Stress analysis and fatigue life prediction of a wobble-plate

A five-stage compressor for compressing natural gas is being designed and evaluated. The compressor operates at 1500 rpm with natural gas pressure of 50 psi. This study examines deformation behavior, stress and strain distribution of the wobble plate component of the compressor. Fatigue loading on the wobble plate is computed from the reaction of compressed gas in each of the five cylinders. The highest pressure in the 5th cylinder is 3000 psi. The calculated stress evolution per revolution of the wobble plate is utilized to predict the fatigue lives of the wobble plate. The fatigue life prediction is performed using Brown-Miller algorithm with Morrow mean stress correction method. Results show that the stress is concentrated in the vicinity of the contact region between the guide plate and the polymer guide ball. The highest stress in the wobble plate and the polymer guide ball is 160.4 MPa and 127.8 MPa respectively. The corresponding predicted fatigue life of the wobble plate is 8x108 cycles. A higher stress gradient in the guide ball (max von Mises stress is 3.3 GPa) is predicted when a harder steel ball is employed. This is due to high stiffness of the mating plate/ball surfaces

Conflict with Others at a Bleeding Frontier: The Case of Tagoi in the Northeastern Nuba Mountains – Sudan

This article looks at the escalating conflict between the Tagoi and Hawazma and their allies over natural resources and political authority in the north-eastern Nuba Mountains, from the Tagoi’s perspective. It explains why and how the Tagoi Area has become a free zone for settlement by the Hawazma and their allies, who have succeeded in developing an independent native administration in the area and have begun to contest the Tagoi’s rights to political authority and land. It illustrates how security concerns associated with the Second Civil War between the government of Sudan (GoS) and the Sudan People’s Liberation Movement/Army (SPLM/A) first and the Sudan/South Sudan international border after the secession of South Sudan in 2011 have contributed to the escalation of this conflict. It also shows how this conflict has recently become entangled with the armed conflict between the GoS and the SPLM/A-North, thus attaining a new dimension

Experiences of physics teachers when implementing problem-based learning : a case study at Entsikeni cluster in the Harry Gwala District Kwazulu-Natal, South Africa

Problem-based learning (PBL) is an active teaching strategy that could be implemented in the South African educational system to assist in developing problem-solving skills, critical thinking skills, collaborative skills, self-directed learning and intrinsic motivation in students. Even though it is not easy to drift from a teacher-centred strategy to a student-centred strategy, but this drift is supposed to be a paradigm drift for the nation. ‘Physics is difficult’ has been the anthem of students in South African high schools. This has led to lower pass rates in physics and as a result low physics career person in society. Physics students in high schools need to be exposed to the PBL strategy since the PBL strategy focuses on real-life problems to develop problem-solving skills, critical thinking skills and self-directed learning in students which are the skills needed for concept formation in Physical Science. Basically, the education of Physical Science students focused on the ability to acquire skills to solve real-life problems. This study focuses on exploring the experiences of high school physics teachers at Entsikeni cluster, South African, when implementing problem-based learning (PBL) in their physics classrooms. The study uses the mixed-method approach where three different research instruments were used to collect quantitative and qualitative data sequentially. Questionnaires, RTOP and interview protocol were employed. The findings of the study indicate that teachers project positive attitudes toward the PBL strategy but may probably not continue to use it because it requires more time than that which is allocated in the Curriculum Assessment and Policy Statement (CAPS) Physical Science document and as a result may not be able to finish their ATP on time. Teachers are teaching physics with no specialization in physics, which probably could lead to poor, pass rates in Physical Science. Teachers were inexperienced in teaching physics in the FET and could probably affect students’ academic performance. It is recommended they apply the PBL strategy to correct the negative effect of their inexperience on students’ performance. It is evident that if inexperienced trained teachers apply an instructional strategy based on research, they tend to develop students' performance as compared to applying the traditional instructional strategy.Science and Technology EducationM. Sc. (Physics Education

2017 Ayvacık depremlerinden etkilenen Yukarıköy geleneksel taş evlerinin durumu

Turkey is considered one of the most earthquake-prone countries in the world. Turkey has hosted many important civilizations in history. Some of the important structures and settlements symbolizing the socio-economic and cultural life of these civilizations have survived to the present day. Located in the rural areas of Turkey, many of the new masonry structures that continue to be constructed under the influence of the structural culture formed by the civilizations are also under the influence of earthquake loads. FebruaryMarch 2017 Çanakkale/Ayvacık-based earth-quakes caused significant damage to the traditional masonry structures. The region in which Gülpınar based earthquakes took place has a significant historical background. The geography of the region where the earthquake took place hosts different civilizations from the chalcolithic period to the present. The examination of this region is important in that it is an earthquake region as well as having a noteworthy historical background. This study examines the behavior of the masonry structures damaged by the mentioned earthquakes, and the causes of damage. The study also reveals the importance of the architectural design of structures under the effect of the earthquake to its users. In the period of new settlement that will take place after the earthquake, in the light of the analyzes, suggestions have been made in order to bring out the structures that are comfortable, safe, and sustainable, considering the structural culture of the region.Türkiye bir deprem ülkesidir. Türkiye’nin bulunduğu topraklar aynı zamanda önemli medeniyetlere ev sahipliği yapmıştır. Bu medeniyetlerin sosyo-ekonomik ve kültürel yaşamlarını simgeleyen önemli yapı ve yerleşmelerin bir bölümü günümüze kadar ayakta kalmayı başarmıştır. Medeniyetlerin oluşturduğu yapısal kültürün etkisinde yapılmaya devam eden yeni yığma yapıların büyük bir bölümü Türkiye’nin kırsal bölgelerinde yer alırken aynı zamanda deprem yüklerinin etkisi altındadır. Şubat-Mart 2017 Çanakkale/Ayvacık merkezli depremler bu bölgedeki geleneksel yığma taş yapılarda önemli hasarlar oluşturmuştur. Gülpınar merkezli depremlerin gerçekleştiği bölge önemli tarihi geçmişe sahiptir. Depremin gerçekleştiği Bölgenin Coğrafyası elverişli olduğundan, kalkolitik döneminden günümüze kadar farklı medeniyetlere ev sahipliği yapmıştır. Bir taraftan deprem bölgesi olması, diğer taraftan önemli tarihi geçmişe sahip olan bölgenin incelenmesi önemlidir. Bu Çalışma, adı geçen depremlerin etkisinde hasar görmüş yığma taş yapıların depreme karşı davranışı ve hasar nedenleri incelenmiştir. Çalışmada ayrıca, depremin etkisindeki yapıların mimari kurgusunun kullanıcıları için ne derece önemli olduğunu ortaya çıkarılmıştır. Depremden sonra bölgede gerçekleşecek yeni yapılaşma döneminde, bölgenin yapısal kültürü dikkate alınarak konforlu, güvenli ve sürdürülebilir özellikte yapıların ortaya çıkması için analizler ışığında öneriler geliştirilmiştir

The variables which affect the success in english teaching in schools

This research has been done to find out the factors influencing the students’ successes in learning a foreign language (English). In other words; the effects of the methods and techniques, used by the teachers on the staff to teach the choosen foreign language, on the students’ success. The main aim of our study to make the foreign language teaching in secondary and high schools more effective and make it suitable by reducing the educational expences for ones who want to learn a foreign language but not having more Money. In our study ıt has been tried to answer some guestions which are suitable for us to make brief comments on the problem defined by us. We can order the guestions like this: 1- What is the level of the suitability of the contents of the choosen course boks to teach the foreign language and the goals of the second language learning? 2- What kind of language learning activities do the teachers use in the course? 3- How do the aims meet the needs of the students? 4- What difficulties have the teachers faced while designing and preparing their course curriculums? A reliable quastionaire prepared with the help of some experts and according to their poinof views has been applied to the teachers in some secondary and high schools in Erzurum directed by the ministry of education to have the data related with the problem defined by us

George W. Bush, September 11th and the rise of the Freedom Agenda in US-Middle East relations: a Constructivist Institutionalist approach

This thesis generates a greater understanding of the George W. Bush administration’s Freedom Agenda for the Middle East and North Africa. It is motivated by two central research questions: How and why was the Freedom Agenda developed? And, how was the Freedom Agenda constituted? To address these questions, a constructivist institutionalist methodology is developed. The value of this undertaking, is that it theorises the relationship between the events of September 11, 2001, and the rise of the Freedom Agenda. Consequently, this research focuses on the narrative constructed in the aftermath of the “crisis”, and how this laid discursive tracks for the evolution of the Freedom Agenda. Furthermore, it is demonstrated that the Bush administration appropriated and articulated multiple discourses into a distinctive ideological-discursive formation, which in turn, sedimented particular definitions of concepts such as ‘democracy’ and ‘freedom’. This created a new policy paradigm, which failed to address the ‘conflict of interests’ problem central to US-Middle East relations. As a result, the Freedom Agenda demonstrated a commitment to regional stability and the gradual reform of ally regimes, whilst seeking to challenge regimes hostile to the US. It was a policy caught between promoting democracy and domination