Characterizations of friction welding joint interface for AISI 316

Because of heat amount is different from peripheral to central of friction welding interface, which is leaded to vary the characterizations along that interface. Current study, respectively, focused on the effect of different friction pressure on micro-structural and mechanical properties of that friction welding joint interface. Presently, these friction pressures are 110, 130, 150 and 170 MPa while kept all other conditions constant. The effects of different friction pressure on welding interface characterization were investigated by EDX, SEM, tensile, compression, impact and hardness tests. The tensile tests carried out on the standardized test piece with diameter 6 mm and 8 mm, thus, compression tests were extracted from the positions of 0°, 45° 90° with test specimen of 4 mm diameter and 6.5 mm length at weld center. Whereas, the impact test pieces were picked up in two positions, the first one is symmetrical, which it obtained to the respect of the rotation axis and the interface, on the other hand, the second one is non-symmetrical with the axis of rotation and symmetrical to the interface, for making the notch head coincide with the center of the welded joint, The obtained results showed that with reducing of friction pressure will present lack of bonding increasing from peripheral toward the welding center, which will responsible on reducing of the mechanical properties such as tensile, compression and impact strength.     

Study of planar structure applying reciprocity technique combined with MGEC and analysis of discontinuity

The 3D structure electromagnetic computation presents several difficulties related to the volume mesh. In fact, the entire volume space must be taken into account even the smallest details. In this article, we propose a formulation based on the reciprocity theorem combined with the generalized equivalent circuit method to model a planar 3D structure with both coaxial and planar excitation. The major advantage of this formulation is the fact to reduce the computational volume into 2D ones in the discontinuity plane. In addition, we focused on the calculation of the discontinuity between the excitation source and the planar structure to determine the exact behavior of the electric coaxial excitation model. The obtained current density, electric field distributions, and the input impedance are presented and discussed in the following sections. An approximately good agreement of input impedance with those obtained by the simulator and measurement is shown.     

Object-oriented query language access to relational databases: A semantic framework for query translation

This research investigates and approach to query processing in a multidatabase system that uses an objectoriented model to capture the semantics of other data models. The object-oriented model is used to construct a global schema, defining an integrated view of the different schemas in the environment. The model is also used as a self-describing model to build a meta-database for storing information about the global schema. A unique aspect of this work is that the object-oriented model is used to describe the different data models of the multidatabase environment, thereby extending the meta database with semantic information about the local schemas. With the global and local schemas all represented in an object-oriented form, structural mappings between the global schema and each local schema are then easily supported. An object algebra then provides a query language for expressing global queries, using the structural mappings to translate object algebra queries into SQL queries over local relational schema. The advantage of using an object algebra is that the object-oriented database can be viewed as a blackboard for temporary storage of local data and for establishing relationships between different databases. The object algebra can be used to directly retrieve temporarily-stored data from the object-oriented database or to transparently retrieve data from local sources using the translation process described in this paper.     

Positive vectors clustering using inverted Dirichlet finite mixture models

In this work we present an unsupervised algorithm for learning finite mixture models from multivariate positive data. Indeed, this kind of data appears naturally in many applications, yet it has not been adequately addressed in the past. This mixture model is based on the inverted Dirichlet distribution, which offers a good representation and modeling of positive non-Gaussian data. The proposed approach for estimating the parameters of an inverted Dirichlet mixture is based on the maximum likelihood (ML) using Newton Raphson method. We also develop an approach, based on the minimum message length (MML) criterion, to select the optimal number of clusters to represent the data using such a mixture. Experimental results are presented using artificial histograms and real data sets. The challenging problem of software modules classification is investigated within the proposed statistical framework, also.     

Fatty acids,sterols, and tocopherols composition in seed oil extracts from four moroccan ecotypes of Ceratonia siliqua L.

Morphological characterization was investigated by agro-morphological criteria related to carob seed size in four different moroccan regions collected in 2018 and 2019. There was no significant difference (p ≤ 0.05) on the seeds lengths and widths. However, a significant difference between seeds thickness and total seeds weight per pod (p ≤ 0.05) were observed between these four populations. The fatty acid, sterol, tocopherol, hydrocarbon, and the unoxygenated composition of carob seed extracts (Ceratonia siliqua L.) were studied. The mean fat yield of the seeds obtained is 1.53%–2.17%, 2.14%–2.15%, 1.61%–1.62%, 1.71%–1.75% for, respectively, the P1 (Meknes), P2 (Fez), P3 (Khemisset), and P4 (Marrakech) in 2018 and 2019. The seed oil was extracted with hexane and the analysis of the fatty fraction was performed by gas chromatography–mass spectrometry (GC–MS). Results show that the major fatty acids for 2018 and 2019 are linoleic acid (61.48%–61.52%, 52.12%–52.14%, 57.76%–58.15%, 61.33%–61.52%), palmitic acid (15.78%–15.81%, 16.44%–16.45%, 19.11%–18.37%, 20.24%–20.32%), oleic acid (11.03%–11.04%, 8.72%–8.82%, 8.51%–8.61%, 8.41%–8.53%), stearic acid (4.35%–3.14%, 5.40%–5.43%, 3.12%–3.13%, 0.96%–1.56%), and cerotic acid (0.62%–0.53%, 4.51%–4.52%, 4.03%–4.06%, 3.84%–3.87%). The unsaturated fatty acids (69.39% in 2018 and 69.68% in 2019) are the most dominant in the four seed extracts compared to the saturated fatty acids. In addition, the oil carob seeds analysis revealed the presence of γ-tocopherol, α-tocopherol and four sterols that included campesterol, stigmasterol, and β-sitosterol. Moreover, the determination of hydrocarbon and un-oxygenated compounds confirmed the existence of major compounds such as heptadecane, 2-methyltriacontane, 1-iodo hexadecane and 1-iodo octadecane. The hierarchical analysis based on the morphological and chromatographic characterization of the seeds allowed the identification of three groups. Consequently, the first group consisted of populations from Marrakesh (P4) and Khemisset (P3), the second group consisted of the P1 from Meknes, and the P2 from Fez constituted the third group.     

Biosorption potential of the mediterranean plant (Posidonia oceanica) for the removal of Cu2+ ions from aqueous media : Equilibrium,kinetic, thermodynamic and mechanism analysis

The biosorption characteristics of copper(II) ions using Posidonia oceanica biomass were investigated. Experimental parameters affecting the biosorption process such as pH level, contact time, biosorbent dosage and temperature were studied. The equilibrium data were applied to the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The Langmuir model fitted very well the equilibrium data, and the maximum uptake of Cu(II) by Posidonia oceanica was found to be 76.92 mg/g. The mean free energy E (10.78 kJ/mol) from the D-R isotherm indicated a chemical ion-exchange mechanism. Kinetic results showed that the pseudo-second-order kinetic model was well fitted to the experimental data. Thermodynamic parameters depicted the exothermic nature of biosorption and the process was feasible and spontaneous. The results of FTIR (Fourier-transform infrared spectroscopy) revealed that carboxyl, amine, and hydroxyl groups on the biomass surface were involved in the biosorption of Cu(II) ions.     

Discrimination des modes pour l’étude des discontinuités dans les circuits planaires

The study of the dispersion phenomena of a planar transmission line in boxed structure is very intricate. In this paper we will try to determine the origin of the different modes by varying the geometrical parameters of the structure at a given frequency. We will also study the complex modes and their effects on thee characterisation of the planar discontinuities.     

Modelling approaches for the estimation of irreducible water saturation and heterogeneities of the commercial Ashtart reservoir from the Gulf of Gabès, Tunisia

Oil production based on reserves in place in the Ashtart oilfield required the precise knowledge of the main reservoir parameters including porosity, permeability and irreducible water saturation. The reservoir series is comprised of Nummulitid but heterogeneous limestones of the El Garia Formation, the petrofacies texture, geometry and petrophysical parameters of which were apprehended using seismic profiles; gamma-ray and sonic lateral logs, as well as cores and cuttings taken in drillwells. The evaluation of residual oil saturation, multiphase flow and oil production techniques from the Ashtart reservoir also depend on variations and zoning of the irreducible water saturation. Estimation of the initial water saturation and hence variations in the capillary pressure in the reservoir, required compilations of porosity data measured on cores, supplemented by additional but computed porosities based on acoustic log diagrams. Furthermore, Gamma Ray, Sonic log, and well to well correlations tied to core results and well cuttings, help recognize the layered lithologies within the El Garia flat lying but stratified, Ypresian in origin reservoir rocks. Abundant permeability and porosity values compiled in the light of seismic sequence and Gamma Ray and Sonic log details, were integrated in an empirical approach using the Leverett J function, to model the irreducible water saturation depending on the capillary pressure distribution in the whole reservoir. Variations of this principal hydraulic parameter in a wide range (S_wir: 12 to 40%) compared to the preceding lithostratigraphic, petrographical and petrophysical results help recognize four main rock pore types in the commercial Ashtart reservoir. These vary from (1) a zone with a rock pore type showing an irreducible water saturation as low as 12%, and a fairly good reservoir character in the lower third part of the lithologic column which is thought to channelize a multiphase fluid flow in the global oilfield, (2) to those zones built-up of rock pore types with higher initial water saturation amounts which in certain cases tend to indicate zones of degraded reservoir. Our study suggests that diagenesis prevalently controls porosity, due to operative dissolutions of the Nummulitid tests/bioclasts, and cementation; moreover, diagenesis exerts effects on permeability by interconnecting intergranular and intratest pore spaces. In contrast, microfracturing enhances permeability of the reservoir. This is notably the case in the fairly permeable central zone in the Ashtart reservoir with excellent petrophysical parameters, but which were found to degrade gradually towards its peripheries.     

A vehicle plate recognition system based on deep learning algorithms

Multimedia Tools and Applications - In modern life, the massive number of vehicles makes it hard for a human being to process its related information. So, it is important to build an automatic...