A Novel Approach for Prediction of Monthly Ground Water Level Using a Hybrid Wavelet and Non-Tuned Self-Adaptive Machine Learning Model

Water Resources Management - In recent decades, due to groundwater withdrawal in the Kabodarahang region, Iran, Hamadan, hazardous events such as sinkholes, droughts, water scarcity, etc., have...     

Synergistic effect of nanoparticles and Thalassospira sp. isolated from Bahregan area in biodegradation of oil sludge

Oil sludge is obtained from the contaminated site of Bahregan area in the Persian Gulf in Iran. Chemotaxis was used for the isolation of alkane-degrading bacteria from oil sludge and the alk genes were determined with specific primers. bac1 identified in Thalassospira was selected as a powerful strain for biodegradation of oil sludge. Biodegradation of oil sludge by bac1 in the presence of nanoparticles was investigated by GC-MS analysis. Synergistic effect of Fe₂O₃ and Fe₃O₄ nanoparticles on bacteria increases the biodegradation of oil sludge and produces cyclosiloxane compound which is used in the field of medicine; however, the Thalassospira reduced its toxicity in the environment.     

Revisiting the free transverse vibration of embedded single-layer graphene sheets acted upon by an in-plane magnetic field

Murmu et al. [23] recently presented a nonlocal model for the transverse vibration of simply supported graphene sheets in the presence of a unidirectional in-plane magnetic field. Further studies showed that the majority of Lorentz’s force components were improperly provided and led to invalid governing equations. To remove such deficiencies, the most general form of Lorentz’s force components is carefully extracted in the present work. The nonlocal equations of motion of the problem are reconstructed and solved again. The influences of crucial parameters on the flexural frequencies of magnetically affected graphene sheets and nanoribbons are examined in detail. Furthermore, the crucial discrepancies between the results obtained in this study and those of the abovementioned previous work are rationally discussed. Some erroneous results of the latter are also rectified.     

An efficient extraction and clean‐up procedure for pesticide determination in olive oil

This work reports a simple, rapid, and effective extraction method based on liquid–liquid extraction (LLE) followed by matrix solid‐phase dispersion‐sonication for detection, identification and quantification of multiclass pesticides in virgin olive oil using liquid chromatography mass spectrometry (LC‐QTOF‐MS). LLE to extract pesticide residues in virgin olive oil was performed in order to study the centrifugation efficiency to obtain high recovery yield and low co‐extract fat residue in the final extract. Different suitable parameters of MSPD procedure were evaluated, such as nature of dispersing phase, clean‐up adsorbent, and volume of eluting solvent (acetonitrile) in different extraction conditions, with or without sonication. The best results were obtained using 5 g of virgin olive oil, 2 g of PSA as dispersant sorbent, 2 g of Florisil/GCB (70:30 w/w) as clean‐up sorbent, and 15 mL of acetonitrile as eluting solvent under conditions of 15 min ultrasonic bath at RT. Method validation was performed in order to study sensitivity, linearity, precision, and accuracy. Average recoveries ranged between 73.7 and 104.2% with relative SDs 5.3–13.4% at three concentration levels (25, 50, and 100 µg/kg). Detection and quantification limits ranged from 1.5 to 5 µg/kg and 3 to 9 µg/kg, respectively.     

Discrete versus Smeared versus Element-Embedded Crack Models on Ring Problem

Three different concepts in finite-element modeling are compared by analyzing a thick-walled concrete ring subjected to an internal pressure. These are the discrete crack, the fixed smeared crack, and an element-embedded crack model called the inner softening band (ISB) model. The results are compared with experimental studies on rings of both normal- and high-strength concrete mixtures with and without spiral reinforcement. The ISB analysis gives the best results with respect to explaining the fracture mechanism as well as consistency in prediction of the ring capacity. The smeared crack model also provides satisfactory results, but in the light of robustness in geometrical modeling and requirement of minimum amount of input data (which all have a physical relevance) the ISB concept in this case is more reliable. The study exposed some deficiencies of the discrete crack method based on the fact that the localization processes and the strain redistribution in the body are often unknown. This also underlines caution in assuming symmetry when softening occurs on a structural level.     

A novel design of 8-bit adder/subtractor by quantum-dot cellular automata

Application of quantum-dot is a promising technology for implementing digital systems at nano-scale. QCA supports the new devices with nanotechnology architecture. This technique works based on electron interactions inside quantum-dots leading to emergence of quantum features and decreasing the problem of future integrated circuits in terms of size. In this paper, we will successfully design, implement and simulate a new full adder based on QCA with the minimum delay, area and complexities. Also, new XOR gates will be presented which are used in 8-bit controllable inverter in QCA. Furthermore, a new 8-bit full adder is designed based on the majority gate in the QCA, with the minimum number of cells and area which combines both designs to implement an 8-bit adder/subtractor in the QCA. This 8-bit adder/subtractor circuit has the minimum delay and complexity. Being potentially pipeline, the QCA technology calculates the maximum operating speed.     

Cooperative multiple relay system for frequency selective environment: outage analysis and power allocation

In this paper, we propose a novel cooperative relaying scheme with multiple relays for frequency selective wireless environment. In our proposed scheme, the frequency selective wireless channel is divided into flat fading sub‐channels. Cooperative relaying is then employed over each sub‐channel to improve the system diversity order. We then investigate the asymptotic behavior of the outage probability and show that the proposed scheme achieves full diversity order in both amplify and forward (AF) and adaptive decode and forward (ADF) relaying scenarios. Furthermore, we propose a power allocation strategy to minimize the system outage probability. Simulation results confirm our analysis and show that the proposed power allocation method outperforms uniform power allocation. Copyright © 2010 John Wiley & Sons, Ltd.     

The Design of Electromagnetic Flowmeter Probes with Homogeneous Luminal Magnetic Fields

Inhomogeneities in magnetic field density are not very critical in pulsating arterial flow, but may be an important consideration in venous flow and branch or asymmetric flow. In this regard, a blood flow probe design has been developed with a magnetic field distribution which varies less than 1% across the lumen. It is shown that the luminal fields of two commercially available probes vary as much as 25%.     

Numerical analysis of crack propagation in tension specimens of concrete considered as a 2D multicracked granular composite

A numerical model is presented to study the mechanisms of microcrack propagation in concrete, the load-displacement response and the trajectories of the crack propagation in specimens under displacement control. The microstructure of concrete in this model is represented by a matrix, inclusions and pre-existing microcracks introduced around the inclusions. Both the matrix and the inclusions are assumed to be elastic, homogeneous brittle materials. The stiffness of the inclusions is considered to be three times higher than that of the matrix. Crack propagation in the numerically-generated concrete is controlled by fracture mechanics-based criteria and is calculated through the finite element method. The influence of the microstructure of concrete, the size and the distribution of grains, the properties of the interfacial zone between grains and the matrix, as well as the boundary conditions, on final crack patterns and load-displacement responses are investigated. The different appearance of the numerical load-displacement curves exhibiting the quasi-brittle behaviour observed in experiments is explained in terms of several points of view, especially the dynamic crack propagation.

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Résumé On présente un modèle numérique que l’on applique à l’étude des mécanismes de la microfissuration du béton, de la réponse en termes de courbe effort-déplacement et des trajectoires de propagation des fissures dans des éprouvettes en déplacement imposé. La microstructure du béton est représenté par une matrice, des inclusions et des microfissures introduites dans la matrice autour des inclusions. Dans ce modèle, la matrice et les inclusions sont considérées comme étant homogènes, élastiques et fragiles. La rigidité des inclusions est trois fois plus grande que celle de la matrice. La propagation des microfissures dans ce modèle numérique du béton est effectuée selon les critères de la mécanique linéaire élastique de la rupture par la méthode des éléments finis. On étudie l’influence de la microstructure du béton, notamment des auréoles de transition, de la taille et la distribution des grains, ainsi que des conditions aux limites imposées aux éprouvettes sur le trajet des fissures et sur l’allure des courbes effort-déplacement. Les résultats obtenus mettent en évidence le comportement semi-fragile observé lors des essais. Ce comportement a été expliqué par différentes causes et notamment par la propagation dynamique des fissures.

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Editorial note J. Wang, P. Navi and C. Huet work at the Laboratory of Building Materials (EPFL), Lausanne, Switzerland, which is a RILEM Titular Member Prof. Huet is a RILEM Senior Member and active on RILEM Technical Committees 107-GCS on Guideliness for the formulation of Creep and Shrinkage prediction models, 114-CCS on Computer programmes for Creep and Shrinkage analysis of concrete structures and 123-MME on Use of Microstructural Models and Expert systems for cementitious materials. Dr. Navi is also a member of Technical Committee 123-MME, as well as 133-TF on Fracture of Timber.