二次纤维水泥土力学特性研究

为弥补水泥土材料受压破坏后承载能力迅速衰减的缺陷,借鉴纤维改善水泥基材料性能的方法,以废纸降解获得二次纤维制成的二次纤维水泥土为研究对象,通过无侧限抗压试验分析其抗压强度、变形特征和破坏形态,提出考虑纤维掺量的应力-应变关系,探索水泥土改良新措施及废纸资源利用新途径。结果表明,1)养护28 d时,同样产生1.42%应变时,水泥土强度下降39%,而掺量为2%的二次纤维水泥土强度下降仅为27%,掺入2%二次纤维不仅可以提高水泥土强度0.42%,也可使水泥土达到峰值应力时产生的应变延后1.82%;2)纤维掺量存在一个阈值,当掺量高于阈值时纤维水泥土强度随养护时间的增加而降低,当掺量低于阈值时变化规律则相反;3)掺入2%和4%的二次纤维使水泥土由中部劈裂破坏转变为土体典型的剪切破坏,破坏时保留了水泥土产生裂纹较少,无明显挤压变形等优点。添加二次纤维可以在保持强度的同时减少水泥土工程缺陷,研究结果丰富了纤维水泥土理论,可为水泥土工程应用及基础研究提供参考。     

不同胶凝掺量对高聚物堆石料力学特性的影响研究

研究高聚物堆石料力学特性,有助于构建适用于该材料的合理本构模型,能较为准确地预测其应用工程结构的应力变形结果。在定性总结了高聚物堆石料力学特性的基础上,建立了考虑聚氨酯掺量与围压影响的峰值强度、变形模量,探索了线性表达式对高聚物堆石料破坏应变与围压关系的适用性,为构建合理的高聚物堆石料本构模型提供了重要的理论参考。     

胶凝砂砾石料修正应变预测模型研究

应变预测模型能反应胶凝掺量60kg/m~3胶凝砂砾石料应力变形特性的数学模型。文章对不同胶凝掺量的胶凝砂砾石料力学特性进行归纳总结,修正了胶凝砂砾石料应变预测模型,对比分析了修正应变预测模型的计算值与试验结果的吻合度,研究表明:修正应变预测模型能很好地用于模拟不同胶凝掺量的胶凝砂砾石料应力变形结果。     

铝硅镀层22 MnB5高强钢高温拉伸性能及本构模型

为了分析和表征热成形用的铝硅镀层22MnB5高强钢的热变形行为,采用Gleeble-3800热模拟试验机,在成形温度750～900℃、应变速率0.1～10 s~(-1)试验条件下实施了铝硅镀层22MnB5高强钢的板材等温拉伸试验,采用双曲正弦型Arrhenius本构模型描述铝硅镀层22MnB5高强钢的高温流变行为,并考虑应变影响构建了模型。结果表明:1)铝硅镀层22MnB5高强钢的真应力随成形温度的升高而降低,随应变速率的增大而升高,在高温低应变速率条件下(900℃,0.1 s~(-1)),峰值应力为134.24 MPa;在低温高应变速率条件下(750℃,10 s~(-1)),峰值应力为381.25 MPa; 2)本构模型预测值与等温拉伸试验值线性拟合的相关系数R~2为0.978,表明构建的本构模型在整个应变范围具有良好的预测精度。研究成果能够准确表征铝硅镀层22MnB5高强钢的热变形行为,为其数值模拟提供材料模型数据支持,并为其热加工工艺研究提供了参考。     

植物纤维复合包装材料缓冲性能模型研究

根据农作物秸秆纤维复合材料静、动态测试数据，对该材料的缓冲性能进行分析；利用S—F本构关系框架，考虑到材料密度、形状函数、应变及应变率等影响因素，建立了复合包装材料的静态压缩本构模型和非线性动态压缩本构模型；并利用实验数据成功识别模型参数。结果表明，该本构模型和实验数据有很高的一致性，为解决农作物秸秆缓冲包装材料的缓冲包装设计、深入研究其缓冲性能、进一步开发利用农作物秸秆提供了重要的理论依据。     

大伙房水库护坡土壤渗透影响因素研究

文章以大伙房水库护坡土为研究对象,通过室内渗透试验、压汞试验研究了龄期、水泥掺量、固化剂掺量等三种因素对土壤渗透性的变化规律及渗透系数与中孔、大孔孔隙率之间的关系进行了回归分析,结果表明:龄期、固化剂掺量和水泥掺量等因素能够使土壤的渗透系数降低一个数量级,其中土壤内部中孔隙数量减少,微孔隙、极微孔隙数量增多;养护龄期由7d到28d时,水化反应趋于稳定;固化剂掺量为3%,水泥掺量为12%时,土壤内部中、大孔隙数量较少;并得出了渗透系数与中孔、大孔孔隙率之间的回归方程,对大伙房水库的渗流安全评价具有实际意义。     

软岩非线性蠕变行为的西原模型改进

为了有效控制地下工程中围岩失稳现象的发生,在描述软岩非线性蠕变行为的基础上,借鉴元件模型的建模方式,将分数阶软体元件替代传统西原模型Kelvin体中的黏滞体,得到基于分数阶微积分的定常蠕变本构模型。引入非线性黏滞系数表达式来改进模型黏弹性部分,通过损伤力学理论描述岩石黏塑性应变,得到一个新的非线性四元件蠕变本构模型。通过所建模型辨识冻结软岩、片岩和泥岩的蠕变试验数据,采用Levenberg-Marqud算法求解模型参数,对比分析试验数据和辨识曲线。结果表明,所建模型对于研究软岩非线性蠕变行为是可行的,具有较好的适用性。在分数阶微积分的基础上通过损伤力学理论描述岩石黏塑性应变,得到的非线性四元件蠕变本构模型可为进一步研究软岩非线性蠕变行为提供参考。     

基坑开挖对邻近箱涵影响的数值模拟

结合复旦大学站基坑开挖工程,应用PLAXIS软件建立基坑与箱涵的数值分析模型,选用能考虑土的小应变特性的硬化土本构模型(HSS模型),分析了加固坑底、设回灌井、削弱箱涵壁厚等几种情况对邻近箱涵的变形发展规律的影响。结果表明:为避免基坑开挖导致箱涵产生过大变形,有必要采用坑底加固、设回灌井等措施。     

冻融作用下水泥改良粉砂土的三轴加载试验

针对冻融作用对民用建筑基础土体力学特性的影响问题,以沈阳某在建民用建筑项目为工程背景,采用水泥作为改良材料,对该项目粉砂土进行不同水泥掺量、不同冻融循环次数下的三轴加载试验,结果表明:随着水泥掺量的逐渐增大,水泥改良粉砂土的偏应力峰值强度、峰值应变和静弹模量均呈逐渐增大趋势;随着冻融循环次数的逐渐递增,水泥改良粉砂土的偏应力峰值强度、峰值应变和静弹模量均呈逐渐减小趋势。     

堤防土体材料增湿变形及持水特性试验研究

针对堤防土体材料的增湿变形与持水特性开展试验研究,设计了不同竖向压应力、不同干密度的常规压缩、土柱筒测试方法。研究得到了土样压缩过程孔隙比变化特征,分析了孔隙比与干密度、测试方法之间影响关系;土体压缩变形特征参数均与干密度呈负相关,分析了两种实验方法之间的差异性;获得了土体材料增湿变形特征,受竖向压应力与干密度影响特性;分析了土样入渗过程持水特征,增湿应变与基质吸力、含水量之间变化关系。文章为研究水利工程中土体材料增湿变形特性以及持水特性提供一定参考。     

Comparing FTTH access networks based on P2P and PMP fibre topologies

There is an ongoing discussion in the market which Next Generation Access (NGA) architecture best suits future needs and which investment and cost differences exist. The discussion can be subsumed as P2P vs. GPON, which is somewhat misleading as this article reveals. The discussion is driven by the fact that the high capital cost and the long asset life time of fibre mean that the technology choices made today will dominate the opportunities for telecommunication business of all market players, incumbents, competitors, content providers and business and residential users for many years in the future.The paper analyzes the cost and other differences between Fibre-to-the-Home (FTTH) access network architectures and their related different wholesale approaches by using the well-known and understood steady state approach applied in other NGA analyses in the past. In addition to the steady state analysis a dynamic cost evaluation is included taking into account the different investment behaviour of the FTTH architectures over time. The results describe investment and cost differences between architectures, incumbents and wholesale based competitive operators. The analysis has been performed for different geotypes (clusters) of decreasing population density in a representative European settlement structure.     

Indigenous peoples’ nutrition transition in a right to food perspective

In indigenous communities the nutrition transition characterized by a rapid westernization of diet and lifestyle is associated with rising prevalence of chronic disease. Field work and literature reviews from two different policy environments, Argentina (Jujuy) and Canada (Nunavut), identified factors that add to indigenous peoples’ disease risk. The analytical framework was the emerging human right to adequate food approach to policies and programmes. Indigenous peoples’ chronic disease risk tends to increase as a result of government policies that infringe on indigenous peoples’ livelihoods and territories, undermining their economic system, values and solidarity networks. Policies intended to increase food security, including food aid, may also fuel the nutrition transition. There is a need to explore further the connection between well-intended policies towards indigenous peoples and the development of chronic diseases, and to broaden the understanding of the role that different forms of discrimination play in the westernization of their lifestyles, values and food habits. Food policies that take due account of indigenous peoples’ human rights, including their right to enjoy their culture, may counteract the growth of chronic disease in these communities.     

A strategic skill based model of supplier integration and its effect on supply management performance

Supplier integration is a tool to help organizations gain competitive advantage. Strategic supply management skills and the supply management function's perceived status are hypothesized as antecedents to supplier integration leading to supply management performance. The sample for this study includes 152 executive level supply management professionals. The empirical results suggest that strategic skills and perceived status are essential antecedents to supplier integration and subsequent performance. Further, the relationship between strategic skills and performance is mediated by supplier integration. Results of a dominance analysis also suggest which strategic skills are most likely to explain status integration, and performance. These findings have significant implications for supply management theory and practice.     

Collectivism,individualism, and outgroup cooperation in a segmented China

A consistent theme in cross-cultural management research is that collectivists are more cooperative than individualists. We use Hofstede's measure for individualism–collectivism and combine it with an experimental measure of cooperation to test this relationship in China. In contrast to the established paradigm, we find that groups with higher individualistic scores are more cooperative than those groups with higher collectivistic scores. We attribute these results to groups being composed of outgroup members. In addition, we find that subjects from the more developed coastal area are more individualistic and cooperative than are subjects from inland China.

Cost allocation of WCDMA and wholesale pricing for mVoIP and data services

This study estimates cost-based prices for wholesale voice and data services provided to 3G (WCDMA) MVNOs according to their distinct types. For estimation, 3G MVNOs are classified into different types, and the overall cost of WCDMA facilities are separated into voice and data components based on their subscriber rates, actual traffic rates, as well as efficiency consideration of traffic rates. The study then calculates cost-based wholesale prices of voice and data services for each of the 3G MVNO types. The result of this study shows that a cost-plus pricing scheme can help achieve the policy goals of the regulator, namely, lowering telecommunications tariffs and facilitating the introduction of new convergent-type services, far more effectively than the current retail-minus pricing scheme. The findings of this study may assist firms in developing business models based on 3G networks and telecom regulators in designing policies related to interconnection, mVoIP, prepaid calls, wholesale services, and network neutrality.     

电子产品的电磁兼容性设计

首先介绍电磁兼容性的基本概念与研究领域,然后重点阐述电子产品的电磁兼容性设计与测量。     

SPYRO在烯烃原料生产方案测算中的应用

文章对SPYRO裂解模拟软件在石化企业烯烃生产原料优化方案测算中的应用进行了比较深度的概括分析.结合该软件在上海石化的实际应用,认为在劣质化原油加工份额不断增加的趋势下,SPYRO裂解模拟软件有助于石化企业在烯烃生产原料优化选择、生产计划合理安排、原油加工生产效益比较等方面为企业相关决策者提供有效地帮助.     

施工企业工程项目部的建设浅论

工程项目的一次性决定了工程项目部的一次性，而工程项目成本中心与企业利润中心地位又辱致工程项目部的临时性，在工程项目实践过程中，项目经理部的一次性在实现其功能的过程中可能会产生很多局限和负面影响，故项目部应具有相对的稳定性，在此基础上，本对工程项目部建设实践进行了初步总结并提出了建议。     

面向对象的程序设计

用Ｃ＋ ＋ 语言阐述面向对象程序设计中封装和继承的概念以及在实际中怎样运用这些概念提高程序设计水平。     

European consumer preferences for beef with nutrition and health claims: A multi-country investigation using discrete choice experiments

The European Union (EU) nutrition labelling policy aims to facilitate consumers’ food choice, stimulate innovation and facilitate the circulation of foods bearing claims across countries. However, the beef industry has not fully taken advantage of utilizing nutrition and health claims based on the EU nutrition labelling policy to differentiate beef products in the market. This study investigates consumer preferences for nutrition and health claims on lean beef steak. Two choice experiments were conducted among 2400 beef consumers in four EU countries (Belgium, France, the Netherlands, United and United Kingdom). Multinomial logit and error component models were estimated. Our results generally suggest that consumer valuation of nutritional and health claims varies across countries. In Belgium, the Netherlands and France, nutrition and health claims on saturated fat yielded higher utilities than claims on protein and/or iron, while the opposite was found among consumers in the UK. The results imply that marketing opportunities related to nutrition and health claims on beef are promising, but that different nutritional marketing strategies are necessary within different countries.