Pub Date : 2012-05-21DOI: 10.1109/APEMC.2012.6237855
Xuequan Yu, Yadong Bai, Yan Zhou, Wei Bai, Lin Yang, J. Min
With the ever-increasing of the speed of the integrated circuit (IC), more and more electromagnetic interference (EMI) problems have been introduced by the high-speed IC. In real engineering applications, the pin map is often employed for the high-speed IC package to reduce such EMI radiation. In this paper, firstly, we propose a simple equivalent antenna model for a 5 Gbps high-speed IC package. After that, we perform the optimization of the pin map of that package, and finally compare the shielding performance of packages before and after the optimization. To validate the proposed equivalent model and the optimization results, we design and fabricate a series of experimental boards with different pin maps, and then compare the measurement results of the radiated fields at three meter distance and the return loss before and after the optimization. We also study the radiation pattern of the package. Through the comparison between the simulation results and measurement results, the accuracy of the proposed equivalent antenna model is validated. Both the simulation and measurement results show that the pin map plays an important role to eliminate the patch antenna effect of the package, thereby greatly affects the package EMI.
{"title":"EMI study of high-speed IC package based on pin map","authors":"Xuequan Yu, Yadong Bai, Yan Zhou, Wei Bai, Lin Yang, J. Min","doi":"10.1109/APEMC.2012.6237855","DOIUrl":"https://doi.org/10.1109/APEMC.2012.6237855","url":null,"abstract":"With the ever-increasing of the speed of the integrated circuit (IC), more and more electromagnetic interference (EMI) problems have been introduced by the high-speed IC. In real engineering applications, the pin map is often employed for the high-speed IC package to reduce such EMI radiation. In this paper, firstly, we propose a simple equivalent antenna model for a 5 Gbps high-speed IC package. After that, we perform the optimization of the pin map of that package, and finally compare the shielding performance of packages before and after the optimization. To validate the proposed equivalent model and the optimization results, we design and fabricate a series of experimental boards with different pin maps, and then compare the measurement results of the radiated fields at three meter distance and the return loss before and after the optimization. We also study the radiation pattern of the package. Through the comparison between the simulation results and measurement results, the accuracy of the proposed equivalent antenna model is validated. Both the simulation and measurement results show that the pin map plays an important role to eliminate the patch antenna effect of the package, thereby greatly affects the package EMI.","PeriodicalId":300639,"journal":{"name":"2012 Asia-Pacific Symposium on Electromagnetic Compatibility","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131826566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-21DOI: 10.1109/APEMC.2012.6237891
B. Ravelo, A. Jastrzebski
In this paper, a microwave negative group delay (NGD) circuit topology comprised of a microwave amplifier associated with RLC-series resonant network operating at RF/microwave frequencies is investigated. The theoretical approach illustrating the functioning of the NGD circuit proposed is established by considering the amplifier S-parameters. To demonstrate the relevance of the concept, a device exhibiting NGD function around 1.25 GHz was designed and investigated. A method of resonating RLC-disturbance correction is proposed. A validation showing the neutralization of the transmission gain and group delay is proposed.
{"title":"NGD circuit using a microwave amplifier for the signal integrity improvement","authors":"B. Ravelo, A. Jastrzebski","doi":"10.1109/APEMC.2012.6237891","DOIUrl":"https://doi.org/10.1109/APEMC.2012.6237891","url":null,"abstract":"In this paper, a microwave negative group delay (NGD) circuit topology comprised of a microwave amplifier associated with RLC-series resonant network operating at RF/microwave frequencies is investigated. The theoretical approach illustrating the functioning of the NGD circuit proposed is established by considering the amplifier S-parameters. To demonstrate the relevance of the concept, a device exhibiting NGD function around 1.25 GHz was designed and investigated. A method of resonating RLC-disturbance correction is proposed. A validation showing the neutralization of the transmission gain and group delay is proposed.","PeriodicalId":300639,"journal":{"name":"2012 Asia-Pacific Symposium on Electromagnetic Compatibility","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133974195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-21DOI: 10.1109/APEMC.2012.6237990
L. Hou, Shu Bai, Jinhui Wang, Xiaohong Peng, Shuqin Geng
In this paper, a signal integrity aware TSV positioning method (SITP) is introduced. Grounded TSV proved to help eliminating TSV-to-TSV coupling. A trench based 3D IC placement method is developed, transforming 2D placement into 3D placement and perform signal TSV placement with flexible grounded TSV Insertion. IBM placement benchmark is used for original 2D placement. By evaluating wire-length and runtime, SITP automatically achieve high performance 3D IC placement with considerable TSV-TSV interference elimination.
{"title":"Signal integrity aware TSV positioning","authors":"L. Hou, Shu Bai, Jinhui Wang, Xiaohong Peng, Shuqin Geng","doi":"10.1109/APEMC.2012.6237990","DOIUrl":"https://doi.org/10.1109/APEMC.2012.6237990","url":null,"abstract":"In this paper, a signal integrity aware TSV positioning method (SITP) is introduced. Grounded TSV proved to help eliminating TSV-to-TSV coupling. A trench based 3D IC placement method is developed, transforming 2D placement into 3D placement and perform signal TSV placement with flexible grounded TSV Insertion. IBM placement benchmark is used for original 2D placement. By evaluating wire-length and runtime, SITP automatically achieve high performance 3D IC placement with considerable TSV-TSV interference elimination.","PeriodicalId":300639,"journal":{"name":"2012 Asia-Pacific Symposium on Electromagnetic Compatibility","volume":"250 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113995310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-21DOI: 10.1109/APEMC.2012.6237901
M. Coenen, A. V. van Roermund
In IEC CISPR 16-4-2 [1, 2] tight impedance requirements are given for artificial mains networks (AMN). Unfortunately, these tight requirements will support measurement uncertainty but still not guarantee low compliance uncertainty if the whole test set-up, up to the port of the equipment being tested, is not taken into account. In this paper the impact of the design of the AMN as well as the mains cable used is evaluated. Incorrect cascading of typical AMN elements: impedance stabilizing network, attenuator(s), high-pass filters and impulse limiter results in erroneous findings which affect measurement uncertainty. Introduction of impedance requirements on the mains cable used enhances the compliance uncertainty by 20 dB, which is demonstrated by simulations and measurements.
{"title":"Reducing compliance uncertainty with AMN measurements","authors":"M. Coenen, A. V. van Roermund","doi":"10.1109/APEMC.2012.6237901","DOIUrl":"https://doi.org/10.1109/APEMC.2012.6237901","url":null,"abstract":"In IEC CISPR 16-4-2 [1, 2] tight impedance requirements are given for artificial mains networks (AMN). Unfortunately, these tight requirements will support measurement uncertainty but still not guarantee low compliance uncertainty if the whole test set-up, up to the port of the equipment being tested, is not taken into account. In this paper the impact of the design of the AMN as well as the mains cable used is evaluated. Incorrect cascading of typical AMN elements: impedance stabilizing network, attenuator(s), high-pass filters and impulse limiter results in erroneous findings which affect measurement uncertainty. Introduction of impedance requirements on the mains cable used enhances the compliance uncertainty by 20 dB, which is demonstrated by simulations and measurements.","PeriodicalId":300639,"journal":{"name":"2012 Asia-Pacific Symposium on Electromagnetic Compatibility","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123902635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-21DOI: 10.1109/APEMC.2012.6237921
Jian Wang, Qing-Qing Zhang, W. Yin
Shielding effectiveness and inner resonance of metallic frustum cone-like cabins illuminated by an intentional EMP are studied in this paper, with one coaxial feeding monopole antenna and some parallel slots on the cabin wall also considered. In our numerical simulations, hybrid FDTD method, integrated with surface mesh model, equivalent coaxial feed model, and thin wire model, are all implemented for handling such a complex three-dimensional (3-D) composite structure. Parametric studies are further carried out to show the shielding effectiveness and inner field resonance characteristics of the cabins with different geometries and the incident IEMP with different directions and polarizations.
{"title":"Characterization of shielding effectiveness of metallic frustum cone-like cabin with one coaxial feeding monopole antenna illuminated by a HEMP","authors":"Jian Wang, Qing-Qing Zhang, W. Yin","doi":"10.1109/APEMC.2012.6237921","DOIUrl":"https://doi.org/10.1109/APEMC.2012.6237921","url":null,"abstract":"Shielding effectiveness and inner resonance of metallic frustum cone-like cabins illuminated by an intentional EMP are studied in this paper, with one coaxial feeding monopole antenna and some parallel slots on the cabin wall also considered. In our numerical simulations, hybrid FDTD method, integrated with surface mesh model, equivalent coaxial feed model, and thin wire model, are all implemented for handling such a complex three-dimensional (3-D) composite structure. Parametric studies are further carried out to show the shielding effectiveness and inner field resonance characteristics of the cabins with different geometries and the incident IEMP with different directions and polarizations.","PeriodicalId":300639,"journal":{"name":"2012 Asia-Pacific Symposium on Electromagnetic Compatibility","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127727080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-21DOI: 10.1109/APEMC.2012.6237953
T. Thosdeekoraphat, C. Thongsopa
In this paper, the effect of cylindrical shield to heating area and location of induction heating for breast cancer hyperthermia treatment with hyperthermia inductive heating are presented. To determine heat distribution in the breast, which electric loss density is analyzed for various aperture sizes and radius of shielded cylindrical. It is a technique to control magnetic field intensity and relocate the heating area by using a cylindrical metal shielding with aperture. In the simulation, the inductive applicator is a ferrite core with diameter of 7 cm and excited by 4 MHz signal. The simulations show that the heating area can be effectively controlled by using the cylindrical shield with adjustable aperture size. The heating efficiency is reduced as the aperture size decreases. If the small heating area is needed, it may require longer treatment time. Nevertheless, the efficiency of heat can be increased by varying the radius size of shielding plate. Moreover, we investigate the position of heating region by varying the orientation of the ferrite core in x direction. The effect of horizontal position of the ferrite core to the heating location is also studied. Simulations show that the heating position can be relocated by changing the orientation of the ferrite core with cylindrical shield. The advantage of the magnetic shielding system is that it can be used to applied for prevent the effects of hyperthermia cancer treatment by induction heating.
{"title":"Development of magnetic shielding system for breast hyperthermia inductive heating","authors":"T. Thosdeekoraphat, C. Thongsopa","doi":"10.1109/APEMC.2012.6237953","DOIUrl":"https://doi.org/10.1109/APEMC.2012.6237953","url":null,"abstract":"In this paper, the effect of cylindrical shield to heating area and location of induction heating for breast cancer hyperthermia treatment with hyperthermia inductive heating are presented. To determine heat distribution in the breast, which electric loss density is analyzed for various aperture sizes and radius of shielded cylindrical. It is a technique to control magnetic field intensity and relocate the heating area by using a cylindrical metal shielding with aperture. In the simulation, the inductive applicator is a ferrite core with diameter of 7 cm and excited by 4 MHz signal. The simulations show that the heating area can be effectively controlled by using the cylindrical shield with adjustable aperture size. The heating efficiency is reduced as the aperture size decreases. If the small heating area is needed, it may require longer treatment time. Nevertheless, the efficiency of heat can be increased by varying the radius size of shielding plate. Moreover, we investigate the position of heating region by varying the orientation of the ferrite core in x direction. The effect of horizontal position of the ferrite core to the heating location is also studied. Simulations show that the heating position can be relocated by changing the orientation of the ferrite core with cylindrical shield. The advantage of the magnetic shielding system is that it can be used to applied for prevent the effects of hyperthermia cancer treatment by induction heating.","PeriodicalId":300639,"journal":{"name":"2012 Asia-Pacific Symposium on Electromagnetic Compatibility","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115964577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-21DOI: 10.1109/APEMC.2012.6237970
A. Engin, J. Bowman
Today; with both RF and digital devices using the same voltage source on a PCB, power filtering is needed more than ever to isolate the noise between these two types of devices for proper operation. Especially the power/ground planes in packages or boards can be a major factor for noise coupling. Simultaneously switching drivers cause supply voltage fluctuations which can propagate both horizontally and vertically between the power/ground planes. The sensitive RF/analog signals have to be isolated from this digital switching noise, which gets coupled through the shared power distribution system. Hence, accurate estimation and improvement of the performance of power/ground planes is critical in a mixed-signal system. This paper introduces a new methodology to minimize the transfer impedance of the power distribution system. This will be achieved by a new design methodology, which we will call the virtual ground fence. At its basic level, the virtual ground fence consists of quarter-wave transmission-line stubs that act as short circuits between power and ground planes at their design frequency. An array of such stubs can then be considered as a ground fence. Power filtering is currently achieved mainly by using discrete decoupling capacitors at low frequencies. The virtual ground fence design is the distributed analog of this methodology at GHz frequency regime.
{"title":"Virtual ground fence: A methodology for GHz power filtering on printed circuit boards","authors":"A. Engin, J. Bowman","doi":"10.1109/APEMC.2012.6237970","DOIUrl":"https://doi.org/10.1109/APEMC.2012.6237970","url":null,"abstract":"Today; with both RF and digital devices using the same voltage source on a PCB, power filtering is needed more than ever to isolate the noise between these two types of devices for proper operation. Especially the power/ground planes in packages or boards can be a major factor for noise coupling. Simultaneously switching drivers cause supply voltage fluctuations which can propagate both horizontally and vertically between the power/ground planes. The sensitive RF/analog signals have to be isolated from this digital switching noise, which gets coupled through the shared power distribution system. Hence, accurate estimation and improvement of the performance of power/ground planes is critical in a mixed-signal system. This paper introduces a new methodology to minimize the transfer impedance of the power distribution system. This will be achieved by a new design methodology, which we will call the virtual ground fence. At its basic level, the virtual ground fence consists of quarter-wave transmission-line stubs that act as short circuits between power and ground planes at their design frequency. An array of such stubs can then be considered as a ground fence. Power filtering is currently achieved mainly by using discrete decoupling capacitors at low frequencies. The virtual ground fence design is the distributed analog of this methodology at GHz frequency regime.","PeriodicalId":300639,"journal":{"name":"2012 Asia-Pacific Symposium on Electromagnetic Compatibility","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114124328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-21DOI: 10.1109/APEMC.2012.6237908
S. Kwak, J. Jo, Seok-Ho Noh, HyeSook Lee, W. Nah, Soyoung Kim
This paper shows a novel simulation method for bulk current injection (BCI) tests of I/O buffer circuits of mobile system memory. The simulation model consists of BCI probe, directional coupler, PCB, PKG, and IC. The proposed method is based on a behavioural I/O buffer model using a pulse generator as an input. A detailed simulation flow is introduced and validated through simulations performed on several injection probe loading conditions using a power decoupling capacitor and an on-chip decoupling capacitor.
{"title":"Bulk current injection test modeling using an equivalent circuit for 1.8V mobile ICs","authors":"S. Kwak, J. Jo, Seok-Ho Noh, HyeSook Lee, W. Nah, Soyoung Kim","doi":"10.1109/APEMC.2012.6237908","DOIUrl":"https://doi.org/10.1109/APEMC.2012.6237908","url":null,"abstract":"This paper shows a novel simulation method for bulk current injection (BCI) tests of I/O buffer circuits of mobile system memory. The simulation model consists of BCI probe, directional coupler, PCB, PKG, and IC. The proposed method is based on a behavioural I/O buffer model using a pulse generator as an input. A detailed simulation flow is introduced and validated through simulations performed on several injection probe loading conditions using a power decoupling capacitor and an on-chip decoupling capacitor.","PeriodicalId":300639,"journal":{"name":"2012 Asia-Pacific Symposium on Electromagnetic Compatibility","volume":"169 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121615655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-21DOI: 10.1109/APEMC.2012.6237798
Zhao Yang, D. Su, Yan Liu, X. Gao
This paper proposes a novel testing method for the electromagnetic interference source identification. In this method, the test scheme is based on the uniform design principles, after redesign for the radiated emission devices, the validation data from the tests shows that the problems are basically solved. Compared to the previous one-to-one investigation for interference diagnostic tests, the effect of this method is remarkable.
{"title":"A novel electromagnetic interference source identification method","authors":"Zhao Yang, D. Su, Yan Liu, X. Gao","doi":"10.1109/APEMC.2012.6237798","DOIUrl":"https://doi.org/10.1109/APEMC.2012.6237798","url":null,"abstract":"This paper proposes a novel testing method for the electromagnetic interference source identification. In this method, the test scheme is based on the uniform design principles, after redesign for the radiated emission devices, the validation data from the tests shows that the problems are basically solved. Compared to the previous one-to-one investigation for interference diagnostic tests, the effect of this method is remarkable.","PeriodicalId":300639,"journal":{"name":"2012 Asia-Pacific Symposium on Electromagnetic Compatibility","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126451049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-21DOI: 10.1109/APEMC.2012.6237949
K. H. Kwan, K. T. Tan, P. L. So
This paper reports the integration of a hybrid system that consist of a proton exchange membrane fuel cell (PEMFC) and an ultra-capacitor (UC) with the UPQC. Apart from performing load sharing with the grid, the overall UPQC is able to handle a wide range of power quality (PQ) problems; thus enhancing the functions of the UPQC and ensures higher network availability, reliability and stability. The UPQC is controlled by the Model Predictive Control (MPC), which has the capability to handle hard constraints. Illustrative examples to demonstrate the robustness and performance of the UPQC with the hybrid system are presented. The proposed hybrid system is generic in nature and can be used with other UPQCs to enhance their performance and capabilities.
{"title":"An unified power quality conditioner for load sharing and power quality improvement","authors":"K. H. Kwan, K. T. Tan, P. L. So","doi":"10.1109/APEMC.2012.6237949","DOIUrl":"https://doi.org/10.1109/APEMC.2012.6237949","url":null,"abstract":"This paper reports the integration of a hybrid system that consist of a proton exchange membrane fuel cell (PEMFC) and an ultra-capacitor (UC) with the UPQC. Apart from performing load sharing with the grid, the overall UPQC is able to handle a wide range of power quality (PQ) problems; thus enhancing the functions of the UPQC and ensures higher network availability, reliability and stability. The UPQC is controlled by the Model Predictive Control (MPC), which has the capability to handle hard constraints. Illustrative examples to demonstrate the robustness and performance of the UPQC with the hybrid system are presented. The proposed hybrid system is generic in nature and can be used with other UPQCs to enhance their performance and capabilities.","PeriodicalId":300639,"journal":{"name":"2012 Asia-Pacific Symposium on Electromagnetic Compatibility","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130459187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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