Heat Treatment Process Study and ANN-GA Based Multi-Response Optimization of C45 Steel Mechanical Properties

Aissa Laouissi,Mohammed Mossaab Blaoui,Hammoudi Abderazek,Mourad Nouioua,Ali Bouchoucha 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.12

The main purpose of the present investigation is to achieve an optimization of the heat treatment process along with improvingthe mechanical properties of Medium-carbon steel C45 illustrated by the tensile strength (Ts), the hardness (HV) andthe elongation (A). This is performed through varying three necessary factors represented by the quench temperature, theholding time and the cooling medium (air, oil and acid solution). An experimental design illustrated by the performance of27 ( ]] ><![CDATA[33 ) tests was adopted for the planning of the experiments. The Response Surfaces Methodology (RSM),the Neural Networks Approach (ANN) and the Genetic Algorithm (GA) were selected for the modeling and optimization ofthe heat treatment process. Analysis of Variance (ANOVA) results show the cooling medium to have the greatest influenceon the mechanical properties of C45 steel with contributions of 47.34% to 74.3%. The experimental results demonstratethat heating at a temperature of T = 800 ◦C for 30 minutes and then performing a quenching in the acid solution gives largevalues of both Ts and HV, and achieves Ts = 1060MPa and HV = 825.

Poster Session : PS 0723 ; Rheumatology ; Splenic Infarcts in a Patient with Systemic Lupus Erythematosus and Autoimmune Phospholipid Syndrome: A Case Report

( Aissa Althea Flavier Hundal ),( Ashish Anil Sule ),( Annamarie Borja ) 대한내과학회 2014 대한내과학회 추계학술대회 Vol.2014 No.1

Background: Systemic lupus with antiphospholipid syndrome is associated with thrombotic manifestations. There is little literature on lupus with anitiphospholipid syndrome patients presenting with splenic infarctions. Case Presentation: This is a case of a 28-year-old Chinese Female who presented with fever, night sweats and splenomegaly and lymphadenopathies. Investigations showed Hemoglobin of 6. 1g/dL, total white cell 8. 1x109/L, Platelets 300x109/L, Absolute Reticulocyte count 182. 5, Direct coombs positive, Bilirubin 12, Lactate Dehydrogenase 1264, Haptoglobin 15, ANA-IFA 640, homogenous pattern, Anti-ds-DNA >200, Lupus anti -coagulant and anti-cardiolipin positive. CT abdomen and pelvis showed splenomegaly with multiple hypodense lesions as well as abdominal and retroperitoneal adenopathy. CT neck was also done which showed polypoidal soft tissue in the nasopharynx. She underwent post-nasal space biopsy, which was negative of malignancy. She had bone marrow aspiration, which revealed hypercellular marrow with increase erythropoesis consistent with peripheral destruction. She also went for biopsy of the spleen, which was negative for tuberculosis and malignancy or lymphoma. Patient was then started on steroids for treatment of systemic lupus erythematosus with autoimmune phospholipid syndrome and showed clinical improvement. Discussion: Splenic hypodensities are usually benign and differential diagnoses include cysts, infarction, metastases, lymphomas, hamartomas, haemangiomas and tuberculosis. In a large, multicenter study, involving 1,000 adult patients with antiphospholipidsyndrome, spleen infarct was present in only 1. 1% of patients. Given the history of fever, splenomegaly and elevated serum lactate dehydrogenase, this case illustrates apossibility of splenic infarctions on the background of a hypercoagulable state, specifi - cally antiphospholipid syndrome. Conclusion: Hypodensities in the spleen in a patient with lupus can be associated with antiphospholipid syndrome with splenic infarctions. It would be necessary to rule out metastases, tuberculosis and lymphoma as differential diagnoses in such cases.

Predicting and analysis of interfacial stress distribution in RC beams strengthened with composite sheet using artificial neural network

Bensattalah Aissa,Benferhat Rabia,Hassaine Daouadji Tahar 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.87 No.6

The severe deterioration of structures has led to extensive research on the development of structural repair techniques using composite materials. Consequently, previous researchers have devised various analytical methods to predict the interface performance of bonded repairs. However, these analytical solutions are highly complex mathematically and necessitate numerous calculations with a large number of iterations to obtain the output parameters. In this paper, an artificial neural network prediction models is used to calculate the interfacial stress distribution in RC beams strengthened with FRP sheet. The R2value for the training data is evaluated as 0.99, and for the testing data, it is 0.92. Closed-form solutions are derived for RC beams strengthened with composite sheets simply supported at both ends and verified through direct comparisons with existing results. A comparative study of peak interfacial shear and normal stresses with the literature gives the usefulness and effectiveness of ANN proposed. A parametrical study is carried out to show the effects of some design variables, e.g., thickness of adhesive layer and FRP sheet.

Agriculture in Tunisia: The challenge between Resources and Climate

( Imed Ben Aissa ),( Mansour Mohsen ) 한국국제농업개발학회 2011 한국국제농업개발학회 춘계학술발표논문집 Vol.2011 No.-

Application of Multivariate Statistics and Geostatistical Techniques to Identify the Distribution Modes of the Co, Ni, As and Au-Ag ore in the Bou Azzer-East Deposits (Central Anti-Atlas Morocco)

Souiri, Muhammad,Aissa, Mohamed,Gois, Joaquim,Oulgour, Rachid,Mezougane, Hafid,El Azmi, Mohammed,Moussaid, Azizi The Korean Society of Economic and Environmental G 2020 자원환경지질 Vol.53 No.4

The polymetallic Co, Ni, Cu, As, Au, and Ag deposits of Bou Azzer East are located in the western part of the Bou Azzer inlier in the Central Anti Atlas, Morocco. Six stages of emplacement of the mineralization have been identified. Precious metals (native gold and electrum) are present in all stages of this deposit except the early nickeliferous stage. From the Statistical analysis of the Co, As, Ni, Au, and Ag contents of a set of 501 samples, shows that the Pearson correlation coefficient between As-Co elements (0.966) is the highest followed by that of the Au-Ag couple (0.506). Principal component analysis (PCA) and hierarchical ascending classification (HAC) of the grades show, that Ni is associated with the pair (As-Co) and Cu is rather related to the pair (Au-Ag). The kriging maps show that the highest values of the Co, As and Ni appear in the contact of the serpentinite with other facies, as for those of Au and Ag, in addition to anomalous zones concordant with those of Co, Ni and As, they show anomalies at the extreme South and North of the study area. The development of the anomalous Au and Ag zones is mainly along the N40-50°E and N145°E directions.

Combined Relay Selection and Cooperative Beamforming for Physical Layer Security

Junsu Kim,Aissa Ikhlef,Robert Schober 한국통신학회 2012 Journal of communications and networks Vol.14 No.4

In this paper, we propose combined relay selection and cooperative beamforming schemes for physical layer security. Generally, high operational complexity is required for cooperative beamforming withmultiple relays because of the required information exchange and synchronization among the relays. On the other hand, while it is desirable to reduce the number of relays participating in cooperative beamforming because of the associated complexity problem, doing so may degrade the coding gain of cooperative beamforming. Hence, we propose combined relay selection and cooperative beamforming schemes, where only two of the available relays are selected for beamforming and data transmission. The proposed schemes introduce a selection gain which partially compensates for the decrease in coding gain due to limiting the number of participating relays to two. Both the cases where full and only partial channel state information are available for relay selection and cooperative beamforming are considered. Analytical and simulation results for the proposed schemes show improved secrecy capacities compared to existing physical layer security schemes employing cooperative relays.

Hydrothermal alterations of the Bou Azzer East Co-Ni-As-Au deposits (central Anti-Atlas, Morocco)

Muhammad Souiri,Mohamed Aissa,Ahmed H. Ahmed,Mohammed El Azmi,Hafid Mezougane,Azizi Moussaid,Abdelaziz El Basbas 한국지질과학협의회 2021 Geosciences Journal Vol.25 No.5

The polymetallic Co, Ni, Cu, Zn, Au and Ag deposits of Bou Azzer East is linked to Bou Azzer ophiolite located in the Central Anti Atlas. The ultramafic rocks are strongly deformed and altered by serpentinization, carbonatization and silicification. The mineralization is hosted by quartz, quartz-carbonate and/or chlorite veins, intimately associated with the serpentinite-quartz diorite contact. The description of alteration phenomena as mineralizing events, especially in Co-Ni arsenides and precious metals Au-Ag is realized. The petro-mineralogical and geochemical studies of the mineralized structures and their surrounding host rocks reveal several types of alterations that developed a lateral zoning at the serpentinite level, with formations of silica-, talc-, carbonate-, and chlorite-rich serpentinites. Nearly all primary silicate minerals have been replaced by serpentine minerals, leaving only relics of primary olivine and chromian spinel. The presence of antigorite dominated serpentinites indicates that the Bou Azzer ultramafic sequence was hydrated at relatively high temperature between 200 and 350 °C. In agreement with fluid inclusions study and the estimated temperatures from the chemical composition of chlorites (220–320 °C), which showed an evolution from ferrous chlorites (pychnochlorite and ripidolite) to magnesian chlorites (penninite and clinochlore). The altered zone is characterized by high metal contents of As, Co, Mo, Ag and Au in the silica-rich serpentinite and Cr, Cu, Zn and Pb in the carbonate-rich serpentinite. The enrichment in these elements result from the action of brines with a high Si content and fluids rich in Ca, Mg and CO2 on serpentinized peridotite, respectively. The chloritite breccia developed mainly in shear zones also shows elevated levels in As, Co, Mo, Ag and Au, buffered by the interaction between the fluid and the surrounding rocks.

Modeling the alkali aggregate reaction expansion in concrete

Sekrane Nawal Zahira,Asroun Aissa 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.1

Alkali aggregate reaction affects numerous civil engineering structures and causes irreversible expansion and cracking. This work aims at developing model to predict the potential expansion of concrete containing alkali-reactive aggregates. First, the paper presents the experimental results concerning the influence of particle size of an alkali-reactive aggregate on mortar expansion studied at 0.15–0.80 mm, 1.25–2.50 mm and 2.5–5.0 mm size fractions and gives data necessary for model development. Results show that no expansion was measured on the mortars using small particles (0.15-0.80 mm) while the particles (1.25–2.50 mm) gave the largest expansions. Finally, model is proposed to simulate the experimental results by studying correlations between the measured expansions and the size of aggregates and to calculate the thickness of the porous zone necessary to take again all the volume of the gel created by this chemical reaction.

Les apprenants coréens du français face aux valeurs de l’imparfait de l’indicatif

Dong-Yeol Park,Aissa Messaoudi 서울대학교 2009 외국어교육연구 Vol.12 No.-

L’imparfait de l’indicatif, dans l’enseignement/apprentissage du français, est très certainement l’une des étapes les plus difficiles dans la maitrise de ce tiroir verbal chez l’apprenant, certes mais aussi chez l’enseignant. En effet, ce dernier ne se borne souvent qu’à enseigner son versant temporel au détriment de son versant modal. C’est un choix malheureusement guidé par un bon nombre d’ouvrages FLE qui ne présentent que peu de ses valeurs modales voire parfois pas du tout. L’apprenant, l’autodidacte surtout, s’en trouve grandement influencé dans son apprentissage croyant reconnaître l’imparfait et l’une de ses valeurs alors qu’en fait le sens est tout autre (nous pensons par exemple à l’imparfait de l’imaginaire: Encore un peu et je tombais!). Partant de ces constats, il est dès lors urgent de revoir la manière d’enseigner cette partie de la langue française, aidé cette fois de manuels qui osent s’attarder sur toutes les valeurs modales de ce «temps», qui n’est pas, à vrai dire, que temporel.

Arbuscular Mycorrhizal Fungi in Bioremediation of Co-Contaminated Soil

Nejla Hechmi,Nadhira Ben Aissa,Hassen Abdenaceur,Naceur Jedidi 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6