基于细观模型多孔沥青混合料力学性能与空隙形态关系研究

为合理评价多孔沥青混合料内部细观结构与其性能的关系,应用有限元软件ABAQUS和蒙特卡洛法（Monte Carlo method）,把多孔沥青混合料看作空隙和非空隙组成的二相体,考虑各相组分,建立了单轴压缩试验模拟所需的2D空隙模型,分析多孔沥青混合料的力学性能与其空隙的分布形态的关系,通过比较不同空隙形状的模型,观察其应力应变特性,得到多孔沥青混合料细观结构内部的损伤规律及其受力特点,即随着空隙边数或棱数的减少,变形增大;比较不同空隙直径范围的模型,观察其应力应变特性,得到多孔沥青混合料细观结构内部的损伤规律及其受力特点,即随着空隙直径范围的增大,多孔沥青混合料的变形增大;对比空隙形状、尺寸、空隙率不同的多孔沥青混合料细观模型变形及力学性能,从中得到力学性能较好的空隙模型,即空隙形状为二十边形,空隙直径范围为3～4 mm,空隙率为18%的多孔沥青混合料细观模型。     

基于弯曲试验模式的环氧沥青混合料动态模量

为研究环氧沥青混合料的动态特性,采用弯曲试验模式,测试并分析-15,5,25,45,60℃以及0.1,0.5,1.0,5.0,10.0,20.0 Hz条件下环氧沥青混合料的动态弯曲模量及其应力依赖性,依据时-温等效原理和WLF模型建立了动态弯曲模量主曲线,并与改性沥青SMA进行对比.研究结果表明:环氧沥青混合料动态弯曲模量主要受温度影响,随温度升高而显著减少,-15℃与60℃时相差2个数量级,动态弯曲模量还随频率的增大而增加;动态弯曲模量具有一定的应力依赖性,随应力水平的增大而减小;非线性S形主曲线连续而光滑,可以很好地预测任意温度和频率组合的动态弯曲模量;环氧沥青混合料动态弯曲模量在宽频范围内均大于改性沥青SMA.     

沥青混合料试验检测方法初探

沥青混合料是路桥施工中较为重要的材料,其性能表现对于施工质量有着较大的影响。对沥青混合料进行试验检测可以掌握具体的性能情况,进而针对存在的问题进行处理,并选择更符合施工要求的沥青混合料。文章根据沥青路面的现状,对常见的沥青混合料类型进行分析,再对多种试验检测方法进行探讨,着重对Superpave配合比设计和马歇尔试验之间的区别进行论述,期望能够加强对沥青混合料试验检测方法的了解,并对沥青混合料的试验检测予以足够的重视,促进路桥施工质量的提高。     

冷再生混合料中最佳乳化沥青用量的方法研究

冷拌乳化沥青混合料最佳沥青用量与旧沥青含量有关,通过100%RAP(RAP为再生沥青路面材料,Reclaimed Asphalt Pavement)和0%RAP两种乳化沥青混合料的60℃马歇尔试验、25℃马歇尔试验及25℃劈裂试验,探讨了确定冷拌乳化沥青混合料最佳乳化沥青用量方法的区别与联系.     

金属管高温拉伸试验方法的研究

本文研究了金属管的高温拉伸试验方法，并且建立了辅助设备。     

汽车用金属板材冲击拉伸响应性能的试验研究

介绍了一种在仪器化摆锤冲击试验机上时矩形板材试样实施冲击拉伸并评价材料动态响应特性的宝钢单杆试验方法.基于试验输出的力一位移一能量曲线,探讨了某车用软钢在102/s应变速率水平时的动态强度、塑性与韧性性能.根据摆锤冲击试验直接测量势能变化得到的冲击吸收功,可对动态应力一应变曲线加以确认与标定,提高了强度性能评价尤其是抗拉强度的量值可靠性,而由曲线标识出的断裂点应变亦可通过测量试样的断裂延伸率加以确认.试验表明针对文中选用的材料,加载应变速率由10-3/s提高至102/s并未对材料的强塑配备产生显著影响,即材料的拉伸破断吸收能保持稳定.而3%预应变诱发的形变硬化效应却显著降低了材料在动态载荷条件下的延塑性特征,使材料更易表现出失稳断裂的趋势.     

绝热层结构等效有限元模型的研究及应用

为了简化绝热层的有限元计算模型,提出了等效换热系数的概念,将绝热层和热交换介质的传热过程简化成等效热交换,并由此给出了平壁和圆筒壁传热的等效换热系数计算公式。该方法不仅极大地简化了热力学中的有限元模型,而且顺利解决了一些由于模型过大导致的问题。仿真结果表明:该方法准确可信,将其应用于鼓风站管道的有限元计算中,取得了令人满意的结果。     

高钛重矿渣作为集料用于沥青混合料的可行性分析研究

以攀西地区高钛重矿渣为研究对象,通过理论及试验研究分析了其作为集料用于沥青混合料的可行性,并与目前沥青混合料常用的玄武岩等天然石料进行了对比分析。研究结果表明：高钛重矿渣表观形貌呈粗糙多孔状且为碱性集料,与沥青黏附性能优于天然石料,粘附性等级为5级;高钛重矿渣为五元渣系,属低钙富钛渣、低活性渣,体积稳定性及高温稳定性好;高钛重矿渣具有优异的颗粒形态特性且力学性能、耐久性能良好,但密度略低于天然石料且吸水率更高;高钛重矿渣作为沥青混合料集料的综合性能不低于天然石料,且具有明显的环境、经济效益。     

研究分析金属材料拉伸试验检测结果的影响因素

在检测与评定金属材料的产品质量时,拉伸试验的应用最为广泛.但是实际试验中,对拉伸试验结果造成影响的因素颇多,对各种影响因素进行明确,并具体分析,然后以分析结果为依据进行相关实验操作规程的制定,确保试验结果真实性、精确性尤为重要.本文通过对实际拉伸试验中遇到的影响因素研究分析,旨在为相关工作研究提供参考.     

国产环氧沥青混合料施T控制与强度增长特性

通过室内试验研究了国产环氧沥青混合料在低温环境条件下的施工和易性、容留时间范围,以及强度增长规律等施工控制特性.选取芯样空隙率和试件马歇尔稳定度作为评价施工质量的性能指标;通过轮碾试验模拟实际施工过程中的碾压成型过程;选择马歇尔试验和布氏粘度试验研究强度增长特性.试验结果表明:国产环氧沥青混合料可以在10℃的低温环境条件下进行施工;混合料在120℃的容留温度条件下最长容留时间达到70min;在国产环氧沥青混合料完全固化以前,混合料强度随着时间和温度的增长而不断增长.最后,用有机化学理论分析了国产环氧沥青混合料强度增长规律的理论依据.     

热轧张力观测器模型的研究与构建

张力观测器模型是微张力控制模型实现的基础,本文提供了一种精确的热轧机架间微张力预报的方法。采用新张力计算模型,结合轧制过程中轧制力臂变化,基于以弹性变形理论为基础的张力方程,设计出张力动态变化的计算方法,由此构建新的热轧微张力控制过程的张力观测器,在生产应用中取得了良好的效果。     

A finite mixture model of growth trajectories of adolescent alcohol use: Predictors and consequences.

[Correction Notice: An erratum for this article was reported in Vol 71(1) of Journal of Consulting and Clinical Psychology (see record 2007-16894-001). On p. 979 of this article, there was an error in the formula presented in Footnote 1. This erratum provides the correct formula.] The current study sought to identify classes of growth trajectories of adolescent alcohol use and to examine the predictors and outcomes associated with the classes. Alcohol use was assessed from Grades 7 to 12 in a school-based sample. Latent growth mixture modeling was used, and results indicated 5 discrete longitudinal drinking patterns. The 2 most common drinking patterns included occasional very light drinking from Grades 7 to 12 and moderate escalation in both quantity and frequency of alcohol use. One group drank infrequently but at high levels throughout the study period. Another group exhibited rapid escalation in both quantity and frequency. The final group started at high levels of frequency and quantity in Grade 7 and showed rapid de-escalation in frequency. Emotional distress and risk taking distinguished the classes, and all classes, particularly rapid escalators, showed elevated levels of alcohol-related problems relative to occasional very light drinkers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

DP980钢的动态力学性能及本构模型构建

随着汽车轻量化事业的不断推进,先进高强DP钢得到了快速的发展和应用.而汽车碰撞过程安全性的模拟仿真,对DP钢提出了动态力学性能数据的迫切需求.利用万能拉伸试验机和高速拉伸试验机系统研究了高强度DP980钢不同应变速率下的力学性能,构建并修正了基于JC模型的动态本构数学模型,并进行了模型计算结果与试验数据的对比分析.试验...     

偏心搅拌混合特性水模试验研究

基于国内外KR搅拌脱硫混合特性的理论成果,提出一种偏心搅拌脱硫新工艺,完成了常规四叶搅拌器与相同叶片结构的WG-3Y搅拌器的偏心搅拌水模试验。试验结果表明,在合理的偏心距和搅拌器潜入深度条件下,偏心搅拌具有明显地改善搅拌混合性能的效果,与常规四叶搅拌器相比,WG-3Y搅拌器的搅拌混合性能更优,偏心距影响程度更大。     

KR搅拌脱硫传输动力学水模实验研究及进展

综述了国内外KR搅拌脱硫流动状态与混合特性的理论及水模实验研究结果,探明了改善KR搅拌脱硫混合效果的主要手段和其局域卷吸混合分散特性;通过介绍国内外改善KR搅拌脱硫动力学条件的水模实验方法、研究结果与实践效果,分析了改善KR搅拌脱硫动力学条件的有效措施,证明了水模实验结果对实际生产的推动作用。     

Viscosity measurement of mould fluxes using inclined plane test and development of mathematical model

Abstract

During the current research and development activities at Tata Steel Teesside Technology Centre, UK, the inclined plane test (IPT) is adopted as a quick method to measure the viscosity/fluidity of mould powders being used currently for continuous casting of different steel qualities and section sizes. The usefulness of the IPT method was also validated by comparing the viscosities that were measured by a high temperature viscometer. It has been established that the IPT measured viscosity values are comparable with the mould powder supplier’s data. The IPT ribbon lengths of different powders have been correlated with the viscosities using an Arrhenius type relationship. The ribbon lengths of the solidified fluxes were found to have a good correlation with the molar ratios of the corresponding powders. Hence, the relationship was further tuned to develop a viscosity prediction model using the chemical compositions of the mould fluxes (i.e. the model can be used for a quick assessment of mould flux viscosity based on its chemical composition).     

"A finite mixture model of growth trajectories of adolescent alcohol use: Predictors and consequences": Correction to Colder et al. (2002).

Reports an error in "A finite mixture model of growth trajectories of adolescent alcohol use: Predictors and consequences" by Craig R. Colder, Richard T. Campbell, Erin Ruel, Jean L. Richardson and Brian R. Flay (Journal of Consulting and Clinical Psychology, 2002[Aug], Vol 70[4], 976-985). On p. 979 of this article, there was an error in the formula presented in Footnote 1. This erratum provides the correct formula. (The following abstract of the original article appeared in record 2002-17393-012.) The current study sought to identify classes of growth trajectories of adolescent alcohol use and to examine the predictors and outcomes associated with the classes. Alcohol use was assessed from Grades 7 to 12 in a school-based sample. Latent growth mixture modeling was used, and results indicated 5 discrete longitudinal drinking patterns. The 2 most common drinking patterns included occasional very light drinking from Grades 7 to 12 and moderate escalation in both quantity and frequency of alcohol use. One group drank infrequently but at high levels throughout the study period. Another group exhibited rapid escalation in both quantity and frequency. The final group started at high levels of frequency and quantity in Grade 7 and showed rapid de-escalation in frequency. Emotional distress and risk taking distinguished the classes, and all classes, particularly rapid escalators, showed elevated levels of alcohol-related problems relative to occasional very light drinkers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development and test of a model linking safety-specific transformational leadership and occupational safety.

The authors developed, tested, and replicated a model in which safety-specific transformational leadership predicted occupational injuries in 2 separate studies. Data from 174 restaurant workers (M age=26.75 years, range=15-64) were analyzed using structural equation modeling (LISREL 8; K. G. J?reskog & D. S?rbom, 1993) and provided strong support for a model whereby safety-specific transformational leadership predicted occupational injuries through the effects of perceived safety climate, safety consciousness, and safety-related events. Study 2 replicated and extended this model with data from 164 young workers from diverse jobs (M age=19.54 years, range=14-24). Safety-specific transformational leadership and role overload were related to occupational injuries through the effects of perceived safety climate, safety consciousness, and safety-related events. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Data mining in a behavioral test detects early symptoms in a model of amyotrophic lateral sclerosis.

"What's wrong with my genetically engineered animal?" is a common yet often difficult to answer question in behavioral phenotyping. We present here a method termed Pattern Array for mining movement patterns and isolating those that best capture an effect of a genetic manipulation. We demonstrate the method by searching for early motor symptoms in the open-field behavior of SOD1 mutant rats, an animal model of amyotrophic lateral sclerosis. Pattern Array was able to identify a unique motor pattern that differentiated the SOD1 mutants from the wild-type controls 2 months before disease onset. This pattern included heavy braking while moving near the arena wall but turning away from it. SOD1 mutants performed this pattern significantly less than wild-type controls in 2 independent data sets. At such early age the SOD1 mutants could not be differentiated from the controls by standard behavioral measures or by subjective observation. The early discovered symptom may enable investigators to test therapies aimed for intervention rather than remediation. Our results demonstrate the feasibility and potential of detecting subtle behavioral effects using data mining strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)