Literature review (Analysis and design of Steel lattice

(Analysis and design of Steel lattice telecommunication tower - Literature review Example â€Å"In the very beginning, more than 100 years ago, the first steel lattice towers for telecommunications were produced of flat-sided profiles like the angular profiles since it was easy to produce and... assemble† (Packer and Willibald, 2006, 45). Since the phone was invented in the 1870s, with the twang on June 2, 1875 and the famous â€Å"Mr. Watson, come here. I want to see you† issued on March 10, 1876, this means that steel lattice towers have been used almost since the start of modern telecommunications, only thirty years or so after the invention of the phone (Bellis, 2011). The early steel lattice telecommunications towers were things of pure efficiency, designed purely for cost-saving and speed (Smith, 2007, 75). Transmission lines make any cost-saving useful because the line requires numerous standardized elements, so the steel lattice towers were often used as a line to run cable (Smith, 2007, 75). However, even in the earliest days of steel lattice constr uction, extensive testing was used, with testing stations pushing the towers to the point of destruction (Smith, 2007, 75). This helped lead to design curves on angle sections. Early towers were far from precarious, but were vulnerable to wind stress. Modern free-standing steel lattice towers have tended to adopt a tubular profile design because of wind stress and material costs, particularly in Northern Europe (Packer and Willibald, 2006, 45). They tend to â€Å"vary in face width from top to bottom† and use different bracing patterns (Smith, 2007, 75). Heights have varied from a mere 10 meters to 200 meters. Steel lattice towers are one of the more common low-lying telecommunication towers design, eclipsing guyed masts until around 150 meters (Smith, 2007, 75). This is because, below 150 meters, the cost â€Å"increases more rapidly with height† since there is a large ratio of height to base width which guyed towers do not need (Smith, 2007, 75). Modern steel free-st anding lattice towers have fallen out of favor in developed countries because of environmental impacts (Urbano, 2001). â€Å"Currently available design solutions with acceptable appearance are not employed in the developing countries, mainly for cost reasons. In the developing countries the use of the traditional lattice transmission towers will continue employing steel angles† (Urbano, 2001, 36). This is not to say they are not in use, but that other alternatives, particularly concrete, have pushed them out of the way. Currently, the tallest free-standing steel lattice construction in the world is the Kiev TV Tower, which was built in 1974 while the Iron Curtain was in full force (Construction Week, 2010). â€Å"The tower weighs 2,700 tons and is unique in the fact that no mechanical fasteners were used in its construction†; every single piece is welded together (Construction Week, 2010). The tower rests on a 100 meter four-legged base, after which is the microwave tr ansmission equipment; at 200 meters, TV and FM transmitting equipment begins. Ironically, the Kiev TV Tower could have been even larger, but it was decided not to be placed in Moscow, and the Moscow tower uses prestressed concrete, though it remains free-standing (Construction Week, 2010). The Kiev tower would have been 30% larger had it been built in Moscow. Another classic of steel lattice design is the

Behaviour Policy in Schools Essay Example | Topics and Well Written Essays - 2000 words

Behaviour Policy in Schools - Essay Example This paper illustrates that the dynamics of educational policy-making keep changing due to changes in the environment. Contrary to previous years where the national government made policies regarding education, nowadays there is more input from other actors both in government and private sphere. The state and local governments are involved as well as the entrepreneurs, consultants, professionals, teachers and school leaders. Furthermore, modern education has been marketized to suit economic interests thus bringing into the context other actors. According to Hulme, R., and Hulme, M., the spaces in which policy is thought and done have also changed. The use of technology has changed the context in that now education can not only be offered at schools but also at home and across national boundaries through e-learning. Policymakers, therefore, have to take into consideration such dynamics. Ainley also observes that education system has evolved from â€Å"national system locally administ ered to a local system nationally administered.† In the United States, there has been a push for more standardized reforms to enhance cohesiveness, fairness, and equity. It is a requirement for schools by the Education and Inspections Act of 2006 to have a behavior policy which includes school rules. This policy is part of the wider national education policies. The aim of this paper is thus to discuss the policy process in schools in relation to behavior policies. To accomplish this, the paper will discuss the standards, institutional contexts and the key actors in policy making.