Internal stress effect on grain-boundary diffusion in submicrocrystalline metals

Grain-boundary diffusion in the regime affected by internal stresses of triple-line disclinations is analysed. The concentration profiles in a stressed solid averaged over a distribution of hydrostatic stress gradients are calculated. It is shown that the stresses from triple-line disclinations in as-prepared submicrocrystalline metals can significantly increase the effective grain-boundary diffusion coefficient, which is obtained by fitting the concentration profiles to the solution of a diffusion equation for an unstressed polycrystal.     

A theoretical exploration and model of consumer expectations,post‐purchase affective states and affective behaviour

Through a detailed review of the service quality and (dis)satisfaction literatures, this paper presents a theoretical model exploring the interrelationship between expectations, affective post‐purchase states and affective behaviour. Drawing together a comprehensive hierarchy of expectations culled from the service quality literature, the authors seek to apply levels of expectation to specific post‐purchase affective states and affective behaviour. The authors argue that consumers have two types of expectation that influence post‐purchase affective states: the core or predictive ‘will be’ expectation; and peripheral expectations—that can range from the ideal standard to the minimum tolerable level. By applying the levels‐of‐expectation approach to the expectation‐disconfirmation paradigm, the authors argue that there are four types of post‐purchase affective states: delight, satisfaction (or positive indifference), acceptance (or negative indifference) and dissatisfaction. These four states may lead onto affective action—ie varying degrees of complaining or complimenting behaviour. The paper presents 11 propositions relating to expectations and their interrelationship with post‐purchase affective states and subsequent consumer behaviour, with the aim of stimulating further scholarly enquiry. The managerial implications of the analysis are also considered. Copyright © 2003 Henry Stewart Publications.     

快速节俭启发式--基于有限理性和生态理性的简单决策规则

本文阐述了德国“马克斯．普朗克人类发展研究所”以Gerd Gigerenzer教授为代表的“适应行为与认知中心”简称“ABC研究中心(组)”关于判断、推理和决策制定简单启发式研究的理论背景、研究思路和技术路线,着重介绍了该研究中心在有限理性和生态理性假设基础上提出的一系列极富创意的快速节俭启发式规则,并对围绕这些简单决策规则开展的研究活动作了简要介绍。     

文本阅读中简单推理情境下的信息整合

研究采用动窗技术探讨了文本阅读中需要简单推理情境下的信息整合发生的时机。本研究通过三个实验证明了在需要简单推理情境下的文本阅读中 ,需要推理的信息整合是即时发生的 ,而不是经过追溯才发生 ,在这种情况下支持文本阅读的更新追随假设理论。同时本研究发现文本阅读中协调性整合不是以词为单位的。     

A statistical model of cleavage fracture in structural steels with power-law distribution of microcrack size

Based on the well-accepted physical understanding that cleavage fracture of structural steels is preceded by plastic deformation, a critical flaw in the Beremin model and its modifications is proposed, and a new statistical model with the power-law distribution of microcracks is obtained to describe the cumulative probability of cleavage fracture. A set of cleavage fracture toughness data of a nuclear pressure vessel steel is used to highlight the difference between the new model and the Beremin model.     

汉语成语谜语问题解决中思路竞争的眼动研究

在谜语问题解决过程中, 可能存在着通过简单联想和新异联想寻找答案这两种思路。两个实验中设置了包括寻常答案与新颖答案在内的若干备择答案(实验1为4个, 实验2为6个)供被试选择, 利用眼动技术记录被试在解题过程中的不同时间段内对新颖答案与寻常答案的平均注视时间, 考察汉语成语谜语问题解决中两种思路之间冲突的过程。实验1操纵了任务要求, 实验2操纵了规则线索的有效性。实验结果表明：(1)在成语谜语问题解决中的一段时间内新异联想和简单联想能够同时发生且形成竞争; (2)选择“新颖且合适答案”的任务要求, 提高了成功形成新颖语义联结的概率, 但是并没有加快新异联想发生、发展的进程, 也没有改变两种思路相互竞争的局面; (3)有效的规则线索可以抑制简单联想, 阻止其发生, 同时可以加快新异联想发生、发展的进程。     

Simple discrimination in stingless bees (Melipona quadrifasciata): Probing for select‐ and reject‐stimulus control

Simple and conditional discrimination training may produce various types of controlling relations. Responses may be controlled primarily by the positive stimulus (select–control relation) or by the negative stimulus (reject–control relation; the subject excludes the negative stimulus and chooses the positive). Bees learn to respond in simple and conditional discriminations. However, no study has searched for reject–control responding in Melipona bees. We trained Melipona quadrifasciata on a simple discrimination task (S+ vs. S‐; e.g., blue vs. yellow) and then probed for stimulus control with two types of probe trials, S+ versus a new stimulus (Select–control probes) and S‐ versus a new stimulus (Reject–control probes). For Group Different, a new‐stimulus color (e.g., white) was used in one type of probe and another color (e.g., black) was used in the other type. For Group Same, a single new‐stimulus color was used in both types of probes. On Select probes, the bees always preferred S+ to the new stimulus. On Reject probes, results were mixed. Depending on the colors used in training and probing, bees responded to both stimuli, and even preferred the S‐. The data suggest no control by the negative function of the S‐ and support the select‐stimulus control hypothesis of responding.     

Influencing surface plastic flow in metals using common chemical media

We demonstrate a unique mechanochemical effect – change in surface plastic flow by action of chemical media such as inks and glues – in large-strain deformation of metals. Unlike other well-known phenomena such as stress corrosion cracking and liquid metal embrittlement, the effect is not catastrophic and is largely material independent. High-speed in situ imaging shows that the media influence the flow by effecting a local ductile-to-brittle transition – from unsteady, large-amplitude, plastic folding, to repeated fracture and segmentation – with large decrease in deformation forces. The benign nature of the media offers opportunities for enhancing performance of metal cutting and deformation processes.     

Influence of plastic strain localisation on the mechanical properties of metal matrix composites

The aim of the present study is to reveal the most critical underlying factor influencing the mechanical properties of metal matrix composites (MMCs). It is shown that the mechanical properties of MMCs are essentially governed by the degree of strain localisation during plastic deformation. In other words, the MMCs exhibit superior mechanical performance only if the strain localisation is obviously inhibited and the accumulated stresses can be effectively transferred out. The work provides a new perspective in guiding the design of next-generation high-performance MMCs by suppressing the strain localisation as far as possible.     

Distribution of Cr atoms in a strained and strain-relaxed Fe89.15Cr10.75 alloy: a Mössbauer effect study

An Fe_89.15Cr_10.75 alloy in a heavily strained (by cold rolling) state and in strain-relaxed states was studied by means of conversion electrons Mössbauer spectroscopy. Analysis of the spectra in terms of a two-shell model revealed significant differences between the studied samples, particularly in values of the hyperfine field and the distribution of Cr atoms within the first two neighbour shells. The latter is quantified in terms of short-range order parameters.