The Role of Bubble Waiting Time in Steady Nucleate Boiling

1999 ◽  
Vol 121 (4) ◽  
pp. 852-855 ◽  
Author(s):  
R. L Judd
Keyword(s):  
Waiting Time ◽  
Nucleate Boiling ◽  
Nucleation Site ◽  
Experimental Results ◽  
Sufficient Energy ◽  
Time Required

Experimental results previously reported by Ibrahim and Judd were examined in order to determine the role of bubble waiting time in steady nucleate boiling. The analysis identified that the time elapsed between the formation of bubbles at a nucleation site is the time required for the liquid which replaced the previous bubble to acquire sufficient energy to sustain the growth of the subsequent bubble, and not the time required to establish the conditions required to enable the nucleus, which formed at the nucleation site, to commence growing into a bubble.

Transport and fluctuations in nonlinear-dissipative systems: role of interparticle collisions

1999 ◽  
Vol 4 ◽  
pp. 31-86 ◽  
Author(s):  
R. Katilius ◽  
A. Matulionis ◽  
R. Raguotis ◽  
I. Matulionienė
Keyword(s):  
Electric Fields ◽  
Carrier Density ◽  
Experimental Results ◽  
Dissipative Systems ◽  
Doped Semiconductors ◽  
Electron Diffusion ◽  
Electron Collisions ◽  
Electric Noise ◽  
Diffusion Phenomena

The goal of the paper is to overview contemporary theoretical and experimental research of the microwave electric noise and fluctuations of hot carriers in semiconductors, revealing sensitivity of the noise spectra to non-linearity in the applied electric field strength and, especially, in the carrier density. During the last years, investigation of electronic noise and electron diffusion phenomena in doped semiconductors was in a rapid progress. By combining analytic and Monte Carlo methods as well as the available experimental results on noise, it became possible to obtain the electron diffusion coefficients in the range of electric fields where inter-electron collisions are important and Price’s relation is not necessarily valid. Correspondingly, a special attention to the role of inter-electron collisions and of the non-linearity in the carrier density while shaping electric noise and diffusion phenomena in the non-equilibrium states will be paid. The basic and up-to-date information will be presented on methods and advances in this contemporary field - the field in which methods of non-linear analytic and computational analysis are indispensable while seeking coherent understanding and interpretation of experimental results.

scholarly journals Towards 6G IoT: Tracing Mobile Sensor Nodes with Deep Learning Clustering in UAV Networks

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3936
Author(s):  
Yannis Spyridis ◽  
Thomas Lagkas ◽  
Panagiotis Sarigiannidis ◽  
Vasileios Argyriou ◽  
Antonios Sarigiannidis ◽  
...  
Keyword(s):  
Deep Learning ◽  
Heuristic Method ◽  
Sensor Nodes ◽  
Convolutional Network ◽  
Received Signal Strength Indicator ◽  
Anchor Nodes ◽  
Time Required ◽  
Rf Signal ◽  
Deep Learning Model

Unmanned aerial vehicles (UAVs) in the role of flying anchor nodes have been proposed to assist the localisation of terrestrial Internet of Things (IoT) sensors and provide relay services in the context of the upcoming 6G networks. This paper considered the objective of tracing a mobile IoT device of unknown location, using a group of UAVs that were equipped with received signal strength indicator (RSSI) sensors. The UAVs employed measurements of the target’s radio frequency (RF) signal power to approach the target as quickly as possible. A deep learning model performed clustering in the UAV network at regular intervals, based on a graph convolutional network (GCN) architecture, which utilised information about the RSSI and the UAV positions. The number of clusters was determined dynamically at each instant using a heuristic method, and the partitions were determined by optimising an RSSI loss function. The proposed algorithm retained the clusters that approached the RF source more effectively, removing the rest of the UAVs, which returned to the base. Simulation experiments demonstrated the improvement of this method compared to a previous deterministic approach, in terms of the time required to reach the target and the total distance covered by the UAVs.

Near-Wall Microlayer Evaporation Analysis and Experimental Study of Nucleate Pool Boiling on Inclined Surfaces

1998 ◽  
Vol 120 (3) ◽  
pp. 641-653 ◽  
Author(s):  
G. F. Naterer ◽  
W. Hendradjit ◽  
K. J. Ahn ◽  
J. E. S. Venart
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heating Surface ◽  
Nucleate Boiling ◽  
Inclined Surfaces ◽  
Wide Range ◽  
Model Predictions ◽  
Microlayer Evaporation ◽  
Near Wall

Boiling heat transfer from inclined surfaces is examined and an analytical model of bubble growth and nucleate boiling is presented. The model predicts the average heat flux during nucleate boiling by considering alternating near-wall liquid and vapor periods. It expresses the heat flux in terms of the bubble departure diameter, frequency and duration of contact with the heating surface. Experiments were conducted over a wide range of upward and downward-facing surface orientations and the results were compared to model predictions. More active microlayer agitation and mixing along the surface as well as more frequent bubble sweeps along the heating surface provide the key reasons for more effective heat transfer with downward facing surfaces as compared to upward facing cases. Additional aspects of the role of surface inclination on boiling dynamics are quantified and discussed.

scholarly journals Role of the Solar Minimum in the Waiting Time Distribution Throughout the Heliosphere

2021 ◽  
Author(s):  
Yosia I Nurhan ◽  
Jay Robert Johnson ◽  
Jonathan R Homan ◽  
Simon Wing
Keyword(s):  
Waiting Time ◽  
Time Distribution ◽  
Solar Minimum ◽  
Waiting Time Distribution

Estimating waiting and idle times for special queuing situations of tree harvesting machines

1981 ◽  
Vol 11 (1) ◽  
pp. 99-104 ◽  
Author(s):  
C. H. Meng
Keyword(s):  
Waiting Time ◽  
Historical Data ◽  
Idle Time ◽  
Processing Times ◽  
Mean Waiting Time ◽  
Analytical Formulae ◽  
Input Time ◽  
Time Required ◽  
Tree Harvesting ◽  
Normally Distributed

The purpose of this study is to develop analytical formulae for special queuing situations which occur during the operations of the felling and processing devices of a tree harvester, and the pickup and processing devices of a tree processor. Analytical formulae are used to estimate mean waiting time and mean idle time; in case 1 both "input" times and processing times are normally distributed; in case 2 "input" times are normally distributed and processing times are Poisson distributed. "Input" time is a term used for convenience to denote time required to fell a tree by a harvester or time required to pick up a tree by a processor. Methods of choosing distributions for representing "input" times and processing times are provided. In addition, there are two examples, using historical data, which demonstrate the applications of the analytical formulae.

Role of Ce2Zr3O10 Phase on the Microstructure and Fracture Toughness of ZTA Composites

2016 ◽  
Vol 840 ◽  
pp. 57-60 ◽  
Author(s):  
Nik Akmar Rejab ◽  
Zhwan Dilshad Ibrahim Sktani ◽  
Afifah Mohd Ali ◽  
Zainal Arifin Ahmad
Keyword(s):  
Fracture Toughness ◽  
Experimental Results ◽  
Mixing Process ◽  
Transformation Toughening ◽  
Simple Route ◽  
Zirconia Toughened Alumina

Despite the impressive development in understanding transformation toughening, tailoring the toughness of zirconia toughened alumina (ZTA) ceramics remained a major challenge. In our research, a simple route based on the powders mixing process of ZTA powders with varying CeO2 additions (0 - 10 wt.%) is developed to investigate this issue. The experimental results clearly reveal that the fracture toughness of ZTA ceramics can be tailored by mixing of ZTA starting powders.

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 Libet’s experiments and the problem of free will

2016 ◽  
Vol 59 (4) ◽  
pp. 23-29
Author(s):  
Andrea Berber
Keyword(s):  
Free Will ◽  
Experimental Results ◽  
Readiness Potential ◽  
Real Effect

The purpose of this paper is to give an answer to the question of the extent to which Libet?s experiments are helping to solve the problem of free will. Relevance of Libet?s experimental results for the problem of free will is contested by the multitude of complaints. These complaints can be divided into three categories: methodological objections, conceptual objections and complaints regarding the interpretation of the role of readiness potential. I am trying to show that only objections that belong to the last group have a real effect. I conclude that Libet?s experiments while providing significant incentives and suggestions for further research did not contribute to solving the problem of free will.

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