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Viewing 91 to 120 of 10280
2016-04-05
Journal Article
2016-01-0178
Feng Zhou, Ercan Dede, Shailesh Joshi
Rankine cycle (RC) is a thermodynamic cycle that converts thermal energy into mechanical work, which is commonly found in thermal power generation plants. Recently there are many studies focusing on applying Rankine cycle to recover low-grade waste heat. The on-road vehicles, which converts around one third of the fuel energy into useful mechanical energy for propulsion, are moving energy conversion systems that generate considerable waste heat. It was found from many researches that Rankine cycle has a great potential to be applied to harvest waste heat from automobiles. However, different from other low-grade waste heat sources, vehicles have limited space for the RC system integration and the waste heat is relatively unstable. In the current paper, the efforts in the past few decades to apply RC to on-road vehicles, specifically passenger cars, are reviewed.
2016-04-05
Journal Article
2016-01-0189
Alaa El-Sharkawy, Ahmed Uddin
A heat pipe is a self-operating device which is capable of transferring large amounts of heat with a minimum temperature differences between the hot end (evaporator) and the cold end (condenser). However, a limited number of research work or analysis has been reported in automotive industry on the applications of heat pipes in power train cooling. The advantage of a heat pipe heat exchanger is the possibility to use a more compact and lighter radiator for example. In addition, the proposed radiator is expected to be more robust as it is less sensitive to variations in ambient temperatures. In this paper, a proposed design for an automotive heat exchanger is investigated. The proposed design is evaluated through thermal simulation of heat pipes using variety of working fluids and wick construction. Different wick designs including wickless heat pipes are evaluated.
2016-04-05
Journal Article
2016-01-0186
Hyunki Sul, Taehoon Han, Mitchell Bieniek, John Hoard, Chih-Kuang Kuan, Daniel Styles
Exhaust gas recirculation (EGR) cooler usage in diesel engine has a great effect on lowering NOx production. Engine coolant cools down the temperature of exhaust gas recirculated to the engine, and significantly reduces the engine out NOx by lowering peak in-cylinder temperature. An ongoing concern is that soot and hydrocarbon foul inside the cold surface of the cooler. The fouling layer reduces heat transfer efficiency and increases pressure drop across the cooler. A number of experimental studies have shown that the fouling layer often tends to grow to the certain steady state level and does not develop further. One potential explanation is the removal mechanism derived by the shear stress applied on the soot and hydrocarbon deposit surface. As the deposit layer thickens, applied shear stress on the fouling surface increases. When critical shear stress is applied, deposit particles start to get removed.
2016-04-05
Journal Article
2016-01-0192
Alaa El-Sharkawy, Ahmed Uddin
Engine mount is one of the temperature sensitive components in the vehicle under-hood. Due to increasing requirements for improved fuel economy, the under-hood thermal management has become very challenging in recent years. In order to study the effects of material thermal degradation on engine mount performance and durability; it is required to estimate the temperature of engine mount rubber during various driving conditions. The effect of temperature on physical properties of natural rubber can then be evaluated and a life of engine mount can be estimated. In this paper, a bench test is conducted where the engine mount is exposed to a step change in the environment around it, and the temperature of the rubber section is recorded at several points till a steady state temperature is reached. A time response curve is generated, from which a time constant is determined.
2016-04-05
Journal Article
2016-01-0191
Gursaran D. Mathur
Water drainage characteristics of an evaporator changes with the age of the vehicle. This is due to the fact that with time, a part of the hydrophilic coating washes off with the moisture that condenses over the evaporator core from the air-stream. Hence, the effectiveness of the water drainage deteriorates. At this condition more water is retained in the evaporator as the contact angle increases. Author has conducted experiments with evaporators taken out of the vehicles with its AC system operated for 6 months, 12 months, 18 months, 24 months, 36 months, and 60 months. Evaporator cores from many suppliers (A, B, C) were used for this investigation. Evaporator cores were recovered from low (Phoenix) and high humidity areas (New Orleans, Houston, Jacksonville). These evaporators were analyzed to determine the effectiveness of the hydrophilic coating as a function of time or vehicle age.
2016-04-05
Journal Article
2016-01-0223
Mikael Karlsson, Mats Abom, Manan Lalit, Ragnar Glav
A thermo-acoustic engine is a device converting thermal energy into high amplitude acoustic waves that can be harvested, for example, to electricity. The core of the device is a stack/regenerator along which a temperature gradient is created using one hot and one cold heat exchanger. Correctly designed, the thermal interaction between the working fluid and the stack assist in amplifying incident acoustic waves. The core is placed in a closed duct network designed to provide good input state condition for the core and the harvesting unit. For the practical application of this technique it is vital to understand and identify optimum design parameters and operating conditions. Especially so in automotive applications where the operating conditions vary significantly over a drive cycle. This works aims at providing a framework for studying the net power generation over a drive cycle.
2016-04-05
Journal Article
2016-01-0202
Bjoern Franzke, Stefan Pischinger, Philipp Adomeit, Christof Schernus, Johannes Scharf, Tolga Uhlmann
In this paper a new approach is presented to modelling wall heat transfer in the exhaust port and manifold within 1D gas exchange simulation to ensure a precise calculation of thermal exhaust enthalpy. One of the principal characteristics of this approach is the partition of the exhaust process in a blow-down and a push-out phase. In addition to the split in two phases, the exhaust system is divided into several sections to consider changes in heat transfer characteristics downstream the exhaust valves. Principally, the convective heat transfer is described by the ordinary characteristic numbers of Nusselt, Reynolds and Prandtl. However, the phase individual correlation coefficients are derived from 3D CFD investigations of the flow in exhaust system combined with Low-Re turbulence modelling. Furthermore, heat losses on the valve and the seat ring surfaces are considered by an empirical model approach.
2016-04-05
Journal Article
2016-01-0281
Alaa El-Sharkawy, Dipan Arora, Abd El-Rahman Hekal, Amr Sami, Muhannad Hendy
In this paper, transient component temperatures in the vehicle under-hood and underbody are estimated. The main focus is on the component temperatures as a result of radiation from exhaust, convection by underbody or under-hood air and heat conduction through the components. The exhaust surface temperature is simulated as function of time and for various vehicle duty cycles such as city traffic, road load and grade driving conditions. At each time step the radiation flux to the surrounding component is estimated, heat addition or removal by convection is evaluated based on air flow, air temperature and component surface area. Geometrical properties of the components are obtained by fitting them into pre-set shapes (e.g., cylinders, spheres, ellipsoids, etc.).
2016-04-05
Journal Article
2016-01-0282
Julio Abraham Carrera
Recent emissions standards have become more restrictive in terms of CO2 and NOx reduction. This has been translated into higher EGR rates at higher exhaust gas temperatures with lower coolant flow rates for much longer lifetimes. In consequence, Thermal Load for EGR coolers has been increased and boiling and its interaction with thermal fatigue are now a critical issue during their development. It is almost impossible to avoid localized boiling inside an EGR cooler and, in fact, it would not be strictly necessary when it is below the Critical Heat Flux (CHF). However when CHF is exceeded, film boiling occurs leading to the sudden drop of the heat transfer rate and the metal temperature rise. In consequence, thermal stress increases even when film boiling is reached only in a small area inside the part. It is very difficult to accurately predict under which conditions CHF is reached and to stablish the margins to avoid it.
2016-04-05
Journal Article
2016-01-0280
Alaa El-Sharkawy, Amr Sami, Abd El-Rahman Hekal, Dipan Arora, Masuma Khandaker
`In this paper, the development a transient thermal analysis model for the exhaust system is presented. Given the exhaust gas temperature out of the engine, a software tool has been developed to predict changes in exhaust gas temperature and exhaust surface temperature under various operating conditions. The software is a thermal solver that will predict exhaust gas and wall surface temperature by modeling all heat transfer paths in the exhaust system which includes multi-dimensional conduction, internal forced/natural convection, external forced/natural convection, and radiation. The analysis approach involves the breaking down of the thermal system into multiple components, which include the exhaust system (manifold, takedown pipe, tailpipe, etc.), catalytic converter, DPF/GPF (diesel particulate filter or gasoline particulate filter), if they exist, thermal shields, etc.
2016-04-05
Journal Article
2016-01-0523
Lauren Abro
This study is to document how NA customer’s perception of Quality has changed over time and has shifted from Quality/Dependability/Reliability (QDR) to Interior Sensory Quality (ISQ) . The idea of perception of quality has changed from basic QDR to the harmony of emotions that excite a customer. Interior Sensory Quality is defined as the harmony of characteristics that combine to make an emotional connection to the vehicles’ interior. Decisions that were previously based on QDR have shifted to more emotional purchase decisions. Now, Toyota wants to correctly appeal to customers’ emotional side through providing class-leading Interior Sensory Quality. To identify key ISQ strengths, weaknesses, and preferences, multiple customer clinics were held across the country. The key goals were to understand customer judgment of ISQ Execution, understand Customer ISQ Priority (by segment), and to understand Customer preference of detailed component areas.
2016-04-05
Journal Article
2016-01-0521
Ronald S. Grossman
The lightweighting of auto components is a crucial strategy for OEMs to achieve increasingly challenging CAFÉ requirements. Research from MIT has found that every 10% reduction in passenger vehicle weight reduces fuel consumption by about 7%. Since fuel economy requirements have already increased by 18% from MY 2012 to 2017, the weight savings strategies that are easiest to implement have largely been exhausted. Seating is the largest interior component by weight, but the foam is often overlooked from lightweighting consideration due to the perception that higher weight, higher density seating is an important aspect of the vehicle’s comfort. It has become a truism that the physical properties associated with seating comfort -- load bearing, resilience, durability - are directly related to foam density.
2016-04-05
Journal Article
2016-01-0656
Jung Hyun Kim, Taewoo KIM, SungJin Park, JungJae HAN, Choongsoo Jung, Young rock Chung, Sangsoo Pae
In cold start driving cycles, high viscosity of the lubrication oil (engine oil) increases the mechanical friction losses compared with warmed up condition. Thus, an engine oil warm up system can provide the opportunity to reduce the mechanical friction losses during cold start. In this study, an engine oil heater using EGR is used for the fast warm up of the engine oil. This paper presents the effect of the engine oil heater on the fuel economy and emissions over a driving cycle (NEDC). A numerical model is developed to simulate the thermal response of the powertrain using multi-domain 1-D commercial powertrain simulation software (GT-Suite) and it is calibrated using test data from a full size sedan equipped with a 2.0L diesel engine. The model consists of an engine model, coolant circuit model, oil circuit model, engine cooling model, friction model, and ECU model.
2016-04-05
Technical Paper
2016-01-0524
Venkat Pisipati, Srikanth Krishnaraj, Amy McGuckin Webb, Pavankumar Reddy Kandukuri
The Automotive industry’s use of digital tools such as Computer Aided Engineering (CAE) to perform virtual validation has progressed to effectively replace a large percentage of physical validation. This is primarily due to cost and time efficiencies virtual validation offers versus conventional physical prototyping and testing. With product development cycles becoming more compressed, CAE has assumed a more significant role in advanced design and structural evaluation. One of the major challenges to upfront effective and efficient CAE analyses is the availability of Computer Aided Design (CAD) data. Many OEMs and their suppliers are looking to leverage existing CAE models by mapping or adapting previous models using morphing tools to develop CAE models for quick analysis feedback. For Tier 1 suppliers, such as Inteva Products, this agility is becoming paramount.
2016-04-05
Technical Paper
2016-01-0208
Xuzhi Du, Zhigang Yang, Hua Zhou, Qiliang Li, Zheyan Jin
The effect of jet geometry on flow, heat transfer and defrosting characteristics was numerically investigated for elliptic and rectangular impinging jets on an automobile windshield. Initially, various turbulence models within the commercial computational fluid dynamics (CFD) package FLUENT were employed and validated for a single jet, and the results indicate that the impinging jet heat transfer is more accurately predicted by the SST k − ω turbulence model, which was then utilized for this study. The aspect ratios (AR) of elliptic and rectangular jets are respectively 0.5, 1.0, and 2.0, with jet-to-target spacing h/d=2, 4 and jet-to-jet spacing c/d=4, and all those situations were numerically analyzed with the same air mass flow and jet open area. It is observed that the heat transfer coefficient and defrosting performance of the oblique windshield are significantly affected by the shape of the jet, and the best results were obtained with the elliptic jet arrangements.
2016-04-05
Technical Paper
2016-01-0230
Gene Titov, Jason Lustbader, Daniel Leighton, Tibor Kiss
MATLAB/Simulink modeling of parallel coolant loop architecture for modern Electric Vehicle Thermal Management Systems Gene Titov, Jason Lustbader, Daniel Leighton and Tibor Kiss Passenger comfort and vehicle component thermal management systems of modern electric vehicles (EVs) are highly integrated designs. While capable of substantially increasing the range, these systems are complex with a large number of possible modes of operation. Prototyping of such systems based on testing is expensive making flexible and accurate computer models of an essence. The National Renewable Energy Laboratory previously developed an air conditioning system simulation model in MATLAB/Simulink and validated its performance against bench test data. In order to model the full EV thermal management system, this A/C model has been extended to incorporate liquid-coolant system components.
2016-04-05
Technical Paper
2016-01-0199
Bin Xu, Xiaobing Liu, John Shutty, Paul Anschel, Zoran Filipi, Simona Onori, Mark Hoffman
This paper presents an Organic Rankine Cycle (ORC) system model for heavy-duty diesel applications. The dynamic, physics-based model includes: parallel heat exchangers for exhaust and EGR circuits, compressible vapor working fluid, distribution and flow control valves, high pressure pump, and reservoir. The physics-based model can track the working fluid phase boundaries within the heat exchangers as well as working fluid pressure dynamics. The model is experimentally validated for a wide range of steady state conditions and transient changes to ORC system setpoints. Validation results reveal the high accuracy of the model in steady state conditions. Moreover, the model also shows the functionality to track the temperature and pressure dynamics of the Organic Rankine Cycle system during system transients. This model can be used for future system and co-simulations, development of control-oriented ORC models, optimization of ORC power generation and model-based control studies.
2016-04-05
Technical Paper
2016-01-0480
Weiguo Zhang, Mark Likich, Mac Lynch, John White
The noise radiated from the snorkel of an air induction system (AIS) can be a major noise source to the vehicle interior noise. This noise source is typically quantified as the snorkel volume velocity which is directly related to vehicle interior noise through the vehicle noise transfer function. It is important to predict the snorkel volume velocity robustly at the early design stage for the AIS development. Design For Six Sigma (DFSS) is an engineering approach that supports the new product development process. The IDDOV (Identify-Define-Develop-Optimize-Verify) method is a DFSS approach which can be used for creating innovative, low cost and trouble free products on significant short schedules. In this paper, an IDD project which is one type of DFSS project using IDDOV method is presented on developing a robust simulation process to predict the AIS snorkel volume velocity. First, the IDDOV method is overviewed and the innovative tools in each phase of IDDOV are introduced.
2016-04-05
Technical Paper
2016-01-0187
Zizhen Yu, Gangfeng Tan, Tianming He, Xuexun Guo, MengYing Yang, Shengguang Xiong
With the improvement of people's awareness on safe driving, hydraulic retarder applications are increasingly widespread. Traditional hydraulic retarder, on the one hand, discharged the waste heat of transmission fluid outside the vehicle by engine cooling system; on the other hand, has to consume engine power to drive water pump and engine cooling fan so as to maintain the normal operation of the cooling system. In this study, the Organic Rankine Cycle (ORC) instead of the traditional hydraulic retarder water-cooling system is applied to achieve the effective temperature control of the hydraulic retarder, meanwhile, the waste heat of transmission fluid could be recovered for saving vehicle’s energy consumption.
2016-04-05
Technical Paper
2016-01-1504
Monica Lynn Haumann Jones, Sheila Ebert-Hamilton, Matthew Reed
Law enforcement officers (LEO) make extensive use of vehicles to perform their jobs, often spending large portions of a shift behind the wheel. Few LEO vehicles are purpose-built; the vast majority are modified civilian vehicles. Data from the field indicate that LEO suffer from relatively high levels musculoskeletal injury that may be due in part to poor accommodation provided by their vehicles. LEO are also exposed to elevated crash injury risk, which may be exacerbated by a compromise in the performance of the occupant restraint systems due to body-borne equipment. A pilot study was conducted to demonstrate the application of three-dimensional anthropometric scanning and measurement technology to address critical concerns related to vehicle design. Detailed posture and belt fit data were gathered from five law enforcement officers as they sat in the patrol vehicles that they regularly used and in a mockup of a mid-sized vehicle.
2016-04-05
Technical Paper
2016-01-0184
Toshio Murata, Tadashi Nakagawa, Hisashi Nishino, Kazunari Matsuura
In order to speed up engine coolant warm-up, the exhaust heat recirculation system collects and reuses the heat from exhaust gases by utilizing the heat exchanger. The conventional system improves actual fuel economy at the scene of the engine restart in winter season only. The heat recirculation system becomes more effective at the low outside temperature because it takes longer time to warm up engine coolant. However, the heat recirculation system becomes less effective at the high outside temperature because it takes shorter time to warm up engine coolant. Therefore, the new exhaust heat recirculation system is developed, which adopted as follows: 1) a fin-type heat exchanger in order to enhance exhaust recirculation efficiency 2) a thinner heat exchanger component and smaller amount of engine coolant capacity in the heat exchanger in order to reduce the heat mass As a result, the actual fuel economy is more improved in winter season.
2016-04-05
Technical Paper
2016-01-0204
Igor Gritsuk, Yurii Gutarevych, Vasyl Mateichyk, Vladimir Volkov
IMPROVING THE PROCESSES OF PREHEATING AND HEATING AFTER TRANSPORT ENGINE START WITH THE HELP OF HEATING SYSTEM BY USING HEATING WITH THE HEAT ACCUMULATOR WITH PHASE TRANSITION The article discusses the features of application system of heating the vehicle engine with heat accumulator with phase transition. The peculiarity of the present system is in the fact that it uses for the heat accumulation the thermal energy of exhaust gases of internal combustion engine during its operation. The results of experimental studies of heating the vehicle engine are shown. The structure of information complex for studing the internal combustion engine of a vehicle with heating system and heat accumulator during the start and heating after starting is described. The complex allows to remote the distant evaluation of engine parameters and heat trainingof engine in the structure of intelligent transport systems.
2016-04-05
Technical Paper
2016-01-0218
Balashunmuganathan Vasanth, Kumar Sathish, Mayur Sah
In an automotive air conditioning, aero-acoustic noise originating from HVAC (Heating Ventilation and Air Conditioning) unit is one of the major concerns for the customer satisfaction. “Fan blower excessive noise” is one among the top issues for all automotive manufacturers. In this paper, a 3D computational analysis is carried out for a passenger car HVAC unit to predict the noise originated from the HVAC unit. HVAC modeling is done using Uni graphics and ANSA and the analysis is carried out using the commercial CFD software STAR CCM+. The inputs for the analysis are the airflow at HVAC Inlet, blower speed and the pressure drop characteristics of evaporator, filter and heater core. The computational model is done by considering the blower region as MRF (Moving Reference Frame) and the air flow is considered incompressible. DES (Detached Eddy Simulation) model is used to resolve the eddies generated by the turbulent flow.
2016-04-05
Technical Paper
2016-01-0249
Balashunmuganathan Vasanth, Kumar Sathish, Murali Govindarajalu, Mohsin Khan
In recent years reducing the automobile HVAC (Heating Ventilation and automobile conditioning) noise inside the vehicle cabin is one of the main criterions for all OEMs to provide comfort level to the passengers. The primary function of the HVAC is to deliver more air to the cabin with less noise generation for various blower speeds. Designing the optimum HVAC with less noise is one of the major challenges for all automotive manufacturers. It is critical to predict the noise level of the HVAC during initial design stages of the program by simulation techniques since the parts shall not be available and physical testing cannot be carried out. In this study, a computational 1D (one dimensional) analysis is carried out to compute the airflow noise originated from the HVAC unit and transferred to the air coming out from the HVAC outlet for the passenger car. Modeling and meshing are done using Unigraphics and the analysis is carried out using the commercial 1D software GT suite.
2016-04-05
Technical Paper
2016-01-1304
Tadayoshi Fukushima, Hitoshi Takagi, Toshio Enomoto, Hiroyuki Sawada, Tomoyuki Kaneda
Interior noise caused by exterior air flow, or wind noise, is one of the noise-and-vibration phenomena for which a systematic simulation method has been desired for enabling their prediction. One of the main difficulties in simulating wind noise is that, unlike most other noises from the engine or road input, wind noise has not one but two different types of sources, namely, convective and acoustic ones. Therefore, in order to synthesize the interior sound pressure level (SPL), the body sensitivities (interior SPL/outer source level) for both types of sources have to be considered. In particular, sensitivity to the convective input has not been well understood, and hence it has not been determined. Moreover, the high-frequency nature of wind noise (e.g., the main energy range extends up to 4000 Hz) has limited the effective application of CAE for determining body sensitivities, for example, from the side window glass to the occupants’ears.
2016-04-05
Journal Article
2016-01-1273
Lakshmikanth Meda, Martin Romzek, Yanliang Zhang, Martin Cleary
Although the technology of combustion engines is quite fully developed, the degree of efficiency is considerably low. A large amount of the energy, around 30 %, is lost as exhaust waste heat, and up to 30 % is dissipated in the cooling circuits. This is a reason why thermal recuperation has a great potential for raising the efficiency of combustion engines. In order to meet ever-increasing consumer demand for higher fuel economy, and to conform to more stringent governmental regulations, auto manufacturers have increasingly looked at thermoelectric materials as a potential method to recover some of that waste heat and improve the overall efficiency of their vehicle fleets. Seeking new possibilities to make vehicles greener and more efficient, the industry wants to use the waste heat which passes through the exhaust system almost completely unused in the past.
2016-04-05
Journal Article
2016-01-1407
Sama Hussein, Benjamin Hamilton, O. Remus Tutunea-Fatan, Evgueni Bordatchev
Retroreflective (RR) optical elements play a critical role in signalling, safety, and aesthetic/styling functionality of automotive lighting. The commonly used inverted-cube RR structures with hexagonal aperture have significant limitations that are primarily rooted in their manufacturing technique that involves complex assemblies/shapes of hexagonal pins and electroforms, particularly in case of freeform surfaces. This study introduces two new types of RR elements, namely: right triangular prism (RTP) and triangular pyramid. The mathematical/analytical models underlying these two new geometries were detailed as the intersection between a cube and a plane placed in a particular relative orientation with respect of each other. Following this, non-sequential optical simulation studies were performed using Zemax OpticStudio software.
2016-04-05
Journal Article
2016-01-1409
J. Christopher Watson, Gennady Dumnov, Alexander Muslaev, Andrey Ivanov, Svetlana Shtilkind
Condensation occurrence in automotive headlights can be detrimental to consumer acceptance of a product. This paper describes a technique for transient numerical simulation of liquid film formation on surfaces during lighting thermal analysis performed using Computational Fluid Dynamics (CFD), including how the film’s properties influence the thermal solution. The numerical technique presented accounts for the change in the film thermal state and thickness due to heat exchange with external fluid flow and solid bodies, surface evaporation/condensation, melting/crystallization within the film volume, and its motion due to gravity and friction forces from the surrounding airflow.
2016-04-05
Journal Article
2016-01-0233
Masayoshi Mori, Manabu Matsumoto, Makoto Ohtani
In order to commercialize thermoelectric heat recovery systems, appropriate cost effectiveness is required. Thus, to improve cost effectiveness, TEG (ThermoElectric Generator) structure compatible with high efficiency and low cost is considered. For achieving high efficiency, a means to utilize high exhaust temperature is investigated. The most preferable installation position is just after the close-coupled catalyzer, but due to strict space limitations, the TEG needs to be small. Therefore, a vacuum space structure is proposed to reduce the size of the TEG and enable installation. 1D system simulation is conducted and clarified that installation of the TEG just after the close-coupled catalyzer results in twice as much power generation compared to normal underfloor installation. For achieving low cost, a means to reduce the number of thermoelectric elements in TEG is examined.
2016-04-05
Journal Article
2016-01-0236
Forrest Jehlik, Eric Rask, Michael Duoba
It is widely understood that cold ambient temperatures negatively impact vehicle system efficiency. This is due to a combination of increased friction (engine oil, transmission, and driveline viscous effects), cold start enrichment, heat transfer, and air density variations. Although the art of quantifying steady state vehicle component efficiency is well understood, transient component efficiencies over dynamic ambient real world conditions is less well understood and quantified. This work characterizes wheel assembly efficiencies of a conventional and electric vehicle over a wide range of ambient conditions. Dynamometer testing over three ambient temperatures and drive cycles was conducted with vehicles instrumented to determine the losses of the output energy of the tire on the dynamometer proportional to the input energy of the half-shafts.
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