钢管混凝土刚性系杆拱桥上部结构施工技术

尼尔森体系钢管混凝土刚性系杆拱桥能提供较大的纵向刚度和良好的动力性能,以满足铁路重载和高速运行的要求。江苏某桥采用先拱后梁和系梁悬臂现浇方法施工,在拱肋拼装、拱肋大节段吊装施工、系梁支架现浇及挂篮悬臂浇筑等工序中采取技术措施,使施工质量满足设计和规范要求。     

变质量力学系统Nidsen方程的形式不变性

力学系统对称性与守恒量的研究在数学、力学、物理学中都具有非常重要的意义。力学系统的对称性与守恒量的近代理论主要有Noether对称性理论和Lie对称性理论。形式不变性是不同于Noether对称性和Lie对称性的一种新的对称性理论。本文研究变质量力学系统Nielsen方程的形式不变性，给出变质量保守力学系统Nielsen方程的形式不变性的定义和判据，研究形式不变性和Noether对称性的关系，并举例说明结果的应用。     

An Architecture of Exception: Transgressing the Everyday – Superflex's Flooded McDonald's

In Flooded McDonald's, a film by Danish artists' collective Superflex, the familiar sight of the fast-food restaurant is replaced by ‘a slowly emerging apocalyptical composition’, as the interior floods, objects are displaced and the retail space fills with water. Jonathan Mosley describes how this destabilised and other disaster-invoked visions of architecture – structures and spaces breaking down – enable us to use our imagination to test the parameters of the everyday.     

Nielsen方程的三重组合梯度表示及其稳定性分析

研究Nielsen方程的三重组合梯度表示以及方程零解稳定性.首先给出4类三重组合梯度系统及其性质.其次,给出完整系统和非完整系统的Nielsen方程转化成三重组合梯度系统的条件;将完整和非完整两类Nielsen方程分别化为三重组合梯度系统并研究方程的零解稳定性.最后,举例验证结果的应用.     

A new theoretical equation for thermal conductivity of two‐phase systems

A new theoretical equation that describes the thermal conductivity of two‐phase composite materials has been proposed. The Cheng‐Vachon equation has been modified by introducing a new parameter named P_{d max}, permitting the new equation to describe the thermal conductivity of composite materials for a wide variety of filler shapes and states of dispersion. The new equation can describe the thermal conductivity of two‐phase materials more accurately than any of the previous equations. Furthermore, this new equation will make it possible to evaluate the dispersion state of the discontinuous phase by measuring the thermal conductivity of the filled polymers or the polymer blends. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1689–1697, 1999     

从含碲金矿中综合回收金、银、碲的试验研究

对河南某含碲金矿石进行了尼尔森重选单因素试验和重选尾矿再浮选试验。在磨矿细度-0.074 mm粒级占60%、给矿浓度25%、离心力强度50g、给矿速度900 g/min条件下获得重选精矿,在磨矿细度-0.074 mm粒级占70%、矿浆pH值为8、捕收剂异戊基黄药用量120 g/t条件下对重选尾矿进行一粗一扫浮选,重选和浮选的合并精矿金、银、碲品位分别为32.88 g/t、39.94 g/t和94.35 g/t,金、银、碲总回收率达到了89.97%、86.48%和81.29%,实现了金、银、碲的有效回收。     

在线Nielsen源的研制

描述如何简单地把标准Ｎｉｅｌｓｅｎ源必建成在线离子源，对它的一些性能进行测试并与标准离子源作了比较，讨论了它们的判别和产生的原因。实验结果表明，两离子源的放电特性无差别，改建后的离子源可考虑用来进行整体靶离子源试验。     

Chetaev型非完整系统Nielsen方程Lie对称性导致的一种守恒量

研究Chetaev型非完整系统Nielsen方程Lie对称性导致的一种守恒量,给出无限小群变换下Chetaev型非完整系统Nielsen方程Lie对称性的确定方程,得到Chetaev型非完整系统Nielsen方程Lie对称性直接导致的一种守恒量及其存在条件,并举例说明结果应用.     

A Systematic and Generalizable Approach to the Heuristic Evaluation of User Interfaces

Heuristic evaluation is one of the most actively used techniques for analyzing usability, as it is quick and inexpensive. This technique is based on following a given set of heuristics, which are typically defined as broad rules of thumb. In this paper, we propose a systematic and generalizable approach to this type of evaluation based on using comprehensive taxonomies as a source for the heuristics. This approach contrasts with other typical approaches, such as following (or adapting) Jakob Nielsen’s heuristics or creating ad hoc heuristics (formally or informally). The usefulness of our approach is investigated in two ways. Firstly, we carry out an actual heuristic evaluation of a mobile app in this manner, which we describe in detail. Secondly, we compare our approach and Nielsen’s. Additionally, we identify some limitations in Nielsen’s heuristics and some inconsistencies between them and established usability models, including Nielsen’s own.     

Assessing economic and demographic factors that influence United States dairy demand

Low-fat dairy products are key components of a healthy diet for all Americans. As the USDA increases its focus on nutrition and healthy eating, it is important to understand the underlying demands for dairy products, both the healthy and the less healthy ones. The consumption of fluid milk products has decreased over the last decade, whereas milk used for manufactured dairy products such as cheese, ice cream, yogurt, and butter, and for use as an ingredient in other food products, has risen. The objective of this study is to determine the effects of changes in demographic variables, retail prices, and total dairy expenditure on at-home consumption of dairy products, using purchase data from Nielsen 2007 Homescan (ACNielsen, New York, NY) data. To derive the demand elasticities for 16 products, a censored Almost Ideal Demand System model is used. Results reveal that demographic variables do have effects on the purchase of the 16 products, and own-price elasticities are 1 or greater for all 16 products for both uncompensated and compensated elasticities except 4: ice cream, refrigerated yogurt, processed cheese, and margarine. A substitution relationship exists among all fluid milk categories, natural and processed cheese, low-fat ice cream, and refrigerated yogurt, butter, and margarine.