Software protection technology has been universally emphasized, with the development of reverse engineering and static analysis techniques. So, it is important to research how to quantitatively evaluate the security o...Software protection technology has been universally emphasized, with the development of reverse engineering and static analysis techniques. So, it is important to research how to quantitatively evaluate the security of the protected software. However, there are some researchers evaluating the security of the proposed protect techniques directly by the traditional complexity metrics, which is not suffident. In order to better reflect security from software complexity, a multi-factor complexity metric based on control flow graph （CFG） is proposed, and the corresponding calculating procedures are presented in detail. Moreover, complexity density models are constructed to indicate the strength of software resisting reverse engineering and code analysis. Instance analysis shows that the proposed method is simple and practical, and can more objectively reflect software security from the perspective of the complexity.展开更多
Atterberg limits and consistency indices are used for classifications of cohesive(fine-grained) soils in relation with compaction and tillage practices. They also provide information for interpreting several soil mech...Atterberg limits and consistency indices are used for classifications of cohesive(fine-grained) soils in relation with compaction and tillage practices. They also provide information for interpreting several soil mechanical and physical properties such as shear strength, compressibility, shrinkage and swelling potentials. Although, several studies have been conducted regarding the land use effects on various soil mechanical properties, little is known about the effects of land use and slope positions on Atterberg limits and consistency indices. This study was conducted to investigate the effects of land use and slope position on selected soil physical and chemical properties, Atterberg limits and consistency indices in hilly region of western Iran. Three land uses including dryland farming, irrigated farming and pasture and four slope positions(i.e., shoulder, backslope, footslope, and toeslope) were used for soil samplings. One hundred eleven soil samples were collected from the surface soil(0-10 cm). Selected physical and chemical properties, liquid limit(LL), plastic limit(PL) and shrinkage limit(SL) were measured using the standard methods; and consistency indices including plastic index(PI), friability index(FI), shrinkage index(SI) and soil activity(A=PI/clay) were calculated. The results showed that irrigated farming significantly increased organic matter content(OM) and OM/clay ratio, and decreased bulk density(ρb) and relative bulk density(ρb-rel) as a result of higher biomass production and plant residues added to the soil compared to other land uses. Except for sand content, OM, ρb, cation exchange capacity(CEC) and calcium carbonate equivalent(CCE), slope position significantly affected soil physical and chemical properties. The highest values of silt, OM/clay and CEC/clay were found in the toeslope position, predominantly induced by soil redistribution within the landscape. The use of complexed(COC)- noncomplexed organic carbon(NCOC) concept indicated that majority of the studied soils were located below the saturation line and the OM in the soils was mainly in the COC form. The LL, PI, FI and A showed significant differences among the land uses; the highest values belonged to the irrigated farming due to high biomass production and plant residues returned to the soils. Furthermore, slope position significantly affected the Atterberg limits and consistency indices except for SL. The highest values of LL, PI, SI and A were observed in the toeslope position probably because of higher OM and CEC/clay due to greater amount of expandable phyllosilicate clays. Overall, soils on the toeslope under irrigated farming with high LL and SI and low values of FI need careful tillage management to avoid soil compaction.展开更多
Computational calculation was performed to investigate the mechanism of trifluoromethylation reactions of iodobenzene with well-defined N-heterocyclic carbene （NHC）-supported Cu~ trifiuor- omethyl complexes. Four pr...Computational calculation was performed to investigate the mechanism of trifluoromethylation reactions of iodobenzene with well-defined N-heterocyclic carbene （NHC）-supported Cu~ trifiuor- omethyl complexes. Four proposed reaction pathways, namely cr-bond metathesis （BM）, concerted oxidative addition-reductive elimination （OARE）, iodine atom transfer （IAT） and single-electron transfer （SET）, have been computed by density functional theory （DFT）. The result indicated that the concerted OARE mechanism is favored among the four reaction pathways, suggesting the trifluoromethylation may occur via concerted OARE mechanism involving Ar-X oxidative addition to the Cu（1） center as the rate determining step.展开更多
The molecular geometry,electronic structure,thermochemistry and infrared spectra of [Mg（CHZ）3]（ClO4）2 and [Mg（CHZ）3]（NO3）2 were comparatively studied using the Heyd-Scuseria-Ernzerhof（HSE） screened hybrid de...The molecular geometry,electronic structure,thermochemistry and infrared spectra of [Mg（CHZ）3]（ClO4）2 and [Mg（CHZ）3]（NO3）2 were comparatively studied using the Heyd-Scuseria-Ernzerhof（HSE） screened hybrid density functional with 6-31G＊＊ basis set.The experimental results show that the complexes have six-coordinated octahedron feature,and the metal-ligand interactions are predominantly ionic in nature.The calculated heats of formation predict that [Mg（CHZ）3]（NO3）2 is more stable than [Mg（CHZ）3]（ClO4）2.Detailed NBO analyses indicate that the ligand-anion interaction plays an important role in the stability for these two energetic complexes.Moreover,the stretching vibration frequencies of N-H bonds shift to lower wave number compared to the free CHZ ligand,which are caused by the delocalizations from N-H bond orbital to lone-pair electron antibond orbital of magnesium.展开更多
The molecular structures of fifteen possible 2-thioxanthine（2TX） complexes with one Hg^2＋ and two Cl-ions were fully optimized using density functional theory B3PW91/6-311＋＋G^＊＊ method. The effective pseudo pot...The molecular structures of fifteen possible 2-thioxanthine（2TX） complexes with one Hg^2＋ and two Cl-ions were fully optimized using density functional theory B3PW91/6-311＋＋G^＊＊ method. The effective pseudo potential LANL2DZ basis set was used for metal Hg^2＋ion. The vibrational analysis was also carried out at the same level. The bond lengths, bond angles, zero point energies, Gibbs free energies, thermodynamic energies and relative energies of all the complexes were obtained. The NBO analysis for natural charge and the second order perturbation energy values was carried out for three stable complexes and the IR spectroscopy of the two complexes was assigned to the experimental data. The results show that the 2-thioxanthine complexes with one Hg^2＋ and two Cl^-ions were formed and the complexes resulting from the thione tautomer are more stable than that of the thiol ones. The order of three complexes with relative lower energy is 2TX（1,3,7）-Hg^2＋-2, 2 TX（1,3,7）-Hg^2＋-1 and 2 TX（1,3,9）-Hg^2＋. The calculated IR spectroscopy of the two complexes agreed with the experimental data.展开更多
基金Key Project of the National Eleventh-Five Year Research Program of China(No.2006BAD10A07)
文摘Software protection technology has been universally emphasized, with the development of reverse engineering and static analysis techniques. So, it is important to research how to quantitatively evaluate the security of the protected software. However, there are some researchers evaluating the security of the proposed protect techniques directly by the traditional complexity metrics, which is not suffident. In order to better reflect security from software complexity, a multi-factor complexity metric based on control flow graph （CFG） is proposed, and the corresponding calculating procedures are presented in detail. Moreover, complexity density models are constructed to indicate the strength of software resisting reverse engineering and code analysis. Instance analysis shows that the proposed method is simple and practical, and can more objectively reflect software security from the perspective of the complexity.
基金Isfahan University of Technology for the financial support of this study
文摘Atterberg limits and consistency indices are used for classifications of cohesive(fine-grained) soils in relation with compaction and tillage practices. They also provide information for interpreting several soil mechanical and physical properties such as shear strength, compressibility, shrinkage and swelling potentials. Although, several studies have been conducted regarding the land use effects on various soil mechanical properties, little is known about the effects of land use and slope positions on Atterberg limits and consistency indices. This study was conducted to investigate the effects of land use and slope position on selected soil physical and chemical properties, Atterberg limits and consistency indices in hilly region of western Iran. Three land uses including dryland farming, irrigated farming and pasture and four slope positions(i.e., shoulder, backslope, footslope, and toeslope) were used for soil samplings. One hundred eleven soil samples were collected from the surface soil(0-10 cm). Selected physical and chemical properties, liquid limit(LL), plastic limit(PL) and shrinkage limit(SL) were measured using the standard methods; and consistency indices including plastic index(PI), friability index(FI), shrinkage index(SI) and soil activity(A=PI/clay) were calculated. The results showed that irrigated farming significantly increased organic matter content(OM) and OM/clay ratio, and decreased bulk density(ρb) and relative bulk density(ρb-rel) as a result of higher biomass production and plant residues added to the soil compared to other land uses. Except for sand content, OM, ρb, cation exchange capacity(CEC) and calcium carbonate equivalent(CCE), slope position significantly affected soil physical and chemical properties. The highest values of silt, OM/clay and CEC/clay were found in the toeslope position, predominantly induced by soil redistribution within the landscape. The use of complexed(COC)- noncomplexed organic carbon(NCOC) concept indicated that majority of the studied soils were located below the saturation line and the OM in the soils was mainly in the COC form. The LL, PI, FI and A showed significant differences among the land uses; the highest values belonged to the irrigated farming due to high biomass production and plant residues returned to the soils. Furthermore, slope position significantly affected the Atterberg limits and consistency indices except for SL. The highest values of LL, PI, SI and A were observed in the toeslope position probably because of higher OM and CEC/clay due to greater amount of expandable phyllosilicate clays. Overall, soils on the toeslope under irrigated farming with high LL and SI and low values of FI need careful tillage management to avoid soil compaction.
基金supported by National Natural Science Foundation of China(Nos.21073144,21173169)Fundamental Research Funds for the Central Universities(No.XDJK2013A008)
文摘Computational calculation was performed to investigate the mechanism of trifluoromethylation reactions of iodobenzene with well-defined N-heterocyclic carbene （NHC）-supported Cu~ trifiuor- omethyl complexes. Four proposed reaction pathways, namely cr-bond metathesis （BM）, concerted oxidative addition-reductive elimination （OARE）, iodine atom transfer （IAT） and single-electron transfer （SET）, have been computed by density functional theory （DFT）. The result indicated that the concerted OARE mechanism is favored among the four reaction pathways, suggesting the trifluoromethylation may occur via concerted OARE mechanism involving Ar-X oxidative addition to the Cu（1） center as the rate determining step.
基金Funded by the National Natural Science Foundation of China(No. 21075138)the Natural Science Foundation of Chongqing Province, China(No.cstc2011jjA50013,No.cstc2011jjA0780)the Education Commission of Chongqing City of China(KJ121311)
文摘The molecular geometry,electronic structure,thermochemistry and infrared spectra of [Mg（CHZ）3]（ClO4）2 and [Mg（CHZ）3]（NO3）2 were comparatively studied using the Heyd-Scuseria-Ernzerhof（HSE） screened hybrid density functional with 6-31G＊＊ basis set.The experimental results show that the complexes have six-coordinated octahedron feature,and the metal-ligand interactions are predominantly ionic in nature.The calculated heats of formation predict that [Mg（CHZ）3]（NO3）2 is more stable than [Mg（CHZ）3]（ClO4）2.Detailed NBO analyses indicate that the ligand-anion interaction plays an important role in the stability for these two energetic complexes.Moreover,the stretching vibration frequencies of N-H bonds shift to lower wave number compared to the free CHZ ligand,which are caused by the delocalizations from N-H bond orbital to lone-pair electron antibond orbital of magnesium.
基金supported by the National Natural Science Foundation of China(No.21643014)the Special Natural Science Foundation of Science and Technology Bureau of Xi’an City Government(No.2016CXWL02)
文摘The molecular structures of fifteen possible 2-thioxanthine（2TX） complexes with one Hg^2＋ and two Cl-ions were fully optimized using density functional theory B3PW91/6-311＋＋G^＊＊ method. The effective pseudo potential LANL2DZ basis set was used for metal Hg^2＋ion. The vibrational analysis was also carried out at the same level. The bond lengths, bond angles, zero point energies, Gibbs free energies, thermodynamic energies and relative energies of all the complexes were obtained. The NBO analysis for natural charge and the second order perturbation energy values was carried out for three stable complexes and the IR spectroscopy of the two complexes was assigned to the experimental data. The results show that the 2-thioxanthine complexes with one Hg^2＋ and two Cl^-ions were formed and the complexes resulting from the thione tautomer are more stable than that of the thiol ones. The order of three complexes with relative lower energy is 2TX（1,3,7）-Hg^2＋-2, 2 TX（1,3,7）-Hg^2＋-1 and 2 TX（1,3,9）-Hg^2＋. The calculated IR spectroscopy of the two complexes agreed with the experimental data.
