Laboratory study of anchor ice evolution around rocks and on gravel beds

2007 ◽  
Vol 34 (1) ◽  
pp. 46-55 ◽  
Author(s):  
Y X Qu ◽  
J Doering
Keyword(s):  
Digital Cameras ◽  
Growth Forms ◽  
Laboratory Studies ◽  
Flow Conditions ◽  
Frazil Ice ◽  
Gravel Beds ◽  
Flow Parameters ◽  
Thermal Growth ◽  
Laboratory Results ◽  
Anchor Ice

A series of laboratory studies was carried out on anchor ice evolution around rocks and on gravel beds. Different arrangements of rocks were set on the flume bed, and two digital cameras were used to monitor the growth forms of anchor ice around the rocks. Evolution forms of anchor ice on gravel beds under different flow conditions were recorded. The results agree well with previous laboratory results. It was observed that anchor ice growth occurred mainly by frazil ice attachment. Thermal growth was also detected through the analysis of temperature curves recorded during experiments, although it is not readily observed from the digital images. In addition, anchor ice density was measured during the experiments. The relationships between flow parameters, such as the Froude number and the Reynolds number, and the density of anchor ice are explored and discussed.Key words: supercooling, turbulence, evolution, anchor ice densities, thermal growth.

Starch-modified fillers for linerboard and paper grades: A perspective review

TAPPI Journal ◽  
2010 ◽  
Vol 9 (4) ◽  
pp. 31-36 ◽  
Author(s):  
YULIN DENG ◽  
PHIL JONES ◽  
LESLIE MCLAIN ◽  
ART J. RAGAUSKAS
Keyword(s):  
Filler Content ◽  
Product Platform ◽  
Laboratory Studies ◽  
The Past ◽  
Development Opportunity ◽  
Laboratory Results ◽  
Addition Rate ◽  
Institute Of Technology ◽  
Paper Product ◽  
Detrimental Impact

High-filler-content paper is a growing research and development opportunity in papermaking. These new products must address traditional paper product properties while providing papermakers with distinct product platform benefits. Over the past decade, a research team involving researchers from the Institute of Paper Science and Technology at Georgia Institute of Technology and from Imerys have significantly advanced the application of starch-encapsulated papermaking fillers. This review summarizes these accomplishments from initial laboratory studies to mill trials. Laboratory results have illustrated that starch-encapsulated fillers can facilitate a near-doubling of filler content over conventional levels at equal tensile and z-direction tensile (ZDT) values. Equally important is that the use of starch-encapsulated kaolin (SEK) filler has been shown to facilitate a doubling of filler addition rate without any detrimental impact on ring crush compared with control studies with filler. Pilot-plant and mill trials have shown that SEK can function as a fiber extender, reduce steam demand for drying by 10%, and increase papermaking speeds and production rates.

Laboratory and field measurements of HONO emissions from agricultural soils in Guangdong of China 

2021 ◽  
Author(s):  
Baobin Han ◽  
Peng Cheng ◽  
Yihang Yu ◽  
Wenda Yang ◽  
Zhilin Tian ◽  
...  
Keyword(s):  
Emission Rate ◽  
Agricultural Soils ◽  
Pore Space ◽  
Primary Source ◽  
Field Measurements ◽  
Laboratory Studies ◽  
Release Rates ◽  
Laboratory Results ◽  
Flux Measurements ◽  
Soil Flux

<p>Laboratory studies indicated that soil could produce considerable nitrous acid (HONO) emissions, which is the main primary source of hydroxyl radical (OH) in the troposphere. However, very few field observations of HONO emission from soil were reported. In order to relate laboratory results and field measurements, we measured HONO emissions from 7 representative agricultural soils (rice, vegetables, orchards, peanuts, potatoes, sugarcane and maize) in Guangdong under controlled laboratory conditions, and took flux measurements on 2 of them (rice and vegetables) by dynamic chambers in the field. Generally, release rates of HONO from the seven soils increased with temperature and varied with soil moisture, and the optimum release rates can be reached under specific values of water-filled pore space (WFPS), which is considered to be beneficial to nitrification. The seven soils' optimum release rates ranged from 1.24 to 43.19 ng kg<sup>-1</sup> s<sup>-1</sup>, and the Q<sub>10</sub> (It is defined as the multiple of the increase of soil gas emission rate when the temperature increases by 10℃) ranged from 1.03 to 2.25. Formulas were deduced from the lab results to express HONO emissions for every soil. Flux measurements on two soils varied around -1 to 4 ng N m<sup>-2</sup> s<sup>-1</sup>, and both showed similar diurnal variations with peaks around noontime and very low even negative values during nighttime. There were good correlations between HONO fluxes and soil temperature (R<sup>2</sup>=0.5). Furthermore, irrigation enhanced the HONO emission substantially. However, a large discrepancy existed between soil HONO emissions measured in lab and low HONO fluxes in field. More investigations are needed to explain the paradox.</p>

An initial assessment of bed destabilization risk past vegetation patches using instrumented particles

2021 ◽  
Author(s):  
Yi Xu ◽  
Valyrakis Manousos ◽  
Panagiotis Michalis
Keyword(s):  
Initial Assessment ◽  
Flow Structures ◽  
Clear Water ◽  
Flow Conditions ◽  
Flow Parameters ◽  
Water Conditions ◽  
The Mean ◽  
Acoustic Doppler Velocimetry ◽  
Patch Density ◽  
Vegetation Patches

<p>Instream vegetation may alter the mean and turbukent flow fields leading to destabilizing riverbed surface, under certain flow conditions. In particular, recent research on instream vegetation hydrodynamics and ecohydrogeomorphology has focused on how energetic flow structures and bulk flow parameters downstream a vegetation may result in riverbed destabilization. This study, demonstrated the application of a 20mm novel instrumented particle in recording entrainment rates downstream simulated vegetation patches of distinct densities, at various distances downstream these. A patch of 6mm acrilic cylinders is used to simulate the emergent vegetation having the same diameter (12cm) and different porosities or densities (void volume equal to 1.25%, 3.15%, 6.25%, 11.25%, and 17.25%). The flow velocity near the instrumented particle is recorded using acoustic Doppler velocimetry (ADV) with appropriate seeding, under clear water conditions. Preliminary results are presented with focus on the effect of vegetation patch density on the flow field and subsequent effects on particle entrainment rates and implications for bed surface destabilisation.</p>

Existence Limits for Straight and Curved Interfaces Exposed to Temperature Gradients

2003 ◽  
Author(s):  
J. M. Floryan ◽  
M. El-Gammal
Keyword(s):  
Thermal Management ◽  
Extreme Values ◽  
Flow Conditions ◽  
Thermocapillary Effect ◽  
Initial Shape ◽  
Interface Deformation ◽  
Strongly Coupled ◽  
Flow Parameters ◽  
Flow Response ◽  
External Heating

Distortion of capillary interfaces exposed to external heating is analyzed. This problem is of interest in material processing under zero gravity conditions and in thermal management of spacecrafts. The analysis is focused on a model problem where thermocapillary effect is the dominant driving force. Flow response to an external heating consists of convection in the liquid and interface deformation, with both effects being strongly coupled. Detailed results are presented in the case of cavity with a free upper surface. It is demonstrated that large interface deformation and rupture represent the dominant response of such dynamical system if the interface is sufficiently long. Flow conditions corresponding to the limits points have been identified. Limit points identify extreme values of flow parameters that guarantee the existence of steady continuous interface. It is shown that rupture can be delayed by changing the mass of the fluid, i.e., changing the initial shape of the interface.

Analysis of Local Flow Structure and Global Compressor Performance During Rotating Stall

2004 ◽  
Author(s):  
Chiara Palomba
Keyword(s):  
Flow Field ◽  
Flow Structure ◽  
Rotational Speed ◽  
Axial Flow ◽  
Rotating Stall ◽  
Performance Parameters ◽  
Flow Conditions ◽  
Local Flow ◽  
Flow Parameters ◽  
Compressor Performance

Rotating stall is an instability phenomenon that arises in axial flow compressors when the flow is reduced at constant rotational speed. It is characterised by the onset of rotating perturbations in the flow field accompanied by either an abrupt or gradual decrease of performances. Although the flow field is unsteady and non axisymmetric, the global operating point is stable and a stalled branch of performance curve may be experimentally determined. The number, rotational speed, circumferential extension of the rotating perturbed flow regions named rotating cells may vary from one compressor to another and may depend on the throttle position. The present work focuses on the interaction between local flow parameters and global compressor performance parameters with the aim of reaching a better understanding of the phenomenon. Starting from the Day, Greitzer and Cumpsty [1] model the detailed flow conditions during rotating stall are studied and related to the global performance parameters. This is done both to verify if the compressor under examination fits to the model and if the detailed flow structure may highlight the physics that in the simple model may hide behind the correlation’s used.

scholarly journals A Radical-Free Approach to Teeth Whitening

2021 ◽  
Vol 9 (12) ◽  
pp. 148
Author(s):  
Mauro Pascolutti ◽  
Dileusa de Oliveira
Keyword(s):  
Hydrogen Peroxide ◽  
Laboratory Studies ◽  
Carbamide Peroxide ◽  
Hard Tissue ◽  
Surface Microhardness ◽  
Surface Profilometry ◽  
Tissue Effects ◽  
Laboratory Results

Background: Traditional bleaching agents based on hydrogen peroxide (HP) or carbamide peroxide (CP) have adverse soft and hard tissue effects. Objectives: This study tested a novel formulation of phthalimidoperoxycaproic acid (PAP) with additives to optimise its safety and effectiveness. Methods: A novel gel (PAP+) was formulated. Laboratory studies assessed effects of six 10-minute exposures to PAP+ vs. commercial CP and HP gels, using surface profilometry and microhardness. The effectiveness of PAP+ in vitro against complex polyphenol stains on enamel was compared to 6% HP. Results: Unlike HP gels, PAP+ gel did not erode enamel. Unlike both CP and HP gels, PAP+ gel did not reduce the surface microhardness of enamel. PAP+ gel on used on polyphenol stains was superior to 6% HP. In this model, six repeated 10-minute treatments with PAP+ gel could improve the shade by approximately eight VITA® Bleachedguide shades. Conclusions: These laboratory results support the safety and effectiveness of this new PAP formula and its use as an alternative to CP and HP with superior safety and effectiveness.

Non-Equilibrium Relaxing Gas Flow Behind Three Dimensional Unsteady Curved Shock Wave

1980 ◽  
Vol 35 (11) ◽  
pp. 1166-1170
Author(s):  
V. D. Sharma ◽  
Radhe Shyam
Keyword(s):  
Shock Wave ◽  
Unsteady Flow ◽  
Gas Flow ◽  
Three Dimensional ◽  
Flow Conditions ◽  
Shock Surface ◽  
Flow Parameters ◽  
Upstream Flow ◽  
Relaxing Gas ◽  
Non Equilibrium

Abstract A shock wave is assumed to exist in a three-dimensional unsteady flow of a relaxing gas. The variation of flow parameters at any point behind the shock surface is determined in terms of the shock geometry and the upstream flow conditions. The expressions for the vorticity and the curvature of a streak line at the rear of the shock surface are also determined in terms of the known quantities.

Algae concentrated by frazil ice: evidence from laboratory experiments and field measurements

1989 ◽  
Vol 1 (4) ◽  
pp. 313-316 ◽  
Author(s):  
D.L. Garrison ◽  
A.R. Close ◽  
E. Reimnitz
Keyword(s):  
Laboratory Experiments ◽  
Spatial Scales ◽  
Field Measurements ◽  
Small Scale ◽  
Natural Setting ◽  
Langmuir Circulation ◽  
Frazil Ice ◽  
Laboratory Results ◽  
Temporal And Spatial ◽  
High Concentrations

A number of studies have suggested that high concentrations of organisms in sea ice may be the result of harvesting and concentration by frazil ice. Laboratory experiments have shown that frazil ice can concentrate organisms from two to four times above levels in the underlying water. The concentrations in nature, however, can be considerably higher. The apparent discrepancy between laboratory results and field observations can be explained by the longer temporal and spatial scales that allow more contact of ice crystals with particles and with one another in the sea. It is also likely that small-scale circulation features, such as Langmuir circulation, enhance the ability of frazil ice to concentrate organisms in a natural setting.

Improvements of electroosmotic consolidation of soft clays by minimizing power loss at electrodes

2002 ◽  
Vol 39 (2) ◽  
pp. 399-408 ◽  
Author(s):  
Guy Lefebvre ◽  
Fabien Burnotte
Keyword(s):  
Electrical Potential ◽  
Soil Improvement ◽  
Laboratory Studies ◽  
Practical Applications ◽  
Soft Clays ◽  
Laboratory Setup ◽  
Laboratory Results ◽  
Electrode Contact ◽  
Important Amount ◽  
Soil Conductivity

Although it appears promising in many laboratory studies, electroosmotic consolidation of soft clays is seldom used in practical applications. A study of well-documented case records of field applications illustrates the difficulty of transmitting the electrical potential to the soil deposit through the use of electrodes. An important amount of the electrical potential is indeed lost at the soil–electrode contact. The loss of potential at this point has been studied in a laboratory setup designed to reproduce the conditions existing in the field during electroosmotic consolidation. The laboratory results confirm that only about a third of the electrical potential applied at the electrodes is effectively transmitted to the soil and available for electroosmotic consolidation. Moreover, the laboratory studies have shown that a chemical treatment to increase the soil conductivity at the soil–electrode contact can double the electrical potential effectively transmitted to the soil and greatly improve the performance of electroosmotic consolidation.Key words: electroosmosis, soft clays, consolidation, potential loss, electrode treatment, soil improvement.

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