Abstract

In this study, performance assessment of selected gas turbine power plants in Nigeria was evaluated using performance indices. The results of the study showed that for the period under review (2006–2010), the percentage shortfalls from the target energy in the selected power plants range from 26.33% to 86.61% as against the acceptable value of 5–10%. The capacity factor of the selected power plants varies from 16.88% to 73.67% as against the international value of 50–80%. The plant use factor varies from 45.89% to 97.03% and the utilization factor varies from 6.31% to 93.074% as against the international best practice of over 95%. From this result, it can be concluded that the generating units were underutilized. This is due to inadequate routine maintenance and equipment fault development. The analyses of reliability indicators revealed that the mean time between failures varies from 5.42 to 378.44 h, the mean time to repair varies from 18.3 to 153.88 h and the plant availability varies from 12.86% to 91.31% as against the Institute of Electrical and Electronics Engineers recommended standard of 99.9%. Evaluation of operating figures of the selected power plants revealed that starting reliability (SR) and operating reliability vary from 71.95% to 93.9% and 5.33% to 55%, respectively. The SR of the selected power plants is low in value compared with standard value of 99.9%. The statistical analysis carried out on plant availability revealed that at 95% confidence level, there is a significant difference in availability of the selected power plants. This indicates differences in their systems installation, operation and maintenance. The performance indicator developed to evaluate the performance indices for the selected stations can also be applicable to other power stations in Nigeria and elsewhere. Measures to improve the performance indices of the plants have been suggested in this paper.

Abstract

This contribution examines the visibility and accessibility of the doctoral dissertations in Library and Information Science in Spanish universities. The analysis shows the inadequacies of available resources that locate the theses in this discipline and calculate the percentage available as full text. Finally, a reflection about the use of classifications in the document databases is included.

Abstract

O transporte aéreo e a indústria de sistemas de defesa foram setores pioneiros na utilização de sistemas computacionais críticos, incrementando os níveis de automação nas atividades de controle do espaço aéreo. Com o crescimento desses setores, verificado pela expansão dos números de vôos, volumes de cargas e usuários, assim como pela ampliação e diversidade das operações militares, os sistemas de controle têm assumido maior complexidade técnica, introduzindo novos recursos de automação ou facilidades adicionais de apoio para funções exercidas manualmente. Essa situação tem ampliado a dependência dos serviços prestados, relativamente à disponibilidade dos sistemas computacionais. Diretrizes de projeto e procedimentos operacionais são estabelecidos para manter os níveis de segurança nos casos de falha, no entanto a disponibilidade torna-se parâmetro crítico, na medida em que algumas falhas podem afetar a eficiência nominal da prestação dos serviços. Nesse cenário, este trabalho propõe um modelo para avaliação da disponibilidade de sistemas de controle do espaço aéreo, a partir de recursos de análises da teoria de filas. Inicialmente é citado um modelo geral para análise de disponibilidade de data centers. Em seguida, é apresentada uma extensão do modelo geral para análise da disponibilidade em sistemas de controle do espaço aéreo. Para isso, considerou-se a intervenção humana existente nessa atividade, cujas decisões de controle são exercidas por operadores qualificados (controladores), tanto nas atividades inerentes ao serviço de controle, quanto nos casos de degradação, nos quais os operadores ou técnicos de manutenção assumem alguma tarefa de reparo, decorrente da eventual indisponibilidade de funções do sistema. Due to the growth in airspace utilization, which can be verified both in terms of the expansions in aerial movements, airports and volumes of transported passengers and cargo, as well as in terms of the expansion of military operations demands and diversity, airspace control activities have been increasing their technical complexity, introducing new features into the existent automation systems or creating additional resources for the automation of some functions previously performed by human operators. This situation has increased the dependence on the availability of the computer systems involved in the services provided by control centers. Project directives and operational procedures are established in order to maintain the safety integrity levels of the systems, in case any failure occurs. However, the availability becomes a critical parameter, once failure events can force an undesirable state of degraded operation, jeopardizing the nominal capacity of the services being performed through any controlled airspace. In this scenario, this work presents an availability model for the computer systems used in airspace control centers, based on analysis from queuing theory. A general model is first presented, referencing a case study that describes the use of queuing models to access the availability of generic data centers. Further considerations are introduced to extend this general model in order to propose its application for the specific computer systems used in airspace control centers, where operational control relies on human activities. In this case, system operation involves intensive use of human-machine interfaces (HMI), for the regular control services provided, and additional technical or operational maintenance activities, occasionally imposed to repair a momentary loss of any function of the system.

Abstract

In this paper a new parking guiding and information system is described. The system assists the user to find the most suitable parking space based on his/her preferences and learned behavior. The system takes into account parameters such as driver's parking duration, arrival time, destination, type preference, cost preference, driving time, and walking distance as well as time-varying parking rules and pricing. Moreover, a prediction algorithm is proposed to forecast the parking availability for different parking locations for different times of the day based on the real-time parking information, and previous parking availability/occupancy data. A novel server structure is used to implement the system. Intelligent parking assist system reduces the searching time for parking spots in urban environments, and consequently leads to a reduction in air pollutions and traffic congestion. On-street parking meters, off-street parking garages, as well as free parking spaces are considered in our system. © 2013 IEEE. 1156 1161 "p"Conference code: 99950 Cited By :12

Abstract

Despite general economic decline and power supply deficiencies, infrastructure made a modest net contribution of less than half a percentage point to Zimbabwe's improved per capita growth performance in recent years. Raising the country's infrastructure endowment to that of the region's middle-income countries could boost annual growth by about 2.4 percentage points. Zimbabwe made significant progress in infrastructure in its early period as an independent state. The country managed to put in place a national electricity network and establish regional interconnection in the power sector; to build an extensive network of roads for countrywide accessibility and integration into the regional transport corridors; to lay the water and sewerage system; and to make progress on building dams and tapping the significant irrigation potential. Unfortunately, at present the cross-cutting issue across all these sectors is Zimbabwe's inability to maintain and rehabilitate the existing infrastructure since the country became immersed in economic and political turmoil in the late 1990s. Neglect of all sectors due to the crisis has resulted in a generalized lack of new investment (in the power and water sectors in particular), and the accumulation of a huge rehabilitation agenda. Quality of service has declined across the board. The power system has become unjustifiably costly, inefficient, and unreliable. The condition of roads has deteriorated to the point that Zimbabwe became a bottleneck on the North-South transport corridor. Rural connectivity hardly exists. Failure to treat potable water, along with the deterioration of the water, sanitation, and garbage disposal systems, was responsible for the spread of cholera in 2008. By 2010 cholera affected most areas of the country and posed a health threat to neighboring countries. Looking ahead, Zimbabwe faces a number of important infrastructure challenges. Zimbabwe's most pressing challenges lie in the power and water sectors. Inefficient and unreliable power supply poses major risks to the economy, while the maintenance and upgrading of existing power infrastructure no longer looks to be affordable. At the same time, overhauling the water and sewerage system is imperative for curbing the public health crisis. Document type: Book

Abstract

The Tool for Rapid Assessment of City Energy (TRACE) is used for conducting rapid assessments of energy use in cities. It helps prioritize sectors with significant energy savings potential, and identifies appropriate energy efficiency interventions across six sectors-transport, municipal buildings, water and waste water, public lighting, solid waste, and power and heat. It is a simple, low-cost, user-friendly, and practical tool that can be applied in any socioeconomic setting. This report is based on the implementation of the TRACE tool in Constanta in July 2013 and it outlines ideas on what the city could further do to improve its energy efficiency performance. It details the analysis carried out and the recommendations derived as a result, for district heating maintenance and upgrade, non-motorized transport, public transport development, parking restraint measures, municipal building benchmarking program, municipal buildings audit and retrofit, street lighting timing program, energy efficiency action plan and strategy, and awareness raising campaigns. Document type: Book

Abstract

Infrastructure improvements contributed 0.6 percentage points to the annual per capita growth of Zambia's gross domestic product (GDP) over the past decade, mostly because of the exponential growth of information and communication technology (ICT) services. Poor performance of the power sector reduced the per capita growth rate by 0.1 percentage point. Simulations suggest that if Zambia's infrastructure platform could be improved to the level of the African leader, Mauritius, per capita growth rates could increase by two percentage points per year. Zambia's high generation capacity and relatively high power consumption are accompanied by fewer power outages than its neighbors. But Zambia's power sector is primarily oriented toward the mining industry, while household electrification, at 20 percent, is about half that in other resource-rich countries. Zambia's power tariffs are among the lowest in Africa and are less than half the level needed to accelerate electrification and keep pace with mining sector demands. Meeting future power demands and raising electrification rates will be difficult without increasing power tariffs. Zambia's infrastructure situation is more hopeful than that of many other African countries. Infrastructure spending needs, though large, are not beyond the realm of possibility, and Zambia's resource wealth and relatively well-off population provide a more solid financing basis than is available to many other countries. Zambia's infrastructure funding gap, though substantial, can be dramatically reduced through measures to stem inefficiencies and lower costs. Document type: Book

Abstract

The Tool for Rapid Assessment of City Energy (TRACE) is used for conducting rapid assessments of energy use in cities. It helps prioritize sectors with significant energy savings potential, and identifies appropriate energy efficiency interventions across six sectors-transport, municipal buildings, water and waste water, public lighting, solid waste, and power and heat. It is a simple, low-cost, user-friendly, and practical tool that can be applied in any socioeconomic setting. This report is based on the implementation of the TRACE tool in Iasi in July 2013 and it outlines ideas on what the city could further do to improve its energy efficiency performance. It details the analysis carried out and the recommendations derived as a result, for energy efficiency action plan and strategy, district heating maintenance and upgrade, non-motorized transport, public transport development, traffic flow optimization, parking restraint measures, municipal building benchmarking program, traffic restraint measures, municipal buildings audit and retrofit, and street lighting timing program. Document type: Book

Abstract

The Tool for Rapid Assessment of City Energy (TRACE) is used for conducting rapid assessments of energy use in cities. It helps prioritize sectors with significant energy savings potential, and identifies appropriate energy efficiency interventions across six sectors-transport, municipal buildings, water and waste water, public lighting, solid waste, and power and heat. It is a simple, low-cost, user-friendly, and practical tool that can be applied in any socioeconomic setting. This report is based on the implementation of the TRACE tool in Timisoara in April 2013 and outlines ideas on what the city could further do to improve its energy efficiency performance. It details the analysis carried out and the recommendations derived as a result, for district heating maintenance and upgrade, non-motorized transport, public transport development, parking restraint measures, municipal buildings audit and retrofit, street lighting timing program, and active leakage of water and pressure management. Document type: Book

Abstract

Better access to improved infrastructure services is an important engine for economic growth. The poor state of infrastructure is a key bottleneck to growth in African countries, and Cameroon is no exception. Between 2000 and 2005, improvements in information and communication technologies boosted Cameroon's growth performance by 1.26 percentage points per capita, while deficient power infrastructure held growth back by 0.28 percentage points. If Cameroon could improve its infrastructure to the level of the middle-income countries of Africa, the growth effect could be on the order of 3.3 percentage points. Cameroon has made significant progress in many aspects of infrastructure. Across a broad range of sectors, the country has made serious efforts to implement institutional reforms with a view to attracting private sector investment. Private sector concessions have been awarded for the Port of Douala, the CAMRAIL railway, the national power utility, and the national water utility (CDE). These arrangements have generally led to performance improvements and attracted significant volumes of finance. Power supply remains expensive and unreliable. Cameroon needs to accelerate the development of some of its prime hydropower sites, which would greatly improve the domestic power situation and potentially allow Cameroon to play its natural role as hydropower exporter to the Central African Power Pool. Cameroon's information and communication technology (ICT) reform remains frozen at an early stage. The telecom incumbent, CAMTEL, remains state-owned and receives substantial public subsidy. The mobile sector is relatively uncompetitive, operating as a duopoly. Moreover, while Cameroon enjoys access to a submarine cable, CAMTEL's monopoly control over the international gateway has prevented consumers from benefiting. Document type: Book