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
A novel aromatic diamine monomer bearing tertbutyl and 4-tertbutylphenyl groups,3,3'-ditertbutyl-4,4'-diaminodiphenyl-4''-tertbutylphenylmethane(TADBP),was prepared and characterized.A series of non-co...A novel aromatic diamine monomer bearing tertbutyl and 4-tertbutylphenyl groups,3,3'-ditertbutyl-4,4'-diaminodiphenyl-4''-tertbutylphenylmethane(TADBP),was prepared and characterized.A series of non-coplanar polyimides(PIs)were synthesized via a conventional one-step polycondensation from TADBP and various aromatic dianhydrides including pyromellitic dianhydride(PMDA),3,3',4,4'-biphenyltetracarboxylic dianhydride(BPDA),4,4'-oxydiphthalic anhydride(OPDA),3,3',4,4'-benzophenone tetracarboxylic dianhydride(BTDA)and 4,4'-(hexafluoroisopropylidene)dipthalic anhydride(6FDA).All PIs exhibit excellent solubility in common organic solvents such as N,N-dimethylformamide(DMF),N,N-dimethylacetamide(DMAc),N-methyl-2-pyrrolidone(NMP),dimethyl sulfoxide(DMSO),chloroform(CHCl3),tetrahydrofuran(THF),and so on.Furthermore,the obtained transparent,strong and flexible polyimide films present good thermal stability and outstanding optical properties.Their glass transition temperatures(Tgs)are in the range of 298 to 347℃,and 10%weight loss temperatures are in excess of 490℃with more than 53%char yield at 800℃in nitrogen.All the polyimides can be cast into transparent and flexible films with tensile strength of 80.5-101 MPa,elongation at break of 8.4%-10.5%,and Young's modulus of 2.3-2.8 GPa.Meanwhile,the PIs show the cutoff wavelengths of 302-356 nm,as well as low moisture absorption(0.30%-0.55%)and low dielectric constant(2.78-3.12 at 1 MHz).展开更多
This paper study the Lie groups admitted by differential equations. It is proved in this paper that for any n-th order autonomous system and any given structure constants Ckij, the system admits n-1 local one paramete...This paper study the Lie groups admitted by differential equations. It is proved in this paper that for any n-th order autonomous system and any given structure constants Ckij, the system admits n-1 local one parameter Lie groups, and the 'non-trivial' structure constants of the Lie module generated by infinitesimal generators of these Lie groups are just Ckij. This result shows that integrable system may admit unsolvable local Lie group.展开更多
Beginning from the premise that the universe is static, and that the cosmological redshift is due to a nonconservative tired light effect, the following examines evidence supporting the prediction that photons will pr...Beginning from the premise that the universe is static, and that the cosmological redshift is due to a nonconservative tired light effect, the following examines evidence supporting the prediction that photons will progressively blueshift when transiting through the gravity wells of galaxies, galaxy clusters, and superclusters. The presence of such a nonvelocity blueshift effect is seen to make a substantial contribution to Virgo cluster galaxy spectra, sufficient to dramatically decrease the cluster’s velocity dispersion and assessed virial mass and eliminate the need to assume the presence of large quantities of dark matter. The effect is also shown to account for the Fingers-of-God effect and Kaiser pancaking effect seen when the spectra of cluster galaxies are plotted in redshift space. The opposite effect, excessive redshifting of photons passing through cosmic voids is able to explain void elongation in redshift space, and also the subnormal luminosity of void galaxies. The proposed cosmological blueshifting phenomenon also explains the downturn of the slope of the Hubble Flow in the vicinity of the Local Group which projects a negative apparent velocity for photons propagating near the Milky Way. It also offers an explanation for the blueshift of the Andromeda galaxy spectra and for Arp’s findings that the spectra of primary galaxies in a cluster tend to be blueshifted relative to their companion galaxies. These photon energy phenomena are anticipated by the physics of subquantum kinetics which predicts that photons traversing long distances through intergalactic space should undergo nonconservative tired-light redshifting, and that photons passing through gravity potential wells should undergo progressive blueshifting. The latter effect may be visualized as a negative nonvelocity Hubble constant.展开更多
For a very long time video processing dealt exclusively with fixed-rate sequences of rectangular shaped images. However, interest has been recently moving toward a more flexible concept in which the subject of the pro...For a very long time video processing dealt exclusively with fixed-rate sequences of rectangular shaped images. However, interest has been recently moving toward a more flexible concept in which the subject of the processing and encoding operations is a set of visual elements organized in both time and space in a flexible and arbitrarily complex way. The moving picture experts group (MPEG- 4) standard supports this concept and its verification model (VM) encoder has adopted scalable rate control (SRC) as the rate control scheme, which is based on the spatial domain and compatible with constant bit rate (CBR) and variable bit rate (VBR). In this paper,a new rate control algorithm based on the DCT domain instead of the pixel domain is presented. More-(over), macroblock level rate control scheme to compute the quantization step for each macroblock has been adopted. The experimental results show that the new algorithm can achieve a much better result than the original one in both peak signal-to-noise ratio (PSNR) and the coding bits, and that the new algorithm is more flexible than test model 5 (TM5) rate control algorithm.展开更多
As a small catalytic DNA molecule, 10-23 DNAzyme has cleavage ability against complementary RNA. Previous studies of chemical modification have shown that its catalytic core can be further optimized in order to obtain...As a small catalytic DNA molecule, 10-23 DNAzyme has cleavage ability against complementary RNA. Previous studies of chemical modification have shown that its catalytic core can be further optimized in order to obtain more powerful catalytic ability. The analogues of 2＇-deoxyadenosine （5） and 2＇-deoxyguanosine （6） could improve the cleavage ability of the DNAzyme when positioned at positions A9, （32 and G14 in the catalytic core, respectively. Moreover, their combinatorial incorporations were studied, the results implicated that the effect was position-dependent, and positive additive results could be achieved at some positions. The highly conserved G1, G2 and G14 could be optimized by single or combinatorial modification with 2＇-deoxyguanosine analogues. Chemical modifications on the functional groups of the core residues would be a feasible approach for the optimization of 10-23 DNAzyme.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supported by the National Natural Science Foundation of China(Nos.51163003,21264005 and 51263005)the fund of Guangxi Natural Science Foundation(Nos.2014GXNSFAA118040,2013GXNSFDA019008)Guangxi Small Highland Innovation Team of Talents in Colleges and Universities,and Fund。
文摘A novel aromatic diamine monomer bearing tertbutyl and 4-tertbutylphenyl groups,3,3'-ditertbutyl-4,4'-diaminodiphenyl-4''-tertbutylphenylmethane(TADBP),was prepared and characterized.A series of non-coplanar polyimides(PIs)were synthesized via a conventional one-step polycondensation from TADBP and various aromatic dianhydrides including pyromellitic dianhydride(PMDA),3,3',4,4'-biphenyltetracarboxylic dianhydride(BPDA),4,4'-oxydiphthalic anhydride(OPDA),3,3',4,4'-benzophenone tetracarboxylic dianhydride(BTDA)and 4,4'-(hexafluoroisopropylidene)dipthalic anhydride(6FDA).All PIs exhibit excellent solubility in common organic solvents such as N,N-dimethylformamide(DMF),N,N-dimethylacetamide(DMAc),N-methyl-2-pyrrolidone(NMP),dimethyl sulfoxide(DMSO),chloroform(CHCl3),tetrahydrofuran(THF),and so on.Furthermore,the obtained transparent,strong and flexible polyimide films present good thermal stability and outstanding optical properties.Their glass transition temperatures(Tgs)are in the range of 298 to 347℃,and 10%weight loss temperatures are in excess of 490℃with more than 53%char yield at 800℃in nitrogen.All the polyimides can be cast into transparent and flexible films with tensile strength of 80.5-101 MPa,elongation at break of 8.4%-10.5%,and Young's modulus of 2.3-2.8 GPa.Meanwhile,the PIs show the cutoff wavelengths of 302-356 nm,as well as low moisture absorption(0.30%-0.55%)and low dielectric constant(2.78-3.12 at 1 MHz).
文摘This paper study the Lie groups admitted by differential equations. It is proved in this paper that for any n-th order autonomous system and any given structure constants Ckij, the system admits n-1 local one parameter Lie groups, and the 'non-trivial' structure constants of the Lie module generated by infinitesimal generators of these Lie groups are just Ckij. This result shows that integrable system may admit unsolvable local Lie group.
文摘Beginning from the premise that the universe is static, and that the cosmological redshift is due to a nonconservative tired light effect, the following examines evidence supporting the prediction that photons will progressively blueshift when transiting through the gravity wells of galaxies, galaxy clusters, and superclusters. The presence of such a nonvelocity blueshift effect is seen to make a substantial contribution to Virgo cluster galaxy spectra, sufficient to dramatically decrease the cluster’s velocity dispersion and assessed virial mass and eliminate the need to assume the presence of large quantities of dark matter. The effect is also shown to account for the Fingers-of-God effect and Kaiser pancaking effect seen when the spectra of cluster galaxies are plotted in redshift space. The opposite effect, excessive redshifting of photons passing through cosmic voids is able to explain void elongation in redshift space, and also the subnormal luminosity of void galaxies. The proposed cosmological blueshifting phenomenon also explains the downturn of the slope of the Hubble Flow in the vicinity of the Local Group which projects a negative apparent velocity for photons propagating near the Milky Way. It also offers an explanation for the blueshift of the Andromeda galaxy spectra and for Arp’s findings that the spectra of primary galaxies in a cluster tend to be blueshifted relative to their companion galaxies. These photon energy phenomena are anticipated by the physics of subquantum kinetics which predicts that photons traversing long distances through intergalactic space should undergo nonconservative tired-light redshifting, and that photons passing through gravity potential wells should undergo progressive blueshifting. The latter effect may be visualized as a negative nonvelocity Hubble constant.
文摘For a very long time video processing dealt exclusively with fixed-rate sequences of rectangular shaped images. However, interest has been recently moving toward a more flexible concept in which the subject of the processing and encoding operations is a set of visual elements organized in both time and space in a flexible and arbitrarily complex way. The moving picture experts group (MPEG- 4) standard supports this concept and its verification model (VM) encoder has adopted scalable rate control (SRC) as the rate control scheme, which is based on the spatial domain and compatible with constant bit rate (CBR) and variable bit rate (VBR). In this paper,a new rate control algorithm based on the DCT domain instead of the pixel domain is presented. More-(over), macroblock level rate control scheme to compute the quantization step for each macroblock has been adopted. The experimental results show that the new algorithm can achieve a much better result than the original one in both peak signal-to-noise ratio (PSNR) and the coding bits, and that the new algorithm is more flexible than test model 5 (TM5) rate control algorithm.
基金The National Natural Science Foundation of China(Grant No.21572268)
文摘As a small catalytic DNA molecule, 10-23 DNAzyme has cleavage ability against complementary RNA. Previous studies of chemical modification have shown that its catalytic core can be further optimized in order to obtain more powerful catalytic ability. The analogues of 2＇-deoxyadenosine （5） and 2＇-deoxyguanosine （6） could improve the cleavage ability of the DNAzyme when positioned at positions A9, （32 and G14 in the catalytic core, respectively. Moreover, their combinatorial incorporations were studied, the results implicated that the effect was position-dependent, and positive additive results could be achieved at some positions. The highly conserved G1, G2 and G14 could be optimized by single or combinatorial modification with 2＇-deoxyguanosine analogues. Chemical modifications on the functional groups of the core residues would be a feasible approach for the optimization of 10-23 DNAzyme.
