The use of functional size measurement(FSM) methods in software development organizations is growing during the years. Also, object oriented(OO) techniques have become quite a standard to design the software and, in p...The use of functional size measurement(FSM) methods in software development organizations is growing during the years. Also, object oriented(OO) techniques have become quite a standard to design the software and, in particular, Use Cases is one of the most used techniques to specify functional requirements. Main FSM methods do not include specific rules to measure the software functionality from its Use Cases analysis. To deal with this issue some other methods like Kramer's functional measurement method have been developed. Therefore, one of the main issues for those organizations willing to use OO functional measurement method in order to facilitate the use cases count procedure is how to convert their portfolio functional size from the previously adopted FSM method towards the new method. The objective of this research is to find a statistical relationship for converting the software functional size units measured by the International Function Point Users Group(IFPUG) function point analysis(FPA) method into Kramer-Smith's use cases points(UCP) method and vice versa. Methodologies for a correct data gathering are proposed and results obtained are analyzed to draw the linear and non-linear equations for this correlation. Finally, a conversion factor and corresponding conversion intervals are given to establish the statistical relationship.展开更多
Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosi...Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosity and surface characteristics of porous materials. To identify suitable adsorbents, we need a reliable computational tool for pore characterization and, subsequently, quantitative prediction of the adsorption behavior. Within the framework of adsorption integral equation(AIE), the pore-size distribution(PSD) is sensitive to the adopted theoretical models and numerical algorithms through isotherm fitting. In recent years, the classical density functional theory(DFT) has emerged as a common choice to describe adsorption isotherms for AIE kernel construction. However,rarely considered is the accuracy of the mean-field approximation(MFA) commonly used in commercial software. In this work, we calibrate four versions of DFT methods with grand canonical Monte Carlo(GCMC) molecular simulation for the adsorption of CH_4 and CO_2 gas in slit pores at 298 K with the pore width varying from 0.65 to 5.00 nm and pressure from 0.2 to 2.0 MPa. It is found that a weighted-density approximation proposed by Yu(WDA-Yu) is more accurate than MFA and other non-local DFT methods. In combination with the trapezoid discretization of AIE, the WDA-Yu method provides a faithful representation of experimental data, with the accuracy and stability improved by 90.0% and 91.2%, respectively, in comparison with the corresponding results from MFA for fitting CO_2 isotherms. In particular, those distributions in the feature pore width range(FPWR)are proved more representative for the pore-size analysis. The new theoretical procedure for pore characterization has also been tested with the methane adsorption capacity in seven activated carbon samples.展开更多
In order to obtain an indirect estimation method of the pore size distribution function(PSDF)for a deformable soil,both the soil-water characteristic curve in the form of gravimetric water content(w-SWCC)and the shrin...In order to obtain an indirect estimation method of the pore size distribution function(PSDF)for a deformable soil,both the soil-water characteristic curve in the form of gravimetric water content(w-SWCC)and the shrinkage curve(SC)are used as the input parameters.The w-SWCC defines the relationship between the gravimetric water content and soil suction.The SC illustrates the variation of the void ratio with respect to different water contents.10 points in the w-SWCC were selected as initial conditions.By adopting different void ratios,a group of soil-water characteristic curve in the form of the degree of saturation(S-SWCC)can be obtained.Based on Kelvin's capillary law,the S-SWCCs can be converted into a group of PSDFs.In the group of PSDFs,each PSDF represents the geometric pore space in soil corresponding to a given void ratio.From the proposed methodology,it is observed that a bimodal PSDF can be gradually changed into a unimodal PSDF when the soil is compressed.The Chataignier clay is selected as the verification and it shows that the simulation results agree well with the measured results from the mercury intrusion porosimetry(MIP)test.In addition,the discrepancies between both direct measurement data using the MIP test and the indirect estimated results from the proposed method are also discussed.展开更多
We present old and new results about the size function of a set providing simple and complete proofs using basic tools of general topology. For instance, the decomposition of the size function is given and, under the ...We present old and new results about the size function of a set providing simple and complete proofs using basic tools of general topology. For instance, the decomposition of the size function is given and, under the calmness property of a set, the right continuity of the size function with respect to both arguments is established. Finally, a classification of its points of discontinuity is given.展开更多
A theoretical study on oligopeptide chains of glycine-alanine by density functional theory(DFT) is given in this paper. Raman spectra of the oligopeptide chains are examined. The geometric structures, frontier orbit...A theoretical study on oligopeptide chains of glycine-alanine by density functional theory(DFT) is given in this paper. Raman spectra of the oligopeptide chains are examined. The geometric structures, frontier orbital, energy gap, atomic charge distribution, density of states and chemical activity of the side chain are studied at the B3LYP/6-31G(d) level. Results show that, with the number of residues increasing, vibrations of typical functional groups present Raman frequency shift, and the energy gap is gradually reduced. The HOMO and LUMO focus on the amino and carboxyl at the ends of oligopeptides. It is helpful for oligopeptides to self-assemble into chains. In addition, different residues(glycine or alanine) at the ends of chains result in the even-odd effect of orbital energy in the growth process. The size effects of physical and chemical properties only exist when the oligopeptides are shorter, and the phenomenon disappeared as the chain continues to grow.展开更多
In the software engineering literature, it is commonly believed that economies of scale do not occur in case of software Development and Enhancement Projects (D&EP). Their per-unit cost does not decrease but increa...In the software engineering literature, it is commonly believed that economies of scale do not occur in case of software Development and Enhancement Projects (D&EP). Their per-unit cost does not decrease but increase with the growth of such projects product size. Thus this is diseconomies of scale that occur in them. The significance of this phenomenon results from the fact that it is commonly considered to be one of the fundamental objective causes of their low effectiveness. This is of particular significance with regard to Business Software Systems (BSS) D&EP characterized by exceptionally low effectiveness comparing to other software D&EP. Thus the paper aims at answering the following two questions: (1) Do economies of scale really not occur in BSS D&EP? (2) If economies of scale may occur in BSS D&EP, what factors are then promoting them? These issues classify into economics problems of software engineering research and practice.展开更多
Sphere packing is an attractive way to generate high quality mesh. Several algorithms have been proposed in this topic, however these algorithms are not sufficiently fast for large scale problems. The paper presents a...Sphere packing is an attractive way to generate high quality mesh. Several algorithms have been proposed in this topic, however these algorithms are not sufficiently fast for large scale problems. The paper presents an efficient sphere packing algorithm which is much faster and appears to be the most practical among all sphere packing methods presented so far for mesh generation. The algorithm packs spheres inside a domain using advancing front method. High efficiency has resulted from a concept of 4R measure, which localizes all the computations involved in the whole sphere packing process.展开更多
Background:A number of hypotheses and theories,such as the Janzen-Connell hypothesis,have been proposed to explain the natural maintenance of biodiversity in tropical and temperate forest ecosystems.However,to date th...Background:A number of hypotheses and theories,such as the Janzen-Connell hypothesis,have been proposed to explain the natural maintenance of biodiversity in tropical and temperate forest ecosystems.However,to date the details of the processes behind this natural maintenance are still unclear.Recently two new nearest-neighbour characteristics were proposed and in this paper we demonstrate how they can contribute to a better understanding of the ontogenesis of global forest structure from localised neighbourhoods.Methods:We applied the new species and size segregation functions together with appropriate test procedures to four example woodland data sets from China at Daqingshan,Jiaohe,Jiulongshan and Xiaolongshan forest regions.In addition we quantified the morphology of the new characteristics and modelled a neighbourhood allometric coefficient linking the two functions.Results:The results revealed quite different species segregation patterns with both conspecific and heterospecific attraction.We found these to be generally matched by equivalent size segregation patterns of attraction of similar and different sizes.It was straightforward to model the size segregation function from the knowledge of the species segregation function by estimating a neighbourhood allometric coefficient.Conclusions:The new characteristics have helped to quantify the extent and rate of decline of neighbourhood interactions in terms of spatial species and size diversity.Through the allometric neighbourhood coefficient the analysis highlighted once more how closely related species and size segregation are,thus supporting the minglingsize hypothesis.Using both a traditional and a restricted random-labelling test has provided a valuable tool for understanding the exact nature of species-mingling and size-inequality relationships.展开更多
Microstructural features including pore size distribution, cell walls and phase compositions of magnesium oxychloride cement foams(MOCF) with various MgO powders and water mixture ratios were studied. Their infl uen...Microstructural features including pore size distribution, cell walls and phase compositions of magnesium oxychloride cement foams(MOCF) with various MgO powders and water mixture ratios were studied. Their infl uences on compressive strength, water absorption and resistance of MOCF were also discussed in detail. The experimental results indicated that moderate and slight excess MgO powders(MgO/MgCl2 molar ratios from 5.1 to 7) were beneficial to the formation of excellent microstructure of MOCF, but increasing water contents(H2O/MgO mass ratios from 0.9 to 1.29) might result in opposite conclusions. The microstructure of MOCF produced with moderate and slight excess MgO powders could enhance the compressive strength, while serious excess MgO powders addition(MgO/MgCl2 molar ratios = 9) would destroy the cell wall structures, and therefore decrease the strength of the system. Although MOCF produced with excess MgO powders could decrease the water absorption, its softening coefficient was lower than that of the material produced with moderate MgO powders. This might be due to the instability of phase 5, the volume expansion and cracking of cell walls as immersed the sample into water.展开更多
Visual cortical prostheses have the potential to restore partial vision. Still limited by the low-resolution visual percepts provided by visual cortical prostheses, implant wearers can currently only "see" pixelized...Visual cortical prostheses have the potential to restore partial vision. Still limited by the low-resolution visual percepts provided by visual cortical prostheses, implant wearers can currently only "see" pixelized images, and how to obtain the specific brain responses to different pixelized images in the primary visual cortex(the implant area) is still unknown. We conducted a functional magnetic resonance imaging experiment on normal human participants to investigate the brain activation patterns in response to 18 different pixelized images. There were 100 voxels in the brain activation pattern that were selected from the primary visual cortex, and voxel size was 4 mm × 4 mm × 4 mm. Multi-voxel pattern analysis was used to test if these 18 different brain activation patterns were specific. We chose a Linear Support Vector Machine(LSVM) as the classifier in this study. The results showed that the classification accuracies of different brain activation patterns were significantly above chance level, which suggests that the classifier can successfully distinguish the brain activation patterns. Our results suggest that the specific brain activation patterns to different pixelized images can be obtained in the primary visual cortex using a 4 mm × 4 mm × 4 mm voxel size and a 100-voxel pattern.展开更多
This paper investigates spatial and temporal distributions of the microphysical properties of precipitating stratiform clouds based on Doppler spectra of rain particles observed by an L-band profiler radar.The retriev...This paper investigates spatial and temporal distributions of the microphysical properties of precipitating stratiform clouds based on Doppler spectra of rain particles observed by an L-band profiler radar.The retrieval of raindrop size distributions(RSDs) is accomplished through eliminating vertical air motion and isolating the terminal fall velocity of raindrops in the observed Doppler velocity spectrum.The microphysical properties of raindrops in a broad stratiform region with weak convective cells are studied using data collected from a 1320-MHz wind profiler radar in Huayin,Shaanxi Province on 14 May 2009.RSDs and gamma function parameters are retrieved at altitudes between 700 and 3000 m above the surface,below a melting layer.It is found that the altitude of the maximum number of raindrops was closely related to the surface rain rate.The maximum number of large drops was observed at lower altitudes earlier in the precipitation event but at higher altitudes in later periods,suggesting decreases in the numbers of large and medium size raindrops.These decreases may have been caused by the breakup of larger drops and evaporation of smaller drops as they fell.The number of medium size drops decreased with increasing altitude.The relationship between reflectivity and liquid water content during this precipitation event was Z = 1.69×10~4M^(1.5),and the relationship between reflectivity and rain intensity was Z = 256I^(1.4).展开更多
文摘The use of functional size measurement(FSM) methods in software development organizations is growing during the years. Also, object oriented(OO) techniques have become quite a standard to design the software and, in particular, Use Cases is one of the most used techniques to specify functional requirements. Main FSM methods do not include specific rules to measure the software functionality from its Use Cases analysis. To deal with this issue some other methods like Kramer's functional measurement method have been developed. Therefore, one of the main issues for those organizations willing to use OO functional measurement method in order to facilitate the use cases count procedure is how to convert their portfolio functional size from the previously adopted FSM method towards the new method. The objective of this research is to find a statistical relationship for converting the software functional size units measured by the International Function Point Users Group(IFPUG) function point analysis(FPA) method into Kramer-Smith's use cases points(UCP) method and vice versa. Methodologies for a correct data gathering are proposed and results obtained are analyzed to draw the linear and non-linear equations for this correlation. Finally, a conversion factor and corresponding conversion intervals are given to establish the statistical relationship.
基金Supported by the National Sci-Tech Support Plan(2015BAD21B05)China Scholarship Council(201408320127)
文摘Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosity and surface characteristics of porous materials. To identify suitable adsorbents, we need a reliable computational tool for pore characterization and, subsequently, quantitative prediction of the adsorption behavior. Within the framework of adsorption integral equation(AIE), the pore-size distribution(PSD) is sensitive to the adopted theoretical models and numerical algorithms through isotherm fitting. In recent years, the classical density functional theory(DFT) has emerged as a common choice to describe adsorption isotherms for AIE kernel construction. However,rarely considered is the accuracy of the mean-field approximation(MFA) commonly used in commercial software. In this work, we calibrate four versions of DFT methods with grand canonical Monte Carlo(GCMC) molecular simulation for the adsorption of CH_4 and CO_2 gas in slit pores at 298 K with the pore width varying from 0.65 to 5.00 nm and pressure from 0.2 to 2.0 MPa. It is found that a weighted-density approximation proposed by Yu(WDA-Yu) is more accurate than MFA and other non-local DFT methods. In combination with the trapezoid discretization of AIE, the WDA-Yu method provides a faithful representation of experimental data, with the accuracy and stability improved by 90.0% and 91.2%, respectively, in comparison with the corresponding results from MFA for fitting CO_2 isotherms. In particular, those distributions in the feature pore width range(FPWR)are proved more representative for the pore-size analysis. The new theoretical procedure for pore characterization has also been tested with the methane adsorption capacity in seven activated carbon samples.
文摘In order to obtain an indirect estimation method of the pore size distribution function(PSDF)for a deformable soil,both the soil-water characteristic curve in the form of gravimetric water content(w-SWCC)and the shrinkage curve(SC)are used as the input parameters.The w-SWCC defines the relationship between the gravimetric water content and soil suction.The SC illustrates the variation of the void ratio with respect to different water contents.10 points in the w-SWCC were selected as initial conditions.By adopting different void ratios,a group of soil-water characteristic curve in the form of the degree of saturation(S-SWCC)can be obtained.Based on Kelvin's capillary law,the S-SWCCs can be converted into a group of PSDFs.In the group of PSDFs,each PSDF represents the geometric pore space in soil corresponding to a given void ratio.From the proposed methodology,it is observed that a bimodal PSDF can be gradually changed into a unimodal PSDF when the soil is compressed.The Chataignier clay is selected as the verification and it shows that the simulation results agree well with the measured results from the mercury intrusion porosimetry(MIP)test.In addition,the discrepancies between both direct measurement data using the MIP test and the indirect estimated results from the proposed method are also discussed.
文摘We present old and new results about the size function of a set providing simple and complete proofs using basic tools of general topology. For instance, the decomposition of the size function is given and, under the calmness property of a set, the right continuity of the size function with respect to both arguments is established. Finally, a classification of its points of discontinuity is given.
基金Supported by the National Natural Science Foundation of China(No.60878063)the Program from Traditional Chinese Medicine Bureau of Guangdong Province(No.2008233)
文摘A theoretical study on oligopeptide chains of glycine-alanine by density functional theory(DFT) is given in this paper. Raman spectra of the oligopeptide chains are examined. The geometric structures, frontier orbital, energy gap, atomic charge distribution, density of states and chemical activity of the side chain are studied at the B3LYP/6-31G(d) level. Results show that, with the number of residues increasing, vibrations of typical functional groups present Raman frequency shift, and the energy gap is gradually reduced. The HOMO and LUMO focus on the amino and carboxyl at the ends of oligopeptides. It is helpful for oligopeptides to self-assemble into chains. In addition, different residues(glycine or alanine) at the ends of chains result in the even-odd effect of orbital energy in the growth process. The size effects of physical and chemical properties only exist when the oligopeptides are shorter, and the phenomenon disappeared as the chain continues to grow.
文摘In the software engineering literature, it is commonly believed that economies of scale do not occur in case of software Development and Enhancement Projects (D&EP). Their per-unit cost does not decrease but increase with the growth of such projects product size. Thus this is diseconomies of scale that occur in them. The significance of this phenomenon results from the fact that it is commonly considered to be one of the fundamental objective causes of their low effectiveness. This is of particular significance with regard to Business Software Systems (BSS) D&EP characterized by exceptionally low effectiveness comparing to other software D&EP. Thus the paper aims at answering the following two questions: (1) Do economies of scale really not occur in BSS D&EP? (2) If economies of scale may occur in BSS D&EP, what factors are then promoting them? These issues classify into economics problems of software engineering research and practice.
基金the National Natural Science Foundation of China (10602002 and 10772005)
文摘Sphere packing is an attractive way to generate high quality mesh. Several algorithms have been proposed in this topic, however these algorithms are not sufficiently fast for large scale problems. The paper presents an efficient sphere packing algorithm which is much faster and appears to be the most practical among all sphere packing methods presented so far for mesh generation. The algorithm packs spheres inside a domain using advancing front method. High efficiency has resulted from a concept of 4R measure, which localizes all the computations involved in the whole sphere packing process.
基金partly supported by the Guangxi Innovation Driven Development Project(No.AA17204087-8)funded by the National Natural Science Foundation of China(project No.31670640)。
文摘Background:A number of hypotheses and theories,such as the Janzen-Connell hypothesis,have been proposed to explain the natural maintenance of biodiversity in tropical and temperate forest ecosystems.However,to date the details of the processes behind this natural maintenance are still unclear.Recently two new nearest-neighbour characteristics were proposed and in this paper we demonstrate how they can contribute to a better understanding of the ontogenesis of global forest structure from localised neighbourhoods.Methods:We applied the new species and size segregation functions together with appropriate test procedures to four example woodland data sets from China at Daqingshan,Jiaohe,Jiulongshan and Xiaolongshan forest regions.In addition we quantified the morphology of the new characteristics and modelled a neighbourhood allometric coefficient linking the two functions.Results:The results revealed quite different species segregation patterns with both conspecific and heterospecific attraction.We found these to be generally matched by equivalent size segregation patterns of attraction of similar and different sizes.It was straightforward to model the size segregation function from the knowledge of the species segregation function by estimating a neighbourhood allometric coefficient.Conclusions:The new characteristics have helped to quantify the extent and rate of decline of neighbourhood interactions in terms of spatial species and size diversity.Through the allometric neighbourhood coefficient the analysis highlighted once more how closely related species and size segregation are,thus supporting the minglingsize hypothesis.Using both a traditional and a restricted random-labelling test has provided a valuable tool for understanding the exact nature of species-mingling and size-inequality relationships.
基金Funded by the National Natural Science Foundation of China(No.51478370)the EPSRC-NSFC Joint Research Projec(No.51461135005)
文摘Microstructural features including pore size distribution, cell walls and phase compositions of magnesium oxychloride cement foams(MOCF) with various MgO powders and water mixture ratios were studied. Their infl uences on compressive strength, water absorption and resistance of MOCF were also discussed in detail. The experimental results indicated that moderate and slight excess MgO powders(MgO/MgCl2 molar ratios from 5.1 to 7) were beneficial to the formation of excellent microstructure of MOCF, but increasing water contents(H2O/MgO mass ratios from 0.9 to 1.29) might result in opposite conclusions. The microstructure of MOCF produced with moderate and slight excess MgO powders could enhance the compressive strength, while serious excess MgO powders addition(MgO/MgCl2 molar ratios = 9) would destroy the cell wall structures, and therefore decrease the strength of the system. Although MOCF produced with excess MgO powders could decrease the water absorption, its softening coefficient was lower than that of the material produced with moderate MgO powders. This might be due to the instability of phase 5, the volume expansion and cracking of cell walls as immersed the sample into water.
基金supported by the National Natural Science Foundation of China,No.31070758,31271060the Natural Science Foundation of Chongqing in China,No.cstc2013jcyj A10085
文摘Visual cortical prostheses have the potential to restore partial vision. Still limited by the low-resolution visual percepts provided by visual cortical prostheses, implant wearers can currently only "see" pixelized images, and how to obtain the specific brain responses to different pixelized images in the primary visual cortex(the implant area) is still unknown. We conducted a functional magnetic resonance imaging experiment on normal human participants to investigate the brain activation patterns in response to 18 different pixelized images. There were 100 voxels in the brain activation pattern that were selected from the primary visual cortex, and voxel size was 4 mm × 4 mm × 4 mm. Multi-voxel pattern analysis was used to test if these 18 different brain activation patterns were specific. We chose a Linear Support Vector Machine(LSVM) as the classifier in this study. The results showed that the classification accuracies of different brain activation patterns were significantly above chance level, which suggests that the classifier can successfully distinguish the brain activation patterns. Our results suggest that the specific brain activation patterns to different pixelized images can be obtained in the primary visual cortex using a 4 mm × 4 mm × 4 mm voxel size and a 100-voxel pattern.
基金Supported by the National Natural Science Foundation of China(41075023)China Meteorological Administration Special Public Welfare Research Fund(GYHY200906039 and GYHY201206042)State Key Laboratory of Severe Weather ResearchFund
文摘This paper investigates spatial and temporal distributions of the microphysical properties of precipitating stratiform clouds based on Doppler spectra of rain particles observed by an L-band profiler radar.The retrieval of raindrop size distributions(RSDs) is accomplished through eliminating vertical air motion and isolating the terminal fall velocity of raindrops in the observed Doppler velocity spectrum.The microphysical properties of raindrops in a broad stratiform region with weak convective cells are studied using data collected from a 1320-MHz wind profiler radar in Huayin,Shaanxi Province on 14 May 2009.RSDs and gamma function parameters are retrieved at altitudes between 700 and 3000 m above the surface,below a melting layer.It is found that the altitude of the maximum number of raindrops was closely related to the surface rain rate.The maximum number of large drops was observed at lower altitudes earlier in the precipitation event but at higher altitudes in later periods,suggesting decreases in the numbers of large and medium size raindrops.These decreases may have been caused by the breakup of larger drops and evaporation of smaller drops as they fell.The number of medium size drops decreased with increasing altitude.The relationship between reflectivity and liquid water content during this precipitation event was Z = 1.69×10~4M^(1.5),and the relationship between reflectivity and rain intensity was Z = 256I^(1.4).