This paper describes an investigation of active bit vibration on the penetration mechanisms and bit-rock interaction for drilling with a diamond impregnated coring bit.A series of drill-off tests(DOTs)were conducted w...This paper describes an investigation of active bit vibration on the penetration mechanisms and bit-rock interaction for drilling with a diamond impregnated coring bit.A series of drill-off tests(DOTs)were conducted where the drilling rate-of-penetration(ROP)was measured at a series of step-wise increasing static bit thrusts or weight-on-bits(WOBs).Two active DOTs were conducted by applying 60 Hz axial vibration at the bit-rock interface using an electromagnetic vibrating table mounted underneath the drilling samples,and a passive DOT was conducted where the bit was allowed to vibrate naturally with lower amplitude due to the compliance of the drilling sample mountings.During drilling,an acoustic emission(AE)system was used to record the AE signals generated by the diamond cutter penetration and the cuttings were collected for grain size analysis.The instrumented drilling system recorded the dynamic motions of the bit-rock interface using a laser displacement sensor,a load cell,and an LVDT(linear variable differential transformer)recorded the dynamic WOB and the ROP,respectively.Calibration with the drilling system showed that rotary speed was approximately the same at any given WOB,facilitating comparison of the results at the same WOB.Analysis of the experimental results shows that the ROP of the bit at any given WOB increased with higher amplitude of axial bit-rock vibration,and the drill cuttings increased in size with a higher ROP.Spectral analysis of the AEs indicated that the higher ROP and larger cutting size were correlated with a higher AE energy and a lower AE frequency.This indicated that larger fractures were being created to generate larger cutting size.Overall,these results indicate that a greater magnitude of axial bit-rock vibration produces larger fractures and generates larger cuttings which,at the same rotary speed,results in a higher ROP.展开更多
An important index to evaluate the process efficiency of coal preparation is the mineral liberation degree of pulverized coal,which is greatly influenced by the particle size and shape distribution acquired by image s...An important index to evaluate the process efficiency of coal preparation is the mineral liberation degree of pulverized coal,which is greatly influenced by the particle size and shape distribution acquired by image segmentation.However,the agglomeration effect of fine powders and the edge effect of granular images caused by scanning electron microscopy greatly affect the precision of particle image segmentation.In this study,we propose a novel image segmentation method derived from mask regional convolutional neural network based on deep learning for recognizing fine coal powders.Firstly,an atrous convolution is introduced into our network to learn the image feature of multi-sized powders,which can reduce the missing segmentation of small-sized agglomerated particles.Then,a new mask loss function combing focal loss and dice coefficient is used to overcome the false segmentation caused by the edge effect.The final comparative experimental results show that our method achieves the best results of 94.43%and 91.44%on AP50 and AP75 respectively among the comparison algorithms.In addition,in order to provide an effective method for particle size analysis of coal particles,we study the particle size distribution of coal powders based on the proposed image segmentation method and obtain a good curve relationship between cumulative mass fraction and particle size.展开更多
Grain size analysis is a common method in the study of sedimentology. For the consolidated sedimentary rocks, the traditional methods are rock slice observation and image analysis. In recent years, laser particle size...Grain size analysis is a common method in the study of sedimentology. For the consolidated sedimentary rocks, the traditional methods are rock slice observation and image analysis. In recent years, laser particle size analyzer is used widely in particle size analysis of sedimentary rock. Unlike the pretreatment of loose samples, the rock samples must be crushed, added acid to wipe out cement, and washed. However, in the step of washing, most of the fines component（less than 63 μm） in the suspended state should be inevitably lost. It will significantly affect the accuracy of particle size analysis, especially for siltstone. This paper presents a siltstone sample pretreatment method which core step is washing acid by centrifuge. Compared with traditional decantation method, the results show that the median particle size reduced 33.2 μm on average. Compared with the precipitation method which is commonly used for handling loose samples, the change of solid-liquid separation time is from 12 h to 10 min, while the average reduction of median particle size is about 15 μm. The grain size value corresponded to the cumulative volume of 10%/90% reduced 2.5 μm/20.3 μm on average. The percentage of the clay component less than 2 μm increased 2.88% on average. The fine particle（2–4 μm） and silt component（4–63 μm） increased 1.71% and 5.56% on average. Based on this method, two kinds of similar lacustrine siltstone were analyzed. They are tempestite and beach bar which are difficult to identify in the Lijin sub-depression, Dongying depression, Shengli oilfield, China. The final grain-size probability plot of tempestite is the type of “one saltation component and three suspension components”. The content of suspension components can reach to 80%–90%. The beach bar is the type of “one saltation component and two suspension components”. The content of suspension components can reach to 40%–45%. They both have the characteristics of high slope which means well sorting. But they can be distinguished based on the suspension sedimentary characteristics which were preserved by maximum degree in this kind of sample pretreatment method.展开更多
The average size of the sand of dune in the vicinity of Tumen River is 0.12～0.30 mm, its standard deviation is 0.45～0.99 φ and the frequency cumulative distribution curve is divided into the single peak and the dou...The average size of the sand of dune in the vicinity of Tumen River is 0.12～0.30 mm, its standard deviation is 0.45～0.99 φ and the frequency cumulative distribution curve is divided into the single peak and the double peak. The Ski of the single peak is negative and the double peak is positive. There are two different areas in the plot of the Ski versus σi* It is shown that the sedimentary environment of the dunes is neritic deposit by the expressions of the grain-size parameters. All of the characters show that the sand dunes in Estuary of Tumen River may be the dunes of sea facies which were changed again by weathering and fluvialaction.展开更多
To reveal the sediment transporting mechanism between the abandoned Huanghe River （Yellow River） Delta and radial sand ridges, “End Member” Model and grain size trend analysis have been employed to separate the “...To reveal the sediment transporting mechanism between the abandoned Huanghe River （Yellow River） Delta and radial sand ridges, “End Member” Model and grain size trend analysis have been employed to separate the “dynamic populations” in the surficial sediment particle spectra and to determine the possible sediment transporting pathway. The results reveal four “dynamic subpopulations”（EM1 to EM4） and two reverse sediment transporting directions： a northward transport tend from the radial sand ridges to mud patch, and a southward transport trend in deep water area outside the mud patch. Combined with the published hydrodynamic information, the transporting mechanism of dynamic populations has been discussed, and the main conclusion is that the transporting of finer subpopulations EM1 and EM2 is controlled by the “anticlockwise residual current circulation” forming during tidal cycle, which favor a northward transporting trend and the forming of mud patch on the north of radial sand ridges, while the transporting of coarser EM3 is mainly controlled by wind driven drift in winter, which favors a southward transporting direction.展开更多
There are 71 surface sediment samples collected from the eastern Beibu Gulf. The moment parameters （i.e. mean size, sorting and skewness） were obtained after applying grain size analysis. The geostatistical analysis...There are 71 surface sediment samples collected from the eastern Beibu Gulf. The moment parameters （i.e. mean size, sorting and skewness） were obtained after applying grain size analysis. The geostatistical analysis was then applied to study the spatial autocorrelation for these parameters; while range, a parameter in the semivariogram that meters the scale of spatial autocorrelation, was estimated. The results indicated that the range for sorting coefficient was physically meaningful. The trend vectors calculated from grain size trend analysis model were consistent with the annual ocean circulation patterns and sediment transport rates according to previous studies. Therefore the range derived from the semivariogram of mean size can be used as the characteristic distance in the grain size trend analysis, which may remove the bias caused by the traditional way of basing on experiences or testing methods to get the characteristic distance. Hence the results from geostatistical analysis can also offer useful information for the determination of sediment sampling density in the future field work.展开更多
Plenty of high-resolution paleoclimate investigations of the last thousand years were carried out to potentially predict future climate changes.Mountainous ombrotrophic peatland is one of the best recorders for high-r...Plenty of high-resolution paleoclimate investigations of the last thousand years were carried out to potentially predict future climate changes.Mountainous ombrotrophic peatland is one of the best recorders for high-resolution paleoclimate studies in the forest area.Grain size analysis was carried out on ombrotrophic peat profile in the eastern mountainous region of Jilin Province,Northeast China.The peat profile lasts the past 2000 a by four radiocarbon(AMS14C)ages.The results showed that the inorganic minerals in the peat profile are mainly silt,with some contribution from clay and a minor amount of sand,which are mainly due to wind dust and suspended transportation.Two paleoclimate stages are found in this peat profile by phytolith analysis,peat cellulose isotope research and historical documents:ca.45–1550 AD,relatively cold period;ca.1550 AD–present,relatively warm period.This finding is important for the initial study of paleoclimatic changes over the last 2000 a in the mountainous area of eastern mountainous area,Jilin Province,Northeast China.展开更多
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
Further geometric morphometric analysis of the genus Eysarcoris was done based on the former studies to classified the nine Eysarcoris species from China. In this study, six characters, such as forewing, hindwing, pyg...Further geometric morphometric analysis of the genus Eysarcoris was done based on the former studies to classified the nine Eysarcoris species from China. In this study, six characters, such as forewing, hindwing, pygophore, head, pronotum and scutellum, were selected to investigate the shape variation of Eysarcoris. Significant divergence in the shapes of the six characters was observed among the species（p 〈 0.05）. For all methods, phenetic similarity based on the six characters agrees with the current status of the genus. The cluster analysis of eight species are consistent with the traditional morphological studies. CVA analysis also shows that the values of the six characters are not equal in taxonomy. Pygophore, forewing, hindwing and pronotum play more important roles in the classification.展开更多
The Co-based catalysts were prepared with different cobalt acetate solutions.Effects of pH value were studied deeply on Fischer–Tropsch synthesis(FTS)through a semi-batch reactor.Among all impregnation solutions(wate...The Co-based catalysts were prepared with different cobalt acetate solutions.Effects of pH value were studied deeply on Fischer–Tropsch synthesis(FTS)through a semi-batch reactor.Among all impregnation solutions(water,butanol,amyl alcohol,acetic acid,nitric acid and ammonium nitrate),the catalyst prepared by NH4NO3solution showed the highest catalytic activity due to its small particle size and high reduction degree.However,the catalyst with the smallest particle size derived from water as impregnation solution exhibited low activity as well as high methane selectivity since it was difficult to be reduced and inactive in FTS.According to FT-IR spectra results,the low intensity of absorbed CO on the catalyst prepared from water solution resulted in low FTS activity.Whereas,the high activity of catalysts prepared from NH4NO3solution could be explained by the high intensity of absorbed CO on the catalysts.The cobalt species on the catalysts prepared under lower pH conditions exhibited smaller particle size distribution as well as lower CO conversion than those prepared at higher pH value.展开更多
Application of light-weight drilling fluids is essential to develop depleted hydrocarbon reservoirs.Recently,colloidal gas aphron(CGA)-based fluids have been introduced for such applications due to their ability in co...Application of light-weight drilling fluids is essential to develop depleted hydrocarbon reservoirs.Recently,colloidal gas aphron(CGA)-based fluids have been introduced for such applications due to their ability in controlling fluid losses.In this work,a comprehensive experimental study was performed to choose the best formulation for CGA fluids by implementing static stability tests,rheological behavior measurements,and bubble size analyses of CGAs.Xanthan gum polymer and sodium dodecyl benzene sulfonate(SDBS),an anionic surfactant,and cetyl trimethyl ammonium bromide(CTAB),a cationic surfactant,were utilized to prepare CGAs.For the range of experiments conducted,the performance of CGA fluids prepared with SDBS was improved by increasing the polymer and surfactant concentrations.However,for CTAB,it was improved by an increase in the polymer concentration and a decrease in the surfactant concentration.The formation of white,long hair-like precipitates observed at high levels of CTAB caused CGA fluid to become rapidly unstable.Also,it was observed that the size of CGAs was significantly influenced by the polymer and surfactant concentrations.The most stable bubbles were formed at 6.86 g/L of polymer concentration.The results of this study provide insights into appropriate formulation for CGA-based fluids which could be potentially applicable in drilling operations.展开更多
The well-known Three Gorges Dam(TGD) within the Yangtze catchment launched its operation in 2003. The effect of the TGD operation on the sediment size on the East China Sea shelf is rarely known. High resolution(0.5 c...The well-known Three Gorges Dam(TGD) within the Yangtze catchment launched its operation in 2003. The effect of the TGD operation on the sediment size on the East China Sea shelf is rarely known. High resolution(0.5 cm sampling) grain size analysis and 137 Cs and 210 Pb dating of the DH8-1 core were conducted with core collected from the distal part of a main sink for the modern Yangtze sediment entering the sea, the Min-Zhe Coastal Mud Deposits(MZCMD) on the inner East China Sea shelf. The 137 Cs dating results show that the core DH8-1 formed during 1946–2012 with a mean deposition rate of 0.65 cm yr^(-1), indicating that the 0.5 cm sampling for grain size analysis in this local area could reflect environmental changes generally on a one-year time scale. The mean grain size of DH8-1 core sediment that deposited after 2003 is significantly larger than that deposited during 1988–2002. After ruling out other possible factors, we infer that the sediment coarsening of DH8-1 core after 2003 is attributed to the TGD operation which causes the erosion of the Yangtze subaqueous delta. Specifically, the TGD operation significantly intensifies the declining trend of the Yangtze sediment loads to the sea despite no decreased water discharge, which results in extensive erosion of the Yangtze subaqueous delta. The relatively coarse sediment of the subaqueous delta is eroded and resuspended by ocean dynamics and then transported by coastal current, finally depositing on the MZCMD area. In addition, the general sediment fining of core DH8-1 that deposited during 1988–2002, comparing with 1946–1987, is mainly caused by dam construction and soil and water conservation within the Yangtze catchment. Our findings are helpful for better understanding the effects of such a huge dam as the TGD on a sediment sink like the MZCMD of such a large river as the Yangtze River.展开更多
This paper describes the structure of the system for separating sulfur from flue gas and dust. In the paper, the velocities of turbulent flow and laminar flow inside the tower, the total of liquid membrance, and the a...This paper describes the structure of the system for separating sulfur from flue gas and dust. In the paper, the velocities of turbulent flow and laminar flow inside the tower, the total of liquid membrance, and the additional flow of rotation fogged fluid are calculated, and the separation of rotation air-solid affected by tower is analyzed. The velocity distribution in quasi free vortex area is obtained from experiment. The minimum separated particle diameter is computed. The paper also studies the chemical reactions of flue gas containing sulfide with the dynamic fogged sulfur separating agent and discusses the main factors related to the effect of separating sulfur and dust. At last, the applications of separating sulfur in industrial stove and collecting dust in environmental engineering are introduced.展开更多
Mountain streams act as conveyors of sediments within the river continuum,where the physical transport of sediments between river reaches through the catchment or between individual parts(e.g.,between hillslopes and c...Mountain streams act as conveyors of sediments within the river continuum,where the physical transport of sediments between river reaches through the catchment or between individual parts(e.g.,between hillslopes and channels)of the catchment is assumed.This study focused on sediment connectivity analysis in the SlavíčRiver catchment in the MoravskoslezskéBeskydy Mts in the eastern part of the Czech Republic.The connectivity index and connectivity index target modelling were combined with an analysis of anthropogenic interventions.Additionally,field mapping,grain size of bed sediments and stream power analysis were used to obtain information about connectivity in the catchment.Based on the analysis and obtained results,terrain topography is the current main driving factor affecting the connectivity of sediment movement in the SlavíčRiver catchment.However,the modelling provided valuable information about high sediment connectivity despite different recent land use conditions(highly forested area of the catchment)than those in historical times from the 16th to 19th centuries when the SlavíčRiver catchment was highly deforested and sediment connectivity was probably higher.The analysis of anthropogenic interventions,field mapping,grain size of bed sediments and stream power analysis revealed more deceleration of sediment movement through the catchment,decreased sediment connectivity with bed erosion,and gradual river channel process transformation in some reaches.Field mapping has identified various natural formations and human-induced changes impacting the longitudinal and lateral connectivity in the SlavíčRiver.For instance,embankments along 48%of the river's length,both on the right and left banks,significantly hinder lateral sediment supply to the channel.Stream power index analysis indicates increased energy levels in the flowing water in the river's upper reaches(up to 404.8 W m^(-2)).This high energy is also observed in certain downstream sections(up to 337.6 W m^(-2)),where it is influenced by human activities.These conditions lead to intensified erosion processes,playing a crucial role in sediment connectivity.Similar observations were described in recent studies that pointed out the long-term human interventions on many streams draining European mountains,where a decrease in sediment connectivity in these streams is linked with sediment deficits and the transformation of processes forming channels.展开更多
Lop Nur is located in the interior of Asian and the lowest part in the eastern Tarim Basin.It is the final destination of major river systems in Tarim Basin and the accumulation center of salt materials(Xia,1987).As
<strong>Background: </strong>Recent decades witnessed a significant growth in terms of phytocompounds based therapeutics, extensively explored for almost all types of existing disorders. They have also bee...<strong>Background: </strong>Recent decades witnessed a significant growth in terms of phytocompounds based therapeutics, extensively explored for almost all types of existing disorders. They have also been widely investigated in Neurodegenerative disorders (NDDs) and Chlorogenic acid (CGA), a polyphenolic compound having potential anti-inflammatory and anti-oxidative properties, emerged as a promising compound in ameliorating NDDs. Owing to its poor stability, bioavailability and release kinetics, CGA needed a suitable nanocarrier based pharmaceutical design for targeting NDDs. <strong>Objective: </strong>The current study is aimed at the <em>in-silico</em> validation of CGA as an effective therapeutic agent targeting various NDDs followed by the fabrication of polymeric nanoparticles-based carrier system to overcome its pharmacological limitations and improve its stability. <strong>Methods:</strong> A successful <em>in-silico</em> validation using molecular docking techniques along with synthesis of CGA loaded polymeric nanoparticles (CGA-NPs) by ionic gelation method was performed. The statistical optimisation of the developed CGA-NPs was done by Box Behnken method and then the optimized formulation of CGA-NPs was characterised using particle size analysis (PSA), Transmission electron microscopy (TEM), Fourier Transform Infrared spectroscopy (FTIR) along with in-vitro release kinetics analysis.<strong> Results & Conclusion:</strong> The results attained exhibited average particle size of 101.9 ± 1.5 nm, Polydispersibility (PDI) score of 0.065 and a ZP of <span style="white-space:nowrap;">−</span>17.4 mV. On a similar note, TEM results showed a size range of CGA-NPs between 90 - 110 nm with a spherical shape of NPs. Also, the data from in-vitro release kinetics showed a sustained release of CGA from the NPs following the first-order kinetics suggesting the appropriate designing of nanoformulation.展开更多
Lemon oil (LO), also known as <em>Citrus limonum</em> is a highly volatile essential oil (EO) with potential therapeutic properties like anti-oxidative, anti-proliferative, anti-fungal and anti-cancerous. ...Lemon oil (LO), also known as <em>Citrus limonum</em> is a highly volatile essential oil (EO) with potential therapeutic properties like anti-oxidative, anti-proliferative, anti-fungal and anti-cancerous. However, the efficacy of LO is limited due to its physiological factors such as high volatility, poor stability (particularly sensitive to sunlight) and quick degradability upon exposure. To overcome these challenges, we formulated lemon oil loaded nanoemulsion system (LO-NE) (oil-in-water), using aqueous titration method. The formulation comprised of lemon oil (LO), Tween 80 and ethanol as oil, surfactant and co-surfactant phases respectively. The existence zone of NE was established by constructing pseudo-ternary phase diagrams using different concentrations of LO, surfactant and co-surfactant (S<sub>mix</sub>). The quantitative estimation of LO was performed using a high throughput gas chromatography, revealing the presence of various compounds like Limonene, Alpha-Pinene and Linalyl acetate followed by the estimation of total phenolics and flavonoid content. The characterization of LO-NE indicated the particle size of 60 ± 2.5 nm along with the polydispersity index of 0.125 and zeta potential of <span style="white-space:nowrap;">−</span>14.9 mV. The size range of the NE particles dispersed in the colloidal system was further verified by TEM micrograph which shows size range between 46.2 - 104.7 nm. All the anti-oxidant assays outcomes exhibited the higher activity of LO-NE in comparison to LO alone with lower IC<sub>50</sub> values. The release kinetics statistical data showed that LO-NE had a sustained release and followed the Higuchi’s model in comparison to burst release of LO alone. Lastly, the stability analysis of the optimised formulation (LO-NE) and LO was estimated through antioxidant assay and subjecting them for thermodynamic stability after 6 months. The results attained, showed higher stability and anti-oxidant capability of LO-NE than LO alone. The study suggested that formulated nanoemulsion can be effectively used as a highly efficacious biologically active alternative nanoformulation against many transdermal disorders.展开更多
Background Bladder leiomyoma is an uncommon type of bladder neoplasms. Most publications are reports of isolated cases. The influence of tumor size on patients＇ early symptoms was seldom analyzed. We aim to investiga...Background Bladder leiomyoma is an uncommon type of bladder neoplasms. Most publications are reports of isolated cases. The influence of tumor size on patients＇ early symptoms was seldom analyzed. We aim to investigate the clinical characteristics of bladder leiomyoma and the influence of tumor size on patients＇ symptoms in Chinese population. Methods We reviewed the medical records of eight patients diagnosed with bladder leiomyoma at our department, collected 53 cases from Chinese National Knowledge Infrastructure （CNKI）, Wangfang data base, and Chinese Biological Medicine Disk, and performed a pooled analysis. The clinical characteristics of the patients were analyzed and then classified into symptomatic and asymptomatic groups. The association between tumor size and the occurrence of symptoms was evaluated. Furthermore, Logistic regression model was constructed to discriminate variables. Results Women comprised the majority of the patients （49/61, 80.3%）. The mean age and tumor size were （42.3＋14.0） years and （45.0＋25.7） mm, respectively. Among all the symptoms, irritative symptoms occurred most frequently （37.7%, 23/61）, followed by obstructive urinary symptoms （31.1%, 19/61）, hematuria （24.6%, 15/61 ）, and abdominal bulge or pain （14.8%, 9/61）. In our study, patients who were 45 years old or younger tended to be asymptomatic compared with elder ones （14/36 vs. 3/25, P=-0.021）. The histological, as well as anatomical, location of tumor, did not show significant differences between symptomatic and asymptomatic patients （P=-0.306 and 0.700）. Tumors larger than 30 mm in the greatest diameter would cause clinical symptoms such as obstructive urinary symptoms （P=0.048） and irritative symptoms （P=0.037）. Logistic regression confirmed the association between tumor size and the occurrence of symptoms, which was related with age. Conclusions Bladder leiomyoma occurs mainly in women and most frequently with irritative symptoms. The occurrence of symptoms is related to tumor size rather than the location： In this setting, patients with endovesical tumors smaller than 30 mm in the greatest diameter tended to be asymptomatic, which were usually treated with transurethrai resection of bladder tumor.展开更多
基金funded by Atlantic Canada Opportunity Agency(AIF contract number:7812636-1920044)
文摘This paper describes an investigation of active bit vibration on the penetration mechanisms and bit-rock interaction for drilling with a diamond impregnated coring bit.A series of drill-off tests(DOTs)were conducted where the drilling rate-of-penetration(ROP)was measured at a series of step-wise increasing static bit thrusts or weight-on-bits(WOBs).Two active DOTs were conducted by applying 60 Hz axial vibration at the bit-rock interface using an electromagnetic vibrating table mounted underneath the drilling samples,and a passive DOT was conducted where the bit was allowed to vibrate naturally with lower amplitude due to the compliance of the drilling sample mountings.During drilling,an acoustic emission(AE)system was used to record the AE signals generated by the diamond cutter penetration and the cuttings were collected for grain size analysis.The instrumented drilling system recorded the dynamic motions of the bit-rock interface using a laser displacement sensor,a load cell,and an LVDT(linear variable differential transformer)recorded the dynamic WOB and the ROP,respectively.Calibration with the drilling system showed that rotary speed was approximately the same at any given WOB,facilitating comparison of the results at the same WOB.Analysis of the experimental results shows that the ROP of the bit at any given WOB increased with higher amplitude of axial bit-rock vibration,and the drill cuttings increased in size with a higher ROP.Spectral analysis of the AEs indicated that the higher ROP and larger cutting size were correlated with a higher AE energy and a lower AE frequency.This indicated that larger fractures were being created to generate larger cutting size.Overall,these results indicate that a greater magnitude of axial bit-rock vibration produces larger fractures and generates larger cuttings which,at the same rotary speed,results in a higher ROP.
基金Supported by the Research and Development Project of Experimental Technology,China University of Mining and Technology(Study on mineral occurrence in coal based on SEM and EDS,S2023Y018)the National Natural Science Foundations of China under Grant 62371451.
文摘An important index to evaluate the process efficiency of coal preparation is the mineral liberation degree of pulverized coal,which is greatly influenced by the particle size and shape distribution acquired by image segmentation.However,the agglomeration effect of fine powders and the edge effect of granular images caused by scanning electron microscopy greatly affect the precision of particle image segmentation.In this study,we propose a novel image segmentation method derived from mask regional convolutional neural network based on deep learning for recognizing fine coal powders.Firstly,an atrous convolution is introduced into our network to learn the image feature of multi-sized powders,which can reduce the missing segmentation of small-sized agglomerated particles.Then,a new mask loss function combing focal loss and dice coefficient is used to overcome the false segmentation caused by the edge effect.The final comparative experimental results show that our method achieves the best results of 94.43%and 91.44%on AP50 and AP75 respectively among the comparison algorithms.In addition,in order to provide an effective method for particle size analysis of coal particles,we study the particle size distribution of coal powders based on the proposed image segmentation method and obtain a good curve relationship between cumulative mass fraction and particle size.
基金supported by the National Natural Science Foundation of China (No. 41572092)the National Science and Technology Major Project (No. 2017ZX05009-002)China Key Laboratory of Land and Resources Ministry of Shale Gas Resource Evaluation and Strategy Selection
文摘Grain size analysis is a common method in the study of sedimentology. For the consolidated sedimentary rocks, the traditional methods are rock slice observation and image analysis. In recent years, laser particle size analyzer is used widely in particle size analysis of sedimentary rock. Unlike the pretreatment of loose samples, the rock samples must be crushed, added acid to wipe out cement, and washed. However, in the step of washing, most of the fines component（less than 63 μm） in the suspended state should be inevitably lost. It will significantly affect the accuracy of particle size analysis, especially for siltstone. This paper presents a siltstone sample pretreatment method which core step is washing acid by centrifuge. Compared with traditional decantation method, the results show that the median particle size reduced 33.2 μm on average. Compared with the precipitation method which is commonly used for handling loose samples, the change of solid-liquid separation time is from 12 h to 10 min, while the average reduction of median particle size is about 15 μm. The grain size value corresponded to the cumulative volume of 10%/90% reduced 2.5 μm/20.3 μm on average. The percentage of the clay component less than 2 μm increased 2.88% on average. The fine particle（2–4 μm） and silt component（4–63 μm） increased 1.71% and 5.56% on average. Based on this method, two kinds of similar lacustrine siltstone were analyzed. They are tempestite and beach bar which are difficult to identify in the Lijin sub-depression, Dongying depression, Shengli oilfield, China. The final grain-size probability plot of tempestite is the type of “one saltation component and three suspension components”. The content of suspension components can reach to 80%–90%. The beach bar is the type of “one saltation component and two suspension components”. The content of suspension components can reach to 40%–45%. They both have the characteristics of high slope which means well sorting. But they can be distinguished based on the suspension sedimentary characteristics which were preserved by maximum degree in this kind of sample pretreatment method.
文摘The average size of the sand of dune in the vicinity of Tumen River is 0.12～0.30 mm, its standard deviation is 0.45～0.99 φ and the frequency cumulative distribution curve is divided into the single peak and the double peak. The Ski of the single peak is negative and the double peak is positive. There are two different areas in the plot of the Ski versus σi* It is shown that the sedimentary environment of the dunes is neritic deposit by the expressions of the grain-size parameters. All of the characters show that the sand dunes in Estuary of Tumen River may be the dunes of sea facies which were changed again by weathering and fluvialaction.
文摘To reveal the sediment transporting mechanism between the abandoned Huanghe River （Yellow River） Delta and radial sand ridges, “End Member” Model and grain size trend analysis have been employed to separate the “dynamic populations” in the surficial sediment particle spectra and to determine the possible sediment transporting pathway. The results reveal four “dynamic subpopulations”（EM1 to EM4） and two reverse sediment transporting directions： a northward transport tend from the radial sand ridges to mud patch, and a southward transport trend in deep water area outside the mud patch. Combined with the published hydrodynamic information, the transporting mechanism of dynamic populations has been discussed, and the main conclusion is that the transporting of finer subpopulations EM1 and EM2 is controlled by the “anticlockwise residual current circulation” forming during tidal cycle, which favor a northward transporting trend and the forming of mud patch on the north of radial sand ridges, while the transporting of coarser EM3 is mainly controlled by wind driven drift in winter, which favors a southward transporting direction.
基金Chinese Offshore Investigation and Assessment Project, No.908-01-ST09 State Student Innovation Training Project, No.SIT-05+1 种基金 Program for New Century Excellent Talents, No.NCET-06-0446 National Natural Science Foundation of China, No.J0630535 Acknowledgement The research vessel Experiment 2 （South China Sea Institute of Oceanology, Chinese Academy of Sciences） performed the field survey and Prof. Lizhe Cai and his colleagues help to collect the sediment samples. Prof. Shu Gao and Asso. Prof. Yongzhan Zhang have provided a lot of support and valuable suggestions for this study. Miss Xiaoqin Du helped with sediment transportation and Mr. Fengyang Min assisted in the operation of related software. The comments from Dr. M. Xia （Great Lakes Environmental Research Laboratory, NOAA, USA） have improved a lot in the presentation of the paper.
文摘There are 71 surface sediment samples collected from the eastern Beibu Gulf. The moment parameters （i.e. mean size, sorting and skewness） were obtained after applying grain size analysis. The geostatistical analysis was then applied to study the spatial autocorrelation for these parameters; while range, a parameter in the semivariogram that meters the scale of spatial autocorrelation, was estimated. The results indicated that the range for sorting coefficient was physically meaningful. The trend vectors calculated from grain size trend analysis model were consistent with the annual ocean circulation patterns and sediment transport rates according to previous studies. Therefore the range derived from the semivariogram of mean size can be used as the characteristic distance in the grain size trend analysis, which may remove the bias caused by the traditional way of basing on experiences or testing methods to get the characteristic distance. Hence the results from geostatistical analysis can also offer useful information for the determination of sediment sampling density in the future field work.
基金Supported by projects of National Natural Science Foundation of China(Nos.40702027,41472173)Ministry of Land and Resources Outstanding Youth Science and Technology Talent Training Program of China(No.201311111).
文摘Plenty of high-resolution paleoclimate investigations of the last thousand years were carried out to potentially predict future climate changes.Mountainous ombrotrophic peatland is one of the best recorders for high-resolution paleoclimate studies in the forest area.Grain size analysis was carried out on ombrotrophic peat profile in the eastern mountainous region of Jilin Province,Northeast China.The peat profile lasts the past 2000 a by four radiocarbon(AMS14C)ages.The results showed that the inorganic minerals in the peat profile are mainly silt,with some contribution from clay and a minor amount of sand,which are mainly due to wind dust and suspended transportation.Two paleoclimate stages are found in this peat profile by phytolith analysis,peat cellulose isotope research and historical documents:ca.45–1550 AD,relatively cold period;ca.1550 AD–present,relatively warm period.This finding is important for the initial study of paleoclimatic changes over the last 2000 a in the mountainous area of eastern mountainous area,Jilin Province,Northeast China.
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.
基金benefited from the National Natural Sciences Foundation of China(31440078,31501840)Shanxi Province Programs for Science and Technology Development(20150311010-7)+1 种基金Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2017169)Graduate Innovation Project in Shanxi Province(2016BY067)
文摘Further geometric morphometric analysis of the genus Eysarcoris was done based on the former studies to classified the nine Eysarcoris species from China. In this study, six characters, such as forewing, hindwing, pygophore, head, pronotum and scutellum, were selected to investigate the shape variation of Eysarcoris. Significant divergence in the shapes of the six characters was observed among the species（p 〈 0.05）. For all methods, phenetic similarity based on the six characters agrees with the current status of the genus. The cluster analysis of eight species are consistent with the traditional morphological studies. CVA analysis also shows that the values of the six characters are not equal in taxonomy. Pygophore, forewing, hindwing and pronotum play more important roles in the classification.
基金financially supported by NSAF(No.U1530155)Ministry of Science and Technology(MOST)of China,US–China Collaboration on Cutting-edge Technology Development of Electric Vehicle,the Nation Key Basic Research Program of China(No.2015CB251100)Beijing Key Laboratory of Environmental Science and Engineering(No.20131039031)
基金financial support from the National Natural Science Foundation of China(21528302)Zhejiang Province Natural Science Foundation(LQ15B060004)
文摘The Co-based catalysts were prepared with different cobalt acetate solutions.Effects of pH value were studied deeply on Fischer–Tropsch synthesis(FTS)through a semi-batch reactor.Among all impregnation solutions(water,butanol,amyl alcohol,acetic acid,nitric acid and ammonium nitrate),the catalyst prepared by NH4NO3solution showed the highest catalytic activity due to its small particle size and high reduction degree.However,the catalyst with the smallest particle size derived from water as impregnation solution exhibited low activity as well as high methane selectivity since it was difficult to be reduced and inactive in FTS.According to FT-IR spectra results,the low intensity of absorbed CO on the catalyst prepared from water solution resulted in low FTS activity.Whereas,the high activity of catalysts prepared from NH4NO3solution could be explained by the high intensity of absorbed CO on the catalysts.The cobalt species on the catalysts prepared under lower pH conditions exhibited smaller particle size distribution as well as lower CO conversion than those prepared at higher pH value.
文摘Application of light-weight drilling fluids is essential to develop depleted hydrocarbon reservoirs.Recently,colloidal gas aphron(CGA)-based fluids have been introduced for such applications due to their ability in controlling fluid losses.In this work,a comprehensive experimental study was performed to choose the best formulation for CGA fluids by implementing static stability tests,rheological behavior measurements,and bubble size analyses of CGAs.Xanthan gum polymer and sodium dodecyl benzene sulfonate(SDBS),an anionic surfactant,and cetyl trimethyl ammonium bromide(CTAB),a cationic surfactant,were utilized to prepare CGAs.For the range of experiments conducted,the performance of CGA fluids prepared with SDBS was improved by increasing the polymer and surfactant concentrations.However,for CTAB,it was improved by an increase in the polymer concentration and a decrease in the surfactant concentration.The formation of white,long hair-like precipitates observed at high levels of CTAB caused CGA fluid to become rapidly unstable.Also,it was observed that the size of CGAs was significantly influenced by the polymer and surfactant concentrations.The most stable bubbles were formed at 6.86 g/L of polymer concentration.The results of this study provide insights into appropriate formulation for CGA-based fluids which could be potentially applicable in drilling operations.
基金the National Natural Science Foundation of China for its financial support (Nos. 41376052, 41030856, 40906024)
文摘The well-known Three Gorges Dam(TGD) within the Yangtze catchment launched its operation in 2003. The effect of the TGD operation on the sediment size on the East China Sea shelf is rarely known. High resolution(0.5 cm sampling) grain size analysis and 137 Cs and 210 Pb dating of the DH8-1 core were conducted with core collected from the distal part of a main sink for the modern Yangtze sediment entering the sea, the Min-Zhe Coastal Mud Deposits(MZCMD) on the inner East China Sea shelf. The 137 Cs dating results show that the core DH8-1 formed during 1946–2012 with a mean deposition rate of 0.65 cm yr^(-1), indicating that the 0.5 cm sampling for grain size analysis in this local area could reflect environmental changes generally on a one-year time scale. The mean grain size of DH8-1 core sediment that deposited after 2003 is significantly larger than that deposited during 1988–2002. After ruling out other possible factors, we infer that the sediment coarsening of DH8-1 core after 2003 is attributed to the TGD operation which causes the erosion of the Yangtze subaqueous delta. Specifically, the TGD operation significantly intensifies the declining trend of the Yangtze sediment loads to the sea despite no decreased water discharge, which results in extensive erosion of the Yangtze subaqueous delta. The relatively coarse sediment of the subaqueous delta is eroded and resuspended by ocean dynamics and then transported by coastal current, finally depositing on the MZCMD area. In addition, the general sediment fining of core DH8-1 that deposited during 1988–2002, comparing with 1946–1987, is mainly caused by dam construction and soil and water conservation within the Yangtze catchment. Our findings are helpful for better understanding the effects of such a huge dam as the TGD on a sediment sink like the MZCMD of such a large river as the Yangtze River.
基金supported by Unité de Catalyse et Chimie du Solide (UCCS)sponsor of scholarship: China scholarship council and School of Environment, Tsinghua University
基金This project was supported by Guangdong Provincial Science and Technology Foundation (No. 980343).
文摘This paper describes the structure of the system for separating sulfur from flue gas and dust. In the paper, the velocities of turbulent flow and laminar flow inside the tower, the total of liquid membrance, and the additional flow of rotation fogged fluid are calculated, and the separation of rotation air-solid affected by tower is analyzed. The velocity distribution in quasi free vortex area is obtained from experiment. The minimum separated particle diameter is computed. The paper also studies the chemical reactions of flue gas containing sulfide with the dynamic fogged sulfur separating agent and discusses the main factors related to the effect of separating sulfur and dust. At last, the applications of separating sulfur in industrial stove and collecting dust in environmental engineering are introduced.
基金supported by an internal grant of the University of Ostrava[SGS10/PřF/2021-Specificity of fluvial landscape in the context of historical and future changes].
文摘Mountain streams act as conveyors of sediments within the river continuum,where the physical transport of sediments between river reaches through the catchment or between individual parts(e.g.,between hillslopes and channels)of the catchment is assumed.This study focused on sediment connectivity analysis in the SlavíčRiver catchment in the MoravskoslezskéBeskydy Mts in the eastern part of the Czech Republic.The connectivity index and connectivity index target modelling were combined with an analysis of anthropogenic interventions.Additionally,field mapping,grain size of bed sediments and stream power analysis were used to obtain information about connectivity in the catchment.Based on the analysis and obtained results,terrain topography is the current main driving factor affecting the connectivity of sediment movement in the SlavíčRiver catchment.However,the modelling provided valuable information about high sediment connectivity despite different recent land use conditions(highly forested area of the catchment)than those in historical times from the 16th to 19th centuries when the SlavíčRiver catchment was highly deforested and sediment connectivity was probably higher.The analysis of anthropogenic interventions,field mapping,grain size of bed sediments and stream power analysis revealed more deceleration of sediment movement through the catchment,decreased sediment connectivity with bed erosion,and gradual river channel process transformation in some reaches.Field mapping has identified various natural formations and human-induced changes impacting the longitudinal and lateral connectivity in the SlavíčRiver.For instance,embankments along 48%of the river's length,both on the right and left banks,significantly hinder lateral sediment supply to the channel.Stream power index analysis indicates increased energy levels in the flowing water in the river's upper reaches(up to 404.8 W m^(-2)).This high energy is also observed in certain downstream sections(up to 337.6 W m^(-2)),where it is influenced by human activities.These conditions lead to intensified erosion processes,playing a crucial role in sediment connectivity.Similar observations were described in recent studies that pointed out the long-term human interventions on many streams draining European mountains,where a decrease in sediment connectivity in these streams is linked with sediment deficits and the transformation of processes forming channels.
文摘Lop Nur is located in the interior of Asian and the lowest part in the eastern Tarim Basin.It is the final destination of major river systems in Tarim Basin and the accumulation center of salt materials(Xia,1987).As
文摘<strong>Background: </strong>Recent decades witnessed a significant growth in terms of phytocompounds based therapeutics, extensively explored for almost all types of existing disorders. They have also been widely investigated in Neurodegenerative disorders (NDDs) and Chlorogenic acid (CGA), a polyphenolic compound having potential anti-inflammatory and anti-oxidative properties, emerged as a promising compound in ameliorating NDDs. Owing to its poor stability, bioavailability and release kinetics, CGA needed a suitable nanocarrier based pharmaceutical design for targeting NDDs. <strong>Objective: </strong>The current study is aimed at the <em>in-silico</em> validation of CGA as an effective therapeutic agent targeting various NDDs followed by the fabrication of polymeric nanoparticles-based carrier system to overcome its pharmacological limitations and improve its stability. <strong>Methods:</strong> A successful <em>in-silico</em> validation using molecular docking techniques along with synthesis of CGA loaded polymeric nanoparticles (CGA-NPs) by ionic gelation method was performed. The statistical optimisation of the developed CGA-NPs was done by Box Behnken method and then the optimized formulation of CGA-NPs was characterised using particle size analysis (PSA), Transmission electron microscopy (TEM), Fourier Transform Infrared spectroscopy (FTIR) along with in-vitro release kinetics analysis.<strong> Results & Conclusion:</strong> The results attained exhibited average particle size of 101.9 ± 1.5 nm, Polydispersibility (PDI) score of 0.065 and a ZP of <span style="white-space:nowrap;">−</span>17.4 mV. On a similar note, TEM results showed a size range of CGA-NPs between 90 - 110 nm with a spherical shape of NPs. Also, the data from in-vitro release kinetics showed a sustained release of CGA from the NPs following the first-order kinetics suggesting the appropriate designing of nanoformulation.
文摘Lemon oil (LO), also known as <em>Citrus limonum</em> is a highly volatile essential oil (EO) with potential therapeutic properties like anti-oxidative, anti-proliferative, anti-fungal and anti-cancerous. However, the efficacy of LO is limited due to its physiological factors such as high volatility, poor stability (particularly sensitive to sunlight) and quick degradability upon exposure. To overcome these challenges, we formulated lemon oil loaded nanoemulsion system (LO-NE) (oil-in-water), using aqueous titration method. The formulation comprised of lemon oil (LO), Tween 80 and ethanol as oil, surfactant and co-surfactant phases respectively. The existence zone of NE was established by constructing pseudo-ternary phase diagrams using different concentrations of LO, surfactant and co-surfactant (S<sub>mix</sub>). The quantitative estimation of LO was performed using a high throughput gas chromatography, revealing the presence of various compounds like Limonene, Alpha-Pinene and Linalyl acetate followed by the estimation of total phenolics and flavonoid content. The characterization of LO-NE indicated the particle size of 60 ± 2.5 nm along with the polydispersity index of 0.125 and zeta potential of <span style="white-space:nowrap;">−</span>14.9 mV. The size range of the NE particles dispersed in the colloidal system was further verified by TEM micrograph which shows size range between 46.2 - 104.7 nm. All the anti-oxidant assays outcomes exhibited the higher activity of LO-NE in comparison to LO alone with lower IC<sub>50</sub> values. The release kinetics statistical data showed that LO-NE had a sustained release and followed the Higuchi’s model in comparison to burst release of LO alone. Lastly, the stability analysis of the optimised formulation (LO-NE) and LO was estimated through antioxidant assay and subjecting them for thermodynamic stability after 6 months. The results attained, showed higher stability and anti-oxidant capability of LO-NE than LO alone. The study suggested that formulated nanoemulsion can be effectively used as a highly efficacious biologically active alternative nanoformulation against many transdermal disorders.
文摘Background Bladder leiomyoma is an uncommon type of bladder neoplasms. Most publications are reports of isolated cases. The influence of tumor size on patients＇ early symptoms was seldom analyzed. We aim to investigate the clinical characteristics of bladder leiomyoma and the influence of tumor size on patients＇ symptoms in Chinese population. Methods We reviewed the medical records of eight patients diagnosed with bladder leiomyoma at our department, collected 53 cases from Chinese National Knowledge Infrastructure （CNKI）, Wangfang data base, and Chinese Biological Medicine Disk, and performed a pooled analysis. The clinical characteristics of the patients were analyzed and then classified into symptomatic and asymptomatic groups. The association between tumor size and the occurrence of symptoms was evaluated. Furthermore, Logistic regression model was constructed to discriminate variables. Results Women comprised the majority of the patients （49/61, 80.3%）. The mean age and tumor size were （42.3＋14.0） years and （45.0＋25.7） mm, respectively. Among all the symptoms, irritative symptoms occurred most frequently （37.7%, 23/61）, followed by obstructive urinary symptoms （31.1%, 19/61）, hematuria （24.6%, 15/61 ）, and abdominal bulge or pain （14.8%, 9/61）. In our study, patients who were 45 years old or younger tended to be asymptomatic compared with elder ones （14/36 vs. 3/25, P=-0.021）. The histological, as well as anatomical, location of tumor, did not show significant differences between symptomatic and asymptomatic patients （P=-0.306 and 0.700）. Tumors larger than 30 mm in the greatest diameter would cause clinical symptoms such as obstructive urinary symptoms （P=0.048） and irritative symptoms （P=0.037）. Logistic regression confirmed the association between tumor size and the occurrence of symptoms, which was related with age. Conclusions Bladder leiomyoma occurs mainly in women and most frequently with irritative symptoms. The occurrence of symptoms is related to tumor size rather than the location： In this setting, patients with endovesical tumors smaller than 30 mm in the greatest diameter tended to be asymptomatic, which were usually treated with transurethrai resection of bladder tumor.
