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

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

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

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

Strategic planning for wood farming development (Case study: Urmia)

YesWood farming is one of the strategies of agricultural development programs to reform unsustainable exploitation of natural resources. Poplar is one of the known species for wood farming in the country. This species is fast-growing and has numerous Colognes has the ability to adapt to different climatic conditions. Fast growth, good economic returns and traditional agricultural knowledge, favorable habitat to agriculture are advantages of poplar for agricultural development. However, the result of previous studies indicates existing barriers to the development of plantation and its development need strategic planning. What seem essential today are strategies to overcome these obstacles. Accordingly, this present study with a holistic view trying to identify the strengths, weaknesses, opportunities and threats of poplar farming. And the most appropriate strategies for the development of poplar farming in Urmia have offered. This research was a Field study and conducted using questionnaires. In this study, strategies were defined using SWOT analysis and the strategies were prioritized using analysis network process. The results showed the history of poplar farming in this region is the most important benefit to development and the many uses for poplar wood is the next priority. Increasingly replacement of poplar farming with alternative cultures is one of the main weaknesses of poplar farming development in this region. After that long return of profitability in poplar farming is the second priority. The most important opportunities for the development were the development of credit specialists to support of poplar farming and the most important threat was lack of annual financing of farmers. Also the results of strategic prioritization showed, Modern irrigation methods to reduce water consumption and planning to teach correct principles of technical planting, farming and harvesting are considered as the most important strategies

On the Diameter and Girth of an Annihilating-Ideal Graph

Let $R$ be a commutative ring with $1\neq 0$ and $\Bbb{A}(R)$ be the set of ideals with nonzero annihilators. The annihilating-ideal graph of $R$ is defined as the graph $\Bbb{AG}(R)$ with the vertex set $\Bbb{A}(R)^{*} = \Bbb{A}(R)\setminus \{(0)\}$ and two distinct vertices $I$ and $J$ are adjacent if and only if $IJ = (0)$. In this paper, we first study the interplay between the diameter of annihilating-ideal graphs and zero-divisor graphs. Also, we characterize rings $R$ when ${\rm gr}(\Bbb{AG}(R))\geq 4$, and so we characterize rings whose annihilating-ideal graphs are bipartite. Finally, in the last section we discuss on a relation between the Smarandache vertices and diameter of $\Bbb {AG}(R)$.Comment: 11 pages, 1 figur

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)

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