858 resultados para Refrigerator cars.
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Design methods and tools are generally best learned and developed experientially [1]. Finding appropriate vehicles for delivering these to students is becoming increasingly challenging, especially when considering only those that will enthuse, intrigue and inspire. This paper traces the development of different eco-car design and build projects which competed in the Shell Eco-Marathon. The cars provided opportunities for experiential learning through a formal learning cycle of CDIO (Conceive, Design, Implement, Operate) or the more traditional understand, explore, create, validate, with both teams developing a functional finished prototype. Lessons learned were applied through the design of a third and fourth eco-car using experimental techniques with bio-composites, combining the knowledge of fibre reinforced composite materials and adhesives with the plywood construction techniques of the two teams. The paper discusses the importance of applying materials and techniques to a real world problem. It will also explore how eco-car and comparing traditional materials and construction techniques with high tech composite materials is an ideal teaching, learning and assessment vehicle for technical design techniques.
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Mass-production, cars, pollution – they all have long become well known and well connected phenomena of the modern life. Nowadays the people can also add to the list such items like awareness, scientific approach, long-term thinking, and environmental responsibility. They are surrounded by a multitude of consumer goods, most of which are produced in a scientific manner, and all of which will more sooner than later end up in the garbage. Cars are the most noticeable – both by size and by numbers – and also the most expensive of all the mass products in people’s view. For many of them they are a clear target for reprimand and regulation, and, as a result, the automotive industry is being increasingly brought under bureaucratic control, together with its whole supplier and distributor network. The author started writing this article in an attempt to place the above process under scrutiny, because it is his firm belief that similar measures, similar tough governmental control will inevitably spill over to other industries, which at the moment are producing more inconspicuous, but still polluting products. The present paper shows the relationship between car-making, supply chain management and the efforts of public administration to protect the environment – a connection with clear practical implications.
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Highways are generally designed to serve a mixed traffic flow that consists of passenger cars, trucks, buses, recreational vehicles, etc. The fact that the impacts of these different vehicle types are not uniform creates problems in highway operations and safety. A common approach to reducing the impacts of truck traffic on freeways has been to restrict trucks to certain lane(s) to minimize the interaction between trucks and other vehicles and to compensate for their differences in operational characteristics. ^ The performance of different truck lane restriction alternatives differs under different traffic and geometric conditions. Thus, a good estimate of the operational performance of different truck lane restriction alternatives under prevailing conditions is needed to help make informed decisions on truck lane restriction alternatives. This study develops operational performance models that can be applied to help identify the most operationally efficient truck lane restriction alternative on a freeway under prevailing conditions. The operational performance measures examined in this study include average speed, throughput, speed difference, and lane changes. Prevailing conditions include number of lanes, interchange density, free-flow speeds, volumes, truck percentages, and ramp volumes. ^ Recognizing the difficulty of collecting sufficient data for an empirical modeling procedure that involves a high number of variables, the simulation approach was used to estimate the performance values for various truck lane restriction alternatives under various scenarios. Both the CORSIM and VISSIM simulation models were examined for their ability to model truck lane restrictions. Due to a major problem found in the CORSIM model for truck lane modeling, the VISSIM model was adopted as the simulator for this study. ^ The VISSIM model was calibrated mainly to replicate the capacity given in the 2000 Highway Capacity Manual (HCM) for various free-flow speeds under the ideal basic freeway section conditions. Non-linear regression models for average speed, throughput, average number of lane changes, and speed difference between the lane groups were developed. Based on the performance models developed, a simple decision procedure was recommended to select the desired truck lane restriction alternative for prevailing conditions. ^
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It has been well documented that traffic accidents that can be avoided occur when the motorists miss or ignore traffic signs. With the attention of drivers getting diverted due to distractions like cell phone conversations, missing traffic signs has become more prevalent. Also, poor weather and other unfriendly driving conditions sometimes makes the motorists not to be alert all the time and see every traffic sign on the road. Besides, most cars do not have any form of traffic assistance. Because of heavy traffic and proliferation of traffic signs on the roads, there is a need for a system that assists the driver not to miss a traffic sign to reduce the probability of an accident. Since visual information is critical for driving, processed video signals from cameras have been chosen to assist drivers. These inexpensive cameras can be easily mounted on the automobile. The objective of the present investigation and the traffic system development is to recognize the traffic signs electronically and alert drivers. For the case study and the system development, five important and critical traffic signs have been selected. They are: STOP, NO ENTER, NO RIGHT TURN, NO LEFT TURN, and YIELD. The system was evaluated processing still pictures taken from the public roads, and the recognition results were presented in an analysis table to indicate the correct identifications and the false ones. The system reached the acceptable recognition rate of 80% for all five traffic signs. The processing rate was about three seconds. The capabilities of MATLAB, VLSI design platforms and coding have been used to generate a visual warning to complement the visual driver support system with a Field Programmable Gate Array (FPGA) on a XUP Virtex-II Pro Development System.
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Brazil’s growing status as a potential world power cannot obscure the characteristics of its other reality: that of a country with vast inequalities and high crime rates. The Comando Vermelho, the most prominent organized crime syndicate in Rio de Janeiro, besieges the beauty and charm that attracts tourists to this city. The CV arose not only as a product of the political dictatorship of the seventies, but also of the disenfranchised urban poor crammed into Rio’s favela slums. Today, the CV presents a powerful challenge to the State’s control of parts of Rio territory. As Brazil’s soft power projection grows, it is seriously challenged by its capacity to eliminate organized crime. Economic growth is not sufficient to destroy a deeply embedded organization like the CV. In fact, Brazil’s success may yet further retrench the CV’s activities. Culpability for organized crime cannot be merely limited to the gangs, but must also be shared among the willing consumers, among whom can be found educated and elite members of society, as well as the impoverished and desperate. The Brazilian government needs a top-down response addressing the schism between rich and poor. However, Brazil’s citizens must also take responsibility and forge a bottom-up response to the drug- and corruption-riddled elements of its most respected members of society. Brazil must target reform across public health, housing, education and above all, law enforcement. Without such changes, Brazil will remain a two-track democracy. Rio’s wealthy will still be able to revel in the city’s beauty albeit from behind armored cars and fortified mansions, while the city’s poor will yield – either as victims or perpetrators – to the desperate measures of organized crime.
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It can be nutritious and healthy if done right. Fruits and vegetables, a granola bar, smoothie, or some fresh squeezed Florida orange juice would be good choices. On the other hand, it can poison you. Perishable protein and dairy products must be packed in a well- insulated cooler with plenty of ice and a refrigerator thermometer kept inside to en-sure the food stays below 40 degrees Fahrenheit. If you are not completely safe, it can kill you. According to Hagerty Insurance of Traverse City, Michigan, the top ten worst foods to consume are coffee, hot soups, tacos, chili, juicy hamburgers, fried chicken, any barbecued food, filled doughnuts, soft drinks, and chocolate. (see Lisa Chin, 2003) It simply takes a sudden scalding spill, an unexpected splash, or dripping condiments, any of which demand your immediate attention, to become an instant fatality.
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Recent events such as Winter Storm [Hurricane] Sandy and Hurricane Katrina have demonstrated that local food supplies must last as long as possible. Current recommendations are to dispose of all refrigerated food four hours after the power is lost. The purpose of this study was to determine if it is possible to safely hold food longer than four hours without power. The results indicate that the food can be held for up to six hours if the door is not opened. If ice is added to the refrigerator, then it will take the food approximately 10 hours to reach 5°C (41°F).
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The development of home refrigerators generally are compact and economic reasons for using simplified configuration. The thermodynamic coefficient of performance ( COP ) is limited mainly in the condenser design for reasons of size and arrangement ( layout ) of the project ( design ) and climatic characteristics of the region where it will operate. It is noteworthy that this latter limitation is very significant when it comes to a country of continental size like Brazil with diverse climatic conditions. The COP of the cycle depends crucially on the ability of heat dissipated in the condenser. So in hot climates like the northeast, north, and west-central dispel ability is highly attenuated compared to the south and southeast regions with tropical or subtropical climates when compared with other regions. The dissipation in compact capacitors for applications in domestic refrigeration has been the focus of several studies, that due to its impact on reducing costs and power consumption, and better use of the space occupied by the components of refrigeration systems. This space should be kept to a minimum to allow an increase in the useful storage volume of refrigerator without changing the external dimensions of the product. Due to its low cost manufacturing, wire on tube condensers continue to be the most advantageous option for domestic refrigeration. Traditionally, these heat exchangers are designed to operate under natural convection. Not always, the benefits of greater compactness of capacitors for forced outweigh the burden of pumping air through the external heat exchanger. In this work we propose an improvement in convective condenser changing it to a transfer mechanism combined in series with conductive pipes and wire to a moist convective porous medium and the porous medium to the environment. The porous media used in the coating was composed of a gypsum plaster impregnated fiber about a mesh of natural cellulosic molded tubular wire mesh about the original structure of the condenser , and then dried and calcined to greater adherence and increased porosity. The proposed configuration was installed in domestic refrigeration system ( trough ) and tested under the same conditions of the original configuration . Was also evaluated in the dry condition and humidified drip water under natural and forced with an electro - fan ( fan coil ) convection. Assays were performed for the same 134- refrigerant charge e under the same thermal cooling load. The performance was evaluated in various configurations, showing an improvement of about 72 % compared with the original configuration proposed in humidification and natural convection.
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Household refrigerators are equipments that represent a significant portion on the eletricity consumption of Brazilian homes. The use of these devices with low energy efficiency contributes to increase the energy consumption. The energy efficiency of a refrigerator is a function of the interaction between the coolant fluid and the components of the thermodynamic cycle. Changes in load and/or nature of the coolant may modify the condensing and/or evaporation pressures. The volumetric capacity of the compressor, the mass flow of coolant and the compression power are dependent parameters of the condensation and evaporation pressures. Thus, the expansion devices exert an importante role in the balance of these pressures, being fundamental for the better performance of the refrigeration cycle. This experimental research aims to investigate the sensitivity of the performance parameters of a household refrigerator operating with R134a and at different evaporation pressures. Therefore, a small refrigerator was instrumented with temperature, pressure sensors and other variables of interest, installed along the cooling circuit, in order to allow the thermal mapping and the evaluation of the equipment performance parameters. The variation of pressure loss in the coolant fluid resulting from the operation of the expansion valve with micrometric adjustment that modifies the evaporation temperature, influencing significantly the performance parameters of the thermodynamic refrigeration cycle.
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The thermodynamic performance of a refrigeration system can be improved by reducing the compression work by a particular technique for a specific heat removal rate. This study examines the effect of small concentrations of Al2O3 (50 nm) nanoparticles dispersion in the mineral oil based lubricant on the: viscosity, thermal conductivity, and lubrication characteristics as well as the overall performance (based on the Second Law of Thermodynamics) of the refrigerating system using R134a or R600a as refrigerants. The study looked at the influences of variables: i) refrigerant charge (100, 110, 120 and 130 g), ii) rotational speed of the condenser blower (800 and 1100 RPM) and iii) nanoparticle concentration (0.1 and 0.5 g/l) on the system performance based on the Taguchi method in a matrix of L8 trials with the criterion "small irreversibility is better”. They were carried pulldown and cycling tests according to NBR 12866 and NBR 12869, respectively, to evaluate the operational parameters: on-time ratio, cycles per hour, suction and discharge pressures, oil sump temperature, evaporation and condensation temperatures, energy consumption at the set-point, total energy consumption and compressor power. In order to evaluate the nanolubricant characteristics, accelerated tests were performed in a HFRR bench. In each 60 minutes test with nanolubricants at a certain concentration (0, 0.1 and 0.5 g/l), with three replications, the sphere (diameter 6.00 ± 0.05 mm, Ra 0.05 ± 0.005 um, AISI 52100 steel, E = 210 GPa, HRC 62 ± 4) sliding on a flat plate (cast iron FC200, Ra <0.5 ± 0.005 um) in a reciprocating motion with amplitude of 1 mm, frequency 20 Hz and a normal load of 1,96 N. The friction coefficient signals were recorded by sensors coupled to the HFRR system. There was a trend commented bit in the literature: a nanolubricant viscosity reduction at the low nanoparticles concentrations. It was found the dominant trend in the literature: increased thermal conductivity with increasing nanoparticles mass fraction in the base fluid. Another fact observed is the significant thermal conductivity growth of nanolubricant with increasing temperature. The condenser fan rotational speed is the most influential parameter (46.192%) in the refrigerator performance, followed by R600a charge (38.606%). The Al2O3 nanoparticles concentration in the lubricant plays a minor influence on system performance, with 12.44%. The results of power consumption indicates that the nanoparticles addition in the lubricant (0.1 g/L), together with R600a, the refrigerator consumption is reduced of 22% with respect to R134a and POE lubricant. Only the Al2O3 nanoparticles addition in the lubricant results in a consumption reduction of about 5%.
Resumo:
The thermodynamic performance of a refrigeration system can be improved by reducing the compression work by a particular technique for a specific heat removal rate. This study examines the effect of small concentrations of Al2O3 (50 nm) nanoparticles dispersion in the mineral oil based lubricant on the: viscosity, thermal conductivity, and lubrication characteristics as well as the overall performance (based on the Second Law of Thermodynamics) of the refrigerating system using R134a or R600a as refrigerants. The study looked at the influences of variables: i) refrigerant charge (100, 110, 120 and 130 g), ii) rotational speed of the condenser blower (800 and 1100 RPM) and iii) nanoparticle concentration (0.1 and 0.5 g/l) on the system performance based on the Taguchi method in a matrix of L8 trials with the criterion "small irreversibility is better”. They were carried pulldown and cycling tests according to NBR 12866 and NBR 12869, respectively, to evaluate the operational parameters: on-time ratio, cycles per hour, suction and discharge pressures, oil sump temperature, evaporation and condensation temperatures, energy consumption at the set-point, total energy consumption and compressor power. In order to evaluate the nanolubricant characteristics, accelerated tests were performed in a HFRR bench. In each 60 minutes test with nanolubricants at a certain concentration (0, 0.1 and 0.5 g/l), with three replications, the sphere (diameter 6.00 ± 0.05 mm, Ra 0.05 ± 0.005 um, AISI 52100 steel, E = 210 GPa, HRC 62 ± 4) sliding on a flat plate (cast iron FC200, Ra <0.5 ± 0.005 um) in a reciprocating motion with amplitude of 1 mm, frequency 20 Hz and a normal load of 1,96 N. The friction coefficient signals were recorded by sensors coupled to the HFRR system. There was a trend commented bit in the literature: a nanolubricant viscosity reduction at the low nanoparticles concentrations. It was found the dominant trend in the literature: increased thermal conductivity with increasing nanoparticles mass fraction in the base fluid. Another fact observed is the significant thermal conductivity growth of nanolubricant with increasing temperature. The condenser fan rotational speed is the most influential parameter (46.192%) in the refrigerator performance, followed by R600a charge (38.606%). The Al2O3 nanoparticles concentration in the lubricant plays a minor influence on system performance, with 12.44%. The results of power consumption indicates that the nanoparticles addition in the lubricant (0.1 g/L), together with R600a, the refrigerator consumption is reduced of 22% with respect to R134a and POE lubricant. Only the Al2O3 nanoparticles addition in the lubricant results in a consumption reduction of about 5%.
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In questa tesi esaminerò alcuni aspetti fondamentali della tecnologia moderna tra cui alcune leggi chiave che spiegheranno come mai la crescente disoccupazione in Europa, e in occidente in generale, non è causata solamente da crisi finanziarie o politiche, ma dall'intrinseca natura della tecnologia stessa. Ci troveremo nella situazione nella quale una persona non sia in grado di trovare un'occupazione non a causa di demeriti propri, ma poiché il sistema è diventato talmente ottimizzato da tagliare completamente la necessità di alcuni ruoli chiave nel sistema di lavoro. Spiegherò quali sono le strategie da attuare per evitare di trovarsi in questo nuovo sistema di occupazione senza un ruolo al suo interno, quali sono le politiche che un governo debba attuare per garantire i necessari bisogni primari dei propri cittadini, le strutture che ogni azienda deve creare per rimanere all'interno del proprio settore di investimento.
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A globalização possibilitou aos países buscarem seus consumidores em qualquer parte, sendo o Brasil o quarto mercado consumidor de automóveis do mundo, e praticamente todos os fabricantes globais buscaram estar presentes neste mercado. Com os chineses, detentores do título de maiores produtores mundiais de automóveis, não seria diferente. Contudo, ao contrário do crescimento constante de sua produção mundial, viram suas vendas estagnarem em baixos níveis no Brasil nos últimos anos. O objetivo deste estudo é compreender o mau desempenho de vendas da marca Chery no Brasil, sob a óptica dos gerentes de vendas das agências de carros usados e dos ex-proprietários. Para tentar responder a esta questão, optou-se por um estudo de caráter exploratório, por meio de uma revisão bibliográfica e uma pesquisa qualitativa, com entrevistas abertas em profundidade com base em um roteiro preestabelecido e um recorte na cidade de São Paulo – SP. Utilizou-se também uma pesquisa secundária em meios eletrônicos, que confirmou as informações obtidas na pesquisa de campo. Conforme apresentado no trabalho, todas as marcas tiveram redução em suas vendas, porém, as marcas chinesas sofreram maiores reduções que às marcas ditas nacionais. Na pesquisa, observa-se que três fatores foram decisivos para o mau desempenho das marcas chinesas e, consequentemente, da marca Chery também. O primeiro foi o aumento do Imposto sobre Produtos Industrializados (IPI), o segundo foi a crise econômica que o Brasil atravessa e o terceiro foi a rejeição aos carros da Chery. Essa rejeição deveu-se a vários fatores, somados às experiências negativas que consumidores tiveram com marcas de veículos importados que deixaram o país, a imagem de que produtos chineses são cópias e ao hipotético preconceito que produtos chineses são de baixa qualidade. Portanto, ouvindo os entrevistados e por meio dos comentários sobre a marca Chery nos meios eletrônicos, pode-se deduzir que somente a crise econômica e o aumento de impostos não justificam totalmente o mau desempenho de vendas da marca Chery. Essa análise indica que os fatores de rejeição aos veículos da marca Chery tiveram participação decisiva nesta queda significativa de suas vendas no período de 2010 a 2014.
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General note: Title and date provided by Bettye Lane.
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General note: Title and date provided by Bettye Lane.