Numerical Simulation Of Sediment Transport And Bedmorphology Around A Hydraulic Structure On A River

Scour around hydraulic structures is a critical problem in hydraulic engineering. Under prediction of scour depth may lead to costly failures of the structure, while over prediction might result in unnecessary costs. Unfortunately, up-to-date empirical scour prediction formulas are based on laboratory experiments that are not always able to reproduce field conditions due to complicated geometry of rivers and temporal and spatial scales of a physical model. However, computational fluid dynamics (CFD) tools can perform using real field dimensions and operating conditions to predict sediment scour around hydraulic structures. In Korea, after completing the Four Major Rivers Restoration Project, several new weirs have been built across Han, Nakdong, Geum and Yeongsan Rivers. Consequently, sediment deposition and bed erosion around such structures have became a major issue in these four rivers. In this study, an application of an open source CFD software package, the TELEMAC-MASCARET, to simulate sediment transport and bed morphology around Gangjeong weir, which is the largest multipurpose weir built on Nakdong River. A real bathymetry of the river and a geometry of the weir have been implemented into the numerical model. The numerical simulation is carried out with a real hydrograph at the upstream boundary. The bedmorphology obtained from the numerical results has been validated against field observation data, and a maximum of simulated scour depth is compared with the results obtained by empirical formulas of Hoffmans. Agreement between numerical computations, observed data and empirical formulas is judged to be satisfactory on all major comparisons. The outcome of this study does not only point out the locations where deposition and erosion might take place depending on the weir gate operation, but also analyzes the mechanism of formation and evolution of scour holes after the weir gates.

Beyond sea, sun and fun in Rio de Janeiro: understanding exchange students motivations and interests

O objetivo deste estudo é compreender o que leva estudantes de intercâmbio ao Rio de Janeiro, quais são suas motivações e interesses que influenciam na escolha dessa cidade, um destino pouco tradicional para intercâmbios, que recebe um crescente número de intercambistas de países desenvolvidos. Também apresentamos uma discussão mais ampla sobre a educação internacional do século 21, posicionando programas de intercâmbio como uma das possíveis iniciativas para a internacionalização de instituições de ensino superior. Para responder essa questão, 20 estudantes de 11 países foram entrevistados. Os resultados indicam que existe muito mais no Rio de Janeiro além do sol e das belas praias. Há uma grande variedade de interesses que explicam porque estudantes de intercâmbio escolhem esse destino. O clichê sobre sol, praia e carnaval se manifestou em diversas respostas, no entanto, nunca como principal fator. Intercambistas se interessam pela cidade por diversos motivos além das atrações turísticas, como aprender português, melhorar o currículo e estar em uma economia emergente. Recomendações para a internacionalização de instituições de educação e uma agenda de pesquisa para o desenvolvimento desse tópico são apresentadas na parte final.

Transport stress in matrinxa, Brycon cephalus (Teleostei : Characidae), at different densities

Matrinxa, Brycon cephalus, is a native teleost fish from the Amazon Basin, and is of economic importance for cultivation for food and sport in Brazil. Mortality losses due to handling and transport of this stenohaline freshwater species are common. The effects of transportation at different densities on the biochemical stress responses of matrinxa (mean weight 1 kg) were examined. Fish were subjected to three different transport densities (100, 200, and 300 kg m(-3)) for four h in water with added salt (0.6%). The fish were bled at departure (baseline level), arrival (immediately after transportation) and at 24 and 96 h after arrival (recovery period). Blood glucose, cortisol, sodium, chloride, potassium and ammonia were used as stress bioindicators. No mortality was observed and no alterations in plasma cortisol were registered. However, blood glucose and ammonia levels increased and serum sodium and plasma chloride decreased on arrival for the fish transported at the highest densities. These stress responses were transient and the concentrations returned to baseline levels within 24 h. This study showed that matrinxa can be transported at densities as high as those tested in the present study, at least under the conditions employed in this study. A recovery period of at least 24 h is strongly recommended.

Bridging infrastructural gaps in Central America: prospects and potential for maritime transport

Includes bibliography

Landlocked countries in South America: transport system challenges

Includes bibliography

The economic costs associated with landlocked status

Two Latin American republics, Bolivia and Paraguay, lack sovereign access to ocean ports. Their landlocked status effectively forces them to export and import products through borders with neighbouring countries; for this purpose, they frequently use land transport modes which are intrinsically more costly than ocean transport. However, being distant from ocean ports is an attribute not only of landlocked countries; but also of states or provinces, such as Mato Grosso, in Brazil, or Tucumán, in Argentina, which belong to countries with direct access to the sea. If perfect political and economic integration were to be achieved in the region, the distances and topographic accidents between points such as La Paz, Bolivia, and Arica, Chile, or Asunción, Paraguay and Paranaguá, Brazil, would remain unchanged. What would disappear would be the delays at border crossings and their related costs. For the two landlocked countries, border expenses, although significant, are a relatively small fraction of the cost of the land segments of international transport. More important for these countries, are the dependency of infrastructure services and the institutional framework of the transit countries for the transport of their external trade.

Third ordinary meeting of the conference of South American ministers of transport, communications and public works

The third ordinary meeting of the Conference of South American Ministers of Transport, Communications and Public Works was held from 6 to 8 November 1996 in Montevideo, Uruguay. Representatives of Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Paraguay, Peru, Uruguay and Venezuela took part. Representatives of the following organizations were present as observers: the Latin American and Caribbean Federation of National Associations of Cargo Agents, the Latin American Railways Association, the Latin American Association for Automated Highway Transport, the Inter-American Development Bank, the Economic Commission for Latin America and the Caribbean (ECLAC), the United Nations Conference on Trade and Development (UNCTAD), the International Road Federation/German Agency for Technical Cooperation (IRF/GTZ); and other representatives from both the private and public sectors.

Integrated transport systems in Latin America and the Caribbean: converging initiatives

The year 1998 is shaping up to be a year of grand regional initiatives focusing on the setting up of regional integrated transport systems. The past six months have seen intense activity in Latin America and the Caribbean. It would seem that the public and private sectors have agreed to launch converging initiatives, each from its own perspectives. In Central America, a multimodal transport project is already under way, while a new transport master plan put forward by the Permanent Secretariat of the General Treaty on Central American Economic Integration (SIECA) is being prepared; in South America, the Latin American Integration Association (LAIA) and Latin American Railways Association (ALAF) have launched a prefeasability study concerning a plan for the sustainable development of transport; the second Summit of the Americas adopted a plan of action that now takes in the work of the Executive Committee of the Western Hemisphere Transport Initiative; and the private sector also held its regional meeting in São Paulo, Brazil, with Intermodal 98, the fourth in a series. These initiatives are taking shape around similar lines of thought and action; their backgrounds are similar, and they tend towards the same goal: taking action in the immediate environment with a view to expanding linkages with the global economy. The background is the observation that after several years of growth, transport infrastructure, equipment and services appear unable to satisfy the growing demand of international trade in the region. The goal is to implement the requisite reforms in the transport sector so as to meet the challenges posed by global competition. This issue of the Bulletin is devoted to news about recent initiatives and possible future developments.

Road maintenance and international competitiveness

The present and subsequent editions of the Bulletin will deal with the issue of road maintenance, its close connection with transport costs and its impact upon the international competitiveness of the countries of Latin America and the Caribbean. When roads are in poor condition, vehicle operating costs increase by 30 to 50% or even more. Autonomous, adequate and regular funding contributes to effective road maintenance and, consequently, to reducing vehicle operating costs.

Facilitation of international trade in goods

The FAL Bulletin is reverting to its original concept, that is, facilitation of trade in the broad sense. In the context of ECLAC, this is a topic covered by the International Trade Unit in the International Trade and Development Finance Division, to which the Transport Unit also belonged until it was incorporated into the Natural Resources and Infrastructure Division in April 1999.In an effort at inter-divisional cooperation starting with this issue, the International Trade Unit will be responsible for preparing four articles per year on trade facilitation for the FAL Bulletin. These are certain to be of great interest not only to those of our readers concerned with multi-modal ocean transport and customs procedures but also to those with links to the broader issue of promoting foreign trade in the region.

CEFACT: an international private/public sector partnership

The Centre for the Facilitation of Procedures and Practices in Administration, Commerce and Transport (CEFACT) constitutes a partnership between the public and private sectors for their mutual benefit. For the private sector, working with governments to improve commerce is critical to improving international competitiveness. For governments, working with the private sector to reduce procedural barriers to trade is critical to improving both their own administrative effectiveness and the economic well-being of their countries. This issue of the Bulletin presents an exposition by the Chairman of the CEFACT, Mr. Henri Martre, at the Trade Facilitation Seminar, carried out between 9 and 10 March of 1998, at the Headquarters of the World Trade Organization, Geneva, Switzerland. Its main purpose is to explain the importance of CEFACT's partnership between the public and private sectors; how this partnership works, and the trade facilitation instruments it has created.

Competitiveness and efficiency in land transport

One of the consequences of the opening of the worlds economies - an integral part of globalization - is increased focus on the efficiency and costs of transport services (on which competitiveness is largely dependent). Countries with inefficient and costly transport services lose out, in terms of economic activity and income, to those with more appropriate transport services. The issue is particularly important in Latin America, where exports mainly consist of bulk consignments of products with comparatively low value/quantity ratios and transport costs are a major determining factor of c.i.f. prices.The determination of competitiveness indices in the long term, however, also needs to include the costs of pollution, congestion and accidents, in addition to the transport costs usually considered as part of the price of freight. Competitiveness, efficiency and the global costs of transport were the main subjects of an international seminar organized in conjunction with the Chilean Institute of Engineers and held on 9 and 10 September 2004 at the Headquarters of the Economic Commission for Latin America and the Caribbean (ECLAC).

Modernization of Customs and Implementation of Single Window Systems for Foreign Trade: Results of an International Seminar-Workshop

An international seminar-workshop entitled "Facilitation of trade and transport in Latin America: situation and outlook" was held at the headquarters of the Economic Commission for Latin America and the Caribbean (ECLAC) on 29 and 30 November 2005, organized jointly by the ECLAC Division of International Trade and Integration and the United Nations Conference on Trade and Development (UNCTAD). The event was attended by about 50 persons involved in customs modernization and/or the implementation of single window systems for foreign trade in 20 Ibero-American countries.The main purpose of the seminar-workshop was to exchange ideas, opinions and proposals concerning the efficient implementation of trade facilitation instruments. The conclusions reached at this event point to the need to seek convergence among the existing trade agreements associated with trade facilitation in Latin America. Customs modernization requires the re-design of processes and procedures in order to achieve interoperability among the systems, and single window systems for foreign trade can only be implemented successfully if clear political leadership is established with broad participation from both public and private organizations.

Institutionality, logistics and international cooperation for the economic and social development: The case of the Plurinational State of Bolivia

Includes bibliography.