Reducing automobile-based gasoline consumption has been a major U.S. public policy issue recently. A key driving force behind policymakers' desire is the concern of environmental externalities and national security. Currently, there are three public policies towards reducing automobile gasoline consumption: raising federal gasoline tax, raising the Corporate Average Fuel Economy (CAFE) Standards and vehicle scrappage subsidies of government to retirement of old vehicles. My research studies the effectiveness of these policies in the United States. Among all polices, economists often argue that higher gasoline tax would be more effective in improving fuel economy efficiency. In my first chapter, I ask how gasoline prices influence households' automobile replacement decisions and thus market fuel economy efficiency, which is measured by average mileage per gallon in a city. I specify and estimate a structural dynamic model of consumer preference for new and used vehicles following the methodology proposed by Gowrisankaran and Rysman (2009). Since gasoline costs accounts for 65% of total operating costs, the current and future gasoline price must need to be taken into consideration for rational forward-looking consumers when they are making vehicle choices. Besides, the replacement decision for vehicles is dynamic as well: facing depreciation as the automobile ages and the improving features for new products, consumers need to decide whether to replace the vehicle in the current period or later. Therefore, a dynamic model of consumer choice would be crucial to correct policy evaluation of fuel economy efficiency, while previous literature fails to consider the dynamics. By taking dynamics into consideration, I am able to capture the inherent dynamic nature of a forward-looking consumer's decision, with rational expectation on the evolution of vehicle attributes and retail gasoline prices. I estimate the model using a rich dataset combing vehicle registration data on different cities, vehicle characteristic data, average gasoline price, etc. Although a high gasoline tax is never put in practice in the U.S. and may not be political feasible, I further conduct an experiment of raising gasoline tax to test how fuel economy efficiency is affected based on my model estimates. Experiments suggest that keeping a $4 gasoline price would result in a steady trend for a city's fleet fuel efficiency increase, while doubling current rate will only increase fuel efficiency in the first several years, but experience drops over time. The Corporate Average Fuel Economy (CAFE) are regulations in the United States that intended to improve the average fuel economy of cars and light trucks sold in the US. However, it is long been realized that with a more fuel efficiency car, consumers may be induced to drive more which partially offsets the original energy saving by the policy. Therefore, to assess the effectiveness of CAFE standards, it is crucial to ask: how fuel economy efficiency, which is measured by mileage per gallon (MPG), affects households' vehicle mileage traveled and its distribution. In my second chapter, I answer the question by estimating a structural model for joint determination of vehicle fuel efficiency choice and vehicle mileage traveled each year with a detailed micro-level data of National Household Travel Survey 2001. I further study the distributional effects on vehicle miles of fuel efficiency using instrumental quantile regression. Comparison on results and tests of weak instruments between my method and literature suggest that my model and choice of instruments provide consistent estimates, while using choice probabilities as instruments is not valid. My results support some earlier findings of rebound effects with a more precise quantitative estimation. In addition, I find new evidence that costs associated with raising CAFE standards vary across different quantiles of annual mileage driven and are especially high for those with below-average vehicle mileage driven. These findings also provide rationale in support of a tax on mileage, which is more effective in reducing gasoline consumptions, comparing to the costs of CAFE standards. My third chapter focus on 2009 CARS Program (Cash-for-Clunker). The 2009 CARS program attempted to boost the sale of new fuel efficient vehicles to replace old gas guzzlers. The program established a two-tier incentive system depending on whether buyers purchased a passenger vehicle or an SUV. The result is that many of the new purchased vehicles are indeed SUVs. The CARS program collected information about the old scrapped vehicles and linked it to the actual purchase of the new vehicles. It is thus possible to analyze the effect of preference inertia in choices by comparing the characteristics of old and new vehicles. The fact that effective prices that consumers face are determined by the mileage class of the old car also allows us to evaluate the distribution of valuation trade-offs between mileage and other characteristics such as size, performance, and vehicle class. My findings suggest that the 2009 Cash-for-Clunker is not very effective in terms of affecting consumers' choice of SUVs and big cars. For transactions under the program, consumers still prefer SUVs and large cars. The extra $1000 rebates actually increase consumers' tastes towards SUVs. / text

Sustainable development has created new demands and led to a new way of thinking within the community-planning realm and has grown in use due to the increasing and changing awareness of environmental issues and their connection to growth within communities. As part ofthe Canadian Federal Gas Tax Fund requirement, municipalities must develop an Integrated Community Sustainability Plan (ICSP). Currently, many municipalities are working towards a sustainable or environmental vision for their community and have developed master plans and policies to implement environmental practices. The issue facing municipalities is how do existing bodies of work support and integrate into the development of an ICSP? The Town of Oakville is used as a case study to investigate the method of reconciling master plans and policies to develop an ICSP. The research methods include a case study, interviews, the analysis ofICSP toolkits and municipal ICSPs. The research identifies successes, limitations, and improvements for the proposed approach.

This thesis presents detailed fuel spray investigations relating to an automotive Gasoline Direct Injection (GDI) pressure-swirl injector, employing a combination of numerical and physical analyses. The emphasis is placed on the near-nozzle in recognition that all later flow processes are dominated by this critical region. To enable the technology to maximise its potential, it is essential to further our understanding of the fundamental flow physics that govern the injection process, which remain largely unknown. The complexity of the spray process has led to many avenues of research. Simplified models are particularly suitable for parametric studies, allowing fast computation of some of the most important design parameters, such as nozzle discharge coefficient, cone angle and initial velocity. More complex methods such as Computational Fluid Dynamics (CFD) offer significantly more detail including the temporal and spatial evaluation of the flow field and fuel distribution, but at the cost of often lengthy computational time, and the need to tune models against physical evidence. Unfortunately none are able to describe all aspects of the injection event simultaneously. A considerable body of existing experimental data gathered under atmospheric conditions has been condensed and carefully presented to provide a comprehensive picture of injector operation. This comprises global spray performance data, spray imaging, and droplet velocity and size maps as a function of time after the Start Of Injection (SOl). These serve to provide a means to develop physical models and to correlate model predictions. Particular attention is drawn to the challenges faced by numerical methods to successfully predict the complex spray behaviour. A fundamental computational study employing the Volume Of Fluid (VOF) method describes droplet break-up under controlled conditions. By varying the Weber number of the flow the expected break-up mechanisms are recovered, and the numerics and case set-up tuned to offer a practical balance between the resource burden and solution accuracy. This paved the way to a detailed 3-D transient analysis of the near-nozzle region of a pressure-swirl injector. Computed results clearly identify the consecutive phases of the fuel spray development, from the initial unsteady jet through to the stable, swirling hollow cone formation. Comparison with experimental measurements revealed that the computational approach is able to capture the main qualitative features of the spray process.

Coal derived synthetic gas (syngas) fuel is a promising solution for today s increasing demand for clean and reliable power. Syngas fuels are primarily mixtures of H2 and CO, often with large amounts of diluents such as N2, CO2, and H2O. The specific composition depends upon the fuel source and gasification technique. This requires gas turbine designers to develop fuel flexible combustors capable of operating with high conversion efficiency while maintaining low emissions for a wide range of syngas fuel mixtures. Design tools often used in combustor development require data on various fundamental gas combustion properties. For example, laminar flame speed is often an input as it has a significant impact upon the size and static stability of the combustor. Moreover it serves as a good validation parameter for leading kinetic models used for detailed combustion simulations. Thus the primary objective of this thesis is measurement of laminar flame speeds of syngas fuel mixtures at conditions relevant to ground-power gas turbines. To accomplish this goal, two flame speed measurement approaches were developed: a Bunsen flame approach modified to use the reaction zone area in order to reduce the influence of flame curvature on the measured flame speed and a stagnation flame approach employing a rounded bluff body. The modified Bunsen flame approach was validated against stretch-corrected approaches over a range of fuels and test conditions; the agreement is very good (less than 10% difference). Using the two measurement approaches, extensive flame speed information were obtained for lean syngas mixtures at a range of conditions: 1) 5 to 100% H2 in the H2/CO fuel mixture; 2) 300-700 K preheat temperature; 3) 1 to 15 atm pressure, and 4) 0-70% dilution with CO2 or N2. The second objective of this thesis is to use the flame speed data to validate leading kinetic mechanisms for syngas combustion. Comparisons of the experimental flame speeds to those predicted using detailed numerical simulations of strained and unstrained laminar flames indicate that all the current kinetic mechanisms tend to over predict the increase in flame speed with preheat temperature for medium and high H2 content fuel mixtures. A sensitivity analysis that includes reported uncertainties in rate constants reveals that the errors in the rate constants of the reactions involving HO2 seem to be the most likely cause for the observed higher preheat temperature dependence of the flame speeds. To enhance the accuracy of the current models, a more detailed sensitivity analysis based on temperature dependent reaction rate parameters should be considered as the problem seems to be in the intermediate temperature range (~800-1200 K).

Made available in DSpace on 2014-12-17T14:08:44Z (GMT). No. of bitstreams: 1 RafhaelAH_DISSERT.pdf: 3286080 bytes, checksum: f7d63c2f5fde3101ddffb2cd1417b11d (MD5) Previous issue date: 2011-02-17 / Efforts in research and development of new technologies to reduce emission levels of pollutant gases in the atmosphere has intensified in the last decades. In this context, it can be highlighted the modern systems of electronic engine management, new automotive catalysts and the use of renewable fuels which contributes to reduce the environmental impact. The purpose of this study was a comparative analysis of gas emissions from a automotive vehicle, operating with different fuels: natural gas, AEHC or gasoline. To execute the experimental tests, a flex vehicle was installed on a chassis dynamometer equipped with a gas analyzer and other complementary accessories according to the standard guidelines of emission and security procedures. Tests were performed according to NBR 6601 and NBR 7024, which define the urban and road driving cycle, respectively. Besides the analysis of exhaust gases in the discharge tube, before and after the catalyst, using the suction probe of the gas analyzer to simulate the vehicle in urban and road traffic, were performed tests of fuel characterization. Final results were conclusive in indicating leaded gasoline as the fuel which most contributed with pollutant emissions in atmosphere and the usual gasoline being the fuel which less contributed with pollutant emissions in atmosphere / Nas ?ltimas d?cadas tem se intensificado os esfor?os em pesquisa e desenvolvimento de novas tecnologias para redu??o dos n?veis das emiss?es de gases poluentes na atmosfera. Neste contexto, destacam-se os modernos sistemas de gerenciamento eletr?nico do motor, os novos catalisadores automotivos e a utiliza??o de combust?veis renov?veis que contribuem para o menor impacto ambiental. A presente pesquisa teve como prop?sito a an?lise comparativa das emiss?es gasosas de um ve?culo automotivo, funcionando com diferentes combust?veis: g?s natural, AECH, ou gasolina. Para execu??o dos testes experimentais, um ve?culo flex foi instalado em um dinam?metro de chassi equipado com analisador de gases e demais acess?rios complementares ao atendimento das diretrizes das normas de emiss?o e procedimentos de seguran?a. Os ensaios foram realizados de acordo com as normas NBR 6601 e NBR 7024, que definem o ciclo de condu??o urbano e estrada, respectivamente. Al?m da an?lise dos gases de escapamento no tubo de descarga, antes e ap?s o catalisador, utilizando a sonda de aspira??o do analisador de gases, para simula??o do ve?culo em tr?fego urbano e estrada, foram realizados testes de caracteriza??o dos combust?veis. Os resultados finais foram conclusivos em apontar a gasolina aditivada como o combust?vel que mais contribuiu com as emiss?es de poluentes na atmosfera e a gasolina comum sendo o combust?vel que menos contribuiu com as emiss?es de poluentes na atmosfera

111f. / Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2013-04-08T15:24:24Z No. of bitstreams: 1 Dissertação Karla Conceição.pdf: 1315216 bytes, checksum: 9a7555a384ee174d65453856c5c12964 (MD5) / Approved for entry into archive by Ana Hilda Fonseca(anahilda@ufba.br) on 2013-05-09T17:28:53Z (GMT) No. of bitstreams: 1 Dissertação Karla Conceição.pdf: 1315216 bytes, checksum: 9a7555a384ee174d65453856c5c12964 (MD5) / Made available in DSpace on 2013-05-09T17:28:54Z (GMT). No. of bitstreams: 1 Dissertação Karla Conceição.pdf: 1315216 bytes, checksum: 9a7555a384ee174d65453856c5c12964 (MD5) Previous issue date: 2010 / CNPq / A influência do número e ordem de tratamentos de oxidação e redução nas propriedades de catalisadores contendo platina, germânio e/ou rênio, suportados em alumina, foi estudada neste trabalho, visando à sua aplicação na reforma catalítica de nafta de petróleo. Os catalisadores foram preparados pelo método de impregnações sucessivas de soluções metálicas (ácido hexacloroplatínico hexahidratado, (perrenato de amônio e cloreto de germânio), em uma y-alumina comercial. As amostras foram submetidas a tratamentos de oxidação e/ou redução durante a impregnação dos metais, sendo obtidos catalisadores monometálicos, bimetálicos e trimetálicos. Os sólidos foram caracterizados por redução termoprogramada, dessorção de piridina a temperatura programada, espectroscopia fotoeletrônica de raios X, espectroscopia no infravermelho com transformada de Fourier de monóxido de carbono adsorvido e avaliadas na desidrogenação do cicloexano e isomerização do n-hexano. Observou-se que o comportamento redutor dos sólidos bimetálicos e trimetálicos é afetado pelo método de preparação. A etapa de oxidação favoreceu uma interação mais forte entre os metais nas amostras bimetálicas contendo germânio e platina, enquanto a redução favoreceu uma interação mais fraca entre os metais e uma interação mais forte do óxido de germânio com o suporte. Nas amostras bimetálicas contendo platina e rênio, a etapa de redução seguida de oxidação favoreceu a interação entre os metais, enquanto nos sistemas trimetálicos a interação entre os metais foi favorecida por pelo menos uma etapa de redução. Foi observado também que o tratamento de oxidação favoreceu a formação de sítios de acidez mais fraca, nos catalisadores formados por platina e germânio e o inverso ocorreu com as amostras bimetálicas contendo rênio. Em todos os casos, o tratamento de redução, conduzido no final da preparação, levou a uma diminuição na quantidade de sítios ácidos fortes, com maior formação de sítios ácidos fracos ou de acidez moderada. Os tratamentos térmicos de oxidação e redução durante a preparação dos catalisadores, conduziram a diferentes distribuições dos metais na superfície dos sólidos, devido às diferentes interações entre eles, que causaram diferentes migrações no sólido. A presença do germânio diminuiu a densidade eletrônica da platina em relação ao catalisador monometálico de platina, enquanto o rênio possui um efeito inverso. Nas amostras bimetálicas contendo rênio, em que foi feito apenas o tratamento de redução ou oxidação, foi observada a formação de sítios com maior deficiência eletrônica que o sólido que sofreu os dois tratamentos. A atividade na desidrogenação do cicloexano foi mais baixa nos catalisadores contendo germânio, ocorrendo o inverso naqueles contendo rênio. Em uma tendência geral, a atividade desidrogenante dos sítios metálicos foi diminuída nos sólidos em que se realizou a redução da platina antes da etapa de oxidação ou não foi feita a redução. Entre os catalisadores trimetálicos, a amostra que sofreu três etapas de oxidação e uma de redução apresentou a atividade mais elevada. Na isomerização do n-hexano, as duas etapas de oxidação favoreceu a atividade da amostra de platina e germânio, o que foi atribuído à formação de sítios adequados para as reações de isomerização. Este catalisador também produziu a maior quantidade de benzeno / Salvador

Submitted by Seiji Fetter (seijifetter@gmail.com) on 2012-03-25T15:05:42Z No. of bitstreams: 1 seijikf dissertacao final.pdf: 455320 bytes, checksum: 36d1a9b7fd17769fb9a735a6e3ef4c8c (MD5) / Approved for entry into archive by Gisele Isaura Hannickel (gisele.hannickel@fgv.br) on 2012-03-26T12:40:27Z (GMT) No. of bitstreams: 1 seijikf dissertacao final.pdf: 455320 bytes, checksum: 36d1a9b7fd17769fb9a735a6e3ef4c8c (MD5) / Made available in DSpace on 2012-03-26T12:55:13Z (GMT). No. of bitstreams: 1 seijikf dissertacao final.pdf: 455320 bytes, checksum: 36d1a9b7fd17769fb9a735a6e3ef4c8c (MD5) Previous issue date: 2012-03-05 / Modelos teóricos de colusão tácita podem fornecer predições sobre preços ou outras variáveis estratégicas que permitam a detecção de conduta anticompetitiva. Esses marcadores de colusão geram hipóteses testáveis sobre o comportamento cíclico dos preços, sua dispersão entre concorrentes e sua variabilidade temporal. Utilizando dados municipais mensais para preços e custos da gasolina, regressões de painel dinâmico em forma reduzida são realizadas para averiguar a aderência empírica desses marcadores. Os efeitos são identificados comparando com 10 municípios que tiveram cartéis operando no varejo de combustíveis. Os resultados corroboraram as predições de preços anticíclicos e redução da dispersão dos preços, ainda que com ressalvas. Porém, não se encontrou evidências de aumento de volatilidade nos preços induzidos por choques adversos de demanda, que pretende capturar uma maior frequência de guerras de preços. A redução da volatilidade dos preços é parcialmente confirmada. / Theoretic models of tacit collusion may offer predictions over prices or other strategic variables that allow for the detection of anticompetitive conduct. These collusion markers generate testable implications on the cyclical movement of prices, its dispersion and its time series variability. Using municipal monthly data of gasoline prices and costs, reduced-form dynamic panel regressions are employed to assess the empirical adherence of these markers. The effects are identified through comparison against 10 municipalities, which exhibited episodes of cartelization. The results point to some evidence of countercyclical pricing and price dispersion reduction. However, no evidence if found for price wars, measured through increased price volatility due to adverse demand shocks. The prediction of price volatility reduction is partially sustained.

Submitted by Rubia Oliveira (rubia.doliveira@hotmail.com) on 2018-02-19T22:50:04Z No. of bitstreams: 1 Rúbia Baptista D´Oliveira_ determinantes preço de revenda combustível gasolina - OFICIAL.pdf: 759138 bytes, checksum: 39a8f098ede88082e289c9fed7ff4407 (MD5) / Approved for entry into archive by Thais Oliveira (thais.oliveira@fgv.br) on 2018-02-20T18:58:03Z (GMT) No. of bitstreams: 1 Rúbia Baptista D´Oliveira_ determinantes preço de revenda combustível gasolina - OFICIAL.pdf: 759138 bytes, checksum: 39a8f098ede88082e289c9fed7ff4407 (MD5) / Made available in DSpace on 2018-02-21T12:40:07Z (GMT). No. of bitstreams: 1 Rúbia Baptista D´Oliveira_ determinantes preço de revenda combustível gasolina - OFICIAL.pdf: 759138 bytes, checksum: 39a8f098ede88082e289c9fed7ff4407 (MD5) Previous issue date: 2018-02-06 / Esse artigo analisa os determinantes do preço do combustível gasolina. Atualmente a gasolina é utilizada por aproximadamente 60% dos veículos leves no Brasil e tem uma parcela relevante no consumo das famílias, portanto é preciso que o consumidor conheça profundamente como funciona o mercado desse produto, desde o produtor até o consumidor final, e principalmente que saiba como é formado o seu preço. O artigo busca então compreender quais são os determinantes do preço de revenda do combustível gasolina no mercado brasileiro e também entender por que ocorrem divergências nos preços dentro de uma mesma cidade. / This article analyzes the determinants of the price of gasoline fuel. Currently, gasoline is used by approximately 60% of light vehicles in Brazil, and has a significant share of household consumption, so it is necessary for the consumer to know deeply how the market of this product works, from the producer to the final consumer, and especially knows how its price is formed. The article then seeks to understand the determinants of the price of gasoline fuel in the Brazilian market, and also to understand why there are divergences in prices within the same city.

LIMA, Kellen Cristina Vilhena. Qualidade de gasolinas automotivas através de Espectroscopia Vibracional FT-Raman, combinada com correlação 2D generalizada. 2005. 305 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2005. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-05-25T22:26:07Z No. of bitstreams: 1 2005_tese_kcvlima.pdf: 10475763 bytes, checksum: e618c6deda94d946c15be6e420912ad1 (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-05-27T18:52:53Z (GMT) No. of bitstreams: 1 2005_tese_kcvlima.pdf: 10475763 bytes, checksum: e618c6deda94d946c15be6e420912ad1 (MD5) / Made available in DSpace on 2015-05-27T18:52:53Z (GMT). No. of bitstreams: 1 2005_tese_kcvlima.pdf: 10475763 bytes, checksum: e618c6deda94d946c15be6e420912ad1 (MD5) Previous issue date: 2005 / It is reported the use of Generalized Two-Dimensional FT-Raman Correlation Spectroscopy (2DCOS-FT-Raman) method to monitor the quality of automotive gasoline in the gas stations. It is presented a procedure to identify the adulteration of automotive gasoline by the illicit addition of ethanol, methanol, aromatic and paraphinic compounds through the analysis of the Raman spectra obtained for different compositions of adulterants added to gasoline “A” type and to gasoline “A” type plus ethanol samples. It is discussed the data preconditioning step, the application of 2DCOS method, and the calibration curves that correlates the integrated intensities of the Raman bands of a given adulterant with its percentage in a given gasoline sample. It shown the protocol for using the 2DCOS-FT-Raman method to verify the adulteration in a given gasoline sample compared with a specific standard. This work emphasizes the flexibility and viability of using this method to have a specific standard for each gasoline distribution firm and also for each new gasoline derived from the refinery. / Relata a utilização da espectroscopia FT-Raman combinada com Correlação 2D Generalizada como método alternativo para a realização do controle de qualidade de Gasolinas automotivas diretamente nos postos de combustível. Apresenta os procedimentos para identificar a adulteração da Gasolina automotiva pela adição irregular de Etanol, Metanol e compostos aromáticos e parafínicos, através da análise dos espectros Raman obtidos para os diferentes adulterantes separadamente, misturados à Gasolina A e misturados à Gasolina A e ao Etanol. Descreve os procedimentos de pré-tratamento sobre os espectros Raman, a aplicação do método de Correlação 2D Generalizada aos sistemas estudados e a determinação das curvas de calibração que relacionam as intensidades integradas das bandas Raman com o teor de adulterante na Gasolina. Apresenta a praticidade de aplicação do método, que possibilita verificar a adulteração da Gasolina automotiva através da comparação entre o espectro Raman da amostra cuja conformidade se deseja verificar com o espectro da amostra padrão. Enfatiza a flexibilidade e a viabilidade de se ter um padrão específico para cada distribuidora, ou até mesmo para cada nova produção de Gasolina da refinaria.

Carbonaceous deposits accumulate on the majority of the inner surfaces of internal combustion engines. The presence of these deposits is known to cause impaired engine performance. This is manifested as increased knocking, higher fuel consumption, higher emissions and other adverse effects. One of the proposed mechanisms for this behaviour is the adsorption and desorption of fuel components in the pores within the deposit. The porous nature of the deposits promotes this behaviour, altering the fuel composition and reducing the amount of fuel entering the combustion chamber. Previous research in this area was aimed at determining the porous structure of the deposits by combining experimental procedures with molecular simulations to investigate adsorption interactions with fuel components. Using a characterisation procedure regularly applied to activated carbons, a molecular model was developed that was able to provide new insights into the deposit structure. This model enabled predictions to be made for the single-component adsorption of normal heptane and iso-octane, two species commonly used as a gasoline reference fuel. Results showed significant adsorption of both species, and highlighted the impact of adsorption into the internal porous structure of the engine deposits. The aim of this thesis is to further investigate adsorption in engine deposits by expanding the studies to more complex systems. We develop a model to predict the adsorption of normal heptane, iso-octane, toluene and their mixtures in deposits of different origins and under different conditions. The study of multi-component mixtures provides insight into selectivity effects of adsorption under confinement, while at the same time bringing the systems under consideration closer to realistic multi-component mixtures that better represent fuel blends. The study also considers for the first time adsorption of aromatic species, both as a single component and in mixtures, since aromatics have a high presence in gasoline fuel. We explore the influence of molecular structure of adsorbing species, composition of the bulk mixture and temperature on the uptake and selectivity behaviour of the engine deposits. We demonstrate that under equilibrium conditions, deposits can adsorb substantial amounts of hydrocarbon species of all types. However, selectivity behaviour in engine deposits was found to be a subtle and complex property, highly sensitive to both pore size and system pressure.