The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Claes Lauritzen - One of the best experts on this subject based on the ideXlab platform.
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spring mediated cranioplasty compared with the modified pi plasty for sagittal synostosis
Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery, 2003Co-Authors: Jose Guimaraesferreira, Fredrik Gewalli, Lisa R. David, Robert Olsson, Hans Friede, Claes LauritzenAbstract:The aim of this study was to compare the safety, morphological outcome, and degree of parental satisfaction of the new spring-mediated cranioplasty with those of the modified pi-plasty in the management of sagittal synostosis. Ten patients with non-syndromic sagittal synostosis treated with the spring-mediated cranioplasty were followed prospectively. A control group of 10 sex-matched patients operated on with the modified pi-plasty procedure was chosen. Cephalometric radiographs were obtained preoperatively and postoperatively at 1 year of age. Cephalic index, Axial Width ratio, length ratio, Width ratio and height ratio were used as objective measures of outcome. Parents were sent a questionnaire to obtain a subjective aesthetic assessment of outcome. Significantly less blood replacement was required (p = 0.003), and shorter duration of postoperative anaesthesia (p = 0.030) and postoperative hospital stay (p = 0.013) were found in the spring-mediated cranioplasty group. There were no complications or deaths in either group. Also significant was the inter-group difference in the postoperative change in the height ratio (p = 0.030), the most change being seen in the spring group. The change in the subjective parental aesthetic evaluation of skull shape was significant in both groups. In conclusion, the spring-mediated procedure was morphologically more effective than the modified pi-plasty procedure in the management of sagittal synostosis with the additional benefits of less blood transfusion needed and shorter duration of hospital stay.
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spring mediated cranioplasty compared with the modified pi plasty for sagittal synostosis
Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery, 2003Co-Authors: Jose Guimaraesferreira, Fredrik Gewalli, Lisa R. David, Robert Olsson, Hans Friede, Claes LauritzenAbstract:The aim of this study was to compare the safety, morphological outcome, and degree of parental satisfaction of the new spring-mediated cranioplasty with those of the modified pi-plasty in the management of sagittal synostosis. Ten patients with non-syndromic sagittal synostosis treated with the spring-mediated cranioplasty were followed prospectively. A control group of 10 sex-matched patients operated on with the modified pi-plasty procedure was chosen. Cephalometric radiographs were obtained preoperatively and postoperatively at 1 year of age. Cephalic index, Axial Width ratio, length ratio, Width ratio and height ratio were used as objective measures of outcome. Parents were sent a questionnaire to obtain a subjective aesthetic assessment of outcome. Significantly less blood replacement was required (p = 0.003), and shorter duration of postoperative anaesthesia (p = 0.030) and postoperative hospital stay (p = 0.013) were found in the spring-mediated cranioplasty group. There were no complications or de...
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Clinical outcome of the modified pi-plasty procedure for sagittal synostosis.
The Journal of craniofacial surgery, 2001Co-Authors: José Guimarães-ferreira, Fredrik Gewalli, Lisa R. David, Robert Olsson, Hans Friede, Claes LauritzenAbstract:The aim of the study was to evaluate the modified pi-plasty procedure for the treatment of sagittal synostosis, assessing the issues of safety, complications, morphological outcome, and degree of parental satisfaction. A retrospective evaluation of 110 patients with nonsyndromal single suture sagittal synostosis operated on with the modified pi-plasty procedure was undertaken. Cephalometric radiographs were obtained preoperatively and postoperatively at ages 3 and 5 years in three standardized projections. The Cephalic Index and the Axial Width Ratio were determined and used as objective outcome measures. An evaluation of the radiographic digital markings was carried out using a Beaten Copper Score. A parental questionnaire was used to obtain a subjective esthetical outcome assessment. The patient population consisted of 76% boys and 24% girls with a 20% incidence of a positive familial history of craniosynostosis. The mean age at surgery was 7.73 months. Morbidity from the procedure was minimal and there were no mortalities. The Cephalic Index changed from a mean preoperative value of 65% to a postoperative mean value of 72% (P = 0.00004). The mean Axial Width Ratio changed from a preoperative 80% to 72% at the 3-year evaluation (P = 0.00029). The Beaten Copper score changed from a mean preoperative value of 2.35 to 5.42 postoperatively at 3 years (P = 0.00001). The response rate to the questionnaire was 86%, and there were significant postoperative improvements in all studied aspects of the skull shape. The modified pi-plasty is a safe technique, and it induces significant objective changes in skull morphology toward normality. It also yields a high degree of parental satisfaction with regard to aesthetic outcome, as evaluated by a written questionnaire.
Muhammad Ilham - One of the best experts on this subject based on the ideXlab platform.
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comparison of uranium plutonium nitride u pu n and thorium nitride th n fuel for 500 mwth gas cooled fast reactor gfr long life without refueling
International Journal of Energy Research, 2018Co-Authors: Ratna Dewi Syarifah, Dwi Irwanto, Khairul Basar, Zaki Suud, Sandro Clief Pattipawaej, Muhammad IlhamAbstract:Summary Comparison of uranium plutonium nitride and thorium nitride fuel for 500 MWth gas-cooled fast reactor has been done. Gas-cooled fast reactor is one type of generation IV reactor that can be operated in high temperature. Due to the high temperature, it can be used in hydrogen production. In this study, we compare the neutronic analysis of two fuel types, ie, uranium nitride fuel (U,Pu)N and thorium nitride fuel (Th,U233)N. The neutronic calculation uses SRAC2006 code system, and the data libraries use JENDL4.0. First, the fuel pin calculation (PIJ calculation) has been done to take the macro data that are used in CITATION calculation. Both uranium and thorium fuel use heterogeneous configuration with 3 variation fuel in the core. F1 is located in the central core, F2 middle core, and F3 outer core. The variation of fuel fraction is 40% until 65%, cladding 10%, and coolant 25% until 40%. For (U,Pu)N fuel, the diameter of the active core is 220 cm, and the height of the active core is 110 cm. And for (Th,U233)N, the diameter of the active core is 250 cm and the height of the active core is 150 cm. The reflector radial-Axial Width is 50 cm. For uranium plutonium nitride fuel, the type of the fuel in one core is varied; ie, F1 is 8%, F2 is 10%, and F3 is 12%. For thorium nitride fuel, the type of the fuel in one core also varied; ie, F1 is 7.8%, F2 is 8%, and F3 is 8.8%. The optimum value of thorium nitride is when fuel fraction of region F1 = 60%, F2 = 57.5%, F3 = 60%, the burn up time up to 20 years without refueling, max k-eff value is 1.0109, and max excess reactivity value is 1.08%. Neutronic analysis shows that both uranium and thorium fuel have excess reactivity value less than 2% but thorium fuel has excess reactivity less than uranium nitride fuel. Uranium fuel has better breeding capability than thorium fuel. Therefore, it is better to use uranium fuel for fast reactor like GFR, which has high breeding capability.
Ratna Dewi Syarifah - One of the best experts on this subject based on the ideXlab platform.
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Performance of Thorium Uranium Nitride (Th, U233)N Fuel for 500 MWth GFR Long-Life Without Refuelling use FIITB-CHI Code
Journal of Physics: Conference Series, 2019Co-Authors: Ratna Dewi Syarifah, Zaki Su’ud, Khairul Basar, Dwi IrwantoAbstract:Performance of Thorium Uranium Nitride Fuel for 500 MWth GFR Long-Life Without Refueling use FI-ITB-CHI code has been done. Gas Cooled Fast Reactor use fast neutron spectrum, and belong to one of fast breeder reactor type. Thorium is three up to four times more abundant than uranium and is widely distributed in nature can be obtained in many countries. Natural thorium does not contain any fissile material and is made up of the fertile Th- 232 isotope only. Thorium fuel and fuel cycles are particularly relevant to countries having large thorium like Indonesia. The calculation use FI-ITB-CHI Code which has been verified by SLAROM code. The core calculation use R-Z geometry dimensional. The multi group diffusion calculation is carried out every year to get neutron flux distribution and power distribution. Then burn up calculation is carried out for each spatial mesh. The reflector radial-Axial Width is 50 cm. Parametric survey with various percentage of plutonium show the critical condition reach when 11% percentage of Pu and 60% fuel volume fraction. When the fuel volume fraction is increase, the reactor can be operated longer. The optimum value of heterogeneous core configuration when use 8% percentage of plutonium for F1, 10% for F2 and 14% for F3. The reactor can be operated almost 25 years without refueling.
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comparison of uranium plutonium nitride u pu n and thorium nitride th n fuel for 500 mwth gas cooled fast reactor gfr long life without refueling
International Journal of Energy Research, 2018Co-Authors: Ratna Dewi Syarifah, Dwi Irwanto, Khairul Basar, Zaki Suud, Sandro Clief Pattipawaej, Muhammad IlhamAbstract:Summary Comparison of uranium plutonium nitride and thorium nitride fuel for 500 MWth gas-cooled fast reactor has been done. Gas-cooled fast reactor is one type of generation IV reactor that can be operated in high temperature. Due to the high temperature, it can be used in hydrogen production. In this study, we compare the neutronic analysis of two fuel types, ie, uranium nitride fuel (U,Pu)N and thorium nitride fuel (Th,U233)N. The neutronic calculation uses SRAC2006 code system, and the data libraries use JENDL4.0. First, the fuel pin calculation (PIJ calculation) has been done to take the macro data that are used in CITATION calculation. Both uranium and thorium fuel use heterogeneous configuration with 3 variation fuel in the core. F1 is located in the central core, F2 middle core, and F3 outer core. The variation of fuel fraction is 40% until 65%, cladding 10%, and coolant 25% until 40%. For (U,Pu)N fuel, the diameter of the active core is 220 cm, and the height of the active core is 110 cm. And for (Th,U233)N, the diameter of the active core is 250 cm and the height of the active core is 150 cm. The reflector radial-Axial Width is 50 cm. For uranium plutonium nitride fuel, the type of the fuel in one core is varied; ie, F1 is 8%, F2 is 10%, and F3 is 12%. For thorium nitride fuel, the type of the fuel in one core also varied; ie, F1 is 7.8%, F2 is 8%, and F3 is 8.8%. The optimum value of thorium nitride is when fuel fraction of region F1 = 60%, F2 = 57.5%, F3 = 60%, the burn up time up to 20 years without refueling, max k-eff value is 1.0109, and max excess reactivity value is 1.08%. Neutronic analysis shows that both uranium and thorium fuel have excess reactivity value less than 2% but thorium fuel has excess reactivity less than uranium nitride fuel. Uranium fuel has better breeding capability than thorium fuel. Therefore, it is better to use uranium fuel for fast reactor like GFR, which has high breeding capability.
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The prospect of uranium nitride (UN-PuN) fuel for 25- 100MWe gas cooled fast reactor long life without refuelling
Journal of Physics: Conference Series, 2016Co-Authors: Ratna Dewi Syarifah, Zaki Su’ud, Khairul Basar, Dwi IrwantoAbstract:The prospect of uranium nitride (UN-PuN) fuel for 25-100MWe Gas Cooled Fast Reactor has been done. This research use helium coolant which has low neutron moderation, chemical inert and single phase. This study use natural uranium and plutonium. Plutonium taken from spent fuel of LWR (Light Water Reactor). So, it can reduced spent fuel in the world. The calculation use SRAC2006 and JENDL 4.0 for the data libraries. First, we calculate PIJ for fuel pin cell calculation and CITATION for core calculation. The reflector radial-Axial Width is 50 cm. The variation of fuel fraction is 40% until 65%, cladding 10%, and moderator 25% up to 50%. The variation of the power is 75-300 MWth (25-100 MWe). The calculation of survey parameter has been done. The variation of percentage plutonium is 7% up to 13%. We have optimum k-eff value in percentage of plutonium 11%. The high powers cause k-eff value high too. Second, the core configuration divided by three variation fuel (F1, F2, and F3). F1 is located in the central core, F2 middle core and F3 outer core. The variation percentage Plutonium for fuel F1:F2:F3 = 8%:10%:12%. The increasing power level make the burn up level increase. All case can reach burn up time plus than 20 years. The thermal powers increase cause the peak power density increase. The power 150 MWth, 225 MWth, and 300 MWth have excess reactivity (%Ak/k) less than 2%.
Dwi Irwanto - One of the best experts on this subject based on the ideXlab platform.
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Performance of Thorium Uranium Nitride (Th, U233)N Fuel for 500 MWth GFR Long-Life Without Refuelling use FIITB-CHI Code
Journal of Physics: Conference Series, 2019Co-Authors: Ratna Dewi Syarifah, Zaki Su’ud, Khairul Basar, Dwi IrwantoAbstract:Performance of Thorium Uranium Nitride Fuel for 500 MWth GFR Long-Life Without Refueling use FI-ITB-CHI code has been done. Gas Cooled Fast Reactor use fast neutron spectrum, and belong to one of fast breeder reactor type. Thorium is three up to four times more abundant than uranium and is widely distributed in nature can be obtained in many countries. Natural thorium does not contain any fissile material and is made up of the fertile Th- 232 isotope only. Thorium fuel and fuel cycles are particularly relevant to countries having large thorium like Indonesia. The calculation use FI-ITB-CHI Code which has been verified by SLAROM code. The core calculation use R-Z geometry dimensional. The multi group diffusion calculation is carried out every year to get neutron flux distribution and power distribution. Then burn up calculation is carried out for each spatial mesh. The reflector radial-Axial Width is 50 cm. Parametric survey with various percentage of plutonium show the critical condition reach when 11% percentage of Pu and 60% fuel volume fraction. When the fuel volume fraction is increase, the reactor can be operated longer. The optimum value of heterogeneous core configuration when use 8% percentage of plutonium for F1, 10% for F2 and 14% for F3. The reactor can be operated almost 25 years without refueling.
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comparison of uranium plutonium nitride u pu n and thorium nitride th n fuel for 500 mwth gas cooled fast reactor gfr long life without refueling
International Journal of Energy Research, 2018Co-Authors: Ratna Dewi Syarifah, Dwi Irwanto, Khairul Basar, Zaki Suud, Sandro Clief Pattipawaej, Muhammad IlhamAbstract:Summary Comparison of uranium plutonium nitride and thorium nitride fuel for 500 MWth gas-cooled fast reactor has been done. Gas-cooled fast reactor is one type of generation IV reactor that can be operated in high temperature. Due to the high temperature, it can be used in hydrogen production. In this study, we compare the neutronic analysis of two fuel types, ie, uranium nitride fuel (U,Pu)N and thorium nitride fuel (Th,U233)N. The neutronic calculation uses SRAC2006 code system, and the data libraries use JENDL4.0. First, the fuel pin calculation (PIJ calculation) has been done to take the macro data that are used in CITATION calculation. Both uranium and thorium fuel use heterogeneous configuration with 3 variation fuel in the core. F1 is located in the central core, F2 middle core, and F3 outer core. The variation of fuel fraction is 40% until 65%, cladding 10%, and coolant 25% until 40%. For (U,Pu)N fuel, the diameter of the active core is 220 cm, and the height of the active core is 110 cm. And for (Th,U233)N, the diameter of the active core is 250 cm and the height of the active core is 150 cm. The reflector radial-Axial Width is 50 cm. For uranium plutonium nitride fuel, the type of the fuel in one core is varied; ie, F1 is 8%, F2 is 10%, and F3 is 12%. For thorium nitride fuel, the type of the fuel in one core also varied; ie, F1 is 7.8%, F2 is 8%, and F3 is 8.8%. The optimum value of thorium nitride is when fuel fraction of region F1 = 60%, F2 = 57.5%, F3 = 60%, the burn up time up to 20 years without refueling, max k-eff value is 1.0109, and max excess reactivity value is 1.08%. Neutronic analysis shows that both uranium and thorium fuel have excess reactivity value less than 2% but thorium fuel has excess reactivity less than uranium nitride fuel. Uranium fuel has better breeding capability than thorium fuel. Therefore, it is better to use uranium fuel for fast reactor like GFR, which has high breeding capability.
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The prospect of uranium nitride (UN-PuN) fuel for 25- 100MWe gas cooled fast reactor long life without refuelling
Journal of Physics: Conference Series, 2016Co-Authors: Ratna Dewi Syarifah, Zaki Su’ud, Khairul Basar, Dwi IrwantoAbstract:The prospect of uranium nitride (UN-PuN) fuel for 25-100MWe Gas Cooled Fast Reactor has been done. This research use helium coolant which has low neutron moderation, chemical inert and single phase. This study use natural uranium and plutonium. Plutonium taken from spent fuel of LWR (Light Water Reactor). So, it can reduced spent fuel in the world. The calculation use SRAC2006 and JENDL 4.0 for the data libraries. First, we calculate PIJ for fuel pin cell calculation and CITATION for core calculation. The reflector radial-Axial Width is 50 cm. The variation of fuel fraction is 40% until 65%, cladding 10%, and moderator 25% up to 50%. The variation of the power is 75-300 MWth (25-100 MWe). The calculation of survey parameter has been done. The variation of percentage plutonium is 7% up to 13%. We have optimum k-eff value in percentage of plutonium 11%. The high powers cause k-eff value high too. Second, the core configuration divided by three variation fuel (F1, F2, and F3). F1 is located in the central core, F2 middle core and F3 outer core. The variation percentage Plutonium for fuel F1:F2:F3 = 8%:10%:12%. The increasing power level make the burn up level increase. All case can reach burn up time plus than 20 years. The thermal powers increase cause the peak power density increase. The power 150 MWth, 225 MWth, and 300 MWth have excess reactivity (%Ak/k) less than 2%.
Fangchao Dang - One of the best experts on this subject based on the ideXlab platform.
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Design and preliminary experiment of a disk-beam relativistic klystron amplifier for Ku-band long-pulse high power microwave radiation
Physics of Plasmas, 2020Co-Authors: Fangchao Dang, Jun Zhang, Yang Fuxiang, Xiaoping ZhangAbstract:Spatial coherent combination of multiple high power microwave (HPM) sources is considered as a promising scheme to improve the equivalent radiation power of the HPM system dramatically. Relativistic klystron amplifier (RKA) is one of the most suitable sources for the coherent power combination owing to its specific capabilities of stable microwave frequency and controllable phase. However, the RKAs operating at high frequency-band are severely limited by the problems of the intense space-charge effect and radio frequency breakdown. The radial-line HPM sources driven by the disk-shape electron beam may provide the potential to alleviate this issue due to its attractive features of the weak space-charge effect, the high power handling capacity, and the strong electron collection ability. In this paper, a disk-beam relativistic klystron amplifier (DB-RKA) is proposed and physically designed aiming to generate long-pulse HPM radiation at Ku-band. The physical idea, design principles, and simulation results are presented in detail. In a preliminary experiment, the disk-shape intense electron beam is well focused with an Axial-Width of 1.2 mm by an improved magnetic-excited method. Furthermore, the DB-RKA is demonstrated to be capable of generating Ku-band HPMs typically with peak power of 320 MW, pulse duration of 100 ns, and gain of 42 dB.
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experimental demonstration of a ku band radial line relativistic klystron oscillator based on transition radiation
Journal of Applied Physics, 2017Co-Authors: Fangchao Dang, Xiaoping Zhang, Jun Zhang, Jinchuan Ju, Huihuang ZhongAbstract:We report on a radial-line relativistic klystron oscillator (RL-RKO), which is physically designed to generate gigawatt-level high power microwaves (HPMs) at Ku-band. The 3π/4 mode of a four-gap buncher is selected to highly modulate the radially propagating intense relativistic electron beam (IREB). A three-gap extractor operating at the π mode is employed to extract the radio-frequency energy efficiently. The Ku-band RL-RKO is investigated experimentally on an intense-current electron beam accelerator. The radially propagating IREB is well focused with an Axial-Width of 2 mm by a radial magnetic field of 0.4 T. Microwaves with a frequency of 14.86 GHz and a power of 1.5 GW are generated, corresponding to an efficiency of 24%, which indicates a significant advance for the research of radial-line HPM sources.
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Experimental demonstration of a Ku-band radial-line relativistic klystron oscillator based on transition radiation
Journal of Applied Physics, 2017Co-Authors: Fangchao Dang, Xiaoping Zhang, Jun Zhang, Huihuang ZhongAbstract:We report on a radial-line relativistic klystron oscillator (RL-RKO), which is physically designed to generate gigawatt-level high power microwaves (HPMs) at Ku-band. The 3π/4 mode of a four-gap buncher is selected to highly modulate the radially propagating intense relativistic electron beam (IREB). A three-gap extractor operating at the π mode is employed to extract the radio-frequency energy efficiently. The Ku-band RL-RKO is investigated experimentally on an intense-current electron beam accelerator. The radially propagating IREB is well focused with an Axial-Width of 2 mm by a radial magnetic field of 0.4 T. Microwaves with a frequency of 14.86 GHz and a power of 1.5 GW are generated, corresponding to an efficiency of 24%, which indicates a significant advance for the research of radial-line HPM sources.