Optimization of Cold-formed Steel Sections using Genetic Algorithm

Most research done on optimization of cold-formed steel members focuses on a single cross-section with set conditions and steel yield strengths. How would this optimiza tion look if different cold-formed cross-sections are compared. Furthermore, how would different cold-formed cross-sections with varying steel yield strength behave in a global optimization. The aim is to study how to reach optimized cross-sections (profiles) for roof trusses in different steel strength classes using a genetic algorithm and create a library of the most optimized cross-sections for certain spans and applied loads. The four selected cross-sections to be analysed are C-section, double back-to-back C-section, hollow square-section and hollow hexagon-section. These profiles can act as diagonals in a roof truss and the compressed diagonals will be analysed. As for the upper chord which is subjected to both compression and bending, only double back-to-back C-sections will be optimized. Matlab functions were generated to calculate the required parameters, buckling modes and capacities for the selected sections. These functions were connected to a genetic algorithm to find the most op timized dimensions for each section. Lastly the most optimized cross-sections with respect to smallest area were selected for different load and span length combination to create a library. The results of the genetic algorithm showed that for the upper chord the higher the steel strength the smaller the area becomes but the section with higher steel strength have a lower utilization ratio. The diagonals which were divided into two groups and were analysed separately showed that the most optimized shape to use is a hollow square-section. However, the connection between the upper chord and the diagonals will not be feasible with closed cross-sections used as diagonals. The chosen cross-section shape is therefore C-section

Experimental and Theoretical Investigation of Impinging Jet Ventilation at Different Cross Sectional Area of Supply Air Duct

يتضمن البحث دراسة عملية ونظرية لحركة الهواء وتوزيع درجة الحرارة داخل حيز باستحدام منظومة تهوية البثق المؤثر لغرفة مكتب واستخدام برامج الحاسوب (ANSYS.15) لحل معادلاث نافير ستوك باستخدام طريقة الفروقات المحددة لمحاكاة وتحليل النموذج المدروس . تم اختبار ثلاثة انواع لمجاري دفع الهواء تم استحدام مجرى هواء مقطع مربع ونصف دائري ومستطيل الشكل بارتقاع(0.14h,0.1h) عن مستوى الارض تم قورنت النتائج النظرية مع القراءات العملية حبث تم التواصل الى ان المقطع المربع هو النوع الاكثر مقبولية  بين الانواع الثلاثة الاخرى في الحالة المدروسة بالنسبة لراحة الشاغلين An experimental and computational analysis of temperature and velocity distribution in an office room have been studied. Office room of dimensions (3m x 1.75m x 3m) with two cross sectional types of supply air duct in the experimental part and three different cross sectional types of supply air duct in the theoretical part is usual as a tested model. The RNG k-  turbulence model was employed to solve the governing equations numerically and validated by comparing the numerical results with experimental data. The impinging jet concept has been proposed as a new ventilation strategy for use in office and industrial buildings. The present work focuses on evaluating the performance of a new impinging jet ventilation. In a theoretical study three types of supply air duct are adopted which are square supply air duct (Type-I), semi-elliptic supply air duct (Type-II) and rectangle supply air duct (Type-III) for two cases of air outlet terminal height from room foot level, 0.14h (case-I) & 0.1h (case-II). The third type (rectangle duct) gives lowest effective and discomfort conditions when compared with the other two types. This study investigated a number of factors influencing draught discomfort and temperature stratification in an office environment equipped with impinging jet ventilation IJV. The factors considered to be: shape of the air supply device, supply airflow rate and supply air temperature. Acceptable Air Distribution Performance Index (ADPI), effective temperature, and ventilation efficiency obtained that the square cross sectional area of supply air duct at 0.1h (case-II) height from foot level gives more acceptable indoor air quality and human thermal comfort when compared with the other types. Also, this type gives good air distribution system not only promotes a comfortable and healthy environment for occupants, but also contributes to energy conservation

Cyclic Fatigue Life of Two Single File Engine-Driven Systems in Simulated Curved Canals

Introduction: This study aimed to evaluate the cyclic fatigue resistance of two single file engine-driven instruments, Reciproc and NeoNiTi, in simulated root canals. Methods and Materials: Two groups of 15 NiTi endodontic instruments with an identical tip size of 0.25 mm were tested: Reciproc R25 (group A) and NeoNiTi A1 (group B). Cyclic fatigue testing was performed in a stainless steel artificial canal. The simulated canals had a 60° angle and 5-mm radius curvature. The Reciproc instruments were operated using the preset program on torque control electric motor specific for the Reciproc instruments, while the NeoNiTi instruments were operated using the manufacturer recommendation. All instruments were rotated until fracture occurred, and the number of cycles to fracture (NCF) and the length of the fractured tip were recorded and registered. Means and standard deviations of NCF and fragment length were calculated for each system and data were subjected to Student’s t test (P<0.05). Results: A statistically significant difference (P<0.05) was noted between Reciproc and NeoNiTi instruments. NeoNiTi A1 instruments were associated with a significantly higher mean NCF as compared to Reciproc R25 instruments (833±176 vs. 318±87 NCF). There was no significant difference (P>0.05) in the mean length of the fractured fragments between the instruments. Conclusion: NeoNiTi instruments were associated with a significantly higher cyclic fatigue resistance than Reciproc instruments.Keywords: Cyclic Fatigue; NeoNiTi; Reciproc; Single-File System

Management of Pulp Canal Obliteration in Mandibular Incisors with Guided Endodontic Treatment: A Case Report

Successful management of mandibular incisors with pulp canal obliteration using guided endodontics is described, for the first time in Iran. A 58-year-old man was referred for root canal treatment of teeth #24, #25 and #26. Upon radiographic examination, partial obliteration of the root canal system was detected. Cone-beam computed tomography (CBCT) was requested to enhance the diagnosis and detection of root canals. Next, a 3-dimensional (3D) guide was designed and printed to aid in localization and access to the root canal system with minimal destruction of the tooth structure. With the use of a targeted 3D guide, a conservative access cavity was prepared to avoid unnecessary removal of tooth structure. The teeth were successfully treated endodontically. Obtained results revealed that the technique can be effective and predictable for the management of calcified canals

The New Perceptions on Life of Iranian Patients with Ankylosing Spondylitis: A Qualitative Study

Various studies suggest that ankylosing spondylitis (AS) as a chronic inflammatory disease with many disabilities can have impacts on different aspects of patients’ life. Despite many quantitative studies, only few qualitative studies have thus far been published on this subject. For the first time, the present study aims at gaining insight into the life experience of Iranian AS patients. We performed a content analysis through semi-structured interviews with twenty-eight patients diagnosed with AS, including three females and twenty-five males with an average age of 38.5 years, to gain insight into their experiences. Whatever the patients expressed was written and transcribed verbatim. Then, we did analysis of the results after each interview. The detailed information completely extracted from the interviews was classified as sub-themes and main themes. Three main themes were identified by the analysis: (i) “Always with pain” describing the effects were found in regard to pain on patients’ life, (ii) “The perceived limitation” describing many difficulties that people may face in the society as a result of their disease, and (iii) “Fearing the unknown future” which implies to both patients and their families have concerns about the future and what will happen. Our research findings in line with other qualitative studies showed that AS disease puts a heavy and intolerable burden on patients and their family. It seems that the experiences of people living with AS can be useful to meet challenges caused by the disease and it can enhance their coping with the disease

LT-ViT: A Vision Transformer for multi-label Chest X-ray classification

Vision Transformers (ViTs) are widely adopted in medical imaging tasks, and some existing efforts have been directed towards vision-language training for Chest X-rays (CXRs). However, we envision that there still exists a potential for improvement in vision-only training for CXRs using ViTs, by aggregating information from multiple scales, which has been proven beneficial for non-transformer networks. Hence, we have developed LT-ViT, a transformer that utilizes combined attention between image tokens and randomly initialized auxiliary tokens that represent labels. Our experiments demonstrate that LT-ViT (1) surpasses the state-of-the-art performance using pure ViTs on two publicly available CXR datasets, (2) is generalizable to other pre-training methods and therefore is agnostic to model initialization, and (3) enables model interpretability without grad-cam and its variants.Comment: 5 pages, 2 figure