Modular Multilevel Converter-Based Hvdc Transmission Systems

High-Voltage Direct Current (HVDC) transmission systems based on Voltage Source Converter (VSC) technology has attracted significant interest recently for transmitting large amounts of power over long distances using back-to-back or point-to-point configurations. VSC-HVDC has been addressed for various HV applications such as DC interconnections, Multi-Terminal HVDC Transmission (MT-HVDC), installation of offshore wind power generation such as Europe super DC grid and installation of other renewable energy sources. Several classes of VSC topologies can be employed in HVDC systems including the conventional two and three-level converters, multilevel converters, and Modular Multilevel Converters (MMCs) that has been recently introduced and investigated for HVDC applications. MMC is penetrating the modern HVDC transmission market, due to its inherent features such as scalability, modularity, and fault ride through capability. Therefore, this thesis investigates and models a point-to-point VSC-based HVDC transmission system using nine-level MMC transient model, and 25-level MMC averaged model using MATLAB/Simulink platform to meet the requirements of HVDC systems such as HV requirements and fault ride through capability. However, a point-topoint HVDC system using conventional two-level converter is modeled and simulated using MATLAB/Simulink as a starting and benchmarking model. MMC transient model employed in this study is based on Half-Bridge Sub-Modules (HB-SMs) due to its simple structure, yet, other structures are discussed. Nevertheless, balancing of the floating capacitors is one of the challenges associated with MMCs. Therefore, capacitor voltage balancing and its modeling is addressed. Then the average model of the MMC-based HVDC system is investigated. Moreover, the behavior during DC side faults is investigated, and the employment of hybrid DC circuit breakers and Hybrid Current Limiting Circuit (HCLC) are introduced for protection and limiting the DC fault current. This introduces a platform for studying large MMC-based HVDC systems in normal operation and during faults

Survey of Personalized Learning Software Systems: A Taxonomy of Environments, Learning Content, and User Models

This paper presents a comprehensive systematic review of personalized learning software systems. All the systems under review are designed to aid educational stakeholders by personalizing one or more facets of the learning process. This is achieved by exploring and analyzing the common architectural attributes among personalized learning software systems. A literature-driven taxonomy is recognized and built to categorize and analyze the reviewed literature. Relevant papers are filtered to produce a final set of full systems to be reviewed and analyzed. In this meta-review, a set of 72 selected personalized learning software systems have been reviewed and categorized based on the proposed personalized learning taxonomy. The proposed taxonomy outlines the three main architectural components of any personalized learning software system: learning environment, learner model, and content. It further defines the different realizations and attributions of each component. Surveyed systems have been analyzed under the proposed taxonomy according to their architectural components, usage, strengths, and weaknesses. Then, the role of these systems in the development of the field of personalized learning systems is discussed. This review sheds light on the field’s current challenges that need to be resolved in the upcoming years

Triggers And Tweets: Implicit Aspect-Based Sentiment And Emotion Analysis Of Community Chatter Relevant To Education Post-Covid-19

This research proposes a well-being analytical framework using social media chatter data. The proposed framework infers analytics and provides insights into the public\u27s well-being relevant to education throughout and post the COVID-19 pandemic through a comprehensive Emotion and Aspect-based Sentiment Analysis (ABSA). Moreover, this research aims to examine the variability in emotions of students, parents, and faculty toward the e-learning process over time and across different locations. The proposed framework curates Twitter chatter data relevant to the education sector, identifies tweets with the sentiment, and then identifies the exact emotion and emotional triggers associated with those feelings through implicit ABSA. The produced analytics are then factored by location and time to provide more comprehensive insights that aim to assist the decision-makers and personnel in the educational sector enhance and adapt the educational process during and following the pandemic and looking toward the future. The experimental results for emotion classification show that the Linear Support Vector Classifier (SVC) outperformed other classifiers in terms of overall accuracy, precision, recall, and F-measure of 91%. Moreover, the Logistic Regression classifier outperformed all other classifiers in terms of overall accuracy, recall, an F-measure of 81%, and precision of 83% for aspect classification. In online experiments using UAE COVID-19 education-related data, the analytics show high relevance with the public concerns around the education process that were reported during the experiment\u27s timeframe

Review: A comparative study on the synthesis of gold and silver nanoparticles using pulsed Laser ablation, extraction plants and plasma methods

Nanoparticles  have very important and unique properties and  qualities that make them important and distinctive in all fields , and they are used in different applications , and on this basis i conducted this study .this review focuses on the progress in the laser ablation , biological and plasma synthesis processes for Au and Ag NP generation, especially in their fabrication fundamentals and potential applications. First, the fundamentals of the laser ablation method are critically reviewed, including the laser ablation mechanism for Au and  Ag NPs and the controlling of their size and shape during fabrication using laser ablation. Second, the fundamentals of the biological method are comprehensively discussed, involving the synthesis principle and the process of controlling the size and shape and preparing Au and Ag NPs using biological methods. Biological route of nanoparticle synthesis , it is an environmentally friendly , low cost and very effective method , Biosynthesis route by  extracting plants possesses great ability to  synthesize various size and shape of metallic nanoparticles Of these biomaterials ,this study focuses on the synthesis of nanoparticles by plant extracts , The biomolecules present in the plants such as terpenoids, flavones, ketones , amino acids  aldehydes, proteins  , vitamins, alkaloids , tannins, phenolics, saponins, and polysaccharides play a vital role in reduction of metals. Third, the synthesis of Au and Ag NPs using plasma route.the plasma method , which is a method consisting of sending a sufficient pulse of  electric current through an electrical wire for materials that conduct electricity , and the wire is thin , and when heated , the wire evaporates , which leads to an explosive shock wave , and this method is a good method for producing metal nanoparticles with good specifications for use in many applications .many of the techniques used to describe these nanoparticles have been discussed , and this review highlights the applications of nanoparticles in various fields such as agriculture , medicine , food , and cosmetics . Thus, this article reviews the achievements and current status of synthesis of nanoparticles by pulsed laser ablation, extraction of plants and plasma routs, and hopes to provide insights into this exciting research frontier. Keywords: synthesis,  gold and silver nanoparticles DOI: 10.7176/APTA/87-04 Publication date: November 30th 2023

A Review of Laser Ablation- Synthesis of Nanoparticles: Concepts and the Principles

Laser tecnique is considered one to prepare different kinds of nano materials esspetially nano particles such as quantum dots, carbon nano tubes, nano wires, and core- shell nano particles. The current study review including nano particles which are prepared by pulsed -laser ablation . The growth procedure of nano particles by laser- ablation is focuced in this study . The important parameters to control of nano particle size and the aims to nano particle preparation by pulsed-laser ablation- technology are then discussed. Keywords:pulsed - Laser ablation technique . parameters of laser . Laser focusing parameters . Mideum of ablation embient . Nano particle preparation DOI: 10.7176/JNSR/14-13-04 Publication date: December 31st 202

Immunology study and the Assessment of parameters in difference Age, Sex of stage resistance infection leishmaniasis in Dayla

The Leishmania parasite belonged to trypanosomatidae family,. Cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL) are endemic in Iraq as one of the neglected tropical diseases. The current drugs which are used as antileishaminial treatment characterized by enormous side effects including their toxicity to human, long term treatment, liver problems, hugely cost. Therefore, there is a necessity to find an alternative treatment marked as low cost, more specific against parasite’s stages, Tumor necrosis factor-alpha (TNF-α), a cytokine that generated by the innate immune response to CL infection, can influence disease clearance in the human host. The effect of this pro-inflammatory cytokine in CL ulcer development during the infection is not well established. The current study was conducted on 88 individaul of both sexes, they were from Diyala province and the capital Baghdad, during the period from October 2020 to February 2021. All suspected cutaneous or visceral patients involved in this study were prediagnosed in the laboratory before processing Tumor Necrosis Factor-alpha (TNF-α) and Adenosine Deaminase Enzyme (ADA) by ELISA colorimetric detection. Total number of confirmed leishmaniasis patients were (n=57) cutaneous patients and (n=16) visceral patients, collected from different hospitals in Diyala province and Baghdad. Positive CL or VL samples were confirmed by microscopic Giemsa staining, In this study, the level of circulating tumor necrosis factor alpha and adenosine deaminase enzyme levels were detected in CL patients of newly diagnosed infection and in patients undergoing different doses of treatment, 2nd and 3rd Pentostam trail-treatment, in addition, VL patients of newly diagnosed infection with no treatment; in comparison to control subjects. Regardless the type of leishmaniasis and according to age, the results showed that TNF-α concentration was higher in patients less than 15 years old, in comparison with other age group over 15 years (15-60) years old, which was 1169.899 ng/ml and 961.206 ng/ml respectively. While according to sex, the higher concentration of TNF-α was recorded in female rather than male, 1030.243 ng/ml and 996.458 ng/ml Regarding ADA enzyme, the highest enzyme activity also recorded in the age group of 1-14 years old, which was 4.749 nanomol/minute/µg, in comparison of patients between 15-60 years old, which was 3.706 nanomol/minute/µg. While according to sex, the maximum enzyme activity was seen in male rather than female (4.296, 4.483) nanomol/minute/µg, respectively. The perceived rise of TNF-α and ADA serum levels may give insights into this pro-inflammatory cytokine as a biomarker in prognosis and tracking disease progression

Effect of Some Heavy Metals on Testosterone Hormone in Infertile Men

الخلفية: يتم تعريف العقم على أنه فشل في تحقيق الحمل بعد عام واحد وأكثر من الاتصال الجنسي غير المحمي بانتظام. ارتبط تعرض الجهاز التناسلي للمعادن الثقيلة أيضًا بالعقم عند الرجال. وهناك عدد كبير من المعادن عبارة عن مواد سامة للجهاز التناسلي ويشتبه في كونها مضطربة لنظام الغدد الصماء. المرضى والطرق: أجريت هذه الدراسة في المعهد العالي لتشخيص العقم والتقنيات المساعدة الإنجابية في جامعة النهرين ومركز استشاري التسمم / مستشفى الجراحات التخصصية في مدينة الطب في الفترة من نوفمبر 2018 إلى أبريل 2019. كان عدد الرجال 150 المسجلين في هذه الدراسة مقسمة إلى مجموعتين ، المريض ومجموعات المراقبة الطبيعية. وشملت مجموعة المرضى 100 رجل تتراوح أعمارهم بين 20-50 سنة. شملت المجموعة الثانية 50 رجلاً يتمتعون بصحة جيدة ولديهم طفلان على الأقل دون أي تاريخ سابق للأمراض الجهازية كمجموعة مراقبة. تم تقدير تركيزات المعادن الثقيلة لجميع مجموعات الدراسة. الهدف من الدراسة الحالية هو تقييم بعض تركيزات المعادن الثقيلة ، في الدم والدم الكامل للمجموعات. تقييم هرمون التستوستيرون في مصل الرجال المصابين بالعقم والضوابط الصحية ودراسة العلاقة بين هذا الهرمون والعناصر النزرة التي قدرت بين الحالات. النتائج : أظهرت تراكيز المعادن الثقيلة وهي كل من النحاس والرصاص والكادميوم زيادة معنوية عالية وتحت مستوى احتمالية اقل من 0.010.01 في مصل دم و دم الرجال العقيمين حيث سجلت (139.7+ 8.49 Mg/dl, 24.18 + 4.30 Mg/dl, 0.31 + 0.10 Mg/dl) على التوالي وعند المقارنة مع التراكيز في مصل الدم و دم الرجال السليمين ( السيطرة ) كانت النتائج  على التوالي(125.14 + 10.12 Mg/dl, 15.24 + 2.69 Mg/dl, 0.16 + 0.03 Mg/dl)  كما أظهرت متوسطات عنصر الزنك (القصدير) انخفاضا معنويا عاليا عند مستوى احتمالية اقل من 0.01      (70.82+9.48Mg/dl) في مصل دم الرجال العقيمين مقارنة مع مجموعة السيطرة حيث كانت كما أظهرت تراكيز هرمون الشحمون الخصوي انخفاضا معنويا عاليا وتحت مستوى احتمالية اقل من 0.01  (185.40 + 61.92 Ng/dl)  (450.35+131.27 Ng/dl) بالمقارنة مع مجموعة الرجال السليمين كذلك كانت علاقة الارتباط لمستويات تراكيز عنصر النحاس وهرمون الشحمون الخصوي في مصل الدم عكسية عند الرجال العقيمين. الاستنتاجات: خلصت هذه الدراسة إلى أن بعض المعادن الثقيلة أظهرت أنها مؤشرات لعقم الرجال. ارتبط مستوى النحاس في المصل سلبًا بمستوى هرمون التستوستيرون في المصل لدى الرجال المصابين بالعقم، وهذه النتيجة يمكن أن تفترض أن النحاس الزائد يعمل كمضاد هرموني. لم تظهر المعادن الثقيلة المتبقية ارتباطًا كبيرًا بالهرمونات المحددة.Background:  Infertility is defined as a failure of achieve a pregnancy after one year and more of regular unprotected sexual intercourse. The exposure of reproductive system to heavy metals has also been associated with male infertility. A large number of metals are toxicants to the reproductive system and are suspected to be endocrine system disruptors.   Patients and methods:  This study performed at the high institute of infertility diagnosis and assisted reproductive technologies in Al-Nahrain University and the Poisoning consultation center / specialized surgeries hospital in the Medical city in period from November 2018 to April 2019.  Number of 150 men were enrolled in this study divided into two groups, the patient and the normal control groups. The infertile group included 100 men aged 20-50 years who they have abnormal seminal fluid analysis parameters. The second group included 50 healthy fertile men who have at least two children without any previous history of systemic diseases as a control group. Heavy metals and testosterone concentrations were estimated for all the study groups. Aim of current study are evaluation of some heavy metals concentrations, in serum and whole blood of groups. Assessment of testosterone hormone in serum of infertile men and healthy controls and study the correlation between this hormone and trace elements which were estimated among cases. Results: The heavy metals Cu, Pb and Cd showed a highly significant increase (p<0.01) in the serum and blood of infertile men (159.77±8.49 µg/dl, 24.18±4.30µg/dl, 0.31±0.10 µg/dl) respectively when compared with their concentrations in healthy control men (125.14±10.12 µg/dl, 15.74±2.69 µg/dl, 0.16±0.03 µg/dl) respectively. The mean levels of Zn showed a highly significant decrease (p<0.01) in the serum of infertile men (70.82±9.48 µg/dl) compared to its mean level in the healthy control group (95.70±11.41 µg/dl). Serum testosterone hormone in infertile men (185.40±61.92 ng/ml) showed a highly significant decrease (p<0.01) as compared with those of healthy men (450.35±131.27 ng/ml). Serum copper level was negatively correlated with serum testosterone level among infertile men. Conclusions: this study concluded that some heavy metals were shown to be an indicators for men infertility. Serum copper level was negatively correlated with serum Testosterone level among infertile men .This result can hypothesize that excess copper acts as a hormonal disrupter. The remaining heavy metals did not show significant correlation with the selected hormones

Evaluating the effects of cultural immersion on counselor trainees\u27 multicultural development and intercultural competence: A metasynthesis of qualitative evidence

This metasynthesis critically surveyed and evaluated the learning impacts on counselor and psychology trainees’ multicultural development and intercultural competence through participating in cultural immersion (CI), based on published qualitative research evidence. Accordingly, this metasynthesis identified and assessed the characteristics, the methodological strengths and qualities, and the thematic findings of 33 qualitative and mixed-methods CI studies resulting from exhaustive database searches. Using a directed content analysis technique, a six-domain analytical framework was applied to code and analyze the themes reported in these studies. The results point to CI intervention as a multifaceted and versatile instructional apparatus that impacted and contributed to trainees’ multicultural development and intercultural learning multidimensionally, across cognitive, perceptual-attitudinal, affective, and skills-behavioral domains. These learning outcomes include trainees’ increased cultural awareness and knowledge (cognitive), enhanced reflexivity on their worldview, positionality, and attitude (perceptual-attitudinal), heightened emotion and growth in cultural empathy (affective), adaptation and display of new behaviors and relational skills and increased multicultural competence (skills-behavioral). Therefore, CI embodies many favorable characteristics of experientially-based learning as stipulated in the existing multicultural counseling and intercultural training literature. These findings lend nuanced empirical support for the application of CI to facilitate counselor trainees’ multicultural orientation, development, and skills, and offer insights into structural facilitators for enhancing immersion training. However, a lack of structural and methodological consistency and theoretical depth among the existing CI studies were observed as major limitations. Implications and recommendations for advancing future CI and multicultural training practice and research are discussed

Comparative Evaluation of Marginal Adaptation of Two Sealers with Two Different Obturation Techniques Using SEM (AN IN VITRO STUDY)

Objective To evaluate and compare the marginal adaptation of epoxy resin-based sealer (AH Plus) versus Bioceramic-based sealer (Total fill BC Sealer) to root canals that were filled by single cone technique & Cold Lateral compaction technique and utilizing scanning electron microscope (SEM). Methods Sixty recently extracted single-rooted mandibular premolars were disinfected. Access cavity preparation was performed followed by cleaning and shaping, using 2.6% NaOCl as final irrigation protocol. Samples were then equally divided into 4 different groups as follows; Group A: AH Plus with CLC technique, Group B: AH Plus with SC technique, Group C: Totalfill BC with CLC technique, and Group D: Total fill Bioceramic sealer with single cone technique. After cleaning and shaping, each sample was obturated with Gutta percha and the sealer according to group of allocation. Afterwards, Transverse sectioning of each root was done at three, six, nine millimeters from the root apex corresponding to the three thirds of the root (apical, middle and coronal thirds). The specimens have been examined under scanning electron microscope (SEM). A commercially accessible software programme (SPSS Chicago, IL, USA) was used for the statistical analysis. The mean and standard deviation were used to describe numerical data. According to data normality, the Kruskall Wallis or ANOVA test was used to compare the data. A P 0.05 significance threshold was used. Every test had two tails. Results BC sealer presented better marginal adaptation than AH Plus sealer. However, On marginal adaption, there was no discernible difference between the two examined obturation techniques. Conclusion BC sealer is a reliable and promising material that improves marginal adaptation. Keywords: AH Plus sealer, BC sealer, Cold lateral condensation, Marginal adaptation, Single cone obturation

An investigation into corneal enzymatic resistance following epithelium-off and epithelium-on corneal cross-linking protocols

The aim of this study was to investigate corneal enzymatic resistance following epithelium off and on riboflavin/UVA cross-linking (CXL). One hundred and fourteen porcine eyes were divided into four non-irradiated control groups and seven CXL groups. The latter comprised; (i) epithelium-off, 0.1% iso-osmolar riboflavin, 9 mW UVA irradiation for 10 min, (ii) disrupted epithelium, 0.1% hypo-osmolar riboflavin, 9 mW UVA for 10 min, (iii) epithelium-on, 0.25% hypo-osmolar riboflavin with 0.01% benzylalkonium chloride (BACS), 9 mW UVA for 10 min, (iv) epithelium-on, 5 min iontophoresis at 0.1 mA for 5 min with 0.1% riboflavin solution, 9 mW UVA for 10 min or (v) 12.5 min, (vi) epithelium-on, prolonged iontophoresis protocol of 25 min with 1.0 mA for 5 min and 0.5 mA for 5 min with 0.25% riboflavin with 0.01% BACS, 9 mW UVA for 10 min or (vii) 12.5 min. Enzymatic resistance was assessed by daily measurement of a corneal button placed in pepsin solution and measurement of corneal button dry weight after 11 days of digestion. This study revealed that the enzymatic resistance was greater in CXL corneas than non-irradiated corneas (p < 0.0001). Epithelium-off CXL showed the greatest enzymatic resistance (p < 0.0001). The prolonged iontophoresis protocol was found to be superior to all other trans-epithelial protocols (p < 0.0001). A 25% increase in UVA radiance significantly increased corneal enzymatic resistance (p < 0.0001). In conclusion, although epithelium-on CXL appears to be inferior to epithelium-off CXL in terms of enzymatic resistance to pepsin digestion, the outcome of epithelium-on CXL may be significantly improved through the use of higher concentrations of riboflavin solution, a longer duration of iontophoresis and an increase in UVA radiance