Feasibility analysis model for construction of soccer stadiums

This current research aims to study the different stadiums worldwide and to analyze the different aspects controlling them in terms of planning, design and construction. In this regard, there have been radical changes in the stadium projects approach over the last 30 years. In the past, soccer stadiums used to be consisted of only a pitch and a seating area for the fans. However, over the last 30 years, an evolution started to take place in utilizing stadiums as economically beneficial projects. Currently, stadiums have all safety requirements and incorporate the latest technological advances in order to achieve maximum efficiency. Furthermore, studying stadiums from different continents concentrates on the positive and negative aspects of these stadiums including different stadiums worldwide. That is an attempt to reach a viable solution to develop successful stadiums in terms of planning, design and construction. Therefore, the main goal of this study is finding a way to have a safe stadium that can generate profits to its owner plus the prospect of finding different funding options that could be used effectively. In this study, the analysis will focus on cost, safety and profitability of each stadium project. Then, we will begin to implement our own created model for a new stadium to be built in Egypt, or any other country worldwide using the Big Mac Index. We will take into consideration the whole process of establishing a new successful soccer stadium project, starting by setting a vision, planning, design and then construction

Upper airway muscle exercises outcome in patients with obstructive sleep apnea syndrome

AbstractBackgroundObstructive sleep apnea syndrome (OSAS) is an important disease that represent a challenge for both patients and physicians to reach optimum choice for treatment mostly because genesis of OSAS is multifactorial. Upper airway muscle function plays a major role in maintenance of the upper airway patency especially during sleep. Oropharyngeal exercises may be an effective treatment option for OSAS.ObjectiveAim of this study was to evaluate upper airway muscle exercise as method to treat OSAS.Patients and methods30 patients divided into 2 groups; Group I moderate OSAS and Group II: severe OSAS patients. Follow up, as regard ESS, AHI, oxygen saturation and snoring was done after 3months of oropharyngeal exercises.ResultsAfter end of study, daytime sleepiness and AHI improved significantly in group I (moderate OSA) 13 out of 15 patients shifted from moderate to mild OSAS. There was significant decrease in oxygen desaturation and snoring index. As for group II, there was decrease but not significant change in same parameters. Only for moderate OSAS, there was, significant decrease in neck circumference, which inversely correlated with changes in AHI (r=0.582; P<0.001).ConclusionUpper airways exercises can be a novel easy non invasive technique to improve AHI, O2 saturation and snoring thus used in treatment of OSAS patients mainly moderate type

Effects of Grain Refining on Columnar-to-Equiaxed Transition in Aluminum Alloys

The effects of grain refining in ultra-pure aluminum, commercially pure aluminum (1050), and Al-7%Si binary alloy were investigated, using different additions of Al-10%Ti, Al-5%Ti-1%B, and Al-4%B master alloys. Thermal analysis and metallography were used to assess the variations in microstructure resulting from these additions, at solidification rates of 0.8°C/s and ~10°C/s. The results revealed that addition of Al-4%B to ultra-pure aluminum forms AlB12 and AlB2 which have no grain-refining effect. Without grain refiner addition, the pure aluminum microstructure exhibits a mixture of columnar and equiaxed grains. Addition of 30ppm Ti is sufficient to promote equiaxed grains at ~10°C/s but requires addition of 1000 ppm B to obtain similar results at 0.8°C/s. Increasing the Si content to 7% reduces the initial grain size of pure aluminum from 2800 μm to ~1850 μm, and further to 450 μm with ddition of ~500ppm B. In commercial aluminum, the B reacts with traces of Ti forming Al3Ti and TiB2 phases which are active grain-refiners. In Al-7%Si, Ti reacts with Si forming (Al,Si)2Ti phase, which is a poor refining agent. This phenomenon is termed poisoning. No interaction between B and Si is observed in the commercial aluminum or Al-7%Si alloy when B is added

Generation and Relaxation of Residual Stresses in Automotive Cylinder Blocks

There is direct proportionality between ultimate tensile stress (UTS) and residual stresses (RS). Residual stresses gradually decrease with decreasing cooling/quenching rates. Quenching in cold water develops highest, whereas air cooling produces lowest, residual stresses. Significant increase in RS is observed in specimens with low dendrite arm spacing (high solidification rate), while lower residual stresses are measured in specimens with high dendrite arm spacing (low solidification rate). For I-4 and V-6 engine blocks, there is refinement in microstructure due to the increase in solidification rate along the cylinder length. The developed residual stresses are normally tensile in both engine types. Air cooling following solution heat treatment produces higher RS compared to warm water and cold water quenching. Solution heat treatment and freezing lead to maximum RS relaxation where 50% of the stresses are reduced after the solution heat treatment step. Aging time and temperature are directly proportional to the residual stresses relaxation. Relaxation of RS also depends on the geometry and size of the workpiece. It should be mentioned here that the I-4 and V-6 cylinder blocks were provided by Nemak-Canada (Windsor-Ontario-Canada). Residual stress measurements technique and procedure are typical of those used by the automotive industry in order to provide reliable data for industrial applications supported by intensive experiments

Seasonal Ammonia Emissions from a Free-Stall Dairy in Central Texas

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Effects of metallurgical parameters on the development of residual stresses in Al-Si alloys used in engine block manufacturing

Using light-weight materials have become an important factor in the automotive industry due to stringent government regulations on fuel consumption. Aluminum alloys are 65% lighter than cast iron enabling significant weight reduction. However, there are several significant challenges associated to the use of hypoeutectic Al-Si alloys in engine block applications. This dissertation investigated the factors influencing the development of residual stresses in I-4 and V-6 engine blocks due to different heat treatments and introducing sub-zero treatment as a mean for reducing residual stresses. The initial section of this thesis explores the development of residual stresses with different casting parameters in A356.1 and B319.1 castings with simple geometries. This analysis involved measurement of tensile properties, microstructural analysis, and residual stress measurement using sectioning technique. The casting parameters include cooling rate, quenching media, aging time and aging temperature. The second phase of this study will investigate the development of residual stress in castings, with more complex shape such as in I-4 and V-6 engine blocks with cast-in gray iron liners, with different heat treatment parameters and sub-zero treatment. An analysis of result shows that higher strength materials, as in B319.1 alloy, produce higher residual stresses compared to material with lower strength, as in the case of A356.1. The results also show that there is direct proportionality between ultimate tensile stresses (UTS) and residual stresses (RS) with quenching rate. The residual stresses were found to gradually decrease with decreasing cooling/quenching rates of the quenching medium. The quenching process develops the highest residual stresses, where quenching in cold water develops the highest, and air cooling the lowest, residual stresses. The relaxation of residual stresses is significantly dependent on aging temperature and proceeds smoothly with the increase in aging time. Finally, significant increase in the residual stresses is observed in specimens with low SDAS, as in the L-shaped casting (high solidification rate), while lower residual stresses are measured in specimens with high SDAS, as in the block casting (low solidification rate). For I4 and V-6 engine blocks, the results suggest that there is refinement in microstructure due to increases cooling rate along the cylinder. The developed residual stresses were found to be tensile for both I-4 and V-6 engine blocks. Furthermore, the variation in the developed residual stresses was found to be insignificant. The results also indicate that air cooling produced the highest residual stresses compared to warm water and cold-water quenching. Solution heat treatment and freezing led to maximum amount of residual stress relaxation where 50% of the residual stresses were reduced after SHT step Aging time and aging temperature is directly proportional to the residual stresses relaxation. L’utilisation de matériaux léger est devenue un important facteur dans l’industrie de l’automobile du aux restrictions imposées par les gouvernements en matières de consommation de carburant fossile. Les alliages d’aluminium sont 65% plus léger que la fonte, ce qui permet une réduction de poids significative. Cependant, il existe encore plusieurs défis à relever concernant l’utilisation d’alliage Al-Si hypoeutectic dans la fabrication de bloc moteur. Cette thèse enquête sur les facteurs infulençant le développement de contraintes résiduelles dans les blocs moteur I-4 et V-6 dus à différents traitements thermiques et introduisant un traitement sous zéro comme moyen de réduction des contraintes résiduelles. La première partie de cette thèse, explore le développement de contraintes résiduelles avec différents paramètres de coulée dans des pièces de géométries simples en alliage A356.1 et B319.1. Cette analyse comprend la mesure des propriétés de traction, l'analyse microstructurale et la mesure de la contrainte résiduelle à l'aide de la technique de coupe. Les paramètres de coulée comprennent la vitesse de refroidissement, les milieux de trempe, le temps de vieillissement et la température de vieillissement. La deuxième phase de cette étude examinera le développement des contraintes résiduelles dans les pièces coulées, avec une forme plus complexe comme dans les blocs moteurs I-4 et V-6 avec chemises en fonte grise coulée, avec différents paramètres de traitement thermique et traitement sous zéro. Une analyse des résultats montre que les matériaux de résistance plus élevée, comme dans l'alliage B319.1, produisent des contraintes résiduelles plus élevées que les matériaux de moindre résistance comme dans le cas du A356.1. Les résultats montrent également qu'il existe une proportionnalité directe entre les contraintes de traction ultimes (UTS) et les contraintes résiduelles (RS) avec la vitesse de trempe. Les contraintes résiduelles diminuent graduellement avec des vitesses de refroidissement / trempe décroissantes du milieu de trempe. Le processus de la trempe dans l'eau froide développe les contraintes résiduelles les plus élevées et le refroidissement à l'air développe les contraintes résiduelles les plus basses. La relaxation des contraintes résiduelles dépend de manière significative de la température de vieillissement et se déroule en douceur avec l'augmentation du temps de vieillissement. Enfin, une augmentation significative des contraintes résiduelles est observée dans les échantillons à faible SDAS, comme dans la coulée en L (taux de solidification élevé), tandis que les contraintes résiduelles plus faibles sont mesurées dans les échantillons à fort SDAS, comme dans la coulée en bloc (taux de solidification bas). Pour les blocs-cylindres I4 et V-6, les résultats suggèrent qu'il y a un raffinement de la microstructure en raison de l'augmentation de la vitesse de refroidissement le long du cylindre. Les contraintes résiduelles développées se sont révélées être en traction pour les blocs moteurs I-4 et V-6. De plus, la variation des contraintes résiduelles développées s'est avérée insignifiante. Les résultats indiquent également que le refroidissement par air a produit les contraintes résiduelles les plus élevées par rapport à la trempe à l'eau chaude et à l'eau froide. Le traitement thermique et la congélation en solution ont conduit à une relaxation maximale de la contrainte résiduelle, lorsque 50% des contraintes résiduelles ont été réduites après l'étape de traitement thermique en solution. Le temps de vieillissement et la température de vieillissement sont directement proportionnels à la relaxation des contraintes résiduelles

Valorization of Rice Husk and Straw Agriculture Wastes of Eastern Saudi Arabia: Production of Bio-Based Silica, Lignocellulose, and Activated Carbon

Bio-based silica, lignocellulose, and activated carbon were simply produced via the recycling of Hassawi rice biomass waste of Al-Ahsa governorate in the eastern Saudi Arabia region using a fast chemical treatment procedure. Rice husk and rice straw wastes were collected, ground, and chemically treated with sodium hydroxide to extract silica/silicate from the dried plant tissues. The liquid extract is then treated with acid solutions in order to precipitate silica/silicate at neutral medium. Lowering the pH of the supernatant to 2 resulted in the precipitation of lignocellulose. Thermal treatment of the biomass residue under N2 gas stream resulted in activated carbon production. Separated products were dried/treated and characterized using several physical examination techniques, such as FT-IR, SEM/EDX, XRD, and Raman spectroscopy in order to study their structure and morphology. Silica and lignocelluloses products were then preliminarily used in the treatment of wastewaters and water-desalination processes

Seeing Radiology Curricula Through Turkish Medical Students’ Eyes: A Survey of Turkish Medical Schools’ Radiology Education

INTRODUCTION Radiology education is essential for nonradiologist specialists and practitioners as well as for radiologists. We conducted a survey to gather the opinions of Turkish medical students from first to sixth grade regarding their radiology curricula, radiology education content, and perceptions of various imaging modalities and to assess the amount, adequacy, and homogeneity of radiology education in various schools. METHODS Turkish medical students were reached by student ambassadors from 10 different schools of medicine via social media and email. They were provided with a 20-question survey—via the SurveyMonkey platform—related to their radiology curriculum and their perceptions of the radiology education at their schools and of different imaging modalities. Subjective parameters were scaled by a 4-point Likert scale and the results are reported by percentages of students. RESULTS A total of 988 medical students (F/M: 61%/39%) from 41 different medical schools participated in this survey. Of those, 57% were preclinical students (≤ third year of medical school), while 43% were clinical students (> third year). More than half of the students (51%) stated that the amount of radiology education included in their curriculum was too little , while 44% of them stated it was just right and only 5% stated it was too much . Only 31% of the participants stated that they were able to review radiology images on their own. When asked about their level of confidence in identifying the position of lines and tubes, pneumonia, pneumothorax, and pleural effusion on chest radiographs, 41%, 39%, 41%, and 41% of the participants, respectively, stated that they were not confident. Thirty-five percent of the participants had not received any training in comparing normal to abnormal imaging of bone fractures, pneumonia, pleural effusion, subdural hemorrhage, or pneumothorax. The majority of the Turkish medical students in this survey had never heard (57%) nor used (64%) the American College of Radiology Appropriateness Criteria. CONCLUSIONS The radiology curriculum in Turkey differs among various schools and most students stated that preclinical radiology course content was inadequate. Further studies and improvements must be conducted to provide high-quality, equitable radiology education that begins during preclinical training with respect to the students’ opinions