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Viewing 1 to 30 of 605
2017-09-19
Technical Paper
2017-01-2164
Markus Kintscher, Hans Peter Monner
Abstract Drag reduction technologies in aircraft design are the key enabler for reducing emissions and for sustainable growth of commercial aviation. Laminar wing technologies promise a significant benefit by drag reduction and are therefore under investigation in various European projects. However, of the established moveable concepts and high-lift systems, thus far most do not cope with the requirements for natural laminar flow wings. To this aim new leading edge high-lift systems have been the focus of research activities in the last five years. Such leading edge devices investigated in projects include a laminar flow-compatible Kruger flap [1] and the Droop Nose concept [2, 3] and these can be considered as alternatives to the conventional slat. Hybrid laminar flow concepts are also under investigation at several research institutes in Europe [4].
2017-04-11
Journal Article
2017-01-9450
Ali Reza Taherkhani, Carl Gilkeson PhD, Philip Gaskell PhD, Rob Hewson PhD, Vassili Toropov PhD, Amin Rezaienia PhD, Harvey Thompson
Abstract This paper investigates the optimization of the aerodynamic design of a police car, BMW 5-series which is popular police force across the UK. A Bezier curve fitting approach is proposed as a tool to improve the existing design of the warning light cluster in order to reduce drag. A formal optimization technique based on Computational Fluid Dynamics (CFD) and moving least squares (MLS) is used to determine the control points for the approximated curve to cover the light-bar and streamline the shape of the roof. The results clearly show that improving the aerodynamic design of the roofs will offer an important opportunity for reducing the fuel consumption and emissions for police vehicles. The optimized police car has 30% less drag than the non-optimized counter-part.
2017-03-28
Technical Paper
2017-01-1230
Cyrille Goldstein, Joel Hetrick
Abstract Mechanical losses in electric machines can contribute significantly to overall system losses in an electric drive [1]. With a permanent magnet synchronous machine (PMSM), measuring mechanical losses is difficult without an un-magnetized rotor. Even with an un-magnetized rotor, physical testing can be time consuming and expensive. This paper presents a simple theoretical model of mechanical drag in an electric machine. The model was built using calculations for bearing, seal, and windage drag and was compared to experimental results from testing with un-magnetized motors. Based on this information, the model was modified to better represent the physical system. The goal of this work is to understand the contributors to mechanical drag, to be able to estimate mechanical losses without physical testing, and to be able to quickly evaluate design choices that could reduce mechanical losses.
2017-03-28
Technical Paper
2017-01-1427
Daniel Koch, Gray Beauchamp, David Pentecost
Abstract Tire disablement events can cause a drag force that slows a vehicle. In this study, the magnitude of the deceleration was measured for different phases of 29 high speed tire tread separation and air loss tests. These deceleration rates can assist in reconstructing the speed of a vehicle involved in an accident following a tire disablement.
2016-10-25
Technical Paper
2016-36-0511
Wilcker Neuwald Schinestzki, Daniel Gustavo Schreiner, Carlos Eduardo Guex Falcão
Abstract The drag reduction system, commonly used in Formula 1, has as task to reduce the drag force that acts in the vehicle’s airfoils, increasing considerably its speed. When it comes to Formula SAE competition, since the speeds are lower than in F1, the purpose of the DRS can easily become the cooling, despite its name. This paper comes to the development of a drag reduction system applied to the frontal wing whose major objective is to increase the mass flow rate of air through the radiator. Based on a preliminary work supported by computational fluid dynamics, a frontal wing DRS can increase the mass flow rate in approximately 65% at an average velocity of 12 meters per second, which allows the team to use a smaller and lightweight radiator. The challenge was to design a lightweight and reliable automatic system, since it cannot fail nor take away the driver’s attention.
2016-09-27
Technical Paper
2016-01-8153
Prashanth Gururaja
Abstract To investigate the feasibility of various test procedures to determine aerodynamic performance for the Phase 2 Greenhouse Gas (GHG) Regulations for Heavy-Duty Vehicles in the United States, the US Environmental Protection Agency commissioned, through Southwest Research Institute, constant-speed torque tests of several heavy-duty tractors matched to a conventional 53-foot dry-van trailer. Torque was measured at the transmission output shaft and, for most tests, also on each of the drive wheels. Air speed was measured onboard the vehicle, and wind conditions were measured using a weather station placed along the road side. Tests were performed on a rural road in Texas. Measuring wind-averaged drag from on-road tests has historically been a challenge. By collecting data in various wind conditions at multiple speeds over multiple days, a regression-based method was developed to estimate wind-averaged drag with a low precision error for multiple tractor-trailer combinations.
2016-09-27
Technical Paper
2016-01-8155
Devaraj Dasarathan, Jonathan Jilesen, David Croteau, Ray Ayala
Abstract Side window clarity and its effect on side mirror visibility plays a major role in driver comfort. Driving in inclement weather conditions such as rain can be stressful, and having optimal visibility under these conditions is ideal. However, extreme conditions can overwhelm exterior water management devices, resulting in rivulets of water flowing over the a-pillar and onto the vehicle’s side glass. Once on the side glass, these rivulets and the pooling of water they feed, can significantly impair the driver’s ability to see the side mirror and to see outwardly when in situations such as changing lanes. Designing exterior water management features of a vehicle is a challenging exercise, as traditionally, physical testing methods first require a full-scale vehicle for evaluations to be possible. Additionally, common water management devices such as grooves and channels often have undesirable aesthetic, drag, and wind noise implications.
2016-09-27
Technical Paper
2016-01-8144
John Lacey
Abstract The trucking industry is being encouraged by environmental and cost factors to improve fuel efficiency. One factor that affects fuel efficiency is the aerodynamic design of the vehicles; that is, the vehicles with lower aerodynamic drag will get better mileage, reducing carbon emissions and reducing costs through lower fuel usage. A significant tool towards developing vehicles with lower drag is the wind tunnel. The automobile industry has made great improvements in fuel efficiency by using wind tunnels to determine the best designs to achieve lower drag. Those wind tunnels are not optimum for testing the larger, longer heavy trucks since the wind tunnels are smaller than needed. The estimated costs for a heavy truck wind tunnel based on automotive wind tunnel technology are quite high. A potential nozzle concept to reduce wind tunnel cost and several other new possible approaches to lower wind tunnel costs are presented.
2016-09-27
Technical Paper
2016-01-8151
Prashanth Gururaja
Abstract To investigate the feasibility of various aerodynamic test procedures for the Phase 2 Greenhouse Gas (GHG) Regulations for heavy-duty vehicles in the United States, the US Environmental Protection Agency conducted, through Southwest Research Institute (SwRI), coastdown testing of several heavy-duty tractors matched to a conventional 53-foot dry-van trailer. Three vehicle configurations were tested, two of which included common trailer drag-reduction technologies. Air speed was measured onboard the vehicle, and wind conditions were measured using a weather station placed along the road side. Tests were performed on a rural road in Texas. One vehicle configuration was tested over several days to evaluate day-to-day repeatability and the influence of changing wind conditions. Data on external sources of road forces, such as grade and speed dependence of tire rolling resistance, were collected separately and incorporated into the analysis.
2016-09-27
Journal Article
2016-01-8016
Devaraj Dasarathan, Matthew Ellis, Surya Chinnamani, Ray Ayala, James Haws
Abstract The primary purpose of this paper is to correlate the CFD simulations performed using PowerFLOW, a Lattice Boltzmann based method, and wind tunnel tests performed at a wind tunnel facility on 1/8th scaled tractor-trailer models. The correlations include results using an aerodynamic-type tractor paired with several trailer configurations, including a baseline trailer without any aerodynamic devices as well as combinations of trailer side skirts and a tractor-trailer gap flow management device. CFD simulations were performed in a low blockage open road environment at full scale Reynolds number to understand how the different test environments impact total aerodynamic drag values and performance deltas between trailer aerodynamic devices. There are very limited studies with the Class-8 sleeper tractor and 53ft long trailer comparing wind tunnel test and CFD simulation with and without trailer aerodynamic device. This paper is to fill this gap.
2016-09-27
Journal Article
2016-01-8022
Petter Ekman, Roland Gardhagen, Torbjörn Virdung, Matts Karlsson
Abstract Reducing energy consumption and emissions are ongoing challenges for the transport sector. The increased number of goods transports emphasize these challenges even more, as greenhouse gas emissions from these vehicles increased by 20 % between 1990 and 2013, in Sweden. One special case of goods transports is the transport of timber. Today in Sweden, around 2000 timber trucks transport around six billion ton kilometers every year. For every ton kilometer these vehicles use around 0.025 liter diesel, and there should exist large possibilities to reduce the fuel consumption and the emissions for these vehicles. Timber trucks spend most of their operation time travelling in speeds of around 80 km/h. At this speed aerodynamic drag contributes to around 30 % of the total vehicle resistance, which makes the aerodynamic drag a significant part of the energy consumption. One of the big challenges with timber trucks is that they travel unloaded half of the time.
2016-09-27
Journal Article
2016-01-8152
Brian R. McAuliffe, David Chuang
Abstract In an effort to support Phase 2 of Greenhouse Gas Regulations for Heavy-Duty Vehicles in the United States, a track-based test program was jointly supported by Transport Canada (TC), Environment and Climate Change Canada (ECCC), the U.S. Environmental Protection Agency (EPA), and the National Research Council Canada (NRC) to assess aerodynamic evaluation methodologies proposed by the EPA and to provide a site-verification exercise against a previous test campaign with the same vehicle. Coast-down tests were conducted with a modern aerodynamic tractor matched to a conventional 16.2 m (53 ft) dry-van trailer, and outfitted with two drag reduction technologies. Enhanced wind-measurement instrumentation was introduced, consisting of a vehicle-mounted fast-response pressure probe and track-side sonic anemometers that, when used in combination, provided improved reliability for the measurements of wind conditions experienced by the vehicle.
2016-09-27
Journal Article
2016-01-8149
Thomas Gheyssens, Gandert Van Raemdonck
Abstract This paper investigates the effect of the frontal edge radius of the Generalized European Transport System (GETS) model on the aerodynamic behavior of three different vehicles in a platoon. Due to the increasing awareness around harmful gases and depleting oil sources, more sustainable transport systems are needed. The efficiency of long-haul, heavy-duty vehicles can be increased by driving in platoon formation in order to decrease aerodynamic drag and to increase fuel mileage. The drag behavior of drafting vehicles is already studied but differences in aerodynamic drag reductions occur on the trailing vehicle. Some studies indicate a drag increase while others predict a drag decrease. In this study, a numerical investigation was performed solving Reynolds Averaged Navier-Stokes equations with the aid of a commercial package. Four different inter-vehicle distances were tested for the vehicles with several different frontal edge radii.
2016-09-27
Journal Article
2016-01-8148
Louis Carbonne, Niklas Winkler, Gunilla Efraimsson
Abstract The prediction in the design phase of the stability of ground vehicles subject to transient crosswinds become of increased concern with drag reduced shapes, lighter vehicles as well as platooning. The objective of this work is to assess the order of model complexity needed in numerical simulations to capture the behavior of a ground vehicle passing through a transient crosswind. The performance of a full-dynamic coupling between aerodynamic and vehicle dynamic simulations, including a driver model, is evaluated. In the simulations a feedback from the vehicle dynamics into the aerodynamic simulation is performed in every time step. In the work, both the vehicle dynamic response and the aerodynamic forces and moments are studied. The results are compared to a static coupling approach on a set of different vehicle geometries. Five car-type geometries and one simplified bus geometry are evaluated.
2016-09-27
Journal Article
2016-01-8147
Justin J. Novacek, Bhargav Sowmianarayanan
Abstract Trailer positioning plays a significant role in the overall aerodynamics of a tractor-trailer combination and varies widely depending on configuration and intended use. In order to minimize aerodynamic drag over a range of trailer positions, adjustable aerodynamic devices may be utilized. For maximum benefit, it is necessary to determine the optimal position of the aerodynamic device for each trailer position. This may be achieved by characterizing a two-dimensional design space consisting of trailer height and tractor-trailer gap length, with aerodynamic drag as the response. CFD simulations carried out using a Lattice-Boltzmann based method were coupled with modeFRONTIER for the creation of multiple Kriging Response Surfaces. Simulations were carried out in multiple phases, allowing for the generation of intermediate response surfaces to estimate predictive error and track response surface convergence.
2016-09-27
Technical Paper
2016-01-8139
Santosh Nalanagula, G T Varadharajan
Abstract Aerodynamic drag contributes to 50-60% of fuel consumption in trucks on highways. The limits of conventional wind tunnel testing have forced researchers to study about the drag and ways of reducing it computationally. Due to the stricter norms and eco-friendly approaches, truck manufacturers have begun to invest more for developing truck aerodynamics. This paper evaluates a European vehicle on European conditions. Drag reduction are mostly made by geometric changes. Pressure drag, a major drag for trucks as they run at lower speeds is produced by the shape of the object. Making streamlined bodies as trucks are tougher since it can affect its purpose. Therefore, addition of some components can suffice the needs. The changes in geometry have been implied and analysis for these geometrical changes are done to analyze the better geometry which can provide drag reduction features. The geometrical changes considered are providing side skirts, boattails and roof deflector angle.
2016-09-27
Journal Article
2016-01-8023
Bernard Tanguay
Abstract A novel method was developed to predict the free-stream velocity experienced by a traveling vehicle based on track-side anemometric measurements. The end objective of this research was to enhance the reliability of the prediction of free-stream conditions in order to improve the accuracy of aerodynamic drag coefficient (CD) assessments from track tests of surface vehicles. Although the technique was applied to heavy-duty vehicles in the present work, it is equally applicable to any vehicle type. The proposed method is based on Taylor’s hypothesis, a principle applied in fluid mechanics to convert temporal signals into the spatial domain. It considers that the turbulent wind velocity fluctuations measured at one point are due to the "passage of an unchanging pattern of turbulent motion over the point". The method is applied to predict the wind velocity that the vehicle will experience as it encounters a wind pattern detected earlier by an anemometer located upwind.
2016-09-27
Journal Article
2016-01-8133
Sam Waltzer, Dennis Johnson, Kuang Wei, Jonathan Wilson
Abstract Commercial, class-8 tractor-trailers were tested to develop a relationship between vehicle speed and fuel savings associated with trailer aerodynamic technologies representative of typical long-haul freight applications. This research seeks to address a concern that many long-distance U.S. freight companies hold that, as vehicle speed is reduced, the fuel savings benefits of aerodynamic technologies are not realized. In this paper, the reductions in fuel consumption were measured using the SAE J1231 test method and thru-engine fueling rates recorded from the vehicle’s electronic data stream. Constant speed testing was conducted on road at different speeds and corresponding testing was conducted on track to confirm results. Data was collected at four (4) vehicle speeds: 35, 45, 55, and 62 miles per hour. Two different trailer aerodynamic configurations were evaluated relative to a baseline tractor trailer.
2016-09-27
Technical Paper
2016-01-2095
Agata Suwala, Lucy Agyepong, Andrew Silcox
Abstract Reduction of overall drag to improve aircraft performance has always been one of the goals for aircraft manufacturers. One of the key contributors to decreasing drag is achieving laminar flow on a large proportion of the wing. Laminar flow requires parts to be manufactured and assembled within tighter tolerance bands than current build processes. Drilling of aircraft wings to the tolerances demanded by laminar flow requires machines with the stiffness and accuracy of a CNC machine while having the flexibility and envelope of an articulated arm. This paper describes the development and evaluation of high accuracy automated processes to enable the assembly of a one-off innovative laminar flow wing concept. This project is a continuation of a previously published SAE paper related to the development of advanced thermally stable and lightweight assembly fixture required to maintain laminar flow tolerances.
2016-09-27
Technical Paper
2016-01-2109
Michael Morgan, Caroline McClory, Colm Higgins, Yan Jin, Adrian Murphy
Aerospace structures are typically joined to form larger assemblies using screw lock or swage lock fasteners or rivets. Countersunk fasteners are used widely in the aerospace industry on flying surfaces to reduce excrescence drag and increase aircraft performance. These fasteners are typically installed to a nominal countersink value which leaves them flush to the surface before being locked into position. The Northern Ireland Technology Centre (NITC) at Queen’s University Belfast has developed and demonstrated two processes which enable high tolerance flush fastening of countersunk fasteners: The ‘Flush Install’ process produces countersunk holes based on the specific geometry of each individual fastener; The ‘Fettle Flush’ process accurately machines fasteners to match the surrounding surface. Flushness values well within the allowable tolerances have been demonstrated for both Flush Install and Fettle Flush processes.
2016-09-27
Technical Paper
2016-01-8134
Lijuan Wang, Adam Duran, Kenneth Kelly, Arnaud Koana, Michael lammert, Robert Prohaska
Abstract In this paper, researchers at the National Renewable Energy Laboratory present the results of simulation studies to evaluate potential fuel savings as a result of improvements to vehicle rolling resistance, coefficient of drag, and vehicle weight as well as hybridization for four powertrains for medium-duty parcel delivery vehicles. The vehicles will be modeled and simulated over 1,290 real-world driving trips to determine the fuel savings potential based on improvements to each technology and to identify best use cases for each platform. The results of impacts of new technologies on fuel saving will be presented, and the most favorable driving routes on which to adopt them will be explored.
2016-09-27
Technical Paper
2016-01-8140
Devaraj Dasarathan, Ashraf Farag, Matthew Ellis
Abstract Recent regulations on greenhouse gas (GHG) emission standards for heavy-duty vehicles have prompted government agencies to standardize procedures assessing the aerodynamic performance of Class 8 tractor-trailers. The coastdown test procedure is the primary reference method employed to assess vehicle drag currently, while other valid alternatives include constant speed testing, computational fluid dynamics (CFD) simulations, and wind tunnel testing. The main purpose of this paper is to compare CFD simulations with a corresponding 1/8th scale wind tunnel test. Additionally, this paper will highlight the impacts of wind tunnel testing on the total drag coefficient performance as compared to full scale open road analysis with and without real world, upstream turbulence wind conditions. All scale model testing and CFD simulations were performed on a class 8 tractor with a standard 53-foot dry-box trailer.
2016-09-20
Technical Paper
2016-01-2018
Syed J. Khalid
Abstract The key commercial aircraft propulsion requirements toward ensuring flight safety, operational efficiency, reduced CO2 footprint, and community acceptability include high installed thrust, low specific fuel consumption, and reduced noise. The objective of this paper is to highlight the various ways turbofan performance can be enhanced. First the advantage of high bypass ratio (BPR) configurations will be explained with the help of clean sheet cycle designs with the corresponding off-design performance. The achievement of hot day performance and improved durability with high BPR designs, and the benefit from core supercharging has been presented. Next, the use of on-line control effector modulations, including variable bypass exhaust nozzle, for further improvement in cruise SFC (up to an indicated 2.6%) is shown. This is followed by a discussion of medium BPR mixed exhaust designs which have a performance advantage compared to the same BPR separate exhaust configurations.
2016-09-20
Technical Paper
2016-01-2019
Richard P. Johnston
Abstract An advanced composite Blended Wing Body (BWB) air frame previously used as a study aircraft to transport a 75-ton military cargo halfway around the world and back unrefueled has been modified and evaluated as a 150-ton heavy lifter. The modifications include enlarging the forward trim canard, reducing fuel load by 151,850 lbs, increasing the high-mach NASA-type counter-rotating propellers from 12 feet to 13 feet diameter, extending the propeller support pylons' height by 6 inches and modifying cruise flight and prop control strategies. Due to structural and propulsion system changes, the air frame Operational Empty Weight (OEW) was increased by 1,850 lbs. but the maximum Take Off Gross Weight (TOGW) was held to 800,000 lbs. Brief descriptions of the major propulsion system components are provided. In addition, a comparison of three different counter-rotating propeller systems is presented. The first is a Standard configuration.
2016-09-18
Journal Article
2016-01-1925
David B. Antanaitis
Abstract The strong focus on reducing brake drag, driven by a historic ramp-up in global fuel economy and carbon emissions standards, has led to renewed research on brake caliper drag behaviors and how to measure them. However, with the increased knowledge of the range of drag behaviors that a caliper can exhibit comes a particularly vexing problem - how should this complex range of behaviors be represented in the overall road load of the vehicle? What conditions are encountered during coastdown and fuel economy testing, and how should brake drag be measured and represented in these conditions? With the Environmental Protection Agency (amongst other regulating agencies around the world) conducting audit testing, and the requirement that published road load values be repeatable within a specified range during these audits, the importance of answering these questions accurately is elevated. This paper studies these questions, and even offers methodology for addressing them.
2016-04-05
Technical Paper
2016-01-0541
Martin Schifko, Hans Steiner, Masayasu Mohri, Christoph Bauinger
Abstract The development of entire car bodies benefits from simulations, especially if they are performed at an early stage of development because they lower the costs for required car body modifications. This paper focuses on a dip paint simulation and describes the simulation process as an e-coat (electric coating) thickness simulation which considers gas bubbles, drainage and buoyancy forces. This paper points out the advantages of this technology by explaining the theory behind this. A new hydrodynamic method is used which performs about 1000 times faster as standard computational fluid dynamics (CFD) solvers. In addition, this method allows executing the computation on standard desktop machines, i.e. no high performance computer (HPC) is needed. In addition we introduce a simple method to calculate the static buoyancy forces of arbitrary homogeneous objects and a simple model movement of an engine hood induced by buoyancy and drag forces.
2016-04-05
Technical Paper
2016-01-0526
Sumiran Manghani, Girish Kumar
Abstract Vehicle performance is highly dependent on the design and material used. Fairing of a Human Powered Vehicle (HPV) is responsible for the reduction in the aerodynamic drag force and its material determines the overall weight and the top speed of the vehicle. Selection of material for fairings depends on various physical, mechanical and manufacturing properties along with practical considerations like availability of material. Today, an ever-increasing variety of composite materials and polymers are available, each of them possessing their own characteristics, applications, advantages and limitations. Many automotive composites are used for manufacturing fairings. Materials like Carbon fiber, Glass fiber (E glass, S glass), Aramid fiber (Kevlar 29, Kevlar 49) are some of the viable options that have been used in the past for manufacturing fairing of HPVs.
2016-04-05
Technical Paper
2016-01-0460
Salem A. Haggag, Abraham Mansouri
Abstract The control of automotive braking systems performance and wheel slip is a challenging problem due to the nonlinear of the braking process, vehicle body dynamics during braking and the tire-road interaction. When the wheel slip is not between the optimal limits during braking, the desired tire-friction force cannot be achieved, which influences the braking distance, the loss in steerability and maneuverability of the vehicle. A simple and at the same time realistic vehicle longitudinal braking model is essential for such challenging problem. In this paper, a new longitudinal rolling/braking lumped-vehicle model that takes vehicle aerodynamic forces in consideration is presented. The proposed model takes the rolling resistance force, the braking force and the aerodynamic lift and drag forces in consideration and investigates their impact on the vehicle longitudinal dynamics especially vehicle braking distance and time.
2016-04-05
Technical Paper
2016-01-1183
Hisham Al Ashkar, Ferdinand Panik, Waldemar Schneider, Thomas Rohrbach, Walter Czarnetzki, Sami Karaki
Abstract The University of Applied Sciences Esslingen (UASE) is a partner in the collaborative EU project PHAEDRUS (high Pressure Hydrogen All Electrochemical Decentralized RefUeling Station) as part of the EU work programme SP1-JTI-FCH.2011.1.8 Research and Development of 700 bar refueling concepts and technologies. The subtask of UASE is the simulation, sizing and analysis of a new concept for a 100 MPa hydrogen refueling station enabling self-sustained infrastructure roll-out for early vehicle deployment volumes, showing the applicability of the electrochemical hydrogen compression (EHC) technology in combination with an on-site anion exchange membrane electrolyser (AEMEC), storage units, precooling and a dispensing system. The electrolyser and the compressor are modeled using the electrochemical equations and the conservation of mole balance.
2016-04-05
Technical Paper
2016-01-0905
Robert J. Middleton, Omnaath Guptha Harihara Gupta, Han-Yuan Chang, George Lavoie, Jason Martz
Abstract This study evaluates the fuel economy implication of powertrain technologies capable of reducing light duty vehicle fuel consumption for compliance with 2025 CAFE standards. In a companion paper, a fully integrated GT-Power engine model was used to evaluate the effectiveness of one plausible series of engine technologies, including valve train improvements such as dual cam phasing and discrete variable valve lift, and engine downsizing with turbocharging and cooled EGR. In this paper, those engine efficiency/performance results are used in a vehicle drive cycle simulation to estimate the impact of engine and transmission technology improvements on light duty vehicle fuel consumption/economy over the EPA’s FTP and HWY test schedules. The model test vehicle is a midsized sedan based on the MY2012 Ford Fusion.
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