Laboratory experiments evaluating sedimentation and mound formation of obliquely discharged sand particles in stagnant water

2019 ◽  
Vol 34 (6) ◽  
pp. 564-576 ◽  
Author(s):  
Masoud Manzouri ◽  
Amir Hossein Azimi
Keyword(s):  
Laboratory Experiments ◽  
Stagnant Water ◽  
Sand Particles ◽  
Mound Formation

Compaction of dune sand backfill by concrete shaft vibrators

1992 ◽  
Vol 29 (2) ◽  
pp. 315-321 ◽  
Author(s):  
S. Idris Mirza
Keyword(s):  
Key Words ◽  
Field Test ◽  
Laboratory Experiments ◽  
Full Scale ◽  
Thin Layers ◽  
Regular Grid ◽  
Dune Sand ◽  
Grid Pattern ◽  
Scale Field ◽  
Sand Particles

Backfilling is a time-consuming operation at any construction project. Because of construction constraints and to minimize excavation and backfilling costs, utility trenches are made as narrow as practicable, which precludes the use of large compactors. The backfill is therefore placed in thin layers and compacted with hand compactors, making backfilling a slow operation. This paper presents the details of development of a fast, effective, and reliable backfill compaction procedure. This method is based on the concept that the sand being a cohesionless material can be easily densified under its own weight by mere vibrations if the intergranular friction between the sand particles is reduced. The method allows placement of saturated dune sand backfill in lifts up to 1 m in thickness, and the compaction is achieved by vibrating the mass by inserting concrete shaft vibrators on a regular grid pattern. The results and analysis of numerous laboratory experiments and 13 full-scale field test trials which form the basis of this compaction technique are also included in this paper. Key words : backfilling, dune sand, intergranular friction, vibrations, concrete shaft vibrators.

Washout of Fine Sand Particles From a Ceramic Tile Roof: Laboratory Experiments Under Simulated Rainfall

2017 ◽  
Vol 228 (9) ◽  
Author(s):  
Alexandre Silveira ◽  
João L. M. P. de Lima ◽  
João R. C. B. Abrantes ◽  
Babar Mujtaba
Keyword(s):  
Ceramic Tile ◽  
Laboratory Experiments ◽  
Fine Sand ◽  
Simulated Rainfall ◽  
Sand Particles

Covering of cometary nucleus by refractory crust and its evolution into asteroid-like body

1999 ◽  
Vol 173 ◽  
pp. 365-370
Author(s):  
Kh.I. Ibadinov
Keyword(s):  
Laboratory Experiments ◽  
Cometary Nucleus ◽  
Sublimation Rate ◽  
Cometary Nuclei ◽  
Short Period Comet ◽  
Short Period ◽  
Brightness Decrease ◽  
Crust Thickness ◽  
Ice Sublimation ◽  
Period Comet

AbstractFrom the established dependence of the brightness decrease of a short-period comet dependence on the perihelion distance of its orbit it follows that part of the surface of these cometary nuclei gradually covers by a refractory crust. The results of cometary nucleus simulation show that at constant insolation energy the crust thickness is proportional to the square root of the insolation time and the ice sublimation rate is inversely proportional to the crust thickness. From laboratory experiments resulted the thermal regime, the gas productivity of the nucleus, covering of the nucleus by the crust, and the tempo of evolution of a short-period comet into the asteroid-like body studied.

Chemical Classification and Particle Sizing of Foundry Sands

1985 ◽  
Vol 43 ◽  
pp. 388-389
Author(s):  
D.S. DeMiglio
Keyword(s):  
Image Analysis ◽  
Energy Dispersive Spectrometer ◽  
Image Analysis System ◽  
Representative Sampling ◽  
Foundry Sands ◽  
Large Atomic Number ◽  
Backscattered Electron ◽  
Sand Particles ◽  
Analysis System ◽  
Reclamation System

Much progress has been made in recent years towards the development of closed-loop foundry sand reclamation systems. However, virtually all work to date has determined the effectiveness of these systems to remove surface clay and metal oxide scales by a qualitative inspection of a representative sampling of sand particles. In this investigation, particles from a series of foundry sands were sized and chemically classified by a Lemont image analysis system (which was interfaced with an SEM and an X-ray energy dispersive spectrometer) in order to statistically document the effectiveness of a reclamation system developed by The Pangborn Company - a subsidiary of SOHIO.The following samples were submitted: unreclaimed sand; calcined sand; calcined & mechanically scrubbed sand and unused sand. Prior to analysis, each sample was sprinkled onto a carbon mount and coated with an evaporated film of carbon. A backscattered electron photomicrograph of a field of scale-covered particles is shown in Figure 1. Due to a large atomic number difference between sand particles and the carbon mount, the backscattered electron signal was used for image analysis since it had a uniform contrast over the shape of each particle.

When Does Voice Have to be More Than Only Listening? Procedural Justice Effects as a Function of Confident Leadership

2010 ◽  
Vol 9 (2) ◽  
pp. 69-78 ◽  
Author(s):  
David De Cremer ◽  
Maarten Wubben
Keyword(s):  
Procedural Justice ◽  
Interaction Effect ◽  
Laboratory Experiments ◽  
Negative Emotions

The present research examined how voice procedures and leader confidence affect participants’ negative emotions and willingness to withdraw. It was predicted that receiving voice would be valued out of instrumental concerns, but only when the enacting leader was high in confidence. Two laboratory experiments indeed showed an interaction between type of voice (pre-decisional vs. post-decisional) and leader’s confidence (low vs. high) on participants’ negative emotions and willingness to withdraw. In particular, post-decision voice only led to more negative responses than did pre-decision voice when the enacting leader was high in confidence. Negative emotions mediated this interaction effect of type of voice on willingness to withdraw. Implications for integrating the leadership and procedural justice literatures are discussed.

Review of Laboratory Experiments in Psychology.

1968 ◽  
Vol 13 (10) ◽  
pp. 536-536
Author(s):  
Peter G. Polson
Keyword(s):  
Laboratory Experiments
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