Dropwise Condensation on/in High Roughness Structures

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Steve Q. Cai ◽  
Avijit Bhunia
Keyword(s):  
High Mobility ◽  
Average Diameter ◽  
Contact Angles ◽  
Surface Cleaning ◽  
Vapor Condensation ◽  
Dew Point ◽  
Dropwise Condensation ◽  
Research Attention ◽  
Hierarchical Roughness ◽  
The One

Water droplets on bio-mimicked hierarchical roughness exhibit superhydrophobic properties, such as large contact angles, minor dynamic hysteresis, and high mobility. Vapor condensation on such superhydrophobic surface enables rapid condensate removal and surface cleaning, thereby significantly enhancing the heat transfer coefficient. In this paper, research attention is given to dropwise condensation on/in specially designed one-tier and hierarchical roughness structures. Utilizing a normal optical tomographic system composed of a Sensi-Cam and a Nikon microscope, close-up visualization is conducted to characterize small condensate droplets, in size of a few micrometers, between structural units of roughness. Experimental snapshots show that, within the one-tier roughness, condensate droplets tend to stick to surrounding structures. Low mobility of these droplets extends their residence time, and therefore increases their average diameter. In comparison, surface energy of the hierarchical structure is significantly reduced. As a result, small condensate droplets behave nonsticky to their surroundings, which enable rapid drain of the droplets and accomplish self-cleaning of the structure. Because of high mobility, the droplet average diameter in the two-tier structure is smaller than those in the one-tire roughness. Condensation sites reach the maximum in the middle of the structure where dew point of moisture is reached. Less condensation droplets on both the top and bottom of the roughness are blamed to the unsaturated moisture and the reduced humidity, respectively.

scholarly journals Multi-Scale Minero-Chemical Analysis of Biomass Ashes: A Key to Evaluating Their Dangers vs. Benefits

2021 ◽  
Vol 13 (11) ◽  
pp. 6052
Author(s):  
Paola Comodi ◽  
Azzurra Zucchini ◽  
Umberto Susta ◽  
Costanza Cambi ◽  
Riccardo Vivani ◽  
...  
Keyword(s):  
Raw Materials ◽  
Average Diameter ◽  
Rietveld Analysis ◽  
Fly Ashes ◽  
Amorphous Content ◽  
Multi Scale ◽  
Italian Law ◽  
Polycyclic Aromatic ◽  
Mineralogical Study ◽  
The One

A multi-methodic analysis was performed on five samples of fly ashes coming from different biomasses. The aim of the study was to evaluate their possible re-use and their dangerousness to people and the environment. Optical granulometric analyses indicated that the average diameter of the studied fly ashes was around 20 µm, whereas only ~1 vol% had diameters lower that 2.5 µm. The chemical composition, investigated with electron probe microanalysis, indicated that all the samples had a composition in which Ca was prevalent, followed by Si and Al. Large contents of K and P were observed in some samples, whereas the amount of potentially toxic elements was always below the Italian law thresholds. Polycyclic aromatic hydrocarbons were completely absent in all the samples coming from combustion plants, whereas they were present in the fly ashes from the gasification center. Quantitative mineralogical content, determined by Rietveld analysis of X-ray powder diffraction data, indicated that all the samples had high amorphous content, likely enriched in Ca, and several K and P minerals, such as sylvite and apatite. The results obtained from the chemo-mineralogical study performed make it possible to point out that biomass fly ashes could be interesting materials (1) for amendments in clayey soils, as a substitution for lime, to stimulate pozzolanic reactions and improve their geotechnical properties, thus, on the one hand, avoiding the need to mine raw materials and, on the other hand, re-cycling waste; and (2) as agricultural fertilizers made by a new and ecological source of K and P.

FORMATION OF THE GENRE OF THE STORY IN THE CHERKESS LITERATURE: IDELOGICAL GUIDES AND THEMATIC REFERENCES

Kavkazologiya ◽  
2021 ◽  
pp. 219-288
Author(s):  
M.A. KHAKUASHEVA ◽  
◽  
L.B. KHAVZHOKOVA ◽  
Keyword(s):  
The Other ◽  
North Caucasus ◽  
Research Attention ◽  
The North ◽  
Initial Stage ◽  
Great Patriotic War ◽  
History Of ◽  
Formation And Evolution ◽  
The One ◽  
Artistic Analysis

The article examines some of the issues of the formation and evolution of the genre of the story in Circassian literature. The relevance of the study is due, on the one hand, to the insufficient development of the stated topic, on the other hand, to the need to identify trends in the development of national prose, starting from the problems of its genesis. In the center of research attention is the ideological and thematic orientation of the Circassian story mainly of the initial stage of evolution, i.e. Soviet era. In particular, the author examines the stories of S. Temirov, I. Amirokov, M. Adamokov, H. Gashokov and others, who laid the foundations of the genre in Circassian literature. During the indicated period, the Circassian tale was the first attempt to comprehend the problems of collective farms, youth brigades, the Soviet attitude to work, the range of urgent problems of young people, their aspirations, the formation of the criteria of Soviet morality. It also reflects various aspects of the Great Patriotic War, mainly as a war for independence. The research uses the method of artistic analysis. The results obtained can be used in compiling special courses on Adyghe (Kabardino-Circassian) prose, writing the history of the literature of the peoples of the North Caucasus.

Excellent Gas Sensing of CdS Nanowires Decorated with Ag Nanoparticles

2019 ◽  
Vol 19 (11) ◽  
pp. 7083-7088 ◽  
Author(s):  
Nan Zhang ◽  
Xiaohui Ma ◽  
Shengping Ruan ◽  
Yanyang Yin ◽  
Chuannan Li ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Ag Nanoparticles ◽  
Gas Sensing ◽  
Average Diameter ◽  
Sensing Properties ◽  
Gas Sensing Properties ◽  
Cds Nanowires ◽  
The Stability ◽  
Ethanol Sensing ◽  
The One

In this study, CdS nanowires (NWs)/Ag nanoparticle materials (CdS@Ag) with Schottky junction were synthesized by a simple process. The Ag nanoparticles with a diameter of 3–10 nm were uniformly scattered on the surface of CdS NWs with an average diameter of 30 nm. The gas sensing properties and the effect of Ag content and relative humidity on the ethanol sensing properties of CdS NWs were investigated in detail. When the relative humidity was below 60% RH, the sensor, especially the one based on [email protected], exhibited an enhanced ethanol sensing response and selectivity compared with that of pristine CdS NWs, which was believed that Ag catalyzed the reaction between ionized oxygen species and ethanol. However, excessive Ag content does not mean a higher response and even decreased the response. Also, the stability of CdS NWs and CdS@Ag NWs was also investigated, which were almost stable for four months.

Average Droplet Diameter Spatial Distribution in a Spray After Gas-Assisted Atomization

2010 ◽  
Author(s):  
Konstantin Pougatch ◽  
Martha Salcudean ◽  
Jennifer McMillan
Keyword(s):  
Droplet Diameter ◽  
Particle Diameter ◽  
Droplet Size Distribution ◽  
Average Diameter ◽  
Diameter Distribution ◽  
Nozzle Orifice ◽  
Average Value ◽  
Local Mean ◽  
The One ◽  
Experimental Findings

Gas-assisted atomization is used in many industries to produce finely dispersed droplets. Knowledge about the droplet size distribution guides the design and development of the nozzle as well as of the whole processes. This knowledge can be obtained through experimental and modeling works that usually complement each another. In this paper we present an application of the mathematical model previously developed for gas-assisted atomization to the prediction of the average droplet diameter distribution in a spray and compare the results with experimental findings. The model is based on a two-fluid Eulerian-Eulerian treatment of the motion of the phases with a catastrophic phase inversion (atomization). It also includes the compressibility effects for the gaseous phase and can be applied to both the flow through the nozzle-atomizer and to the dispersion of the spray. The model accounts for the break-up and coalescence of bubbles and droplets due to interfacial shear and collisions. The diameter of the particle (bubble or droplet) is represented by its local mean average value that varies throughout the flow field. Simulations are conducted for the flow of air and water through the convergent-divergent nozzle, which is similar to the one used in commercial fluid cokers, a bitumen upgrading apparatus, for steam-assisted atomization of bitumen. It is found that while there are wide experimentally observed local distributions of the particle diameter, the concept of the average diameter still allows for satisfactory predictions of its average values and spatial variations. In agreement with the experiments, the numerical model demonstrated that the largest droplet diameter is located in the axial area, and the diameter values reduce towards the periphery of the jet. In addition, the average diameter increases slightly and its radial variation becomes more uniform as the distance from the nozzle orifice increases.

THEORETICAL DESIGN OF LIGHT-EMITTING POLYMERS — SUBSTITUTION EFFECTS OF EXCITED STATE ORDERING OF POLYDIACETYLENE AND POLYACETYLENE

2006 ◽  
Vol 05 (spec01) ◽  
pp. 391-400 ◽  
Author(s):  
LIPING CHEN ◽  
XINJUAN HOU ◽  
LINGYUN ZHU ◽  
SHIWEI YIN ◽  
Z. SHUAI
Keyword(s):  
Excited States ◽  
High Mobility ◽  
Molecular Orbital Calculation ◽  
Electron System ◽  
Substitution Effects ◽  
Electron Model ◽  
Light Emitting ◽  
Correlated Electron ◽  
The One ◽  
Correlated Electron System

The excited states structure, essential in determining the light-emitting properties, in a correlated electron system behaves differently from the one-electron system. Previous investigations show that upon proper chemical substitution, the non-emissive polyacetylene (PA) can be designed to be strongly light-emitting materials. On the basis of the correlated quantum chemical calculations within the INDO/EOM-CCSD approach, we systematically studied both the pristine and substituted polydiacetylene (PDA) about the low-lying excited states orderings. PDA possesses high mobility, but it is non-emissive. We predict that it is impossible to cause PDA to be light-emitting. From these numerical results, we propose a simple and practical rule to design conjugated light-emitting polymers, which require only a molecular orbital calculation instead of sophisticated correlated calculations. This rule is derived from physical pictures of correlated electron model, and is found to be in agreement with the existing experiments for various substituted PA and poly(p-phenylenebutadiynylene) (PPPB).

scholarly journals Deuterium NMR and Raman Spectroscopic Studies on Conformational Behavior of Lipophilic Chains in the C12E3 / Decane / Water System

2002 ◽  
Vol 57 (6-7) ◽  
pp. 320-326 ◽  
Author(s):  
Akimitsu Tonegawa ◽  
Ayako Michiue ◽  
Takashi Masuda ◽  
Keiichi Ohno ◽  
Hiroatsu Matsuura ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Order Parameter ◽  
Water System ◽  
High Mobility ◽  
Spectroscopic Studies ◽  
Surfactant Molecule ◽  
Deuterium Nmr ◽  
Cross Sectional ◽  
Structure Changes ◽  
The One

The order parameter and the conformations of the lipophilic chains in the C12E3 / decane / water ternary system have been studied by deuterium NMR and C-D stretching Raman spectroscopy. The order parameter and the trans fraction of the C-C bond of decane molecules decrease steadily or remain nearly constant with increasing decane concentration without noticeable changes at the phase transitions. On addition of decanemolecules to the C12E3 /water system, the effective volume of the lipophilic part of a single surfactant molecule increases as a result of the penetration of the added decane molecules into the lipophilic layer, leading to a high mobility of the alkyl chain. To minimize the resulting increase in the effective cross-sectional area of a surfactant molecule, the molecular chains of the surfactant reorient remarkably in the concentration region near the phase transitions, and the shape of the self-organizing structure changes to the one with a larger packing parameter.

Self-Assembled Nano-Needles of Polyaniline, Efficient Structures in Controlling Electrical Conductivity

2011 ◽  
Vol 1312 ◽  
Author(s):  
Michael I. Ibrahim ◽  
Maria J. Bassil ◽  
Umit B. Demirci ◽  
Georges El Haj Moussa ◽  
Mario R. El Tahchi ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Oxidative Polymerization ◽  
Weight Ratio ◽  
High Mobility ◽  
Average Diameter ◽  
Xrd Analysis ◽  
Visible Range ◽  
Mobility Of Charge Carriers ◽  
Vis Spectroscopy ◽  
Size And Morphology

ABSTRACTPolyaniline (PANI) is one of the most interesting conducting polymers with a wide and controllable conductivity range, synthesized easily via chemical or electrical route, stable chemically and environmentally, having high absorption in the visible range and high mobility of charge carriers. Under different conditions, PANI morphology can be controlled yielding to the creation of nano-tubes, belts, rods, fibers and particles.In this study, the chemical oxidative polymerization which consists of mixing aniline hydrochloride (A-HCl) with ammonium peroxydisulfate (APS) was used to synthesize HCl doped PANI. Fixing the weight ratio A-HCl/APS defined by the IUPAC while varying their quantities leads to the formation of PANI nanoparticles with variable diameters. In addition, PANI nano-needles of 60 nm average diameter at the center are also obtained. Different methods are used to investigate of 1-D morphologies. The electrical conductivity of bulk PANI pellets is measured using the four-point probe technique. The absorption in the visible range of PANI particles and nano-needles is determined by UV-Vis spectroscopy. XRD analysis was performed to study the effect of PANI particle size and morphology on the crystallinity of the powder. Such structures could be used in hybrid solar cells for higher conversion efficiencies.

scholarly journals EFEKTIVITAS GEL EKSTRAK ETANOL BAWANG PUTIH (Allium sativum L.) TERHADAP BAKTERI Staphylococcus aureus

2020 ◽  
Vol 2 (2) ◽  
pp. 105-112
Author(s):  
Irene Puspa Dewi ◽  
Ilham Maslan Orde ◽  
Verawaty Verawaty
Keyword(s):  
Staphylococcus Aureus ◽  
Allium Sativum ◽  
Ethanol Extract ◽  
Average Diameter ◽  
Inhibition Zone ◽  
Traditional Medicines ◽  
Significant Difference ◽  
Irritation Test ◽  
Gel Preparation ◽  
The One

Garlic (Allium sativum L.) is one of the traditional medicines which has an antibacterial efficacy compound namely Allisin which is able to inhibit the growth of Staphylococcus aureus bacteria. This study aims to formulate the garlic bulb extract into a good gel preparation for use as an acne drug and to determine the antibacterial effectiveness of the ethanol extract of garlic gel against the bacterium Staphylococcus aureus using the wells method. The gel evaluation was carried out to meet the requirements with organoleptic test parameters, homogeneity, pH, spreadability, adhesion and irritation test. This study uses extracts of 10% and 20% concentrations, at each concentration being able to inhibit the growth of Staphylococcus aureus bacteria. In the formula, the concentration of 20% has a inhibition zone diameter of 1.59 cm and a concentration of 10% has a inhibition of 1.50 cm. Statistical test results using the One Way ANOVA test found that there was no significant difference between the average diameter of inhibition of garlic extract gel concentration of 10% with a concentration of 20%.

scholarly journals Effect of User Mobility upon Trust Building among Autonomous Content Routers in an Information-Centric Network

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Jerzy Konorski ◽  
Jakub Grochowski
Keyword(s):  
Autonomous Agents ◽  
High Mobility ◽  
Mobility Model ◽  
Trust Building ◽  
User Mobility ◽  
Negative Effect ◽  
Current Content ◽  
Content Availability ◽  
The One ◽  
Willingness To Cooperate

The capability of proactive in-network caching and sharing of content is one of the most important features of an information-centric network (ICN). We describe an ICN model featuring autonomous agents controlling the content routers. Such agents are unlikely to share cached content with other agents without an incentive to do so. To stimulate cooperation between agents, we adopt a reputation and trust building scheme that is able to explicitly account for both objective current content availability and subjective willingness to cooperate. The scheme is further complemented with a so-called one-time goodwill mechanism introduced to avoid penalizing agents failures to provide temporarily unavailable content. In a simulated ICN environment under a modified Random Waypoint user mobility model, we investigate the resiliency of the reputation and trust building scheme to subversion, that is, strategic (selfish or malicious) agents acquiring higher trust values than honest ones, for varying user mobility scenarios. The scheme proves resilient in low-mobility scenarios, while increased user mobility is shown to have a negative effect. The one-time goodwill mechanism partly remedies this for high-mobility scenarios. We validate the results by comparison with an existing reputation and trust building scheme and with an alternative user mobility model.

scholarly journals What is the best temperature-humidity index equation to indicate heat stress in crossbred dairy calves in a tropical environment?

2019 ◽  
Vol 49 (1) ◽  
Author(s):  
Fernanda Gatti de Oliveira Nascimento ◽  
Hellen Cris Pinto Aguiar ◽  
Gustavo Moya Rodrigues ◽  
Ednaldo Carvalho Guimarães ◽  
Mara Regina Bueno de Mattos Nascimento
Keyword(s):  
Heat Stress ◽  
Dew Point ◽  
Tropical Environment ◽  
Dairy Calves ◽  
Sensible Heat ◽  
Dew Point Temperature ◽  
Physiological Variables ◽  
Temperature Humidity Index ◽  
Humidity Index ◽  
The One

ABSTRACT: The aim of this study was to determine among nine temperature-humidity index (THI) equations, the one that best represents the effects of heat stress on crossbred dairy calves reared in a tropical environment. Twelve male and female calves, aged 20 to 60 days, and raised in a tropical pen were evaluated. Respiratory (RR) and heart rates (HR), rectal (RT), body surface (BST), dry bulb (Tdb) and wet bulb (Tbw) temperatures, partial vapor pressure (Pv), relative humidity (RH) and dew point temperature (Tpo) were quantified in the morning and afternoon. Nine THI equations were calculated. The highest correlation between physiological variables and this was used to select the best THI equation. Averages for nine THI equations, Tdb, Twb, Pv, Tdp, RR, HR, RT, and BST were higher in the afternoon than in the morning, whereas that for RH was the opposite. The highest values for RT occurred at temperatures above 26.4°C and when humidity was below 55.5%. The Tdb and Pv correlations with RR (0.697 and 0.707), RT (0.703 and 0.706) and BST (0.818 and 0.817) were significant and positive, whereas the RH correlations with the same physiological variables were significant and negative (-0.622, -0.590 and -0.638, respectively). The best index was the THI sensible heat-based ( T H I = 3.43 + 1.058 x T d b - 0.293 x R H + 0.0164 x T d b x R H + 35.7), which was significantly correlated with RR (r=0.668 and r²=0.446), HR (r=0.259 and r²=0.067), RT (r=0.693 and r²=0.479) and BST (r=0.807 and r²=0.650). In conclusion, the THI sensible heat-based equation best represents the effects of heat stress on crossbred dairy calves reared in a tropical environment.

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