Pesquisa, projeto e construção de um sistema de ignição sem distribuidor

This work intends to know the most types of ignition systems, studying its history, the way it works, applications and some examples. The assembly of a distributor less ignition system is also required. All vehicles powered by internal combustion engines need an ignition system that allows this engine to ignite the air-fuel mixture using its ignition system in the best possible manner. The main goal of an ignition system is to obtain a spark having enough energy to start the chemical reaction of the oxygen and the fuel. It took a study dealing with the various types of ignition systems since their creation at the beginning of the last century until 2015. The work starts studying the high tension magneto ignition system and later together with the low tension ignition system, going on with the conventional ignition system and finally accomplishing with the various types of electronic ignition systems. It was studied and implemented an electronic circuit to power a double spark ignition system also known as wasted spark ignition system. This circuit was assembled with an electric pulse generator and powered mechanically by a dc electric motor of the variable rpm type

AN ANALYSIS OF SMALL BUSINESS LOAN GUARANTEE FUNDS

Small businesses are considered important engines for job growth and economic development by policy makers worldwide. One of the most commonly cited constraints of small businesses is a lack of access to capital. To address this constraint, small business loan guarantee programs have been established in over 100 countries. There are a variety of types of guarantee funds, with the most significant differences being which borrowers are eligible for guarantees, and how borrowers are approved for guarantees. There is currently no clear delineation between types of programs and the economic conditions they operate in, though some trends are becoming apparent. However, these trends may not be leading to the best economic outcomes possible. By better matching the structure of the guarantee fund to the economic conditions it operates in, the program’s success in meeting economic development goals may be greatly improved. Many programs in developing countries may not be taking advantage of bank expertise and may be limiting the scope of their effectiveness. At the same time, programs in developed countries may be wasting resources by scattering their efforts too thinly and subsidizing less competitive firms to the detriment of local economic development.

Distance software: design and analysis of distance sampling surveys for estimating population size

1. Distance sampling is a widely used technique for estimating the size or density of biological populations. Many distance sampling designs and most analyses use the software Distance. 2. We briefly review distance sampling and its assumptions, outline the history, structure and capabilities of Distance, and provide hints on its use. 3. Good survey design is a crucial prerequisite for obtaining reliable results. Distance has a survey design engine, with a built-in geographic information system, that allows properties of different proposed designs to be examined via simulation, and survey plans to be generated. 4. A first step in analysis of distance sampling data is modeling the probability of detection. Distance contains three increasingly sophisticated analysis engines for this: conventional distance sampling, which models detection probability as a function of distance from the transect and assumes all objects at zero distance are detected; multiple-covariate distance sampling, which allows covariates in addition to distance; and mark–recapture distance sampling, which relaxes the assumption of certain detection at zero distance. 5. All three engines allow estimation of density or abundance, stratified if required, with associated measures of precision calculated either analytically or via the bootstrap. 6. Advanced analysis topics covered include the use of multipliers to allow analysis of indirect surveys (such as dung or nest surveys), the density surface modeling analysis engine for spatial and habitat-modeling, and information about accessing the analysis engines directly from other software. 7. Synthesis and applications. Distance sampling is a key method for producing abundance and density estimates in challenging field conditions. The theory underlying the methods continues to expand to cope with realistic estimation situations. In step with theoretical developments, state-of- the-art software that implements these methods is described that makes the methods accessible to practicing ecologists.

Information and Communication Technologies for Educational Development: The Case of Cybercafés at Obafemi Awolowo University, Ile-Ife, Nigeria

This study examines the use of Cybercafés/Internet resources and the evaluation of their usefulness. About eight Cybercafés located in the university community were used in this study. Questionnaires, interviews with the Cybercafé owners, staff and users as well as personal observations made during inspection of these cafés were used in this study. The data were analysed according to the background of the Internet users. The richness and high speed, accuracy, and authority were used by users to judge the quality of the Internet. Information such as the establishment of the café's facilities, membership and the future of the Cybercafés were also looked into. Finally, one can clearly see that the dominating impact of digital technology has crossed the Rubicon of controversy. The result of the survey shows that forty percent of the users learnt to use the internet by self instruction, thirty five percent learnt from colleagues or friends. Those in the sciences use the internet the most, the channel mostly used in obtaining information is the search engines. A large number of students, faculties and researchers make use of the internet in obtaining information. Many of those of those users make use of the Cybercafés in the university community.

BIRD HAZARDS TO AIRCRAFT

When I spoke to the third Bird Control Seminar in 1966 on "Ecological Control of Bird Hazards to Aircraft", I reviewed what we had accomplished up to that time. I spoke about the extent of the problem, the bird species involved and the methods we used to make the airports less attractive to birds that created hazards to aircraft. I wish to discuss today our accomplishments since 1966. I have presented a number of papers on the topic including one with Dr. W. W. H. Gunn, in 1967 at a meeting in the United Kingdom, and others in the United States (1968 and 1970) and at the World Conference on Bird Hazards to Aircraft in Canada in 1969. There is no longer any question about the consequences of collision between birds and aircraft. Aircraft have not become less vulnerable either. Engines on the Boeing 747 have been changed as a result of damage caused by ingested birds. Figures crossing my desk daily show that while we are reducing the number of serious incidents and cutting down repair costs, we will continue to have bird strikes. Modification of the airport environment (Solman, 1966) has gone on continuously since 1963. The Department of Transport of Canada has spent more than 10 million dollars modifying major Canadian airports to reduce their attractiveness to birds. Modifications are still going on and will continue until bird attraction has been reduced to a minimum.

Airport Bird Threat in North America from Large Flocking Birds (geese) (as Viewed by an Engine Manufacturer)--Part 1

In worldwide aviation operations, bird collisions with aircraft and ingestions into engine inlets present safety hazards and financial loss through equipment damage, loss of service and disruption to operations. The problem is encountered by all types of aircraft, both military and commercial. Modern aircraft engines have achieved a high level of reliability while manufacturers and users continually strive to further improve the safety record. A major safety concern today includes common-cause events which involve significant power loss on more than one engine. These are externally-inflicted occurrences, with the most frequent being encounters with flocks of birds. Most frequently these encounters occur during flight operations in the area on or near airports, near the ground instead of at cruise altitude conditions. This paper focuses on the increasing threat to aircraft and engines posed by the recorded growth in geese populations in North America. Service data show that goose strikes are increasing, especially in North America, consistent with the growing resident geese populations estimated by the United States Department of Agriculture (USDA). Airport managers, along with the governmental authorities, need to develop a strategy to address this large flocking bird issue. This paper also presents statistics on the overall status of the bird threat for birds of all sizes in North America relative to other geographic regions. Overall, the data shows that Canada and the USA have had marked improvements in controlling the threat from damaging birds - except for the increase in geese strikes. To reduce bird ingestion hazards, more aggressive corrective measures are needed in international air transport to reduce the chances of serious incidents or accidents from bird ingestion encounters. Air transport authorities must continue to take preventative and avoidance actions to counter the threat of birdstrikes to aircraft. The primary objective of this paper is to increase awareness of, and focus attention on, the safety hazards presented by large flocking birds such as geese. In the worst case, multiple engine power loss due to large bird ingestion could result in an off-airport forced landing accident. Hopefully, such awareness will prompt governmental regulatory agencies to address the hazards associated with growing populations of geese in North America.

Estudo da viabilidade da implantação de frotas de veículos elétricos e híbridos elétricos no atual cenário econômico, político, energético e ambiental brasileiro

Currently there are two car models that use electricity in their propulsion systems, the electric vehicle and the hybrid electric vehicle. The electric vehicles are classified as vehicles that use electric motors in their propulsion system and batteries as a power source, on the other hand, the hybrid vehicles are classified as vehicles that use both electric motors and internal combustion engines in their propulsion system, using both batteries and líquid fuels as a power source. The main goal of this work is to analyze the characteristics of electric and hybrid electric vehicles and demonstrate the unfeasibility of the electric vehicle in the current economic, political, energetic and environmental brazilian scenario, for this purpose it was realized a study about the current brazilian situation regarding to electricity generation, current conservation status of road network, lack of electrical infrastructure for charging batteries, national lithium reserves, environmental characteristics, tax incentives, economic scenario, oil market and political positioning related to the implantation of electric or hybrid electric fleets in nacional territory. The operational characteristics analysis of electric and hybrid electric vehicles in this current scenario leads to the conclusion that currently a growth of electric vehicles fleets on a national scale is totally impractical in the Brazil, Thus, the introduction of green vehicles probably will occur primarily with hybrid electric models, motivated mainly due the bigger autonomy of this models compared to electric models, lower cost of hybrid electric models compared to electric models, factors related to the lack of recharging infrastructure and also factors related to political positioning

Gás natural no panorama brasileiro e um estudo de caso no setor automotivo

The intended purpose of this paper is to present the main aspects of natural gas applied to the public transportation as well as the environmental, economical and technical impacts in this sector. Also it is given specific information to be considered when comparing natural gas to other fuels, specially the diesel. At this point is presented the types of internal combustion engines (Otto and Diesel cycle) and which type is used in each vehicle. Moreover, it is presented the main standards pollutant emission (Euro, US and Proconve) with a brief explanation of the tests made in order to approve the engines. This paper is focused on heavy duty vehicles. Also in this paper is exposed the economic impact due to the natural gas use in the public transportation fleet. In addition is presented a real case (of Berlin) and an estimative to a Brazilian city, presenting the potential of natural gas as vehicular fuel in Brazil, as well as financial and environmental aspects of the substitution

Freio eletrodinamométrico usando um inversor de frequência e um motor de indução trifásico

Considering that the Brazilian energy source is based on hydroelectric power plants, every moment that it does not rain enough, we are likely to suffer power outage. Making the rational use of energy not only is wise, but also important for financial issues. The industrial sector is of great importance to Brazilian economic context, because it is one that creates more wealth and jobs. It should be noted that it is one of the sectors that consume more electricity. One of the most used equipment in industry is the three phase induction motor, which ends up providing significant waste of energy. For that reasons, studying three phase induction motors is important. One of the ways to evaluate the parameter of the three phase induction motor is using a dynamometer mechanic or electric. This work aims at further studies (and development) of electrodynamometer brake, a type of electrical dynamometer, that is the only one with reversible use. This means, it is possible to measure both the torque and the power transmitted by the electric motors, by the direct method and the indirect. Besides it allows greater stability in the imposition of charges, due to its nature of being able to regenerate the energy imparted by the engines being tested

Pesquisa, projeto e construção de um sistema de ignição sem distribuidor

This work intends to know the most types of ignition systems, studying its history, the way it works, applications and some examples. The assembly of a distributor less ignition system is also required. All vehicles powered by internal combustion engines need an ignition system that allows this engine to ignite the air-fuel mixture using its ignition system in the best possible manner. The main goal of an ignition system is to obtain a spark having enough energy to start the chemical reaction of the oxygen and the fuel. It took a study dealing with the various types of ignition systems since their creation at the beginning of the last century until 2015. The work starts studying the high tension magneto ignition system and later together with the low tension ignition system, going on with the conventional ignition system and finally accomplishing with the various types of electronic ignition systems. It was studied and implemented an electronic circuit to power a double spark ignition system also known as wasted spark ignition system. This circuit was assembled with an electric pulse generator and powered mechanically by a dc electric motor of the variable rpm type

Structure-semantics interplay in complex networks and its effects on the predictability of similarity in texts

The classification of texts has become a major endeavor with so much electronic material available, for it is an essential task in several applications, including search engines and information retrieval. There are different ways to define similarity for grouping similar texts into clusters, as the concept of similarity may depend on the purpose of the task. For instance, in topic extraction similar texts mean those within the same semantic field, whereas in author recognition stylistic features should be considered. In this study, we introduce ways to classify texts employing concepts of complex networks, which may be able to capture syntactic, semantic and even pragmatic features. The interplay between various metrics of the complex networks is analyzed with three applications, namely identification of machine translation (MT) systems, evaluation of quality of machine translated texts and authorship recognition. We shall show that topological features of the networks representing texts can enhance the ability to identify MT systems in particular cases. For evaluating the quality of MT texts, on the other hand, high correlation was obtained with methods capable of capturing the semantics. This was expected because the golden standards used are themselves based on word co-occurrence. Notwithstanding, the Katz similarity, which involves semantic and structure in the comparison of texts, achieved the highest correlation with the NIST measurement, indicating that in some cases the combination of both approaches can improve the ability to quantify quality in MT. In authorship recognition, again the topological features were relevant in some contexts, though for the books and authors analyzed good results were obtained with semantic features as well. Because hybrid approaches encompassing semantic and topological features have not been extensively used, we believe that the methodology proposed here may be useful to enhance text classification considerably, as it combines well-established strategies. (c) 2012 Elsevier B.V. All rights reserved.

A new damage model for composite laminates

Aircraft composite structures must have high stiffness and strength with low weight, which can guarantee the increase of the pay-load for airplanes without losing airworthiness. However, the mechanical behavior of composite laminates is very complex due the inherent anisotropy and heterogeneity. Many researchers have developed different failure progressive analyses and damage models in order to predict the complex failure mechanisms. This work presents a damage model and progressive failure analysis that requires simple experimental tests and that achieves good accuracy. Firstly, the paper explains damage initiation and propagation criteria and a procedure to identify the material parameters. In the second stage, the model was implemented as a UMAT (User Material Subroutine), which is linked to finite element software, ABAQUS (TM), in order to predict the composite structures behavior. Afterwards, some case studies, mainly off-axis coupons under tensile or compression loads, with different types of stacking sequence were analyzed using the proposed material model. Finally, the computational results were compared to the experimental results, verifying the capability of the damage model in order to predict the composite structure behavior. (C) 2011 Elsevier Ltd. All rights reserved.

Determination of the activation energies of beef tallow and crude glycerin combustion using thermogravimetry

The present study deals with the determination of the activation energy for the thermal decomposition of two renewable fuels crude glycerin and beef tallow. The activation energies were investigated by using a thermogravimetric analyzer (TGA) in the temperature range of 25-600 degrees C in atmosphere of synthetic air. The TG curves of the thermal decomposition process of both samples were divided into several phases and the second, called PH2, was chosen for the kinetic study because it is associated with the combustion ignition. Differential Thermal Analysis (DTA) showed an endothermic event at the PH2 region for the crude glycerin corresponding to devolatilization, while for beef tallow, this step presented an exothermic event, called LTO (low-temperature oxidation), which is correlated with devolatilization followed by combustion. For the entire PH2, activation energy values for crude glycerin were between 90 kJ mol(-1) and 42 kJ mol(-1), while for the beef tallow they ranged from 50 kJ mol(-1) to 113 kJ mol (1). The activation energy values obtained at the pre-ignition stage - conversion between 0 and 0.45 - showed that the crude glycerin with higher values requires an additional energetic support at the start of combustion processes and the beef tallow ignites more easily, presenting lower values. According to the Wolfer's equation, a direct relation between the activation energy and the ignition delay is established and the results of this study provides useful data for the development and design of new combustion chambers and engines when non-traditional fuels are used as feedstock. (C) 2012 Elsevier Ltd. All rights reserved.

Nitrous oxide emissions from gasohol, ethanol and CNG light duty vehicles

A sample of 21 light duty vehicles powered by Otto cycle engines were tested on a chassis dynamometer to measure the exhaust emissions of nitrous oxide (N2O). The tests were performed at the Vehicle Emission Laboratory of CETESB (Environmental Company of the State of Sao Paulo) using the US-FTP-75 (Federal Test Procedure) driving cycle. The sample tested included passenger cars running on three types of fuels used in Brazil: gasohol, ethanol and CNG. The measurement of N2O was made using two methods: Non Dispersive InfraRed (NDIR) analyzer and Fourier Transform InfraRed spectroscopy (FTIR). Measurements of regulated pollutants were also made in order to establish correlations between N2O and NOx. The average N2O emission factors obtained by the NDIR method was 78 +/- 41 mg.km(-1) for vehicles running with gasohol, 73 +/- 45 mg.km(-1) for ethanol vehicles and 171 +/- 69 mg.km(-1) for CNG vehicles. Seventeen results using the FTIR method were also obtained. For gasohol vehicles the results showed a good agreement between the two methods, with an average emission factor of 68 +/- 41 mg.km(-1). The FTIR measurement results of N2O for ethanol and CNG vehicles were much lower than those obtained by the NDIR method. The emission factors were 17 +/- 10 mg.km(-1) and 33 +/- 17 mg.km(-1), respectively, possibly because of the interference of water vapor (present at a higher concentration in the exhaust gases of these vehicles) on measurements by the NDIR method.

MOOGLE: a metamodel-based model search engine

Models are becoming increasingly important in the software development process. As a consequence, the number of models being used is increasing, and so is the need for efficient mechanisms to search them. Various existing search engines could be used for this purpose, but they lack features to properly search models, mainly because they are strongly focused on text-based search. This paper presents Moogle, a model search engine that uses metamodeling information to create richer search indexes and to allow more complex queries to be performed. The paper also presents the results of an evaluation of Moogle, which showed that the metamodel information improves the accuracy of the search.