An experimental study of the initial volumetric strain rate effect on the creep behaviour of reconstituted clays

Clayey soils tend to undergo continuous compression with time, even after excess pore pressures have substantially dissipated. The effect of time on deformation and mechanical response of these soft soils has been the subject of numerous studies. Based on these studies, the observed time-dependent behaviour of clays is mainly related to the evolution of soil volume and strength characteristics with time, which are classified as creep and/or relaxation properties of the soil. Apart from many empirical relationships that have been proposed in the literature to capture the rheological behaviour of clays, a number of viscid constitutive relationships have also been developed which have more attractive theoretical attributes. A particular feature of these viscid models is that their creep parameters often have clear physical meaning (e.g. coefficient of secondary compression, Cα). Sometimes with these models, a parameter referred to as initial/reference volumetric strain rate, v̇₀ has also been alluded as a model parameter. However, unlike Cα, the determination of v̇₀ and its variations with stress level is not properly documented in the literature. In an attempt to better understand v̇₀, this paper presents an experimental investigation of the reference volumetric strain rate in reconstituted clay specimens. A long-term triaxial creep test, at different shear stress levels and different strain rates, was performed on clay specimen whereby the volumetric strain rate was measured. The obtained results indicated the stress-level dependency and non-linear variation of v̇₀ with time

Cavitation in high-capacity tensiometers: effect of water reservoir surface roughness

High-capacity tensiometers (HCTs) are sensors made to measure negative pore water pressure (suction) directly. In this paper, a new approach is proposed to expand the range and duration of suction measurements for a newly designed HCT. A new technique is employed to reduce significantly the roughness of the diaphragm’s surface on the water reservoir side in order to minimise the possibility of gas nuclei development and the subsequent early cavitation at the water–diaphragm interface. The procedures employed for the design, fabrication, saturation and calibration of the new tensiometers are explained in detail. Furthermore, the performance of the developed HCTs is examined based on a series of experiments carried out on a number of unsaturated clay specimens. An improvement in maximum sustainable suction in the range of 120–150% of their nominal capacity was obtained from different surface treatment methods. Moreover, the results show an improvement of up to 177% for the long-term stability of measurements, compared to the developed ordinary HCTs with untreated diaphragms

Oil Spill Detection Analyzing “Sentinel 2“ Satellite Images: A Persian Gulf Case Study

Oil spills near exploitation areas and oil loading ports are often related to the ambitions of governments to get more oil market share and the negligence at the time of the loading in large tankers or ships. The present study investigates one oil spill event using multi sensor satellite images in the Al Khafji (between Kuwait and Saudi Arabia) zone. Oil slicks have been characterized with multi sensor satellite images over the Persian Gulf and then analyzed in order to detect and classify oil spills in this zone. In particular this paper discusses oil pollution detection in the Persian Gulf by using multi sensor satellite images data. Oil spill images have been selected by using Sentinel 2 images pinpointing oil spill zones. ENVI software for analysing satellite images and ADIOS (Automated Data Inquiry for Oil Spills) for oil weathering modelling have been used. The obtained results in Al Khafji zone show that the oil spill moves towards the coastline firstly increasing its surface and then decreasing it until reaching the coastline

Tetramethylammonium hydroxide (TMAH) as an efficient catalyst for the one-pot synthesis of 1,2-dihydro-1-aryl- naphtho[1,2-e][1,3]oxazine-3-ones under solvent-free conditions

1,2-Dihydro-1 -arylnaphtho[1,2-e][1,3]oxazine-3-one derivatives were synthesized in high yields using an efficient and one-pot condensation of 2-naphthol, aromatic aldehydes and urea catalyzed by tetramethylammonium hydroxide (TMAH) under solvent-free conditions. KEY WORDS: TMAH, Naphthoxazine-3-one, Solvent-free reaction, 2-Naphthol, Multi-component reactions Bull. Chem. Soc. Ethiop. 2016, 30(1), 161-164.DOI: http://dx.doi.org/10.4314/bcse.v30i1.1

Impact of loss on the wave dynamics in photonic waveguide lattices

We analyze the impact of loss in lattices of coupled optical waveguides and find that in such case, the hopping between adjacent waveguides is necessarily complex. This results not only in a transition of the light spreading from ballistic to diffusive, but also in a new kind of diffraction that is caused by loss dispersion. We prove our theoretical results with experimental observations.Comment: Accepted for publication in PRL, 5+8 pages (Paper + Supplemental material), 4 figure

The algebraic hyperstructure of elementary particles in physical theory

Algebraic hyperstructures represent a natural extension of classical algebraic structures. In a classical algebraic structure, the composition of two elements is an element, while in an algebraic hyperstructure, the composition of two elements is a set. Algebraic hyperstructure theory has a multiplicity of applications to other disciplines. The main purpose of this paper is to provide examples of hyperstructures associated with elementary particles in physical theory.Comment: 13 page

Canola traits and some soil biological parameters in response to fertilization and tillage management

This study describes the effects of fertilization and tillage methods on soil microbial community and canola traits. A field experiment was carried out in 2009 to 2010 growing season. Experiments were arranged in a split plot based on randomized complete block design with three replications. Main plots consisted of no tillage (T1), minimum tillage (T2) and conventional tillage (T3). Six strategies for obtaining the basal fertilizer requirement including (N1): farmyard manure; (N2): compost; (N3):chemical fertilizers; (N4): farmyard manure + compost; (N5): farmyard manure + compost + chemical fertilizers and (N6): control, were arranged in sub plots. Results show that the activities of all enzymes were generally higher in the N4 treatment than in the unfertilized and chemical fertilizer treatments. The phosphatase, catalase and urease activities in the N3 treatment were significantly lower than in the farm yard manure (FYM) and compost treatments (CT). The activity of all enzyme activity tended to be higher in the NT treatment. The highest leaf N, P and K containing grain and grain yield was obtained from N5 treatment. Applying CT system caused to a reduction in grain yield as compared with chisel plowing.Key words: Enzyme activity, compost, farmyard manure, tillage

THE SMARANDACHE VERTICES OF THE COMAXIMAL GRAPH OF A COMMUTATIVE RING

The concept of a Smarandache vertex (or S-vertex for short) in a (simple) graph (Definition 2.5) was first introduced by the second author [8] in order to study the Smarandache zero-divisors of a commutative ring which was introduced by Vasantha Kandasamy in [10] for semigroups and rings (not necessarily commutative)

Effect of different levels and particle sizes of perlite on serum biochemical factors of broiler chicks

The objective of this study was to investigate the effects of different levels and particle sizes of perlite in broiler chicks’ diets on serum biochemical factors. For the stated purpose, 280 day-old Ross 308 broiler chicks were allocated to seven treatments and four replications in a factorial experiment on the basis of randomized complete block design. One factor consisted of two levels (perlite particle sizes of 1.5 and 3 mm) and the other factor included three levels of perlite (1, 3 and 5% of diet). A control treatment with no perlite was also included in the experiment. Based on the results obtained, the perlite levels and particle sizes did not affect the serum Ca, P, Cl, Na and Fe, however, they influenced the serum Mg and K significantly (P < 0.05). It seems that perlite did not have any major impact on the biochemical factors of chick's serum.Key words: Perlite, aluminosilicate, particle size, serum biochemical factors