Cross-sectional homogenization for full-core calculations of small and complex reactor configurations,such as research reactors,has been recently recognized as an interesting and challenging topic.This paper presents ...Cross-sectional homogenization for full-core calculations of small and complex reactor configurations,such as research reactors,has been recently recognized as an interesting and challenging topic.This paper presents the development of a PARCS/Serpent model for the neutronics analysis of a research reactor type TRIGA Mark-II loaded with Russian VVR-M2 fuel(known as the Dalat Nuclear Research Reactor or DNRR).The full-scale DNRR model and a supercell model for a shim/safety rod and its surrounding fuel bundles with the Monte Carlo code Serpent 2 were proposed to generate homogenized fewgroup cross sections for full-core diffusion calculations with PARCS.The full-scale DNRR model with Serpent 2 was also utilized as a reference to verify the PARCS/Serpent calculations.Comparison of the effective neutron multiplication factors,radial and axial core power distributions,and control rod worths showed a generally good agreement between PARCS and Serpent 2.In addition,the discrepancies between the PARCS and Serpent 2 results are also discussed.Consequently,the results indicate the applicability of the PARCS/Serpent model for further steady state and transient analyses of the DNRR.展开更多
The International Conference on Arginine and Pyrimidines （ICAP） had its origin as an arginine workshop organised by a group of microbiologists led by Werner Maas in 1972 （Rubio, 2003）. The shared requirement of ca...The International Conference on Arginine and Pyrimidines （ICAP） had its origin as an arginine workshop organised by a group of microbiologists led by Werner Maas in 1972 （Rubio, 2003）. The shared requirement of carbamoyl phosphate in both arginine and pyrimidine metabolism led to a natural association of researchers working in both fields.展开更多
Due to the strong attacking ability, fast speed, simple implementation and other characteristics, differential fault analysis has become an important method to evaluate the security of cryptosystem in the Internet of ...Due to the strong attacking ability, fast speed, simple implementation and other characteristics, differential fault analysis has become an important method to evaluate the security of cryptosystem in the Internet of Things. As one of the AES finalists, the Serpent is a 128-bit Substitution-Permutation Network(SPN) cryptosystem. It has 32 rounds with the variable key length between 0 and 256 bits, which is flexible to provide security in the Internet of Things. On the basis of the byte-oriented model and the differential analysis, we propose an effective differential fault attack on the Serpent cryptosystem. Mathematical analysis and simulating experiment show that the attack could recover its secret key by introducing 48 faulty ciphertexts. The result in this study describes that the Serpent is vulnerable to differential fault analysis in detail. It will be beneficial to the analysis of the same type of other iterated cryptosystems.展开更多
Radiopharmaceuticals are used in nuclear medicine for diagnostic or therapeutic acts. The short decay half-lives of medical radioisotopes, especially those used for diagnostics, imply that they should be produced cont...Radiopharmaceuticals are used in nuclear medicine for diagnostic or therapeutic acts. The short decay half-lives of medical radioisotopes, especially those used for diagnostics, imply that they should be produced continuously and transported as quickly as possible to the medical units where they are used. Neutron-rich medical radioisotopes are generally produced in research reactors, like technetium-99m, lutetium-177, holmium-166 and iodine-131. On the other hand, proton-rich radioisotopes are produced via reactions with charged particles from accelerators like fluorine-18, gallium-67, iodine-123 and thallium-201. Beside this, innovative nuclear reactors are advocated as solutions to the issues of nuclear waste production and proliferation threats. Fast neutron, thorium-cycle and accelerator-driven subcritical (ADS) reactors are some of the most promising of them, proposed as safer fuel breeders and “waste burners”. This article examines the use of a fast thorium-cycle ADS with liquid lead-bismuth eutectic coolant for the production of molybdenum-99/technetium-99m and lutetium-177. Burnup simulation has been made with the Monte-Carlo (MC) code SERPENT. It is demonstrated that MC codes can advantageously be used to determine the optimal irradiation time for a given radioisotope in a realistic reactor core. It is also shown that fast thorium-cycle ADS is an economical option for the production of medical radioisotopes.展开更多
A new record of the homalopsid snake, Gerarda prevostiana is presented from a mangrove-dominated patch in the vicinity of Kampung Bako, Sarawak, East Malaysia, and this comprises the first published record from the Su...A new record of the homalopsid snake, Gerarda prevostiana is presented from a mangrove-dominated patch in the vicinity of Kampung Bako, Sarawak, East Malaysia, and this comprises the first published record from the Sundaic Island of Borneo. A possible second locality for the species is a ca. 6.68 km site to its northeast, Kampung Buntal, based on an unlocated museum specimen. The species is widespread in mainland Southeast Asia, with additional records to the west （the Indian Subcontinent） and east （the Philippines Archipelago）, but was previously unrecorded from the islands of the Sundas. The secretive habits of the species, including the occupancy of mud lobster （Thalassinia spp.） mounds in mostly inaccessible, swampy habitats may be a reason for its perceived rarity and few published records.展开更多
This study presents a benchmark evaluation of the new ENDF/B-VIII.0 nuclear data library for the Organization for Economic Co-operation and Development/Nuclear Energy Agency Medium 1000 MWth sodium-cooled fast reactor...This study presents a benchmark evaluation of the new ENDF/B-VIII.0 nuclear data library for the Organization for Economic Co-operation and Development/Nuclear Energy Agency Medium 1000 MWth sodium-cooled fast reactor(SFR).The study presented herein covers both SFR core types,i.e.,metallic fueled(MET-1000)and oxide fueled(MOX-1000),simulated using the continuous-energy Monte Carlo Serpent2 code.The neutronics performances of the ENDF/B-VIII.0-based simulations were compared mainly to two libraries:ENDF/B-VII.1 and JENDL-4.0.The comparison includes several neutronics parameters evaluated for the beginning and end of the cycle conditions.These parameters include the effective multiplication factor keff,total effective delayed neutron fraction beff,sodium void reactivity(DqNa),Doppler constant(DqDoppler),and control rod worth(DqCR).In addition,a sensitivity study was used to reveal the major isotope/reaction pairs contributing to the discrepancy observed in the performance of the three libraries using 33 and 44-energy-group structures.展开更多
This paper explored algebraic features of nonlinear parts in Serpent encryption algorithm and offered an 11-round Serpent-128 impossible differential algebraic attack through utilizing the method in constructing S-box...This paper explored algebraic features of nonlinear parts in Serpent encryption algorithm and offered an 11-round Serpent-128 impossible differential algebraic attack through utilizing the method in constructing S-box algebraic equations.The new method analyzed block ll-round Serpent with 2127 selected plaintexts and 2-29 bytes memory space at the same time of giving a new design principle of S-box anti-algebraic attack.展开更多
The decrease in species richness toward higher latitudes is an expected biogeographical pattern.This pattern could be related to particular envi-ronmental constraints and the evolutionary history of clades.However,spe...The decrease in species richness toward higher latitudes is an expected biogeographical pattern.This pattern could be related to particular envi-ronmental constraints and the evolutionary history of clades.However,species richness does not fully represent the evolutionary history of the clades behind their distributions.Phylogenetic diversity better clarifies the role of historical factors in biogeographical patterns.We analyzed envi-ronmental and historical drivers related to latitudinal variation in species richness and phylogenetic diversity of Atlantic Forest endemic snakes.We implemented species distribution models,from voucherbased locality points,to map the snake ranges and diversity.We used generalized additive mixed models to evaluate the relationships among the diversity metrics and area,topographical roughness,and past climate change velocity since the Last Maximum Glacial in the Atlantic Forest latitudinal gradient.Contrary to the expected general pattern,species richness was higher toward higher latitudes,being positively related to past climatic stability.Species richness also increased with total area and higher topographical roughness.Phylogenetic diversity,on the other hand,showed opposite relationships related to the same factors.Phylogenetic diversity increased with lower climatic stability in lower latitudes.Thus,dimensions of diversity were affected in different ways by historical and environmental constraints in this unique and threatened biodiversity hotspot.展开更多
基金the Ministry of Science and Technology of Vietnam(No.DTCB.06/18/VKHKTHN).
文摘Cross-sectional homogenization for full-core calculations of small and complex reactor configurations,such as research reactors,has been recently recognized as an interesting and challenging topic.This paper presents the development of a PARCS/Serpent model for the neutronics analysis of a research reactor type TRIGA Mark-II loaded with Russian VVR-M2 fuel(known as the Dalat Nuclear Research Reactor or DNRR).The full-scale DNRR model and a supercell model for a shim/safety rod and its surrounding fuel bundles with the Monte Carlo code Serpent 2 were proposed to generate homogenized fewgroup cross sections for full-core diffusion calculations with PARCS.The full-scale DNRR model with Serpent 2 was also utilized as a reference to verify the PARCS/Serpent calculations.Comparison of the effective neutron multiplication factors,radial and axial core power distributions,and control rod worths showed a generally good agreement between PARCS and Serpent 2.In addition,the discrepancies between the PARCS and Serpent 2 results are also discussed.Consequently,the results indicate the applicability of the PARCS/Serpent model for further steady state and transient analyses of the DNRR.
基金sponsored by MRC Functional Genomics Unit at the University of Oxford, the Journal of Genetics and Genomics, and Dutscher Scientific
文摘The International Conference on Arginine and Pyrimidines （ICAP） had its origin as an arginine workshop organised by a group of microbiologists led by Werner Maas in 1972 （Rubio, 2003）. The shared requirement of carbamoyl phosphate in both arginine and pyrimidine metabolism led to a natural association of researchers working in both fields.
基金supported by the National Natural Science Foundation of China under Grant No.61003278,No.61073150 and No.61202371Innovation Program of Shanghai Municipal Education Commission under Grant No.14ZZ066+5 种基金the open research fund of State Key Laboratory of Information Securitythe Opening Project of Shanghai Key Laboratory of Integrate Administration Technologies for Information Securitythe Fundamental Research Funds for the Central Universities,National Key Basic Research Program of China under Grant No.2013CB338004China Postdoctoral Science Foundation under Grant No.2012M521829Shanghai Postdoctoral Research Funding Program under Grant No.12R21414500the National Social Science Foundation of China under Grant No.13CFX054
文摘Due to the strong attacking ability, fast speed, simple implementation and other characteristics, differential fault analysis has become an important method to evaluate the security of cryptosystem in the Internet of Things. As one of the AES finalists, the Serpent is a 128-bit Substitution-Permutation Network(SPN) cryptosystem. It has 32 rounds with the variable key length between 0 and 256 bits, which is flexible to provide security in the Internet of Things. On the basis of the byte-oriented model and the differential analysis, we propose an effective differential fault attack on the Serpent cryptosystem. Mathematical analysis and simulating experiment show that the attack could recover its secret key by introducing 48 faulty ciphertexts. The result in this study describes that the Serpent is vulnerable to differential fault analysis in detail. It will be beneficial to the analysis of the same type of other iterated cryptosystems.
文摘Radiopharmaceuticals are used in nuclear medicine for diagnostic or therapeutic acts. The short decay half-lives of medical radioisotopes, especially those used for diagnostics, imply that they should be produced continuously and transported as quickly as possible to the medical units where they are used. Neutron-rich medical radioisotopes are generally produced in research reactors, like technetium-99m, lutetium-177, holmium-166 and iodine-131. On the other hand, proton-rich radioisotopes are produced via reactions with charged particles from accelerators like fluorine-18, gallium-67, iodine-123 and thallium-201. Beside this, innovative nuclear reactors are advocated as solutions to the issues of nuclear waste production and proliferation threats. Fast neutron, thorium-cycle and accelerator-driven subcritical (ADS) reactors are some of the most promising of them, proposed as safer fuel breeders and “waste burners”. This article examines the use of a fast thorium-cycle ADS with liquid lead-bismuth eutectic coolant for the production of molybdenum-99/technetium-99m and lutetium-177. Burnup simulation has been made with the Monte-Carlo (MC) code SERPENT. It is demonstrated that MC codes can advantageously be used to determine the optimal irradiation time for a given radioisotope in a realistic reactor core. It is also shown that fast thorium-cycle ADS is an economical option for the production of medical radioisotopes.
基金the Sarawak Forest Department for issuance of a research permit(No.NCCD.907.4.4 Jld.7–39)a Fundamental Research Grant[Grant No:FRGS/07(04)787/2010(68)]from the Ministry of Higher Education of Malaysia for supporting our study on the herpetofauna of Sarawak.Y.M.
文摘A new record of the homalopsid snake, Gerarda prevostiana is presented from a mangrove-dominated patch in the vicinity of Kampung Bako, Sarawak, East Malaysia, and this comprises the first published record from the Sundaic Island of Borneo. A possible second locality for the species is a ca. 6.68 km site to its northeast, Kampung Buntal, based on an unlocated museum specimen. The species is widespread in mainland Southeast Asia, with additional records to the west （the Indian Subcontinent） and east （the Philippines Archipelago）, but was previously unrecorded from the islands of the Sundas. The secretive habits of the species, including the occupancy of mud lobster （Thalassinia spp.） mounds in mostly inaccessible, swampy habitats may be a reason for its perceived rarity and few published records.
基金the Research Institute of Science and Engineering at the University of Sharjah(No.1802040790-P).
文摘This study presents a benchmark evaluation of the new ENDF/B-VIII.0 nuclear data library for the Organization for Economic Co-operation and Development/Nuclear Energy Agency Medium 1000 MWth sodium-cooled fast reactor(SFR).The study presented herein covers both SFR core types,i.e.,metallic fueled(MET-1000)and oxide fueled(MOX-1000),simulated using the continuous-energy Monte Carlo Serpent2 code.The neutronics performances of the ENDF/B-VIII.0-based simulations were compared mainly to two libraries:ENDF/B-VII.1 and JENDL-4.0.The comparison includes several neutronics parameters evaluated for the beginning and end of the cycle conditions.These parameters include the effective multiplication factor keff,total effective delayed neutron fraction beff,sodium void reactivity(DqNa),Doppler constant(DqDoppler),and control rod worth(DqCR).In addition,a sensitivity study was used to reveal the major isotope/reaction pairs contributing to the discrepancy observed in the performance of the three libraries using 33 and 44-energy-group structures.
基金Supported by the Natural Science Foundation of Hubei Province(Q20102905)
文摘This paper explored algebraic features of nonlinear parts in Serpent encryption algorithm and offered an 11-round Serpent-128 impossible differential algebraic attack through utilizing the method in constructing S-box algebraic equations.The new method analyzed block ll-round Serpent with 2127 selected plaintexts and 2-29 bytes memory space at the same time of giving a new design principle of S-box anti-algebraic attack.
基金supported by grants from Fundacao de Amparo a Pesquisa do Estado de Sao Paulo(FAPESP 2014/23677-9 and 2020/12658-4)Conselho Nacional de Desenvolvimento Cientifico e Tecnol6gico(CNPq,405447/2016-7).R.J.S.thanks CNPq for the research fellowship(307956/2022-9).J.A.R.A.thanks Instituto Serrapilheira for the postdoctoral fellowship.
文摘The decrease in species richness toward higher latitudes is an expected biogeographical pattern.This pattern could be related to particular envi-ronmental constraints and the evolutionary history of clades.However,species richness does not fully represent the evolutionary history of the clades behind their distributions.Phylogenetic diversity better clarifies the role of historical factors in biogeographical patterns.We analyzed envi-ronmental and historical drivers related to latitudinal variation in species richness and phylogenetic diversity of Atlantic Forest endemic snakes.We implemented species distribution models,from voucherbased locality points,to map the snake ranges and diversity.We used generalized additive mixed models to evaluate the relationships among the diversity metrics and area,topographical roughness,and past climate change velocity since the Last Maximum Glacial in the Atlantic Forest latitudinal gradient.Contrary to the expected general pattern,species richness was higher toward higher latitudes,being positively related to past climatic stability.Species richness also increased with total area and higher topographical roughness.Phylogenetic diversity,on the other hand,showed opposite relationships related to the same factors.Phylogenetic diversity increased with lower climatic stability in lower latitudes.Thus,dimensions of diversity were affected in different ways by historical and environmental constraints in this unique and threatened biodiversity hotspot.
