scholarly journals Interaction of the Nucleation Phenomena at Adjacent Sites in Nucleate Boiling

1983 ◽  
Vol 105 (1) ◽  
pp. 3-9 ◽  
Author(s):  
M. Sultan ◽  
R. L. Judd
Keyword(s):  
Active Sites ◽  
Heating Surface ◽  
Nucleate Boiling ◽  
Copper Surface ◽  
Nucleation Sites ◽  
Theoretical Predictions ◽  
Experimental Findings ◽  
Relationship Of ◽  
The Relationship ◽  
Different Levels

The present investigation is an original study in nucleate pool boiling heat transfer combining theory and experiment in which water boiling at atmospheric pressure on a single copper surface at two different levels of heat and different levels of subcooling was studied. Cross spectral analysis of the signals generated by the emission of bubbles at adjacent nucleation sites was used to determine the relationship of the time elapsed between the start of bubble growth at the two neighbouring active sites with the distance separating them. The experimental results obtained indicated that for the lower level of heat flux at three different levels of subcooling, the elapsed time and distance were directly related. Theoretical predictions of a temperature disturbance propagating through the heating surface in the radial direction gave good agreement with the experimental findings, suggesting that this is the mechanism responsible for the activation of the surrounding nucleation sites.

scholarly journals Spatial Distribution of Active Sites and Bubble Flux Density

1978 ◽  
Vol 100 (1) ◽  
pp. 56-62 ◽  
Author(s):  
M. Sultan ◽  
R. L. Judd
Keyword(s):  
Heat Flux ◽  
Spatial Distribution ◽  
Flux Density ◽  
Vapor Bubble ◽  
Active Sites ◽  
Heating Surface ◽  
Copper Surface ◽  
Emission Frequency ◽  
Nucleation Sites ◽  
Different Levels

An experimental investigation is presented concerning the boiling of water at atmospheric pressure on a single copper surface in which the spatial distribution of active nucleation sites was investigated at different levels of heat flux and subcooling. The results obtained indicated that the active sites were located randomly on the heating surface, since the distribution of active sites followed the Poisson relationship. Changes in heat flux and sub-cooling did not affect the distribution of active nucleation sites although additional active sites formed among the sites which had already been activated when heat flux was increased. The frequency of vapor bubble emission and the bubble flux density have been studied as well. The results obtained showed that the heat flux had a great effect on the vapor bubble emission frequency although the influence of subcooling was of lesser significance. However, the bubble flux density was found to be non-uniformly distributed over the heating surface contrary to what had been expected.

An Experimental Investigation of the Effect of Subcooling on Bubble Growth and Waiting Time in Nucleate Boiling

1985 ◽  
Vol 107 (1) ◽  
pp. 168-174 ◽  
Author(s):  
E. A. Ibrahim ◽  
R. L. Judd
Keyword(s):  
Heat Flux ◽  
Waiting Time ◽  
Bubble Growth ◽  
Nucleate Boiling ◽  
Copper Surface ◽  
Growth Theory ◽  
Growth Time ◽  
Time Data ◽  
Relationship Of ◽  
Different Levels

The effect of subcooling on bubble waiting time and growth time for water boiling on a copper surface was examined in conjunction with measurements obtained over a range of subcooling from 0 to 15°C and three different levels of heat flux 166, 228, and 291 kW/m2. The growth-time data was successfully correlated with a model that combined the bubble growth theory of Mikic, Rohsenow, and Griffith with the bubble departure diameter relationship of Staniszewski, thereby establishing confidence in the measuring procedure. The waiting time data agreed with the predictions of the Han and Griffith waiting time theory at lower levels of subcooling but then showed a behavior contrary to that predicted for higher levels of subcooling.

scholarly journals Risk Taking with Variable Resources: a Field and a Laboratory Experiment

2018 ◽  
Vol 1 (1) ◽  
pp. 36-57
Author(s):  
Klára Faragó ◽  
Ajna Uatkán
Keyword(s):  
Field Experiment ◽  
Risk Taking ◽  
Laboratory Experiments ◽  
Real Life ◽  
Laboratory Setting ◽  
Theoretical Predictions ◽  
Experimental Findings ◽  
The Relationship ◽  
Different Levels ◽  
Available Resources

AbstractBackground: Theoretical predictions and experimental findings concerning the relationship between risk taking and accumulated resources are contradictory. In contrast to laboratory experiments, studies conducted in an ecologically valid environment allow for the evaluation of available resources and the motivational impact of potentially serious consequences for risk taking. Objective: Our aim was to (i) examine the influence of available resources on risk taking in an ecologically valid field experiment; and (ii) to compare “real life” and laboratory experiments assessing risk taking. Method: To reproduce real decisions involving real stakes, the students were asked to choose between exam questions representing different levels of difficulty. Available resources of the students were defined as the amount of points accumulated during the semester. In parallel, the laboratory experiments were conducted to assess risk taking in a laboratory setting. Results: The two experimental setups yielded different results. In the field experiment, risk taking decreased with the available resources, whereas the laboratory experiments suggested an inverse tendency. The influence of contextual effects was only prominent in the field experiment.Conclusion: The results of the field experiment support the variable risk preference model, whereas the risk-sensitivity theory could only be validated in the laboratory setting.

The Risk Tolerance Measure in the 2016 Survey of Consumer Finances: New, But Is It Improved?

2021 ◽  
pp. JFCP-19-00022
Author(s):  
Kyoung Tae Kim ◽  
Sherman D. Hanna ◽  
Dongyue Ying
Keyword(s):  
Negative Relationship ◽  
Risk Tolerance ◽  
Stock Ownership ◽  
Survey Of Consumer Finances ◽  
Consumer Finances ◽  
Two Measures ◽  
Complex Patterns ◽  
Relationship Of ◽  
The Relationship ◽  
Different Levels

The Survey of Consumer Finances (SCF) has included a 4-level risk tolerance measure since 1983. In 2016, the SCF also included an 11-level risk tolerance measure. We compare the two measures, and develop suggestions for using the new measure. While the new measure is seemingly simpler than the old measure, we demonstrate that it does not have a monotonic relationship with owning stock assets, with a pattern similar to the relationship of the old measure to stock ownership. We also identify complex patterns of factors related to different levels of the new measure, for instance education has a negative relationship at one level but positive at another level. Those using the new measure should consider the complex patterns we demonstrate.

scholarly journals Characteristics of emotional state and cognitive processes in patients with ischemic stroke in acute period

2019 ◽  
Vol 3 (24) ◽  
pp. 40-44
Author(s):  
Yu. V. Kotsyubinskaya ◽  
A. V. Kazakov ◽  
N. Yu. Safonova
Keyword(s):  
Ischemic Stroke ◽  
Cognitive Processes ◽  
Emotional State ◽  
Therapeutic Process ◽  
Anxiety And Depression ◽  
Anterior Cortex ◽  
Acute Period ◽  
Relationship Of ◽  
The Relationship ◽  
Different Levels

Currently, studies aimed at assessing the emotional state and cognitive processes associated with the processing of emotionally determined information in patients with ischemic stroke, as well as finding the relationship between them are particularly relevant, mainly for the subsequent optimization of the therapeutic process. In order to identify the features of the emotional state and cognitive processes, a group of patients with ischemic stroke in the acute period in the amount of 25 people was examined. It was established that in patients with a lesion in the anterior cortex, depressive states in the acute period of stroke are more pronounced. Patients successfully reproduce emotionally significant words in comparison with neutral words; an interrelation between the level of anxiety and depression was found, which indicates that these states are comorbid. But, in turn, the relationship of the severity of anxiety and depression with the cognitive processes of recognition and reproduction, as well as differences in mnestic and gnostic activity in patients with different levels of anxiety and depression were not identified. After the treatment with Semax an improvement was noted.

A comparison of three low-persistence viruses of the strawberry

1957 ◽  
Vol 8 (6) ◽  
pp. 652
Author(s):  
LL Stubbs
Keyword(s):  
Cross Protection ◽  
Mixed Infections ◽  
Fragaria Vesca ◽  
Symptom Development ◽  
Relationship Of ◽  
The Relationship ◽  
Different Levels

Three low-persistence viruses of mild, severe, and intermediate virulence, respectively, on strawberry (Fragaria vesca L.) seedlings have been isolated from Australian strawberry varieties. Studies concerned with the relationship of these viruses have shown that both the intermediate and severe types will multiply in F. vesea plants previously infected with the mild type of virus. Moreover, infection with this latter virus does not delay symptom development when the plants are inoculated with either the intermediate or severe types, and symptoms are intensified in each case. The mild and severe viruses were separated from mixed infections by serially transferring aphids (Pentatrichopus fragaefolii (Cock.)) bred on the infected plants. Separation was achieved by chance, and not as a result of different levels of persistence in the vector which the experiments were designed to exploit. In most instances both viruses were transmitted. The identity of the viruses is discussed in relation to known cross-protection phenomena.

Target Acquisition in Cluttered Environments

1992 ◽  
Vol 36 (18) ◽  
pp. 1425-1429 ◽  
Author(s):  
Deborah P. Birkmire ◽  
Robert Karsh ◽  
B. Diane Barnette ◽  
Ramakrishna Pillalamarri
Keyword(s):  
Target Acquisition ◽  
Regression Analyses ◽  
Cluttered Environments ◽  
Video Images ◽  
Detection Probabilities ◽  
Visual Clutter ◽  
Relationship Of ◽  
Global And Local ◽  
The Relationship ◽  
Different Levels

The relationship of human target acquisition times and detection probabilities to electronically measured visual clutter was investigated. Ninety computer-generated scenes simulating infrared imagery and containing different levels of clutter and zero, one, two, or three targets were produced. Targets were embedded in these scenes counterbalancing for range and position. Global and local clutter were measured using both statistical variance and probability of edge metrics. Thirty-three aviators, tankers, and infantry soldiers were shown still-video images of the 90 scenes and were instructed to search for targets. Analyses indicate differences between the aviators and tankers in search times and types of errors. Results of multiple regression analyses of global clutter, local clutter, range, target dimension, target complexity, number of targets, and experience on search times are given and discussed in terms search strategies.

THE ROLE OF EXOGENOUS FACTORS IN THE FOREST BIOTA FORMATION

2015 ◽  
Vol 10 (2) ◽  
pp. 105-109 ◽  
Author(s):  
Курбанова ◽  
Saniya Kurbanova ◽  
Глушко ◽  
Sergey Glushko ◽  
Прохоренко ◽  
...  
Keyword(s):  
Adaptive Strategy ◽  
Forest Sites ◽  
Different Types ◽  
Exogenous Factors ◽  
Relationship Of ◽  
The Relationship ◽  
Further Development ◽  
Biological Component ◽  
Different Levels

Forest sites are formed in the interaction of heterogeneous components of biogeosystem. The increase or decrease of biological component in forest biogeosystems defines the different types of strategy with opposite characteristics, representing the different lines of adaptation (to the biological medium and abiotic environment). The manifestation of adaptive strategy requires appropriate tools, which are evolving on the basis of accumulated property (information capacity) and prevailing forest sites. Forest sites can be seen as an external “order” on the evolution of adaptations. Silvicultural properties of forest biological systems work enough in the interaction of different forms of matter (biological, abiotic), mapping out a hierarchy of biogeosystems. The information potential of forest biota interconnects different levels of systemic organization of forest biogeosystems. Further development of biogeocenology and the theory and ecosystems will allow to investigate the relationship of forest biota with exogenous forest-forming factors.

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