聚合物改性沥青混凝土施工温度研究

文章测试了改性沥青和普通沥青的黏-温曲线,研究了成型温度和击实次数对沥青混凝土马歇尔试件孔隙率的影响,随着温度下降,马歇尔试件孔隙率3%所需的击实次数越来越多。当温度小于130℃时,改性沥青混合料的孔隙率很难达到3%以下。在此基础上确定了改性沥青混凝土的碾压温度,并通过摊铺试验进行了验证。     

无砂大孔混凝土配合比的设计与应用

无砂大孔混凝土就是不含砂的混凝土,它由水泥,粗集料和水拌和而成,粗集料可以是碎石也可以是卵石。由于没有细集料,所以其中存在着较大的孔洞,孔洞的大小与粗集料的粒径大致相等。由于这些孔洞的存在,使得无砂大孔混凝土与一般的混凝土具有不同的性能。它具有表观密度小,水泥用量少,热传导系数小,便于运输和简化管理等特点。而且无砂大孔混凝土施工简便,靠自重落料即可成型,不需插捣,对工人技术水平要求不高等优点。     

沥青混凝土路面病害浅析

通过对沥青混凝土路面外观集料不均匀、泛油、剥皮、裂缝和明显离析等现象分析,找出病害原因。     

新型道路复合沥青材料改性剂的选择与配比优化

为了优化沥青路面材料的减振降噪性能,延长路面的使用寿命,对现有沥青材料进行改性优化。选用硅藻土和玄武岩纤维作为改性剂对沥青材料进行复合改性,依据孔隙率、阻尼比、矿料间隙率、吸声系数、流值变形量、马歇尔稳定度、沥青饱和度7个参数确定复合改性沥青材料的配比,制备出硅藻土与玄武岩纤维复合改性沥青材料。分别对硅藻土单掺杂沥青材料、玄武岩纤维单掺杂沥青材料和硅藻土与玄武岩纤维复合改性沥青材料进行了力学特性试验,分析其物理性能,并对不同沥青混合料的减振降噪性能进行了对比测试。结果表明,硅藻土和玄武岩纤维复合掺杂最佳配比：油石质量比为5.5%,玄武岩纤维掺杂比为0.3%,硅藻土掺杂比为7.5%。复合材料的减振降噪性能优于普通沥青材料,与其相比,最优配比下的新型复合材料吸声系数峰值高出38.89%,吸声系数均值高出30.30%。复合改性沥青材料具有良好的减振降噪性能并且具有显著的高温稳定性和低温抗裂性,研究结果可为同质路面材料的进一步优化提供参考,对于提高道路的服务能力具有实际应用价值。     

泡沫沥青冷再生混合料材料设计及其抗车辙性能评价

为研究如何合理利用沥青路面回收材料,通过一系列室内试验设计了泡沫沥青冷再生混合料并评价了其路用性能(抗车辙性能)。混合料设计阶段确定了最佳发泡条件:发泡温度为150~155℃,发泡用水量为3%,膨胀比为16,半衰期为9 s,最佳沥青用量为2.8%,混合料最佳含水量为3.81%。车辙试验数据显示:当空隙率为4.3%时车辙深度为1.63 mm,空隙率为5.0%时车辙深度为2.43 mm,空隙率为6.1%时车辙深度为3.45 mm,即随混合料空隙率的增大,车辙深度逐渐增加且增加趋势显著,表明混合料抗车辙性能逐渐减弱,因此建议泡沫沥青冷再生混合料空隙率设计不超过5.0%,且泡沫沥青冷再生混合料适用于沥青面层结构中的中下面层使用,不适用于上面层使用。研究结果为泡沫沥青冷再生混合料进行路段试验提供了理论参考。     

公路沥青路面施工中应注意的问题

在公路工程中沥青路面是具有良好使用品质的路面结构,所以得到了广泛的运用,在公路工程施工中得到了迅速的发展。为了进一步保证公路施工过程顺利高效的进行,保证公路在投入使用之后能够最大发挥作用,进而以宁(南京)-连(连云港)平原微丘区一级公路为例,其中淮阳市境K78+400～K98+143路段的沥青碎石铺筑时沥青混合料出现比较严重的离析现象,鉴于这个现象,对沥青路面施工中原料的质量控制、沥青混合料拌和、摊铺以及碾压的施工技术措施,同时针对材料的性能和施工过程,提出一些建议,希望可以起到一定的参考作用。     

新疆沥青混凝土心墙坝心墙拱效应影响分析

心墙是沥青混凝土心墙坝的主要防渗屏障,心墙料与过渡料的不均匀沉降导致了心墙拱效应,可能导致心墙产生水平裂缝和水力劈裂.文章基于新疆某沥青混凝土心墙坝施工期和运行期监测资料,分析心墙拱效应在监测资料中的反应及其对心墙变形和渗流的影响,结果表明:施工期,心墙与坝壳料之间的不均匀沉降随填筑高程增加逐渐增大,心墙拱效应增强;蓄...     

风机参数对立体冷库气流组织影响的数值模拟

为使立体冷库温度场更加均匀,研究立体库气流组织不同工况下的变化规律。利用FLUENT软件分别对冷风机送风速度在3.7～15.7 m/s、送风温度在240～248 K以及6种摆放位置下立体库内气流流动与传热过程进行数值模拟,并据此探析立体库气流组织特征分布及冷却性能指标。结果表明,风速对立体冷库性能影响显著,预冷时间随风速增加呈指数减小,温度场分布更均匀,但在冷藏阶段风速过大会造成气流扰动,温度场均匀性降低且能耗骤升;送风温度变化对气流组织分布无显著影响,与冷却速率呈反比关系,增幅基本一致;风机摆放采用主流背向式,气流干扰小且温度场降温均匀。立体冷库风机风速优选12.7 m/s,风温高于冷藏温度2 K,可保证降温速率与降温均匀特性,摆放形式优先采用主流背向式,温度场波动范围为-1～1 K,缩短了冷库在无装载情况下的开机预冷时间。研究结果有利于提高冷库冷却性能和货物冷藏品质,可为立体冷库内气流组织设计方案提供参考。     

基于数字图像处理技术的再生混凝土数值模拟

为了研究骨料形态对再生混凝土材料力学性能的影响,基于势能原理的基面力元法,利用图像处理技术和MATLAB软件,建立了再生混凝土真实骨料细观模型。应用FORTRAN分析软件对再生混凝土试件进行单轴拉伸试验的数值模拟,研究了真实骨料细观模型再生混凝土宏观应力-应变曲线变化规律和试件的破坏形态。结果显示,真实骨料模型得到的宏观应力-应变曲线和试验曲线吻合度较高,骨料形状对试件的破坏形态影响较小。模型可真实地模拟再生混凝土在单轴拉伸作用下的损伤破坏过程,准确地反映试件的实际骨料形态。     

有限元法在热轧辊三维温度场研究中的应用

多功能轧光机的关键技术是轧光辊与热轧辊的设计及制造。针对电热棒加热方式的缺点,采用导热油循环加热方案来解决。分析热轧辊三维温度场,可以进一步改进热轧辊的结构及加热方式,获得更高质量的轧光织物。本文采用大型有限元分析软件ANSYS对热轧辊三维温度场进行分析计算。结果表明:在轧辊端部的温度梯度变化的主要方向仍是沿径向,但还有一些温度梯度沿轴向变化。提高轧辊端部温度分布均匀性是改善热轧辊温度均匀性的关键。     

Divergent patterns of engagement in Internet standardization: Japan,Korea and China

This article analyzes the engagement of Japanese, Korean and Chinese participants in the development of Internet standards at IETF on the basis of four quantitative metrics: attendance, patenting, authorship and leadership. The results are strikingly divergent. Japanese involvement in Internet standardization began early and Japan was, for many years, second only to the U.S. in terms of IETF participation. Though Japanese participation has declined since the early 2000s, Japan remains a major contributor to IETF standardization. Korean involvement in IETF has always been significant, but below the levels of Japan and major European countries. Korean participation in IETF has also declined over the past decade, and has been dominated by one firm, Samsung. Though meaningful Chinese involvement in IETF did not begin until the mid-2000s, it has rapidly expanded in recent years. Today, China is a major player in numerous areas of Internet standardization in terms of three metrics (participation, patenting and leadership), and is rapidly gaining in terms of document authorship as well. Most of China׳s recent IETF involvement can be attributed to Huawei, though other Chinese firms have recently begun to increase their participation in the organization. Thus, contrary to some views that China׳s engagement with standardization is primarily one of indigenous innovation and “catching up”, China׳s experience with IETF demonstrates deliberate and effective engagement with a major Western standards-development organization on its own terms.     

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.     

Whose Image is it Anyway?: Some Considerations of the Curricular Importance of Subject Image in Secondary School Design and Technology Education

This paper explores the idea that a sense of school subject image is a necessary feature of curriculum management and a potent force for change. The discussion centres on the view that all school subjects have an image and that if those intimately involved with the subject do not control the image then someone else does! In such circumstances the image is the product of past encounters and old euphemisms and is unlikely to hold the changed realities.The UK developments in Design and Technology education (the term Design and Technology is used to denote the school subject defined under this heading by the UK National Curriculum, 1995) have created something of an image problem which has interesting international parallels. Some of these problems are due to clearly discernible internal tensions and an ambiguous relationship with other subject areas.Through greater attention to subject image internal controversies might be acknowledged and resolved, relationships with other subject areas can be more meaningfully understood and practitioners can be helped to make sense of curriculum change.     

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.     

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.     

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.

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。     

蒸汽热量计量应用的探析

研究了石油化工企业的燕汽计量情况,着重对蒸汽热量计量的合理性进行了分析,阐述了蒸汽热量计量的依据及计算方法,以及蒸气热量计量对节能降耗的重要意义.     

论传统旗袍文化与现代时装

中国的旗袍文化蕴含着非常丰富的文化内涵和设计思想,如今旗袍的普及受到一定的限制,只有经过改良,才可变局限性为可行性,才可使旗袍焕发青春,走向新时代。