡再生剂)、改性(信拓-3再生剂)两种不同类型以及不同掺量(4%、8%、12%)的再生剂制得再生沥青,同时对不同再生剂进行扩散试验。对原样、短期老化及再生沥青进行了宏观指标(针入度、延度、软化点)和红外光谱(FTIR)分析。结果表明:SBS改性沥青在短期老化过程中软化点升高,亚砜基特征峰和官能团指数增大,丁二烯(CH2=CH2)基特征峰、丁二烯基指数、针入度、延度减小,添加再生剂亚砜基特征峰、官能团指数、软化点减小,针入度、延度增大;普通再生剂在再生SBS改性沥青制备过程中基质沥青的老化及SBS改性剂的降解程度大于改性再生剂;再生剂掺量为8%时,对短期老化SBS改性沥青改善效果明显;再生剂在短期老化SBS改性沥青扩散过程中,改性沥青性能有一定的改善,但未恢复到原来水平,直接搅拌制备的再生SBS改性沥青性能明显优于再生剂在短期老化SBS改性沥青扩散形成的再生SBS改性沥青。     

不同生物油再生沥青性能比选

为确定生物油对老化沥青性能的恢复能力,比选出再生能力较强的一种生物油并确定其最佳掺量,采用植物沥青、餐厨废弃油脂和工业用动物油3种生物油作为再生剂,分别对老化SBS改性沥青进行再生,通过测定生物油再生沥青的针入度、延度、软化点和布氏黏度并进行薄膜加热试验,研究生物油种类和掺量对老化沥青各项性能的影响规律。结果表明,3种生物油对老化SBS改性沥青的基础性能和耐老化性均有一定的恢复能力,其中餐厨废弃油脂对老化沥青再生能力较强,并且社会和经济效益较高,植物沥青和工业用动物油次之;餐厨废弃油脂被选为最佳再生生物油,掺量为4%时能够使老化SBS改性沥青的黏滞性和高温性能得到完全恢复,因此被确定为最佳掺量。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...