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Viewing 1 to 30 of 75
1990-02-01
Technical Paper
900482
M. C. Leschiutta, J. A. Eng, J. K. Martin
A nonintrusive diagnostic technique has been developed by which dynamic axial piston-position and tilt-angle measurements have been made in a single-cylinder research engine. A laser beam, introduced into the combustion chamber through an optical port in the cylinder head, was reflected by a polished surface on the piston crown. Motion of the reflected beam, carrying with it information on piston position and piston tilt, was monitored by a set of receiving optics. Piston motion was studied as a function of both engine speed and cylinder pressure (i.e., piston loading.) Measured axial piston-position was found to deviate from the theoretical position calculated from the measured crank-shaft position owing to the effects of tilt and piston loading. Furthermore, evidence of piston veer (tilt of the piston in a plane parallel to the axis of the wrist pin) was observed, which had an effect on the accuracy of the axial piston-position measurement.
2005-10-24
Technical Paper
2005-01-3743
Kushal Narayanaswamy, Randy P. Hessel, Christopher J. Rutland
An approach to accurately capture overall behavior in a system level model of DI Diesel HCCI engine operation is presented. The modeling methodology is an improvement over the previous effort [36], where a multi-zone model with detailed chemical kinetics was coupled with an engine cycle simulation code. This multi-zone technique was found to be inadequate in capturing the fuel spray dynamics and its impact on mixing. An improved methodology is presented in this paper that can be used to model fully and partially premixed charge compression ignition engines. A Computational Fluid Dynamics (CFD) driven model is used where the effects of fuel injection, spray evolution, evaporation, and turbulent mixing are considered. The modeling approach is based on the premise that once the initial spray dynamics are correctly captured, the overall engine predictions during the combustion process can be captured with good accuracy.
2006-04-03
Technical Paper
2006-01-0263
Stephen B. England, Christopher J. Rutland, David E. Foster, Yongsheng He
An integrated system model containing sub-models for a diesel engine, NOx and soot emissions, and a diesel particulate filter (DPF) has been used to simulate stead-state engine operating conditions. The simulation results have been used to investigate the effect of DPF loading and passive regeneration on engine performance and emissions. This work is the continuation of previous work done to create an overall diesel engine/exhaust system integrated model. As in the previous work, a diesel engine, exhaust system, engine soot emissions, and diesel particulate filter (DPF) sub-models have been integrated into an overall model using Matlab Simulink. For the current work new sub-models have been added for engine-out NOx emissions and an engine feedback controller. The integrated model is intended for use in simulating the interaction of the engine and exhaust aftertreatment components.
2006-04-03
Technical Paper
2006-01-0027
Yong Sun, Rolf D. Reitz
A multi-dimensional Computational Fluid Dynamics (CFD) code with detailed chemistry, the KIVA-CHEMKIN-GA code, was employed in this study, where Genetic Algorithms (GA) were used to optimize heavy-duty diesel engine operating parameters. A two-stage combustion (TSC) concept was explored to optimize the combustion process at high speed (1737 rev/min) and medium load (57% load). Two combustion modes were combined in this concept. The first stage is ideally Homogeneous Charge Compression Ignition (HCCI) combustion and the second stage is diffusion combustion under high temperature and low oxygen concentration conditions. This can be achieved for example by optimization of two-stage combustion using multiple injection or sprays from two different injectors.
1998-08-11
Technical Paper
981930
K. Gebert, R. L. Barkhimer, N. J. Beck, D. D. Wickman, K. V. Tanin, S. Das, Rolf D. Reitz
Hydraulically intensified medium pressure common rail (MPCR) electronic fuel injection systems are an attractive concept for heavy-duty diesel engine applications. They offer excellent packaging flexibility and thorough engine management system integration. Two different concepts were evaluated in this study. They are different in how the pressure generation and injection events are related. One used a direct principle, where the high-pressure generation and injection events occur simultaneously producing a near square injection rate profile. Another concept was based on an indirect principle, where potential energy (pressure) is first stored inside a hydraulic accumulator, and then released during injection, as a subsequent event. A falling rate shape is typically produced in this case. A unit pump, where the hydraulic intensifier is separated from the injector by a high-pressure line, and a unit injector design are considered for both concepts.
2006-04-03
Technical Paper
2006-01-1150
Hoojoong Kim, Rolf D. Reitz, Song-Charng Kong
Combustion in an HSDI diesel engine using different injectors to realize low emissions is modeled using detailed chemical kinetics in this study. Emission characteristics of the engine are investigated using injectors that have different included spray angles, ranging from 50 to 130 degrees. The engine was operated under PCCI conditions featuring early injection times, high EGR levels and high intake temperatures. The Representative Interactive Flamelet (RIF) model was used with the KIVA code for combustion and emission modeling. Modeling results show that spray targeting plays an important role in determining the in-cylinder mixture distributions, which in turn affect the resulting pollutant emissions. High soot emissions are observed for injection conditions that result in locally fuel rich regions due to spray impingement normal to the piston surface.
2006-04-03
Technical Paper
2006-01-1149
Y. Ra, Rolf D. Reitz, M. W. Jarrett, T. P. Shyu
The effect of piston ring pack crevice flow and lubricant oil vaporization on heavy-duty diesel engine deposits is investigated numerically using a multidimensional CFD code, KIVA3V, coupled with Chemkin II, and computational grids that resolve part of the crevice region appropriately. Improvements have been made to the code to be able to deal with the complex geometry of the ring pack, and sub-models for the crevice flow dynamics, lubricating oil vaporization and combustion, soot formation and deposition were also added to the code. Eight parametric cases were simulated under reacting conditions using detailed chemical kinetics to determine the effects of variations of lube-oil film thickness, distribution of the oil film thickness, number of injection pulses, and the main injection timing on engine soot deposition. The results show that crevice-borne hydrocarbon species play an important role in deposit formation on crevice surfaces.
2006-04-03
Technical Paper
2006-01-1084
Kushal Narayanaswamy, Christopher J. Rutland
A comprehensive system level modeling approach is used to understand the effects of the various physical actuators during diesel HCCI transients. Control concepts during transient operations are simulated using a set of actuators suitable for combustion control in diesel HCCI engines (intake valve actuation, injection timing, cooled EGR, intake boost pressure and droplet size). The impact of these actuating techniques on the overall engine performance is quantified by investigating the amount of actuation required, timing of actuation and the use of a combination of actuators. Combined actuation improved actuation space that can be used to phase combustion timing better and in extending the operating range. The results from transient simulations indicate that diesel HCCI operation would benefit from the combined actuation of intake valve closure, injection timing, boost and cooled EGR.
2006-04-03
Technical Paper
2006-01-0921
Achuth Munnannur, Neerav Abani, Rolf D. Reitz
The heavy-duty diesel engine industry is required to meet stringent emission standards. There is also the demand for more fuel efficient engines by the customer. In a previous study on an engine with variable intake valve closure timing, the authors found that an early single injection and accompanying premixed charge compression ignition (PCCI) combustion provides advantages in emissions and fuel economy; however, unacceptably high peak pressures and rates of pressure-rise impose a severe operating constraint. The use of a Pressure Reactive Piston assembly (PRP) as a means to limit peak pressures is explored in the present work. The concept is applied to a heavy-duty diesel engine and genetic algorithms (GA) are used in conjunction with the multi-dimensional engine simulation code KIVA-3V to provide an optimized set of operating variables.
2007-04-16
Technical Paper
2007-01-0227
Tanet Aroonsrisopon, Dennis G. Nitz, John O. Waldman, David E. Foster, Minoru Iida
This computational study compares predictions and experimental results for the use of direct injected iso-octane fuel during the negative valve overlap (NVO) period to achieve HCCI combustion. The total fuel injection was altered in two ways. First the pre-DI percent, (the ratio of direct injected fuel during the NVO period “pre-DI” to the secondary fuel supplied at the intake manifold “PI”), was varied at a fixed pre-DI injection timing, Secondly the timing of the pre-DI injection was varied while all of the fuel was supplied during the NVO period. A multi-zone, two-dimensional CFD simulation with chemistry was performed using KIVA-3V release 2 implemented with the CHEMKIN solver. The simulations were performed during the NVO period only.
2007-04-16
Technical Paper
2007-01-0219
John Waldman, Dennis Nitz, Tanet Aroonsrisopon, David E. Foster, Minoru Iida
A single cylinder Yamaha research engine was operated with gasoline HCCI combustion using negative valve overlap (NVO). The injection strategy for this study involved using fuel injected directly into the cylinder during the NVO period (pre-DI) along with a secondary injection either in the intake port (PI) or directly into the cylinder (DI). The effects of timing of the pre-DI injection along with the percent of fuel injected during the pre-DI injection were studied in two sets of experiments using secondary PI and DI injections in separate experiments. Results have shown that by varying the pre-DI timing and pre-DI percent the main HCCI combustion timing can be influenced as a result of varied heat release during the negative valve overlap period along with hypothesized varied degrees of reformation of the pre-DI injected fuel. In addition to varying the main combustion timing the ISFC, emissions and combustion stability are all influenced by changes in pre-DI timing and percent.
2007-04-16
Technical Paper
2007-01-0188
Chun Lan, Andrew W. Caswell, Laura A. Kranendonk, Scott T. Sanders, Yasuhira Urata, Yasuhira Okura
1 ABSTRACT An all fiber-optic sensor has been developed to measure H2O mole fraction and gas temperature in an HCCI engine. This absorption-spectroscopy-based sensor utilizes a broad wavelength (1320 to 1380 nm) source (supercontinua generated by a microchip laser) and a series of fiber Bragg gratings (19 gratings centered on unique water absorption peaks) to track the formation and temperature of combustion water vapor. The spectral coverage of the system promises improved measurement accuracy over two-line diode-laser based systems. Meanwhile, the simplicity of the fiber Bragg grating chromatic dispersion approach significantly reduces the data reduction time and cost relative to previous supercontinuum-based sensors. The data provided by the system is expected to enhance studies of the chemical kinetics which govern HCCI ignition as well as HCCI modeling efforts.
2006-10-16
Technical Paper
2006-01-3390
Shiyou Yang, Lin-Shu Wang, Hongzhong Gu, Kangyao Deng, Yi Cui
A newly developed turbocharging system, named MIXPC, is proposed and the performance of the proposed system applied to diesel engines is evaluated. The aim of this proposed system is to reduce the scavenging interference between cylinders, and to lower the pumping loss in cylinders and the brake specific fuel consumption. In addition, exhaust manifolds of simplified design can be constructed with small dimensions, low weight and a single turbine entry. A simulation code based on a second-order FVM+TVD (finite volume method + total variation diminishing) is developed and used to simulate engines with MIXPC. By simulating a 16V280ZJG diesel engine using the MPC turbocharging system and MIXPC, it is found that not only the average scavenging coefficient of MIXPC is larger than that of MPC, but also cylinders of MIXPC have more homogeneous scavenging coefficients than that of MPC, and the pumping loss and BSFC of MIXPC are lower than those of MPC.
2006-11-13
Technical Paper
2006-32-0047
Takeru Ibara, Minoru Iida, David E. Foster
Gasoline fueled Homogeneous Charge Compression Ignition (HCCI) combustion with internal exhaust gas re-circulation using Negative Valve Overlap (NOL) was investigated by means of calculation and experiment in order to apply this technology to practical use with sufficient operating range and with acceptable emission and fuel consumption. In this paper we discuss the basic characteristics of NOL-HCCI with emphasis on the influence of intake valve timing on load range, residual gas fraction and induction air flow rate. Emission and fuel consumption under various operation conditions are also discussed. A water-cooled 250cc single cylinder engine with a direct injection system was used for this study. Three sets of valve timing were selected to investigate the effect of intake valve opening duration. Experimental results demonstrated that an engine speed of approximately 2000rpm yields an NMEP (Net Mean Effective Pressure) range from 200kPa to 400kPa.
2005-10-24
Technical Paper
2005-01-3883
Hyungsuk Kang, Patrick V. Farrell
Transient engine tests were performed to investigate behavior of transient emissions--hydrocarbon (HC) and oxides of Nitrogen (NOx)--in a 2.4L turbocharged four cylinder High Speed Direct Injection (HSDI) diesel engine which is coupled to a hydrostatic transient dynamometer. Emissions were measured from one exhaust port 5 cm downstream of the exhaust valve and from the exhaust pipe 14 cm below the wastegate of the turbocharger. These measurements were made with fast response HC and NOx measurement analyzers. The experiments were conducted by increasing torque at constant speed and by increasing speed at constant torque, in conventional diesel combustion regions. The emissions from the two locations are compared. The transient effects of Exhaust Gas Recirculation (EGR) rates and injection timing on HC and NOx are described and the effects of linear and step load change on emissions are compared.
2004-03-08
Technical Paper
2004-01-1756
Tanet Aroonsrisopon, Philipp Werner, John O. Waldman, Volker Sohm, David E. Foster, Takeshi Morikawa, Minoru Iida
A single cylinder CFR research engine has been run in HCCI combustion mode at the rich and the lean limits of the homogeneous charge operating range. To achieve a variation of the degree of charge stratification, two GDI injectors were installed: one was used for generating a homogeneous mixture in the intake system, and the other was mounted directly into the side of the combustion chamber. At the lean limit of the operating range, stratification showed a tremendous improvement in IMEP and emissions. At the rich limit, however, the stratification was limited by the high-pressure rise rate and high CO and NOx emissions. In this experiment the location of the DI injector was in such a position that the operating range that could be investigated was limited due to liquid fuel impingement onto the piston and liner.
2004-10-25
Technical Paper
2004-01-2997
Kushal Narayanaswamy, Christopher J. Rutland
An integrated system based modeling approach has been developed to understand early Direct Injection (DI) Diesel Homogeneous Charge Compression Ignition (HCCI) process. GT-Power, a commercial one-dimensional (1-D) engine cycle code has been coupled with an external cylinder model which incorporates sub-models for fuel injection, vaporization, detailed chemistry calculations (Chemkin), heat transfer, energy conservation and species conservation. In order to improve the modeling accuracy, a multi-zone model has been implemented to account for temperature and fuel stratifications in the cylinder charge. The predictions from the coupled simulation have been compared with experimental data from a single cylinder Caterpillar truck engine modified for Diesel HCCI operation. A parametric study is conducted to examine the effect of combustion timing on four major control parameters. Overall the results show good agreement of the trends between the experiments and model predictions.
2003-10-27
Technical Paper
2003-01-3232
Yongsheng He, Christopher J. Rutland
A cylinder model was developed using artificial neural networks (ANN). The cylinder model utilized the trained ANN models to predict engine parameters including cylinder pressures, cylinder temperatures, cylinder wall heat transfer, NOx and soot emissions. The ANN models were trained to approximate CFD simulation results of an engine. The ANN cylinder model was then applied to predict engine performance and emissions over the standard heavy-duty FTP transient cycle. The engine responses varying over the engine speed and torque range were simulated in the course of the transient test cycle. It was demonstrated that the ANN cylinder model is capable of simulating the characteristics of the engine operating under transient conditions reasonably well.
2005-04-11
Technical Paper
2005-01-0947
David J. Kapparos, Indranil Brahma, Andrea Strzelec, Christopher J. Rutland, David E. Foster, Yongsheng He
An overall diesel engine and aftertreatment system model has been created that integrates diesel engine, exhaust system, engine emissions, and diesel particulate filter (DPF) models using MATLAB Simulink. The 1-D engine and exhaust system models were developed using WAVE. The engine emissions model combines a phenomenological soot model with artificial neural networks to predict engine out soot emissions. Experimental data from a light-duty diesel engine was used to calibrate both the engine and engine emissions models. The DPF model predicts the behavior of a clean and particulate-loaded catalyzed wall-flow filter. Experimental data was used to validate this sub-model individually. Several model integration issues were identified and addressed. These included time-step selection, continuous vs. limited triggering of sub-models, and code structuring for simulation speed. Required time-steps for different sub models varied by orders of magnitude.
2005-04-11
Technical Paper
2005-01-0148
Y. Ra, Rolf D. Reitz
A numerical study of the effects of injection parameters and operating conditions for diesel-fuel HCCI operation is presented with consideration of Variable Geometry Sprays (VGS). Methods of mixture preparation are explored that overcome one of the major problems in HCCI engine operation with diesel fuel and conventional direct injection systems, i.e., fuel loss due to wall impingement and the resulting unburned fuel. Low pressure injection of hollow cone sprays into the cylinder of a production engine with the spray cone angle changing during the injection period were simulated using the multi-dimensional KIVA-3V CFD code with detailed chemistry. Variation of the starting and ending spray angles, injection timing, initial cylinder pressure and temperature, swirl intensity, and compression ratio were explored. As a simplified case of VGS, two-pulse, hollow-cone sprays were also simulated.
2005-04-11
Technical Paper
2005-01-0374
Achuth Munnannur, Song-Charng Kong, Rolf D. Reitz
The strategy of variable Intake Valve Closure (IVC) timing, as a means to improve performance and emission characteristics, has gained much acceptance in gasoline engines; yet, it has not been explored extensively in diesel engines. In this study, genetic algorithms are used in conjunction with the multi-dimensional engine simulation code KIVA-3V to investigate the optimum operating variables for a typical heavy-duty diesel engine working with late IVC. The effects of start-of-injection timing, injection duration and exhaust gas recirculation were investigated along with the intake valve closure timing. The results show that appreciable reductions in NOx+HC (∼82%), soot (∼48%) and BSFC (∼7.4%) are possible through this strategy, as compared to a baseline diesel case of (NOx+HC) = 9.48g/kW-hr, soot = 0.17 g/kW-hr and BSFC = 204 g-f/kW-hr. The additional consideration of double injections helps to reduce the high rates of pressure rise observed in a single injection scheme.
2005-04-11
Technical Paper
2005-01-0219
Manshik Kim, Mike P. Liechty, Rolf D. Reitz
In this paper, optimized single and double injection schemes were found using multi-dimensional engine simulation software (KIVA-3V) and a micro-genetic algorithm for a heavy duty diesel engine. The engine operating condition considered was at 1737 rev/min and 57 % load. The engine simulation code was validated using an engine equipped with a hydraulic-electronically controlled unit injector (HEUI) system. Five important parameters were used for the optimization - boost pressure, EGR rate, start-of-injection timing, fraction of fuel in the first pulse and dwell angle between first and second pulses. The optimum results for the single injection scheme showed significant improvements for the soot and NOx emissions. The start of injection timing was found to be very early, which suggests HCCI-like combustion. Optimized soot and NOx emissions were reduced to 0.005 g/kW-hr and 1.33 g/kW-hr, respectively, for the single injection scheme.
2003-09-16
Technical Paper
2003-32-0018
T. Kim, J. B. Ghandhi
The KIVA 3V code has been applied to predict combustion chamber heat flux in an air-cooled utility engine. The KIVA heat flux predictions were compared with experimentally measured data in the same engine over a wide range of operating conditions. The measured data were found to be approximately two times larger than the predicted results, which is attributed to the omission of chemical heat release in the near-wall region for the heat transfer model applied. Modifying the model with a simple scaling factor provided a good comparison with the measured data for the full range of engine load, heat flux sensor location, air-fuel ratio and spark timings tested. The detailed spatially resolved results of the KIVA predictions were then used to develop a simplified model of the combustion chamber temporally integrated heat flux using an artificial neural network (ANN).
2003-09-16
Technical Paper
2003-32-0081
H. Z. Foudray, J. B. Ghandhi
The scavenging process in a direct-injection two-stroke research engine was examined by using an electromagnetically controlled poppet valve to sample the trapped charge. A physical model was developed to characterize the scavenging based solely on the measured trapped gas composition. This method obviates the need to measure the post-combustion composition of the trapped charge, which significantly eases the sampling valve requirements. The valve that was developed proved to be very robust and was able to sample over 30% of the trapped mass at 3000 rpm. The measured scavenging efficiency was found to agree well with the non-isothermal two-zone perfect mixing limit of scavenging. The scavenging efficiency was found to increase with delivery ratio, and was nearly independent of speed.
2004-03-08
Technical Paper
2004-01-0092
Satbir Singh, Song-Charng Kong, Rolf D. Reitz, Sundar R. Krishnan, K. Clark Midkiff
The combustion and emissions of a diesel/natural gas dual-fuel engine are studied. Available engine experimental data demonstrates that the dual-fuel configuration provides a potential alternative to diesel engine operation for reducing emissions. The experiments are compared to multi-dimensional model results. The computer code used is based on the KIVA-3V code and consists of updated sub-models to simulate more accurately the fuel spray atomization, auto-ignition, combustion and emissions processes. The model results show that dual-fuel engine combustion and emissions are well predicted by the present multi-dimensional model. Significant reduction in NOx emissions is observed in both the experiments and simulations when natural gas is substituted for diesel fuel. The HC emissions are under predicted by numerical model as the natural gas substitution is increased.
2004-03-08
Technical Paper
2004-01-0102
Zhichao Tan, Rolf D. Reitz
A universal engine combustion model based on the level-set approach was developed in this study. It was first used to model combustion in Spark Ignition (SI) and Direct Injection Spark Ignition (DISI) engines when combined with the Discrete Particle Spark Ignition model, in which the ignition kernel is represented by particles. Once the flame kernel grows to a size that the turbulent flame is fully developed, the G-equation model is used to track the subsequent propagation of the turbulent flame. When combined with a characteristic time combustion model, the triple flame structure that is found in DISI engine combustion was successfully modeled. The model was also applied to simulate diesel combustion where the diffusion combustion regime is dominant. In this case, the ignition was modeled using the Shell auto-ignition model. Satisfactory agreement with features of the conceptual diesel combustion model of Dec [1997] was found.
2004-03-08
Technical Paper
2004-01-0552
Volker Sohm, Song-Charng Kong, David E. Foster, Takeshi Morikawa, Minoru Iida
Multi-dimensional computational efforts using comprehensive and skeletal kinetics have been made to investigate the cool flame region in HCCI combustion. The work was done in parallel to an experimental study that showed the impact of the negative temperature coefficient and the cool flame on the start of combustion using different fuels, which is now the focus of the simulation work. Experiments in a single cylinder CFR research engine with n-butane and a primary reference fuel with an octane number of 70 (PRF 70) were modeled. A comparison of the pressure and heat release traces of the experimental and computational results shows the difficulties in predicting the heat release in the cool flame region. The behavior of the driving radicals for two-stage ignition is studied and is compared to the behavior for a single-ignition from the literature. Model results show that PRF 70 exhibits more pronounced cool flame heat release than n-butane.
2004-03-08
Technical Paper
2004-01-0530
Harmit Juneja, Youngchul Ra, Rolf D. Reitz
The effect of injection rate shape on spray evolution and emission characteristics is investigated and a methodology for active control of fuel injection is proposed. Extensive validation of advanced vaporization and primary jet breakup models was performed with experimental data before studying the effects of systematic changes of injection rate shape. Excellent agreement with the experiments was obtained for liquid and vapor penetration lengths, over a broad range of gas densities and temperatures. Also the predicted flame lift-off lengths of reacting diesel fuel sprays were in good agreement with the experiments. After the validation of the models, well-defined rate shapes were used to study the effect of injection rate shape on liquid and vapor penetration, flame lift-off lengths and emission characteristics.
2004-03-08
Technical Paper
2004-01-0558
Amar Patel, Song-Charng Kong, Rolf D. Reitz
A reduced chemical reaction mechanism is developed and validated in the present study for multi-dimensional diesel HCCI engine combustion simulations. The motivation for the development of the reduced mechanism is to enhance the computational efficiency of engine stimulations. The new reduced mechanism was generated starting from an existing n-heptane mechanism (40 species and 165 reactions). The procedure of generating the reduced mechanism included: using SENKIN to produce the ignition delay data and solution files, using XSENKPLOT to analyze the base mechanism and to identify important reactions and species, eliminating unimportant species and reactions, formulating the new reduced mechanism, using the new mechanism to generate ignition delay data, and finally adjusting kinetic constants in the new mechanism to improve ignition delay and engine combustion predictions to account for diesel fuel cetane number and composition effects.
2004-03-08
Technical Paper
2004-01-0050
A. C. Alkidas, P. A. Battiston, D. J. Kapparos
This paper is a continuation of an earlier paper, which examined the steady-state internal heat transfer in the exhaust system of a diesel powered, light-duty vehicle. The present paper deals with the heat transfer of the exhaust system during two types of transient testing, as well as, the estimation of the exhaust systems external heat transfer. Transient heat transfer was evaluated using: a simple fuel-step transient under constant speed and the New European Driving Cycle (NEDC). The thermal response of the external walls varied considerably for the various components of the exhaust system. The largest percent difference between the measured temperatures and the corresponding quasi-steady estimates were about 10%, which is attributed to thermal storage. Allowing for thermal storage resulted in an excellent agreement between measurements and analysis.
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