Particle size distribution of coarse aggregates through mechanical sieving gives results in terms of cumu- lative mass percent. But digital image processing generated size distribution of particles, while being fast a...Particle size distribution of coarse aggregates through mechanical sieving gives results in terms of cumu- lative mass percent. But digital image processing generated size distribution of particles, while being fast and accurate, is often expressed in terms of area function or number of particles. In this paper, a mass model is developed which converts the image obtained size distribution to mass-wise distribution, mak- ing it readily comparable to mechanical sieving data. The concept of weight/particle ratio is introduced for mass reconstruction from 2D images of particle aggregates. Using this mass model, the effects of several particle shape parameters （such as major axis, minor axis, and equivalent diameter） on sieve-size of the particles is studied. It is shown that the sieve-size of a particle strongly depend upon the shape param- eters, 91% of its variation being explained by major axis, minor axis, bounding box length and equivalent diameter. Furthermore, minor axis gives an overall accurate estimate of particle sieve-size, error in mean size （D-50） being just 0.4%. However, sieve-size of smaller particles （〈20 ram） strongly depends upon the length of the smaller arm of the bounding box enclosing them and sieve-sizes of larger particles （〉20 mm） are highly correlated to their equivalent diameters. Multiple linear regression analysis has been used to generate overall mass-wise particle size distribution, considering the influences of all these shape parameters on particle sieve-size. Multiple linear regression generated overall mass-wise particle size distribution shows a strong correlation with sieve generated data. The adjusted R-square value of the regression analysis is found to be 99 percent （w.r,t cumulative frequency）. The method proposed in this paper provides a time-efficient way of producing accurate （up to 99%） mass-wise PSD using digital image processing and it can be used effectively to renlace the mechanical sieving.展开更多
This sedimentary is from a largest basin of Afghanistan,which covers an area of 9772 km2.It is located about 80 km,at west side of Kabul.In this research,we studied different types of heavy and light minerals,gravel a...This sedimentary is from a largest basin of Afghanistan,which covers an area of 9772 km2.It is located about 80 km,at west side of Kabul.In this research,we studied different types of heavy and light minerals,gravel analysis in river sediments.Logar River is core stream flowing over basin,it carries diverse masses of sediments from dissimilar parts of surroding montians.Further,in the months of summer while snowmelting is started,transfer diverse materials and cause different traces to be made.Area of basin is enclosed by mountain range and separated into two sections,majore part is Khawat Olya and second one is Khawat Sufla.The main aim of study is to characterize different sizes and types of minerals in river load for the previous geological periods.This research is therefore essential to explain different sizes and type of minerals in river sediments,which is no any study has been conducted in the study area.This study found out that the category of sediments is related to the parental materials that are placed in the close mountains such as;gneiss,limestone,and granite,dissimilar varities of conglomerate,slate,schist,reefs,conglomerate and sandston.展开更多
Pearl millet at various moisture content （6.2, 9.4 and 12.3%, d.b.） and feed rates （3, 6 and 9 kg/h） was ground using hammer mill and its physical properties viz. arithmetic mean diameter, geometric mean diameter,...Pearl millet at various moisture content （6.2, 9.4 and 12.3%, d.b.） and feed rates （3, 6 and 9 kg/h） was ground using hammer mill and its physical properties viz. arithmetic mean diameter, geometric mean diameter, thousand grain weight, aspect ratio, specific surface area, surface area and bulk density were studied. Sieve analysis results showed that the increase in moisture content produced more medium sized particles with decreased percent weight retained in pan. Bond＇s work index, Kick＇s constant and average particle size were increased with the decrease in total surface area at higher moisture levels. The highest energy （2.34 KWh/kg） was consumed for 12.3% moisture content. Various grinding characteristics were significantly affected by moisture content and feed rate either individually or in combination and correlated in terms of Bond＇s work index, Kick＇s constant, total surface area, average particle size, effectiveness of milling and bulk density. Milling loss was found to be higher at lower moisture level and decreased with the increase of moisture content as well as feed rate. The loose and compact bulk density was ranged between 46.8-199.5 kg m^-3and 53.5-254.1 kg m^-3, respectively among the entire sieve fractions. Water absorption capacity increased with the decrease in particle size,展开更多
The amount of fine material available in the soil is significant in Atterberg limits and methylene blue tests. In the context of Atterberg limits, increased amount of clay minerals contained in the soil increases liqu...The amount of fine material available in the soil is significant in Atterberg limits and methylene blue tests. In the context of Atterberg limits, increased amount of clay minerals contained in the soil increases liquid and plastic limit values;however, increasing sand content reduces the moisture content reducing the water retention capacity of the soil which in return reduces the plasticity index (PI) value. In the case of methylene blue test, which is used to specify the quality of the amount of fine material, existence of clay in the medium increases the pollution level of the sand and the amount of methylene solution (V1) used. In this study, soil classes were determined and pollution rates were identified with Atterberg limits, pycnometer, sieve analysis, hydrometer analysis and methylene blue tests conducted on 11 different natural soil samples collected from different regions. From the data obtained, first the relationship between PI and methylene blue (MB) was examined and was evaluated according to the results of the “single regression” method. Furthermore, the other coefficient of uniformity (Cu), coefficient of graduation (Cc), unit weight of soils (γs) parameters obtained from experimental studies were also subjected to “multiple regression analysis” in order to reveal their impact on the MB and this impact was confirmed taking both statistical analyses into account.展开更多
This paper experimentally investigates the namely, normal density concrete and structural low-density energy absorption potential of two types of concrete floors, concrete, containing secondary （shrinkage and tempera...This paper experimentally investigates the namely, normal density concrete and structural low-density energy absorption potential of two types of concrete floors, concrete, containing secondary （shrinkage and temperature） reinforcements. The test program considered the following secondary reinforcements： 1） traditional welded-wire steel mesh, 2） steel fiber and 3） poly composite fiber. To estimate the extent to which crushing of floor slab materials would help absorb energy, a series of concrete penetration tests employing patch loading was undertaken on scaled down model slabs. Each concrete-secondary reinforcement combination considered slabs of 50 mm in depth with square plan dimensions ranging from 50 to 500 mm, resulting in a total of 30 test specimens. The first part of the paper discusses the test specimens, the test setup, and the test procedure. The second part of the paper presents the experimental results and establishes the energy absorption of different concrete- secondary reinforcement combinations. Sieve analysis results of the crushed specimens were used to derive a ＂work index＂ value that relates the pulverized particle size distributions to energy inputs. The work index values of concrete-secondary reinforcement systems can be used to assess the energy dissipation potential associated with such floor slabs in buildings undergoing progressive collapse. The results indicate that floors with secondary reinforcements could play an important role in helping arrest global progressive collapse.展开更多
基金Indian Institute of Technology,Kharagpur in India for supporting this work
文摘Particle size distribution of coarse aggregates through mechanical sieving gives results in terms of cumu- lative mass percent. But digital image processing generated size distribution of particles, while being fast and accurate, is often expressed in terms of area function or number of particles. In this paper, a mass model is developed which converts the image obtained size distribution to mass-wise distribution, mak- ing it readily comparable to mechanical sieving data. The concept of weight/particle ratio is introduced for mass reconstruction from 2D images of particle aggregates. Using this mass model, the effects of several particle shape parameters （such as major axis, minor axis, and equivalent diameter） on sieve-size of the particles is studied. It is shown that the sieve-size of a particle strongly depend upon the shape param- eters, 91% of its variation being explained by major axis, minor axis, bounding box length and equivalent diameter. Furthermore, minor axis gives an overall accurate estimate of particle sieve-size, error in mean size （D-50） being just 0.4%. However, sieve-size of smaller particles （〈20 ram） strongly depends upon the length of the smaller arm of the bounding box enclosing them and sieve-sizes of larger particles （〉20 mm） are highly correlated to their equivalent diameters. Multiple linear regression analysis has been used to generate overall mass-wise particle size distribution, considering the influences of all these shape parameters on particle sieve-size. Multiple linear regression generated overall mass-wise particle size distribution shows a strong correlation with sieve generated data. The adjusted R-square value of the regression analysis is found to be 99 percent （w.r,t cumulative frequency）. The method proposed in this paper provides a time-efficient way of producing accurate （up to 99%） mass-wise PSD using digital image processing and it can be used effectively to renlace the mechanical sieving.
文摘This sedimentary is from a largest basin of Afghanistan,which covers an area of 9772 km2.It is located about 80 km,at west side of Kabul.In this research,we studied different types of heavy and light minerals,gravel analysis in river sediments.Logar River is core stream flowing over basin,it carries diverse masses of sediments from dissimilar parts of surroding montians.Further,in the months of summer while snowmelting is started,transfer diverse materials and cause different traces to be made.Area of basin is enclosed by mountain range and separated into two sections,majore part is Khawat Olya and second one is Khawat Sufla.The main aim of study is to characterize different sizes and types of minerals in river load for the previous geological periods.This research is therefore essential to explain different sizes and type of minerals in river sediments,which is no any study has been conducted in the study area.This study found out that the category of sediments is related to the parental materials that are placed in the close mountains such as;gneiss,limestone,and granite,dissimilar varities of conglomerate,slate,schist,reefs,conglomerate and sandston.
文摘Pearl millet at various moisture content （6.2, 9.4 and 12.3%, d.b.） and feed rates （3, 6 and 9 kg/h） was ground using hammer mill and its physical properties viz. arithmetic mean diameter, geometric mean diameter, thousand grain weight, aspect ratio, specific surface area, surface area and bulk density were studied. Sieve analysis results showed that the increase in moisture content produced more medium sized particles with decreased percent weight retained in pan. Bond＇s work index, Kick＇s constant and average particle size were increased with the decrease in total surface area at higher moisture levels. The highest energy （2.34 KWh/kg） was consumed for 12.3% moisture content. Various grinding characteristics were significantly affected by moisture content and feed rate either individually or in combination and correlated in terms of Bond＇s work index, Kick＇s constant, total surface area, average particle size, effectiveness of milling and bulk density. Milling loss was found to be higher at lower moisture level and decreased with the increase of moisture content as well as feed rate. The loose and compact bulk density was ranged between 46.8-199.5 kg m^-3and 53.5-254.1 kg m^-3, respectively among the entire sieve fractions. Water absorption capacity increased with the decrease in particle size,
文摘The amount of fine material available in the soil is significant in Atterberg limits and methylene blue tests. In the context of Atterberg limits, increased amount of clay minerals contained in the soil increases liquid and plastic limit values;however, increasing sand content reduces the moisture content reducing the water retention capacity of the soil which in return reduces the plasticity index (PI) value. In the case of methylene blue test, which is used to specify the quality of the amount of fine material, existence of clay in the medium increases the pollution level of the sand and the amount of methylene solution (V1) used. In this study, soil classes were determined and pollution rates were identified with Atterberg limits, pycnometer, sieve analysis, hydrometer analysis and methylene blue tests conducted on 11 different natural soil samples collected from different regions. From the data obtained, first the relationship between PI and methylene blue (MB) was examined and was evaluated according to the results of the “single regression” method. Furthermore, the other coefficient of uniformity (Cu), coefficient of graduation (Cc), unit weight of soils (γs) parameters obtained from experimental studies were also subjected to “multiple regression analysis” in order to reveal their impact on the MB and this impact was confirmed taking both statistical analyses into account.
文摘This paper experimentally investigates the namely, normal density concrete and structural low-density energy absorption potential of two types of concrete floors, concrete, containing secondary （shrinkage and temperature） reinforcements. The test program considered the following secondary reinforcements： 1） traditional welded-wire steel mesh, 2） steel fiber and 3） poly composite fiber. To estimate the extent to which crushing of floor slab materials would help absorb energy, a series of concrete penetration tests employing patch loading was undertaken on scaled down model slabs. Each concrete-secondary reinforcement combination considered slabs of 50 mm in depth with square plan dimensions ranging from 50 to 500 mm, resulting in a total of 30 test specimens. The first part of the paper discusses the test specimens, the test setup, and the test procedure. The second part of the paper presents the experimental results and establishes the energy absorption of different concrete- secondary reinforcement combinations. Sieve analysis results of the crushed specimens were used to derive a ＂work index＂ value that relates the pulverized particle size distributions to energy inputs. The work index values of concrete-secondary reinforcement systems can be used to assess the energy dissipation potential associated with such floor slabs in buildings undergoing progressive collapse. The results indicate that floors with secondary reinforcements could play an important role in helping arrest global progressive collapse.
