第16届国际理论和应用力学大会

<正> 1.一般情况 国际理论和应用力学联合会(IUTAM)召开的第16届国际理论和应用力学大会(ICTAM),于1984年8月20—25日在丹麦的哥本哈根举行。会议参加者共700余人。会议除开幕大会报告(Alfven:空间研究和宇宙中流体介质力学的新方法)和闭幕大会报告(Keller:力学研究的进展和问题)外,还按分组报告、分组开场报告,一般报告和墙报等多种方式进行,大会重点主题是一个:“海洋与结构的波相互作用”, “多组分介质的微

边界层分离数值解

<正> 用N-S方程直接求解分离流的工作近几年已有不少。但这种计算比较费机时,需要存储最也大。在实际应用中,边界层理论仍然是研究分离流的一种好的近似方法。本文对二维、定常、不可压层流的分离流动进行了数值分析。主要内容有:(1)从典型的以流函数表示的边界层方程出发,对分离流进行数值计算。Keller和Cebeci曾用此方程求解过附体流动的反问题。在具有相似性解的条件下,这个方程简化为著名的Falkner-Skan方程,在初始剖面,这个方程简化为Blasius方程。(2)给

弹性波波面强度的变化

<正> 在一定的边界条件和初始条件下求解非定常弹性动力学问题一般相当困难,但根据Huygens-Kirchhoff原理可以得出任何时刻波面(或间断面)的位置。本文严格建立了波面强度,即速度、应变、应力等的间断值住传播过程中的变化规律,以及发生反射、折射时的规律,达有助于了解问题的概况,特别是波头的情况。本文的工作是J.B.Keller对于声波的研究的推广。

Reflection of shock-wave in pur foam from rigid wall

Keller proposed that a building, a mechanical installation or a body wrapped bya layer of foam plastics may be an efficient means for protection from damage ofblast wave. However, the practical effect was beyond expectation. For example, agunner wearing the foam plastics-padded waistcoat was injured more seriously by theblast wave from a muzzle. Monti took the foam plastics as homogeneous two-phasemedium and analyzed it with the theory of dusty flow. The obtained results showthat the peak pressure behind the reflected shock wave from rigid wall with foamcoat exceeds obviously that without foam coat under the same condition. Gel'fand,Patz and Weaver made experimental observations by means of shock tubes and veri-

辐照和退火对聚乙烯单晶结构的影响

高聚物的单晶结构是高分子物理的一个基本课题，对它的掌握有助于高聚物结晶动力学和晶体结构的研究。对聚乙烯单晶中分子链的折迭方式历来存在两种不同的观点。一是以A.Keller为代表有规近邻折叠模式，另一个是以P.J.Flory为代表的无规返折即“插线板”模式。这两种模式均有自己的实验证据和理论根据，但也有各自不能解释的现象。两种观点至今难以统一，一是由于高聚物的分子量大且分散，导致结晶结构很复杂。二是由于实验手段的非直接性，现有许多方法获得的信息往往是宏观的或较大结构尺度上的。对微观结构的反应不一定客观和有效。有鉴于此，应当在现有的实验水平上，尽可能用较直接的方法进行研究。以往的研究侧重于从“静”的方面，即不改变单晶状况进行探测，这样做考察问题的角度较单一，再加上实验手段的限制，不易得到更多的信息。本实验从“动”的方面着手研究，即引入退火和辐照两个因素，既研究单晶结构，又研究不同剂量辐照和不同温度退火后单晶结构的实化。由于结构和结构的变化之间存在一定的因果关系，所以二者可互为印证。这样既可以增加考察问题的角度，又可以掌握辐照对单晶结构的影响。以及退火过程中单晶结构的细致变化。采用的主要实验手段是混合晶红外光谱法，它可以给出单个分子的结晶茎干在单晶中的分布，是目前比较直接的方法。为了得到单晶的“微观”结构和较大尺度的结构，并使二者互相印证，还采用了低频拉曼谱，X射线（SAXS和WAXD）以及示差扫描量热法等手段。对聚乙烯／氘代聚乙烯混合晶进行了综合研究，得到如下结论。1.证实了PEH和PED的结晶行为一致，可以互为代表。二者的重量比大于40／1时，混合晶能够给出单个PED分子的茎干在晶体中排布方式的信息，且此信息完全适合于聚乙烯单晶。2.辐照不仅在非晶区产生交联点，还对晶区产生不可忽略的影响。辐照使晶区发生畸变和一定程度的断链。造成较大折叠块的含量及微晶尺寸随剂量增大而减小。这些结构上的变化使熔点随剂量的对数降低，结晶熔融热随剂量线性减小。这些结果修正和补充了前人对单晶辐照效果的观点。3. 辐照单晶的结构在退火前后均以（110）方向分子链近邻折叠形成的折叠块为主，同时也存在单独茎干的成分。这表明高分子物理中两种相对立的分子链折叠观点是可以统一的，二者的结合将更利于恰当描述单晶结构。退火使单晶结晶度和结晶完善程度提高的结构原因在于相对较小的折迭块重新组合成相对较大的折迭块。4.辐照单晶退火后，仍存在一定程度的折叠块。与未辐照时相比，剂量越大，较大折叠块越少，单独茎干的成分越多，且结构变化的程度越小。同一退火温度下，剂量越大，晶体越不稳定，结晶熔融热相应越低。5.无论辐照与否，单晶结构的变化均与退火温度有直接关系，不同退火温度下的退火机理不同。本实验中，90℃以下退火时，分子主要以蛇游式方式运动。105℃退火时也存在分子链的蛇游式运动，但是熔融再结晶占主导作用。

量子能谱中的长程关联

从可积系统求迹公式出发 ,运用Einstein Brillouin Keller(EBK)量子化条件 ,导出了二维无关联振子系统周期轨道作用量量子化条件 ,由此发现了量子能级与周期轨道之间的对应关系 .这种对应关系表明 ,如果两条能级对应的周期轨道的拓扑相同 ,这两条能级对回归函数的贡献相干 .回归谱中的一个峰是量子能谱中一组与具有相同拓扑的周期轨道相对应的能级之间相干的结果 ,这一组能级间存在着长程关联 .

用ANUDEM建立水文地貌关系正确DEM的方法研究

针对区域尺度的径流、水土流失定量评价和植被适宜性评价等研究工作需要,利用1∶25万数字地形图和ANUDEM软件,对黄土丘陵区中等分辨率水文地貌关系正确DEM建立方法进行了研究。结果表明该方法所建立的DEM,可以正确反映地貌梁、沟结构及其与流水线网络的关系,对地形描述的能力优于TIN方法建立的DEM;利用ANUDEM和1∶25万地形图插值建立黄土丘陵区DEM的三个主要参数分别为分辨率50或100,计算迭代次数40,第二糙率系数0.8。

品牌属性权重判断的反应时研究

In current days, many companies have carried out their branding strategies, because strong brand usually provides confidence and reduce risks to its consumers. No matter what a brand is based on tangible products or services, it will possess the common attributes of this category, and it also has its unique attributes. Brand attribute is defined as descriptive features, which are intrinsic characteristics, values or benefits endowed by users of the product or service (Keller, 1993; Romaniuk, 2003). The researches on models of brand multi-attributes are one of the most studied areas of consumer psychology (Werbel, 1978), and attribute weight is one of its key pursuits. Marketing practitioners also paid much attention to evaluations of attributes. Because those evaluations are relevant to the competitiveness and the strategies of promotion and new product development of the company (Green & Krieger, 1995). Then, how brand attributes correlate with weight judgments? And what features the attribute judgment reaction? Especially, what will feature the attribute weight judgment process of consumer who is facing the homogeneity of brands? Enlightened by the lexical hypothesis of researches on personality traits of psychology, this study choose search engine brands as the subject and adopt reaction time, which has been introduced into multi-attributes decision making by many researchers. Researches on independence of affect and cognition and on primacy of affect have cued us that we can categorize brand attributes into informative and affective ones. Meanwhile, Park has gone further to differentiate representative and experiential with functional attributes. This classification reflects the trend of emotion-branding and brand-consumer relationship. Three parts compose the research: the survey to collect attribute words, experiment one on affective primacy and experiment two on correlation between weight judgment and reaction. The results are as follow: In experiment one, we found: (1) affect words are not rated significantly from cognitive attributes, but affect words are responded faster than cognitive ones; (2) subjects comprehend and respond in different ways to functional attribute words and to representative and experiential words. In experiment two, we fund: (1) a significant negative correlation between attributes weight judgment and reaction time; (2) affective attributes will cause faster reaction than cognitive ones; (3) the reaction time difference between functional and representative or experiential attribute is significant, but there is no different between representative and experiential. In sum, we conclude that: (1): In word comprehension and weight judgment, we observed the affective primacy, even when the affect stimulus is presented as meaningful words. (2): The negative correlation between weight judgment and reaction time suggest us that the more important of attribute, the quicker of the reaction. (3): The difference on reaction time of functional, representative and experiential reflects the trend of emotional branding.