Institutional repository of university M'Hamed Bougara Boumerdes
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Co-Precipitation Synthesis of NiFe2O4 Using NH4HCO3 as Precipitant: Characterization and Photocatalytic Degradation of Organic Pollutant
No full textStructural properties and the photocatalytic activity of the synthesized NiFe2O4 via co-precipitation process using NH4HCO3 as a precipitating agent were studied. The resulting sample was calcined at 550°C and the formation of pure ferrite phase with spinel structure was confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy methods. The morphology of this spinel was investigated using a scanning electron microscopy (SEM). The optical absorption spectroscopy obtained the optical band gap (Eg = 1.81 eV). This material was applied as a photocatalyst for the photodegradation under UV light of Congo Red (CR) a persistent and recalcitrant dye. The effect of catalyst dose, initial concentration, and pH on photocatalytic degradation was investigated. Degradation efficiency of 82% was achieved for 3 h with a catalyst dose of 0.5 g/L. Furthermore, the material exhibited better photocatalytic activity in an alkaline medium, and the degradation kinetics followed a pseudo-first-order reaction
نظريات العلاقات الدولية : محاضرا ت مقدمة لطلبة السنة ثانية ليسانس علوم سياسي
No full textيعتبر هذا المقياس رصد للأهم التحولات النظرية الكبرى التي شهدها حقل
العلاقات الدّولية من بدايات ظهوره كحقل معرفي بداية القرن العشرين وتبلور أولى
النقاشات النظرية فيما عرف بالنقاش النظري الأول بين المثالية والواقعية إلى
التطورات اللاحقة خاصة التي اعقبت الثورة السلوكية فترة الخمسينات والستينات
التي كان من نتائجها النقاش النظري الثاني ووصولا إلى النقاش ما بين البرادايمي )
النيواقعية، النيوليبرالية،النيوماركسية( والذي هيمن على الحقل طيلة الثمانينات
إلى التحولات العميقة التي شهدها مجال التنظير بعد نهاية الحرب الباردة. فيما
عرف بالنقاش النظري الرابع بين العقلانية والتأملية والبنائية.....
A medical comparative study evaluating electrocardiogram signal-based blood pressure estimation
No full textIn general, blood pressure (BP) is measured using standard methods (medical monitors), which are widely used, or from physiological sensor data, which is a difficult task usually solved by combining several signals. In recent research, electrocardiogram (ECG) signals alone have been used to estimate blood pressure. The authors present a comparative study that evaluates ECG signal-based blood pressure estimation using complexity analysis to extract features, comparing the results obtained with a random forest regression model as well as with the combination of a stacking-based classification module and a regression module. It was determined that the best result obtained is a mean absolute error range of 3.73 mmHg with a standard deviation of 5.19 mmHg for diastolic blood pressure (DBP) and 5.92 mmHg with a standard deviation of 7.23 mmHg for systolic blood pressure (PAS)
Application of Deep Transfer Learning in Medical Imaging for Thyroid Lesion Diagnostic Assistance
No full textThis academic work evaluates and compares the performance of various deep convolutional neural network (DCNN) architectures in classifying thyroid nodules into two categories, malignant and benign, using ultrasound images. The dataset comprises 269 cases of benign lesions and 526 cases of malignant lesions. Given the limited dataset size, we employ a progressive learning approach with three established CNN models: VGG-16, ResNet-50, and EfficientNet. Initially pretrained on ImageNet, these models undergo further fine-tuning using a radiographic image dataset related to a different medical condition but similar to our domain. Different levels and fine-tuning strategies are applied to these models. A supervised softmax classifier is used for classifying lesions as malignant or benign, with the exception of the VGG-16 model. For the VGG-16 model, two additional classifiers, Support Vector Machine (SVM) and Random Forest (RF), are evaluated. The results obtained demonstrate the possibility of easily transitioning from the classification of one disease to another, even with a limited number of images, by leveraging the knowledge already acquired from another extensive database
Machine learning classifiers for predicting the presence of cancer using gene expression data from CTCs/CTMs
No full text108 p. : ill.This thesis focuses on developing and evaluating machine learning classifiers for predicting the presence of seven types of cancer using gene expression data from CTCs and CTMs. The cancers investigated include liver cancer, breast cancer, colorectal cancer, non small cell lung cancer, pancreatic cancer, prostate cancer, and melanoma. The study involves building binary classifiers to distinguish each cancer type from others and multiclass classifiers to predict all seven cancer types. The goal is to compare these approaches and identify the most effective model for accurate cancer prediction. The findings demonstrate the significant potential of machine learning models in enhancing cancer diagnostics using minimally invasive methods.Among the models evaluated, the Random Forest multi-classifier emerged as the most reliable and effective, making it highly recommended for practical use in cancer diagnosis
Analysis and design of terahertz microstrip antenna based on photonic band gap substrate
No full text139 p. : ill. ; 30 cmIn a wireless communication system, a microstrip patch antenna is gaining importance
as a most powerful technology trend and it is applicable for the development
of minimal weight, low profile, low cost and high-performance antenna. However, the designed conventional patch antennas in terahertz encounter several drawbacks including
narrow bandwidth, low gain due to high atmospheric path loss, low efficiency,
and surface wave excitation. To overcome these drawbacks, microstrip patch antenna
arrays based on photonic crystals are advantageous by providing extra performance.
The main objective of this thesis is to develop and analyze array antennas operating
in the terahertz band (0.1-10 THz) based on photonic crystal structures that satisfy
the important requirements of high directivity, gain and radiation efficiency which will
be candidates for use in high-speed communication, spectroscopy molecular, security
imaging, sensing and medical diagnosis. To achieve this goal, commercial software
such as Ansys HFSS and CST Microwave Studio will be used. Further, a variety
of microstrip terahertz patch array antennas based on modified photonic band gap
substrates are designed and analyzed. The radiation characteristics of the proposed
antennas are compared to previously reported papers. Finally, a novel MIMO indoor
communication system using a graphene-based 1 x 2 microstrip patch antenna array
is developed and studied based on different substrates, including homogeneous,
periodic photonic crystals and optimized photonic crystals substrates for terahertz
communications channel capacity enhancement. The outcomes showed a remarkable
enhancement compared with previously reported studie
إشكالية مأسسة المجتمع المدني وأثـرها في بناء الثقافة السياسية في الجزائر
No full text299 ص. ، 30 سمشكل المجتمع المدني أحد تطورات المجتمعات الإنسانية في المجال الإجتماعي، وتعاضم دوره بشكل كبير في الدول الغربية إبان ما عرفته من إضطرابات في نظم الحكم والإستقرار السياسي، فكان للنظريات العقدية إسهام أكبر في بلوة فكرة المجتمع المدني ودواعي إعتماد النظم السياسية عليه في العملية السياسية، وقد جاء تداول هذا التنظيم في المجتمعات العربية والإفريقية متأخرا نوعا ما، حيث جابه الحركات الإستعمارية في هذه الدول أين كان له إسهام أكبر في تحررها، فلم يستعمل الخطاب العربي مفهوم المجتمع المدني سوى في بدايات القرن الماضي.
جاءت تجربة الجزائر كذلك حديثة في مجال تنظيم المجتمع المدني، الذي عرف تراجعا في نشاطه إبان الحقبة الإستعمارية منذ بدايتها حتى سنة 1901، بعد صدور قانون الجمعيات الفرنسي، ولم تكن التنظيمات المنتشرة تلك الفترة تقريبا إلا التي سمح القانون الفرنسي بتأسيسها، وإستمر الوضع على حاله حتى بعد الإستقلال وحتى سنة 1989، إذ لم تتواجد تنظيمات المجتمع المدني إلا في الحالة التي سمحت السلطة السياسية القائمة آنذاك بتأسيسها، وفي الغالب هي -ونقصد تنظيمات المجتمع المدني- المنضوية تحت مظلة الحزب الواحد.
حاولنا في هذه الدراسة تسليط النظر على ظاهرة المجتمع المدني في الجزائر، والإشكاليات التي تمخضت عن محاولة مأسستها كتنظيم رسمي يسهم في بناء الدولة، بالتركيز على التفاعلات والعلاقات بينها وبين الدولة، وكيف حاولت السلطة إحتوائها وتوظيفها لخدمة توجهها، من خلال إعادة مراجعة مختلف المصادر والمراجع حول الظاهرة، وإنطلقت دراستنا من الفترة 1999 وحتى 2019، وهي المرحلة التي شهدت خروجا من نفق أزمة أمنية خانقة، وإنتهت بأزمة سياسية خانقة في المقابل، بعد أن طوى حراك 22 فيفري مرحلة سياسية تميز فيها المجتمع المدني بضعف أدواره المنوط به على الرغم من تطوره الكمي.
إستنتجنا في المقابل أن المجتمع المدني خلال الفترة المشار إليها، تميز بالضعف لما أصابه من محاولات لكبح أدواره وتكييفها لموائمة ميول السلطة وبرامجها، ومن خلال مراجعتنا أيضا للأطر الدستورية والقانونية المنظمة لنشاط المجتمع المدني بمختلف أطيافه (مؤسسات تعليمية، أحزاب، جمعيات، نقابات...)، توصلنا إلى أن دوره في البناء السياسي والإجتماعي والإقتصادي للدولة، لم يعدو أن يكون مجرد شريكاً ثانوياً، ولا تكون مشاركته إلا في صيغة مبادرة فقط يمكن للسلطة السياسية الإلتزام بها أو عدم الإلتزام بها، دون أن ننسى محاولات إحتوائه من خلال الحدود المالية والتنظيمية التي فرضت عليه بموجب القوانين والتشريعا
Commande de variateur de vitesse d’un Moteur asynchrone triphasé
No full text81 p. : ill. ; 30 cmLe présent mémoire se concentre sur l'analyse et la mise en oeuvre d'un variateur de vitesse destiné à remplacer le coupleur hydraulique défectueux de la pompe alimentaire dans la station thermique de CAP-DJINET. Ce travail commence par une présentation détaillée de l'entreprise SONELGAZ et de son installation CAP-DJINET, suivie d'une étude approfondie de la pompe alimentaire et des critères de sélection du moteur asynchrone triphasé et de son
variateur de vitesse. Ensuite, une simulation comparative entre deux commandes qui sont : la pleine onde et la modulation de largeur d'impulsion (MLI) est effectuée, dans le but d’évaluer les performances du variateur dans les deux situations. Nous nous sommes penchés sur la commande MLI qui s’avère la plus performante et plus facile à mettre en oeuvre. Enfin, le mémoire se termine par la conception et la mise en oeuvre pratique du variateur, avec une réflexion sur les améliorations futures possibles pour optimiser davantage l'efficacité énergétique et le contrôle de ce système crucial pour l'usin
Computer numerical control machine tool wear monitoring through a data-driven approach
No full textThe susceptibility of tools in Computer Numerical Control (CNC) machines makes them the most vulnerable elements in milling processes. The final product quality and the operations safety are directly influenced by the wear condition. To address this issue, the present paper introduces a hybrid approach incorporating feature extraction and optimized machine learning algorithms for tool wear prediction. The approach involves extracting a set of features from time-series signals obtained during the milling processes. These features allow the capture of valuable characteristics relating to the dynamic signal behavior. Subsequently, a feature selection process is proposed, employing Relief and intersection feature ranks. This step automatically identifies and selects the most pertinent features. Finally, an optimized support vector machine for regression (OSVR) is employed to predict the evolution of wear in machining tool cuts. The proposed method’s effectiveness is validated from three milling tool wear experiments. This validation includes comparative results with the Linear Regression (LR), Convolutional Neural Network (CNN), CNN-ResNet50, and Support Vector Regression (SVR) method
Contribution to the NBTI effect study in MOS devices
No full text122 p. : ill. ; 30 cmThis thesis delves into the Negative Bias Temperature Instability (NBTI) effect in Metal-OxideSemiconductor
(MOS) devices, specifically Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs). The study comprehensively examines challenges posed by NBTI in the
gate dielectric, impacting device parameters like threshold voltage. The research focuses on
empirical work and advanced characterization techniques.
This work highlights the significance of MOSFETs in electronic device development and
emphasizes the imperative need for fast measurement techniques to accurately characterize
NBTI. An overview explores MOS devices and NBTI, introducing technologies such as silicon
oxy-nitride ( ) and high-K (HK) insulators. The exploration encompasses various NBTI
models, delving into the response of classical and advanced MOS devices to NBTI. Also, the
research unfolds in the experimental setup within the Characterization room with the
Semiconductor Device Reliability team, outlining devices, technologies, instruments, software,
and heating systems instrumental in the measurements. It introduces the fast pulsed currentvoltage
(FPIV) technique using the OPA818 amplifier and the separated single pulse charge
pumping (SSPCP) technique. Plus, it discusses experimental results gleaned through the
implemented techniques, scrutinizing NBTI in MOSFETs with varying oxide thicknesses. It
explores the enhanced FPIV technique and introduces the newly devised SSPCP technique,
providing a nuanced perspective on interface traps along the MOSFET channe