Production of bronze powders by water jet cooled rotating disc atomisation

Abstract

New type of water jet cooled rotating disc atomisation unit was designed and constructed. The raw material was melted in graphite crucible with high frequency induction heating, and atomisation was performed in high purity argon gas atmosphere. Cu–10Sn alloy was atomised to investigate the effect of production parameters, such as disc speed, disc surface condition, liquid metal flowrate, disc fin number and superheat of liquid metal with respect to mean particle size and powder yield rate. The produced powders appeared spherical, rounded, ligamentous, irregular and flaky, depending on particle size. The mean particle size of produced powders was in the range of 100–250 μm with 65–85% powder yield rate depending of atomisation parameters. The ZrO₂ material coated disc with four fins gave the finer mean particle size and higher powder yield rate in comparison with uncoated disc with two fins.     

Transfer of magnitude and spatial mappings to the SNARC effect for parity judgments.

Left–right keypresses to numerals are faster for pairings of small numbers to left response and large numbers to right response than for the opposite pairings. This spatial numerical association of response codes (SNARC) effect has been attributed to numbers being represented on a mental number line. We examined this issue in 3 experiments using a transfer paradigm. Participants practiced a number magnitude-judgment task or spatial stimulus–response compatibility task with parallel or orthogonal stimulus–response dimensions prior to performing a parity-judgment task. The SNARC effect was enhanced following a small–left/large–right magnitude mapping but reversed following a small–right/large–left mapping, indicating that associations between magnitude and response defined for the magnitude-judgment task were maintained for the parity-judgment task. The SNARC effect was unaffected by practice with compatible or incompatible spatial mapping for the parallel spatial task but was larger following up–right/down–left mapping than up–left/down–right mapping for the orthogonal spatial task. These results are inconsistent with the SNARC effect being due to a horizontal number line representation but consistent with a view that correspondence of stimulus and response code polarities contributes to the effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mental comparison: P300 component of the ERP reflects the symbolic distance effect

The symbolic distance effect was studied in a numerical comparison task by means of behavioural measures and event-related potentials (ERP). Two numbers in the range from 11 to 20 were presented simultaneously and the subjects had to indicate if the right side number was smaller or larger than the left side number. Reaction time, error rate and ERPs were selectively averaged according to the numerical differences between the two numbers. The symbolic distance effect was confirmed: Reaction times and error rates decreased significantly with increasing difference between the two numbers. A significant distance effect was also found for both P300 amplitude and latency. The larger the numerical difference the larger the P300 amplitude and the P300 latency tended to be shorter. This finding suggests that the numerical difference is effective already during stimulus encoding.     

Primed numbers: Exploring the modularity of numerical representations with masked and unmasked semantic priming.

In Experiment 1, participants classified a 1st number (prime) as smaller or larger than 5 and then performed the same task again on a 2nd number (target). In Experiment 2, participants classified a target number as smaller or larger than 5, while unknown to them a masked number was displayed for 66 ms prior to the target. Primes and targets appeared in Arabic notation, in verbal notation, or as random dot patterns. Two forms of priming were analyzed: quantity priming (a decrease in response times with the numerical distance between prime and target) and response priming (faster responses when the prime and target were on the same side of 5 than when they were not). Response priming transferred across notations, whereas quantity priming generally did not. Under conditions of speeded processing, the internal representation of numerical quantities seems to dissociate into multiple notation-specific subsystems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two-digit number comparison: Decade-unit and unit-decade produce the same compatibility effect with number words.

This study explored the processing of 2-digit number words by examining the unit-decade compatibility effect in Spanish. Participants were required to choose the larger of 2-digit number words presented in verbal notation. In compatible trials the decade and unit comparisons led to the same response (e.g., 53–68) while in incompatible trials the decade and unit comparisons led to different responses (e.g., 59–74). Participants were slower on compatible trials as compared to incompatible trials. In Experiments 2 and 3, we evaluated whether the reverse compatibility effect in Spanish was only due to a pure left-to-right encoding which favours the decade processing in this language (decade-unit order). When participants processed 2-digit number words presented in reverse form (in the unit-decade order), the same reverse compatibility effect was found. This pattern of results suggests that participants have learnt a language-dependent process for analysing written numbers which is used irrespective of the specific arrangement of units and decades in the comparison task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A generalized fraction: An entity smaller than one on the mental number line.

The representation of fractions in long-term memory (LTM) was investigated by examining the automatic processing of such numbers in a physical comparison task, and their intentional processing in a numerical comparison task. The size congruity effect (SiCE) served as a marker of automatic processing and consequently as an indicator of the access to the primitives of numerical representation in LTM. Mixed pairs composed of a natural number and a fraction showed both a SiCE and a distance effect. The SiCE for mixed pairs was stable across relative sizes of natural numbers compared to the fraction digits (Experiment 4). However, comparing pairs of fractions revealed a strong influence of fractional components: An inverse SiCE was found for pairs of unit fractions (Experiment 1), while no SiCE was found for pairs of non-unit fractions (Experiments 2–3). This leads to the conclusions that: (1) there are no unique representations of distinct fraction values in LTM, and (2) there is a representation of a “generalized fraction” as an “entity smaller than one” that emerges from the notational structure common to all fractions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Are Arabic and verbal numbers processed in different ways?

Four experiments were conducted in order to examine effects of notation--Arabic and verbal numbers--on relevant and irrelevant numerical processing. In Experiment 1, notation interacted with the numerical distance effect, and irrelevant physical size affected numerical processing (i.e., size congruity effect) for both notations but to a lesser degree for verbal numbers. In contrast, size congruity had no effect when verbal numbers were the irrelevant dimension. In Experiments 2 and 3, different parameters that could possibly affect the results, such as discriminability and variability (Experiment 2) and the block design (Experiment 3), were controlled. The results replicated the effects obtained in Experiment 1. In Experiment 4, in which physical size was made more difficult to process, size congruity for irrelevant verbal numbers was observed. The present results imply that notation affects numerical processing and that Arabic and verbal numbers are represented separately, and thus it is suggested that current models of numerical processing should have separate comparison mechanisms for verbal and Arabic numbers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Letter localization, not discrimination, is constrained by attention

Shaw (1984; Shaw, Mulligan & Stone, 1983) measured the probability of detecting a target letter in displays containing different numbers of items. The set size effect was significantly larger than the effect predicted by unlimited-capacity models of visual processing, and Shaw concluded that attention constrains the discrimination of complex, but not simple, patterns. We re-examined the role of attention in letter discrimination by measuring the effect of set size on the contrast needed to identify a target embedded among distractors. The results of 5 experiments show that set size effects are small for letter discrimination, but large for letter localization. The findings suggest that the large set size effect reported by Shaw (1984) was a result of asking subjects to localize the target. In addition, the results are consistent with the hypothesis that limited processing capacity constrains the perceptual processes involved in letter localization, but not discrimination.     

流体转杯离心粒化特性试验

 针对高温熔融高炉渣转杯粒化技术,为了探索离心粒化过程中熔渣颗粒形成的机理及熔渣体流量、转杯转动速度等参数对颗粒粒径的影响,以水为粒化试验工质,以直径110 mm的转杯为离心粒化器,开展了离心粒化可视化试验。研究了工质在转杯表面的流动和在转杯边缘形成液丝、液丝断裂成液滴的机理,以及液丝长度、顶端液滴粒径随时间的变化趋势;基于图像处理技术分析了转杯转速、工质流量对粒化液滴的粒径分布和平均粒径的影响规律。结果表明：转杯表面液膜在转杯边缘形成若干凸起,并沿转杯运动的切线方向延伸形成液丝,液丝长度随时间呈线性变化关系,液丝顶端液滴粒径基本保持不变;随着工质流量降低和转杯转速升高,液滴平均粒径呈减小趋势,液滴速度接近转杯圆周速度。     

Selective Interference With the Use of Visual Images in the Symbolic Distance Paradigm.

Eight experiments investigated the effects of visual, spatial, auditory, and executive interference on the symbolic comparison of animal size and ferocity, semantic goodness of words, and numbers. Dynamic visual noise (DVN) and the reading of visually presented stimulus items were shown to selectively interfere with response times on the animal size comparison task, though the slope of the symbolic distance function remained unchanged. Increased change of DVN significantly increased interference, but interference was reduced by equiluminant DVN. Spatial tracking reduced the slope of the symbolic distance function in contrast to an executive task that only increased mean latency and errors for all comparisons. Results suggest that the generation of an image is necessary for size comparison, but neither imagery nor executive function is responsible for the frequently observed distance-time function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Figural aftereffects and spatial attention

Distracting attention away from the location of an adaptation figure reduces the positional shift of a displaced test figure in the figural aftereffect (FAE). Participants performed an alignment task after adaptation involving various manipulations of spatial attention. In 1 condition, participants counted how often numbers occurred in an alphanumeric sequence presented during adaptation. (The sequence also appeared in a comparison condition, but no attention was required.) The FAE was reduced when the alphanumeric sequence attended to was in the center of the display while the adaptation figure was 3 degrees eccentric but not when the pattern was superimposed on the adaptation figure. Forced attention to 1 feature of the adaptation figure, its orientation, did not reduce the FAE (Experiment 3). To obtain a maximum FAE, the span of attention must cover the adaptation figure.     

脱氧顺序对铝钛复合夹杂物的影响

 通过扫描电镜-能谱仪检测和分析了不同铝钛脱氧顺序下钢中夹杂物的形貌、成分、尺寸、数量和分布等参数,通过热力学计算分析了脱氧过程中钢液中的化学反应和夹杂物优势区图。结果表明,脱氧剂添加顺序对夹杂物形貌影响很大,先加钛后加铝的脱氧方式下,钢液中形成了较多含有铁相(“空心”)的具有浓度梯度的铝钛复合夹杂物。夹杂物径向长度增加,夹杂物也更容易偏聚。所以先加钛后加铝不利于夹杂物尺寸细小化,不利于夹杂物弥散分布。先加铝后加钛的脱氧方式下,钢中形成氧化铝夹杂,不会被溶解的钛还原,因此夹杂物内部不含有铁相。夹杂物主要为Al-Ti-O(-N)类夹杂。夹杂物尺寸和数量小于先加钛后加铝钢中的夹杂物。通过FactSage计算结果、化学反应分析和试验检测结果,探究了不同铝钛脱氧顺序下夹杂物形成和演变机理,分析了具有浓度梯度的“空心结构”的铝钛复合夹杂物形成机理,讨论了脱氧剂添加顺序对夹杂物尺寸、数量和分布等特征的影响规律。发现先加钛后加铝的脱氧方式下,钛氧化物会与金属铝反应,钛氧化物逐渐转变为“空心”氧化铝壳,同时溶解的铝、钛和氧发生氧化反应,形成了具有浓度梯度的Al₂O₃-TiO_x复合夹杂物,最终钛氧化物完全转变为氧化铝壳而消失。随着铁液的填充,形成了含有铁相的铝钛夹杂物。     

Interference effects from divided attention during retrieval in younger and older adults.

The authors examined how retrieval, under divided attention (DA) conditions, is affected by the type of material in a concurrent task, and whether aging produces larger interference effects on memory. Young and old adults studied a list of unrelated words under full attention, and recalled them while performing either an animacy decision task to words or an odd-digit identification task to numbers. The animacy-distracting task interfered substantially with retrieval, and the size of the effect was not amplified in older compared with younger adults. DA using the odd-digit task did not produce as large an interference effect. These findings support the component-process model of memory, and pose problems for resource models of interference from DA at retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Congruency proportion reveals asymmetric processing of irrelevant physical and numerical dimensions in the size congruity paradigm.

When the proportion of congruent trials in conflict tasks is manipulated (e.g., Stroop, Simon), the typical result is that the magnitude of the conflict effect increases as the proportion of congruent trials increases. The present experiment investigated the influence of Congruency Proportion in the context of the Size Congruity Paradigm. Congruency Proportion had a significant impact on the Numerical Judgement Task (judging which of two numbers is numerically larger), but not on the Physical Judgement Task (judging which of two numbers is printed in a larger font). These data support the inference that physical size information is processed before, and more fluently than, numerical size information. The implications of this asymmetry are discussed in terms of the relative role of semantic and physical size information in representations of magnitude, and the role they play in both of these tasks. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

How the great apes (Pan troglodytes, Pongo pygmaeus, Pan paniscus, and Gorilla gorilla) perform on the reversed contingency task: The effects of food quantity and food visibility.

S. T. Boysen and G. G. Berntson (1995) found that chimpanzees performed poorly on a reversed contingency task in which they had to point to the smaller of 2 food quantities to acquire the larger quantity. The authors compared the performance of 4 great ape species (Pan troglodytes, Pongo pygmaeus, Pan paniscus, and Gorilla gorilla) on the reversed contingency task while manipulating food quantity (0-4 or 1-4) and food visibility (visible pairs or covered pairs). Results showed no systematic species differences but large individual differences. Some individuals of each species were able to solve the reversed contingency task. Both quantity and visibility of the food items had a significant effect on performance. Subjects performed better when the disparity between quantities was smaller and the quantities were not directly visible. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Fuzzy picture processing: Effects of size reduction and blurring on emotional processing.

Previous studies have suggested that picture size reduction affects emotional reactions, possibly because scenes subtending a small visual angle are perceived as being more distant and less relevant compared to larger stimuli. However, pictures that subtend a small visual angle also contain few fine-grained details, which may determine less vivid representations and responses compared to larger and more detailed images. Critically, the present study compared two different types of manipulations, namely size reduction and low-pass spatial filtering, which determined similar detail loss but affected visual angles differently. Affective modulation was assessed using an evaluative task and a behavioral interference task. Results showed that the availability of fine-grained details, independently of visual angle, modulated emotional evaluation. Moreover, interference in an unrelated task was unaffected by either size reduction or low-pass spatial filtering. These findings suggest that high spatial frequencies affect subjective emotional response whereas attentional capture by affective stimuli seems to rely on information that is sufficient to allow a categorization of picture content. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychological treatment of late-life anxiety: An empirical review.

This study provides a meta-analytic review of nonpharmacological interventions for late-life anxiety, focusing on treatment efficacy. Included in the analysis are studies in which a comparison was made either to a control condition or to another treatment. A total of 15 outcome studies, published or reported between January 1975 and January 2002, were identified involving 495 participants (mean age exceeding 55.0 years and a grand mean of 69.5 years) and providing 20 separate treatment interventions. The analysis indicated that psychological interventions were reliably more effective than no treatment on self-rated and clinician-rated measures of anxiety, yielding an effect size of .55. Maintenance of treatment gains (a minimum of 6 months follow-up) was insufficiently reported across studies to allow for a reliable demonstration of an overall estimate of long-term efficacy. It is concluded that psychological interventions produce significant improvements, but the analyses must be qualified by data limitations in the research synthesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of number signals on reading and recall.

Examined the influence of number signals (i.e., numbers or number words preceding important textual information) on text recall. 120 undergraduates read and recalled 2 texts containing 10 target sentences each. Reading times were recorded for each target sentence. For half of the Ss, the target sentences were preceded by numbers indicating their organization; for the other half, the target sentences were not signaled. Half of the Ss completed a free-recall task, while the remainder completed a cued-recall task. Results indicate that Ss read target sentences more slowly if they were signaled than if they were unsignaled. Ss' recalls of target information followed the text organization more closely if the sentences were signaled. Signaling aided free recall of target sentences, but had no effect on cued recall. Results demonstrate that number signals directed attention to the sentences they marked, led to better encoding of the organization of target information, and influenced the process of recalling the target information. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Immediate versus delayed visual memory task performance among schizophrenic patients and normal control subjects

In an exploratory study, 10 schizophrenic patients and 10 normal control subjects performed immediate and delayed memory tasks, which were variants of previously developed continuous performance tests. Both tasks required participants to identify five-digit numbers which were repeated. Numbers were presented in series for 500 ms each and separated by a 500-ms time-out period. In the immediate memory task, subjects were to respond if a number was identical to the one that had immediately preceded it. The delayed memory task differed from the first task in that a longer delay (3.5 s) between stimuli was introduced, and during this delay distracter stimuli appeared. While normal control subjects performed accurately on both tasks (exceeding 80% correct detections), schizophrenic patients performed poorly, performing worse on the delayed memory task than on the immediate memory task. Rates of commission errors (responses made to similar, but not identical numbers) were nearly equal between groups on the immediate memory task, but on the delayed memory task normal control subjects made relatively more commission errors while schizophrenic patients made fewer commission errors. No differences in response latencies were observed between subject groups or tasks. This paradigm may prove useful in discriminating subtle differences in immediate and delayed memory capability among psychiatric populations and normal control subjects.     

Context-sensitive adjustments of cognitive control: Conflict-adaptation effects are modulated by processing demands of the ongoing task.

Dynamic adjustments of cognitive control in response to interference from irrelevant stimulus attributes have repeatedly been shown. The purpose of the current research was to investigate how these control adjustments are modulated by the processing demands of a primary task. To this end, the authors combined a primary task (a number comparison task: classifying digits as smaller or larger than 5) with a Simon task. Control adjustments were observed in the form of typical sequential modulations of the Simon effect. In addition, the authors found sequential modulations of the numerical distance effect and an interaction of both effects. Results suggest that not only response conflict due to interference from task-irrelevant features but also processing demands of task-relevant features determine the level of control adjustment in the subsequent trial. (PsycINFO Database Record (c) 2010 APA, all rights reserved)