| 1. |
- Holmqvist, Kristian, 1976, et al.
(författare)
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Heavy vehicle frontal sled crash test analysis chest deflection response in the Hybrid III dummy
- 2013
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Ingår i: International Journal of Crashworthiness. - : Informa UK Limited. - 1358-8265 .- 1754-2111. ; 18:2, s. 126-138
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to analyse the Hybrid III dummy chest loading in heavy vehicle frontal crashes. In total, eight truck front-to-trailer-type sled tests were performed. The Hybrid III, in driver position, was equipped with the chest deflection sensor system RibEye and its standard potentiometer sensor was compared with the RibEye deflection data. The chest impact point was established by using Fuji film impression, as well as from video data. Chest-to-steering wheel rim contact occurred in all tests. Differences in chest loading were found between the Hybrid III dummy reference test and the load case identified in this study, predominantly impact velocity, direction, distribution and location of loading. The steering wheel rim contact is the major contributor to chest deflection. The chest deformation consists of anterior/posterior compression and upward deflection of the sternal plate. The Hybrid III standard chest deflection sensor is not reliable in this load case due to the modes of sternal displacement and the single-point measurement location. Combining the RibEye system with global dummy kinematic data and accurate contact detection is required to fully assess chest deflection. New biomechanical data are needed to adapt the injury risk assessment to the identified load case.
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| 2. |
- Holmqvist, Kristian, 1976, et al.
(författare)
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IMPROVING HYBRID III INJURY ASSESSMENT IN STEERING WHEEL RIM TO CHEST IMPACTS USING RESPONSES FROM FINITE ELEMENT HYBRID III AND HUMAN BODY MODEL
- 2014
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 15:2, s. 196-205
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The main aim of this study was to improve the quality of injury risk assessments in steering wheel rim to chest impacts when using the Hybrid III crash test dummy in frontal heavy goods vehicle (HGV) collision tests. Correction factors for chest injury criteria were calculated as the model chest injury parameter ratios between finite element (FE) Hybrid III, evaluated in relevant load cases, and the Total Human Model for Safety (THUMS). This is proposed to be used to compensate Hybrid III measurements in crash tests where steering wheel rim to chest impacts occur.Methods: The study was conducted in an FE environment using an FE-Hybrid III model and the THUMS. Two impactor shapes were used, a circular hub and a long, thin horizontal bar. Chest impacts at velocities ranging from 3.0 to 6.0m/s were simulated at 3 impact height levels. A ratio between FE-Hybrid III and THUMS chest injury parameters, maximum chest compression C-max, and maximum viscous criterion VCmax, were calculated for the different chest impact conditions to form a set of correction factors. The definition of the correction factor is based on the assumption that the response from a circular hub impact to the middle of the chest is well characterized and that injury risk measures are independent of impact height. The current limits for these chest injury criteria were used as a basis to develop correction factors that compensate for the limitations in biofidelity of the Hybrid III in steering wheel rim to chest impacts.Results: The hub and bar impactors produced considerably higher C-max and VCmax responses in the THUMS compared to the FE-Hybrid III. The correction factor for the responses of the FE-Hybrid III showed that the criteria responses for the bar impactor were consistently overestimated. Ratios based on Hybrid III and THUMS responses provided correction factors for the Hybrid III responses ranging from 0.84 to 0.93. These factors can be used to estimate C-max and VCmax values when the Hybrid III is used in crash tests for which steering wheel rim to chest interaction occurs.Conclusions: For the FE-Hybrid III, bar impacts caused higher chest deflection compared to hub impacts, although the contrary results were obtained with the more humanlike THUMS. Correction factors were developed that can be used to correct the Hybrid III chest responses. Higher injury criteria capping limits for steering wheel impacts are acceptable. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.
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| 3. |
- Shaw, G., et al.
(författare)
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TORSO DEFORMATION IN FRONTAL SLED TESTS: COMPARISION BETWEEN THOR NT, THOR NT WITH THE CHALMERS SD-1 SHOULDER, AND PMHS
- 2010
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Ingår i: International IRCOBI Conference on the Biomechanics of Impact. ; , s. 247-264
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Konferensbidrag (refereegranskat)abstract
- This study compares the thoracic deformation response of the 50th percentile male THOR NTfrontal crash dummy and the response of the THOR modified with the SD-1 shoulder (THOR SD-1)relative to the thoracic response of eight 50th percentile male PMHS. The prototype ChalmersUniversity SD-1 shoulder was designed to be more human-like in terms of geometry and range ofmotion in comparison to the standard THOR NT shoulder. The dummies and PMHS were restrainedby a three-point restraint in a driver-side configuration and were subjected to a simulated 40 km/hfrontal crash. The most prominent difference between the responses of the dummies and PMHSinvolved motion of the lower right anterior ribcage measurement site that is the farthest lateraldistance from the diagonal shoulder belt. During the impact event, this site moved substantiallyanteriorly and away from the spine for the PMHS. The PMHS lower right “bulge out” behavior isbelieved to be caused by inertial loading of the ribcage, underlying organs, and soft tissue overlyingthe torso. The THOR SD-1 shoulder altered the shoulder belt position relative to the thoracicdeflection measurement sites resulting in a different distribution of deformation for the uppermeasurement sites although the average upper site deformation was similar to that recorded for thestandard THOR shoulder.
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| 4. |
- Törnvall, Fredrik, 1975
(författare)
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A New Shoulder for the THOR Dummy Intended for Oblique Collisions
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Offset and oblique frontal car collisions represent a type of crash in which severe and fatal injuries frequently occur. This indicates the importance of having protective systems in vehicles for these types of collisions. Evaluation of such protective systems requires access to crash test dummies that accurately replicate the human body kinematics. The objectives of this research are to develop and evaluate a new shoulder that is anticipated to facilitate the development of safety systems for cars involved in offset and oblique frontal collisions.First, the performance of current frontal impact dummies in oblique impact situations was investigated. Tests were carried out in far-side (away from the shoulder belt anchor) and near-side (towards the shoulder belt anchor) collisions. The Hybrid III dummy did not show human-like head kinematics. The THOR dummy showed human-like head kinematics, but slipped out of the shoulder belt more easily than a post mortem human subject (PMHS) in the 45° far-side collisions. It was found that the THOR shoulder may not be adequately biofidelic.Next, five volunteers and a THOR dummy were tested in a rig where both arms were statically loaded in three directions, forward, diagonally forward-upwards and upwards, while the sternum was supported. The displacement between the right shoulder and the sternum was estimated by means of photo analysis. The THOR dummy was observed to be stiffer and to allow a smaller shoulder range-of-motion then the volunteers. Three belted PMHSs and a THOR dummy were then tested in 0° full-frontal tests, in 45° far-side tests and in 30° near-side tests to study the shoulder and belt-to-shoulder interaction. High-speed video recorded the motions of the test subjects. For the 45° far-side impact, it was concluded that the PMHSs did not slip out of the shoulder belt as easily as the THOR NT did. Further analysis revealed that the geometrical properties of the shoulder bones may be important for the interaction with the shoulder belt in oblique impacts. The response of the human shoulder complex may also influence the head kinematics and thereby head-to-door interaction in oblique near-side collisions.A new mechanical shoulder prototype was developed for the THOR NT dummy, the THOR SD-1NT. Its design was based on results from the volunteer and the first PMHS study. The shoulder design, SD-1, was intended to have bony surface landmarks and a range-of-motion similar to that of a human, to enable improved belt-to-shoulder interaction during a collision. To resemble the human shoulder stiffness during anterior motion, the SD-1 was designed to have a linearly increasing resistance. The THOR SD-1NT was evaluated against the second PMHS study. It is believed that the geometrical properties and bony landmarks of the SD-1 are in accordance with the human anatomy, and that they provide a human-like belt-to-shoulder interaction, especially during oblique impacts. However, the SD-1 needs further tuning, especially the shoulder range-of-motion. Therefore, a second prototype of the shoulder design, SD-2, was built.
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| 5. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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A New THOR Shoulder Design: A Comparison with Volunteers, the Hybrid III and THOR NT
- 2007
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Ingår i: Traffic Injury Prevention. - 1538-957X .- 1538-9588. ; 8:3, s. 211-222
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Tidskriftsartikel (refereegranskat)abstract
- Objective Since the shoulders are rarely seriously injured in frontal or oblique collisions, they have been given low priority in the development of frontal impact crash test dummies. The shoulder complex geometry and its kinematics are of vital importance for the overall dummy kinematics. The shoulder complex also influences the risk of the safety belt slipping off the shoulder in oblique forward collisions. The first aim of this study was to develop a new 50th percentile male THOR shoulder design while the second was to compare the new shoulder, mounted on a THOR NT dummy, with volunteer, THOR NT and Hybrid III range-of-motion and stiffness data. The third aim was to test the repeatability of the new shoulder during dynamic testing and to see how the design behaves with respect to belt slippage in a 45° far-side collision.Methods The new 50th percentile THOR shoulder design was developed with the aid of a shell model of the seated University of Michigan Transportation Research Institute (UMTRI) 50th percentile male with coordinates for joints and bony landmarks (Schneider et al., 1983). The new shoulder design has human-like bony landmarks for the acromion and coracoid processes. The clavicle curvature and length are also made similar to that of a male human, as is the range-of-motion in the anterior-posterior, superior-inferior and medial-lateral directions. The new shoulder design was manufactured and tested under the same conditions that Törnvall et al. (2005b) used to compare the shoulder range-of-motion for the volunteers, Hybrid III and THOR Alpha. The new design was also tested in two dynamic test configurations: the first was a 0° full-frontal test and the second was a 45° far-side test. The dummy tests were conducted with an R-16 seat with a three-point belt, the ΔV was 27.0 ±0.5 km/h and the maximum peak acceleration was approximately 14.6 ±0.5 g for each test.Results A new shoulder design with geometry close to that of humans was developed to be retrofitted to the THOR NT dummy. The results showed that the range-of-motion for the new shoulder complex during static loading was larger by at least a factor of three, for the maximum load (200 N/arm), than that of either the Hybrid III or the THOR NT; this means it was more similar to the volunteers’ range-of-motion. It was observed that the THOR NT with the new shoulder did not slide out of the shoulder-belt during a far-side collision. The performance of the new shoulder was reasonably repeatable and stable during both the static tests and the sled tests.Conclusions A new shoulder for the THOR NT has been designed and developed, and data from static range-of-motion tests and sled tests indicate that the new shoulder complex has the potential to function in a more human-like manner on the THOR dummy.
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| 6. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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A New THOR Shoulder Design: Its Range-of-Motion in Comparison with Volunteers, the Hybrid III and THOR NT
- 2006
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Ingår i: International IRCOBI Conference on the Biomechanics of Impact. ; , s. 409-412
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Konferensbidrag (refereegranskat)abstract
- There is a need for dummies that mimic crash victims kinematics in oblique and offset frontal collisions. Improved seatbelt-to-dummy interaction in crash testing is also desirable. Hence, a new THOR shoulder was developed and evaluated in comparison with volunteers, the Hybrid III and THOR NT shoulder range-of-motion. The new shoulder has human-like bony landmarks, clavicle curvature and length, and joints. The evaluation showed that the range-of-motion for the static loading of the new shoulder was similar to that of the volunteers. This was not so for the Hybrid III and THOR NT. The data indicates that the new shoulder design can provide more human-like shoulder motions in a crash test.
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| 7. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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Comparison of Shoulder Range-of-Motion and Stiffness between Volunteers, Hybrid III and THOR Alpha in Static Frontal Impact Loading
- 2005
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Ingår i: International Journal of Crashworthiness. - : Informa UK Limited. - 1358-8265 .- 1754-2111. ; 10:2, s. 151-160
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare the shoulder range-of-motion and stiffness between volunteers and 50th percentile dummies in static loading conditions simulating frontal collisions. Five volunteers a Hybrid III and a THOR Alpha were positioned in a test rig where both arms were statically loaded in the forward-upward direction at 90°, 135° and 170° angles while the sternum was supported. The distances between right shoulders and sternums were estimated by means of photo analysis. The photo analysis showed that the volunteers’ range-of-motion was at least three times larger for the maximum load (200 N/arm) than those of the Hybrid III and the THOR Alpha. The results indicate that the biofidelity of the dummies used today in full-frontal, oblique and offset frontal collisions may be improved by redesigned shoulder complexes. The dummies would then better predict the human kinematics and the loading of the chest by various restraint systems.
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| 8. |
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| 9. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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EVALUATION OF DUMMY SHOULDER KINEMATICS IN OBLIQUE FRONTAL COLLISIONS
- 2008
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Ingår i: IRCOBI. - 9783033015807 ; , s. 195-210
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Konferensbidrag (refereegranskat)abstract
- The present study evaluates shoulder kinematics of the Hybrid III and THOR NT, with the firstversion of a new shoulder design (SD-1), in 45° far-side, full frontal and 30° near-side collisions. Intotal eleven dummy tests were conducted in the three collision angles, while film and instrument datawere generated and compared with those of PMHS data from Törnvall (2008). For the 45° far-sideimpact, the THOR SD-1NT dummy retained the shoulder belt on the shoulder during on-loading, as didthe PMHSs, whereas the THOR NT did not. In the 30° near-side impact,
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| 10. |
- Törnvall, Fredrik, 1975
(författare)
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Evaluation of Shoulder-Complex Motion in Frontal and Oblique Impact Loadings - A Comparison between Frontal Impact Dummies and the Human Body
- 2004
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Offset and angled frontal impacts represent a crash type that is more common than full-frontal collisions. Several studies have shown that over 70% of all frontal impacts are offset or oblique. These studies thus indicate the importance of having crash tests representing offset and oblique frontal collisions so that protective systems may be evaluated that offer offset or oblique occupant protection. The evaluation of such protective systems requires access to biofidelic crash test dummies that accurately replicate the human body motion in frontal impacts with oblique dummy loadings. This thesis investigates how the performance of todays 50th percentile male frontal impact dummies may be improved in oblique collisions with oblique frontal occupant motions.In the first part of this thesis the kinematics of the 50th percentile male frontal impact dummies, Hybrid III, THOR 99 and THOR Alpha, were compared with corresponding kinematics of PMHS in oblique crash tests. The PMHS data included results from oblique frontal, near side (the occupant moves into the shoulder belt anchor) and far side (the occupant moves away from the shoulder belt anchor), sled tests at 15°, 30° and 45° angles. The test subjects were belted with three-point belts and the impact speed was 30 km/h. The results indicated that the frontal impact dummies slipped out of the shoulder belts more easily than the PMHS. This was mainly an effect of stiffer shoulder complexes than those of the PMHS.The results from the first part of this thesis was the foundation of the second part were the shoulder range-of-motion and resistance of motion i.e. stiffness was compared between volunteers and that of the 50th percentile male frontal impact dummies, Hybrid III and THOR Alpha. The test conditions were in static loading conditions simulating frontal collisions. Five volunteers, a Hybrid III and a THOR Alpha were positioned in a test rig where both arms were loaded statically in the forward-upward direction at 90, 135 and 170 angles while sternum was supported. The results showed that the volunteers motions are at least three times larger for the maximum load (200 N/arm) than those of the Hybrid III and the THOR Alpha.The results in this study indicate that the biofidelity of the dummies used today in full-frontal, oblique and offset frontal collisions may be improved by redesigned shoulder complexes. The dummies should then better predict human head and T1 kinematics, and load distribution of the chest.
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| 11. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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Frontal Impact Dummy Kinematics in Oblique Frontal Collisions: Evaluation against Post Mortem Human Subject Test Data
- 2005
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Ingår i: Traffic Injury Prevention. - 1538-957X .- 1538-9588. ; 6:4, s. 340-350
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Tidskriftsartikel (refereegranskat)abstract
- Objective Today, a predominant percentage of vehicles involved in car crashes are exposed to oblique or frontal offset collisions. The aim of this study is to evaluate the 50th percentile male Hybrid III, THOR 99 and THOR Alpha dummies by comparing them with the corresponding kinematics of post mortem human subjects (PMHS) in this type of collision.Methods The PMHS data include results from oblique frontal collision tests. They include sled tests with near-side and far-side belt geometries at 15°, 30° and 45° angles. The test subjects were restrained with a three-point lap-shoulder belt and the ?V was 30 km/h.Results The results from the Hybrid III and THOR 99 tests showed that, in most of the test, the head trajectories were an average of approximately 0.1 m shorter than those from equivalent PMHS. The Hybrid III and THOR 99 far-side belt geometry tests showed that the belt remained in place longer on the shoulder of the Hybrid III than on the THOR 99 and the THOR Alpha. This was probably due to a stiffer lumbar spine in the Hybrid III and to a large groove in the steel of the superior surface of the Hybrid III shoulder structure. The THOR 99 escaped from the shoulder belt about 40 - 50 ms earlier than the THOR Alpha. The results from the THOR Alpha tests show that the head trajectory accorded fairly well with the PMHS data, as long as the shoulder belt did not slip off the shoulder. Although the THOR Alpha shoulder escaped the shoulder belt in the 45° far-side belt geometry, the PMHS did not. This may be due to the THOR Alpha shoulder design, with approximately 0.05 m smaller superior and medial shoulder range-of-motion, in combination with a relatively soft lumbar spine.Conclusions The THOR Alpha provides head trajectories similar to those of the PMHS under these loading conditions, provided the shoulder belt remains in position on the shoulder. When the shoulder belt slipped off the dummy shoulder, the head kinematics was altered. The shoulder range-of-motion may be a contributing factor to the overall kinematics of an occupant in oblique frontal impact situations where the occupant moves in a trajectory at an angle from that of the longitudinal direction of the car.
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| 12. |
- Östh, Jonas, 1983, et al.
(författare)
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Muscle Activation Strategies in Human Body Models for the Development of Integrated Safety
- 2015
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Ingår i: The 24th ESV Conference Proceedings.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Human Body Models (HBMs) have been used in crash safety research for some time, and are now emerging as tools for the development of restraints systems. One important challenge in the development of advanced restraint systems is to integrate sensory information about the pre-crash phase (time to collision, impact speed and direction, occupant position) to alter restraint activation parameters. Restraint activation can begin even before the beginning of an impact, providing additional time to reposition or restrain the occupant. However, any such pre-crash intervention would invoke a muscle response that needs to be taken into account in HBMs used in simulation of integrated restraints. The objective of this paper is to provide an update on state-of-the-art modeling techniques for active musculature in HBMs. Examples of applications are presented, to illustrate future challenges in modeling of car occupants muscle responses to restraint activation.The most common approach for modeling active muscle force in HBMs is to use Hill-type models, in which the force produced is a function of muscle length, shortening velocity, and activation level. Active musculature was first implemented in cervical spine models. These models were applied to study occupant kinematic responses and injury outcome in rear-end, lateral, and frontal impacts; it was found that active musculature is essential for studying the response of the cervical spine. One approach utilized to represent muscle activity in HBMs is to use experimentally recorded muscle activities or activity levels acquired through inverse optimization in open-loop. More recently, in order to represent car occupant muscle responses in pre-crash situations, closed-loop control has been implemented for multibody and finite element HBMs, allowing the models to maintain their posture and simulate reflexive responses. Studies with these models showed that in addition to feedback control, anticipatory postural responses needs to be included to represent driver actions such as voluntary braking. Current HBMs have the capacity to model (utilizing closed-loop control) active muscle responses of car occupants in longitudinal pre-crash events. However, models have only been validated for limited sets of data since as high quality volunteer data, although it exists, is scarce. Omni-directional muscle responses have been implemented to some extent, but biofidelity of the simulated muscle activation schemes has not been assessed. Additional experimental volunteer muscle activity measurements (with normalized electromyogram recordings) in complex 3D-loading scenarios are needed for validation and to investigate how muscle recruitment depends on occupant awareness and varies between individuals. Further model development and validation of muscle activations schemes are necessary, for instance startle responses, and individual muscle control. This could improve assessment of restraint performance in complex accident scenarios, such as multiple impacts, far-side impacts and roll-over situations.
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