Several tritylodontid taxa have been reported from the Upper Jurassic of the Wucaiwan area in the Junggar Basin of Xinjiang,northwestern China,including Yuanotherium minor.The original study described the partially pr...Several tritylodontid taxa have been reported from the Upper Jurassic of the Wucaiwan area in the Junggar Basin of Xinjiang,northwestern China,including Yuanotherium minor.The original study described the partially preserved postcanine teeth in the middle of the left upper maxilla.After detailed re-examination of the specimen and by CT scanning,3D reconstruction,and scanning electron microscopy observations,we provided a more detailed description of the osteology,neurosensory,and tooth wear pattern for all the bones preserved in this specimen and clarified some characters.Based on new information about the cusp wear pattern,the chewing movement pattern of the dentition and detailed cusp morphology,we discussed the cuspal homology of upper cheek teeth of tritylodontids and postulate a standardized method for cusp identification.We hypothesize that the unique maxilla characteristics furnish the evidence for transitional stages about the evolution of the upper jaw-palate structure in tritylodontids.展开更多
A controversial taxon,Hipparion plocodus,is reviewed in the present study.Hi.plocodus has been confirmed to be a valid species with definite diagnostic characteristics,represented by cranial specimens from Baode,Shanx...A controversial taxon,Hipparion plocodus,is reviewed in the present study.Hi.plocodus has been confirmed to be a valid species with definite diagnostic characteristics,represented by cranial specimens from Baode,Shanxi Province.The phylogenetic analysis performed in the present study,with a new matrix,shows that Hi.plocodus forms a monophyletic group with a European species,Hippotherium malpassii.Actually,no close relationship between so-called Hm.malpassii and the genus Hippotherium has been identified,and the record of stratigraphic range of this genus in late stage of Late Miocene is currently absent.Herein previously Hi.plocodus and Hm.malpassii have both attributed into“Hipparion”before the discovery of better material.Evolutionary stages and correlative absolute age showed that these two species should derive independently from some primitive clade.During the late stage of the Late Miocene,the development of the Asian summer monsoon enhanced the humidity of China,with forest and wood habitats expanding considerably under this setting.As the result,one Eurasian closed-habitat lineage thus extended its range into China,which had become very suited for it,give rise to“Hi.”plocodus.展开更多
Perleididae is a group of stem neopterygian fishes known only from the Triassic.Here,we report the discovery of a new perleidid,Teffichthys wui sp.nov.,based on six well-preserved specimens from the late Smithian(Olen...Perleididae is a group of stem neopterygian fishes known only from the Triassic.Here,we report the discovery of a new perleidid,Teffichthys wui sp.nov.,based on six well-preserved specimens from the late Smithian(Olenekian,Early Triassic)marine deposits of Jurong,Jiangsu and Chaohu,Anhui,China.This new discovery documents the third and youngest species of Teffichthys,which is slightly younger than the Dienerian(Induan)T.elegans from Guizhou and the early Smithian T.madagascariensis from Madagascar.The new species shows diagnostic features of Teffichthys(presence of a spiracular,38-41 lateral line scales,and no more than three epaxial rays in the caudal fin)but differs from T.madagascariensis and T.elegans in some autapomorphies(e.g.,a horizontal opercle/subopercle contact and smooth scales with a nearly straight posterior margin).The diagnostic features for the genus Teffichthys and the family Perleididae are emended based on detailed comparisons of the new taxon with other perleidids.The phylogenetic relationships of perleidids with other stem neopterygians are discussed using a cladistic approach,and the results provide new insights into the phylogeny and classification of main stem neopterygian clades.展开更多
In the South Yellow Sea Basin,Mesozoic–Paleozoic marine strata are generally well developed with large thickness,and no substantial breakthroughs have been made in hydrocarbon exploration.Through research,it is belie...In the South Yellow Sea Basin,Mesozoic–Paleozoic marine strata are generally well developed with large thickness,and no substantial breakthroughs have been made in hydrocarbon exploration.Through research,it is believed that the Upper Permian–Lower Triassic can be regarded as a long-term base-level cycle.Based on drilling data,characteristics of the lithology–electric property combination cyclicity,and the special lithology,the long-term base-level cycle was divided into five medium-term base-level cycles(MC1–MC5).On this basis,the Permian–Triassic sedimentary systems and their filling model were analyzed in accordance with the change of base-level cycle and transition of sedimentary environment,as well as characteristics of the drilling sedimentary facies and seismic facies.The results show that there were six sedimentary systems(fluvial,delta,tidal flat,open platform,restricted platform,and continental shelf)developed in the Upper Permian–Lower Triassic,the sedimentary systems were distributed such that the water was deep in the northwest and shallow in the southeast,and there were two base-level cycle filling models(a relatively stable tidal flat facies and a rapidly transgressive continental shelf facies to stable platform facies)developed in the Upper Permian–Lower Triassic.These models can provide a basis for evaluation of the Mesozoic–Paleozoic hydrocarbon geology in the South Yellow Sea Basin.展开更多
A series of marine natural gas fields were recently discovered in oolitic dolomites of the Lower Triassic Feixianguan formation, northeastern Sichuan Basin, southwest China. The mechanism forming these reservoir dolom...A series of marine natural gas fields were recently discovered in oolitic dolomites of the Lower Triassic Feixianguan formation, northeastern Sichuan Basin, southwest China. The mechanism forming these reservoir dolomites is debatable, limiting the ability to characterize these reservoir successfully. Based on the investigation of the representative Dukouhe, Luojiazhai, and Puguang areas, this issue was addressed by examining the distribution, petrology, and geochemistry of the dolomites, the most comprehensive study to date was provided. Dolomitization occurred at a very early stage of diagenesis, as shown by the petrological features of the rock fabric. Vadose silt, which is composed primarily of dolomitic clasts, is found in the primary and secondary pores of the oolitic dolomite. This indicates that the overlying strata were subjected to dolomitization when the Feixianguan formation was located in the vadose zone. Therefore, it may be inferred that the dolomitization which occurred before the formation was exposed to meteoric conditions. The spatial distribution and geochemical characteristics of the dolomite indicate that dolomitization occurred as a result of seepage reflux. The degree of dolomitization decreases with increasing distance from the evaporative lagoon. Furthermore, the type and porosity of the dolomite vary in different zones of the upward-shoaling sequence, with the porosity gradually decreasing from the highest layer to the lowest layer. This reflects a close relationship between dolomitization and seawater evaporation during the formation of the dolomite. Geochemical analysis provided further evidence for the relationship between the dolomitization fluid and the coeval seawater. The 87Sr/86Sr and 813C isotopes, as well as the abundances of trace elements, Fe and Mn, indicate that seawater concentrated by evaporation acted as the dolomitization fluid. These results also show that dolomitization most likely occurred in a semi-closed diagenetic environment. Therefore, the main mechanism of oolitic dolomite formation is seepage reflux, which occurred at an early stage of diagenesis.展开更多
A special experiment setup was designed to observe the interaction between bubbles and particle in flotation cell and to analyze the bubble characteristics such as bubble size, distribution and bubble-loading efficien...A special experiment setup was designed to observe the interaction between bubbles and particle in flotation cell and to analyze the bubble characteristics such as bubble size, distribution and bubble-loading efficiency. Bubbles in water-gas system and three-phase system were measured. The results indicate that with the current setup the bubbles as small as 10 μm can be easily distinguished. The average size of the bubbles generated under the given conditions in two-phase system is 410 μm at frother concentration of 0.004%, which is in good correspondence with the results of other works. The effect of frother on bubble size was probed. Increasing frother concentration from 0 to 0.004% causes a reduction of bubble size from 700 to 400 μm. The bubble loading efficiency was reported. The result indicates that the fine particle is more easily entrapped than the coarse particle. Some factors, which have effect on measurement accuracy were discussed. The aeration speed has a significant effect on the accuracy of results, if it surpasses 30 mL/s, and the image becomes unclear due to the entrapment of fine particle. Another factor, which can affect observing results, is the sampling position. At a wrong sampling position, the images become unclear.展开更多
Actual sandstone micromodel was used in this work to conduct the microscopic waterflooding experiment of ultra-low sandstone reservoir,since the inside seepage characteristics of microscopic waterflooding process of C...Actual sandstone micromodel was used in this work to conduct the microscopic waterflooding experiment of ultra-low sandstone reservoir,since the inside seepage characteristics of microscopic waterflooding process of Chang 8 ultra-low permeability sandstone reservoir of Upper Triassic Yanchang formation in Huaqing region of the Ordos Basin,China is difficult to observe directly.Combined with physical property,casting thin sections,constant-rate mercury injection capillary pressure and nuclear magnetic resonance,the influence of reservoir property on the waterflooding characteristics in pores were analyzed and evaluated.Seepage paths of waterflooding characteristics were divided into four types:homogeneous seepage,reticular-homogeneous seepage,finger-reticular seepage and finger-like seepage,the waterflooding efficiency of which decreases in turn.More than 70%of residual oil occurs as flowing-around seepage and oil film.Physical property,pore structure and movable fluid characteristics are all controlled by digenesis and their impacts on waterflooding efficiency are in accordance.Generally,the pore throat radius size and distribution and movable fluid percentage are closely related to waterflooding law.展开更多
To simulate the process of electrode operation, a dynamic model describing the electrode system of three-phase electric arc furnace was developed. This new model can be divided into three submodels in terms of the pra...To simulate the process of electrode operation, a dynamic model describing the electrode system of three-phase electric arc furnace was developed. This new model can be divided into three submodels in terms of the practical situation. They are the power supply system model the electric arc model and the hydraulic actuator system model. According to the basic circuit theory, the power supply system model where the high voltage transmission circuit and mutual inductances were considered, was set up. The electric arc model, which was novel for the electrode control, served as the electrical load and was connected to the power supply system model. The hydraulic actuator system model consists of the proportional valve part that is modeled to capture the dead-zone nonlinear characteristics and the hydraulic cylinder part where the impact of the load force is taken into account. By comparing simulation data and actual data, the results show that the electrode system model is proved to be accurate.展开更多
Two reagents including salicylhydroxamic acid(SHA) and tributyl phosphate(TBP) were tested as collectors either separately or together for electro-flotation of fine cassiterite(<10 μm).Subsequently,the flotation m...Two reagents including salicylhydroxamic acid(SHA) and tributyl phosphate(TBP) were tested as collectors either separately or together for electro-flotation of fine cassiterite(<10 μm).Subsequently,the flotation mechanism of the fine cassiterite was investigated by adsorbance determination,electrophoretic mobility measurements and Fourier transform infra-red(FT-IR) spectrum checking.Results of the flotation experiments show that with SHA as a collector,the collecting performance is remarkably impacted by the pulp pH value as the floatability of cassiterite varies sharply when the pH changes,and flotation with SHA gives distinct maximum at about pH 6.5.Additionally,the floatability of cassiterite is determined by using SHA and TBP as collectors.The range of pulp pH for good floatability is broadened in the presence of TBP as auxiliary collector,and the utilization of TBP improves the recovery of cassiterite modestly.Moreover,the optimum pH value for cassiterite flotation is associated with adsorbance.The results of FT-IR spectrum and the electrophoretic mobility measurements indicate that the adsorption interaction between the collectors and the cassiterite is dominantly a kind of chemical bonding in the form of one or two cycle chelate rings due to the coordination of carbonyl group,hydroxamate and P=O group to the metal tin atoms,where the oxygen atoms contained in carbonyl group,hydroxamate and P=O group of the polar groups have the stereo conditions to form five-membered rings.In addition,the adsorption interactions of SHA and TBP on the surfaces of cassiterite are also dominated by means of hydrogen bonds.展开更多
An efficient calibration algorithm for an ambulatory audiometric test system is proposed. This system utilizes a personal digital assistant (PDA) device to generate the correct sound pressure level (SPL) from an audio...An efficient calibration algorithm for an ambulatory audiometric test system is proposed. This system utilizes a personal digital assistant (PDA) device to generate the correct sound pressure level (SPL) from an audiometric transducer such as an earphone. The calibrated sound intensities for an audio-logical examination can be obtained in terms of the sound pressure levels of pure-tonal sinusoidal signals in eight-banded frequency ranges (250, 500, 1 000, 2 000, 3 000, 4 000, 6 000 and 8 000 Hz), and with mapping of the input sound pressure levels by the weight coefficients that are tuned by the delta learning rule. With this scheme, the sound intensities, which evoke eight-banded sound pressure levels by 5 dB steps from a minimum of 25 dB to a maximum of 80 dB, can be generated without volume displacement. Consequently, these sound intensities can be utilized to accurately determine the hearing threshold of a subject in the ambulatory audiometric testing environment.展开更多
Wuhan Tianxingzhou Changjiang (WTC) Bridge and Nanjing Dashengguan Changjiang (NDC) Bridge are two super high-speed railway 3-trusses composite bridges. This is the first time of using three trusses in such large brid...Wuhan Tianxingzhou Changjiang (WTC) Bridge and Nanjing Dashengguan Changjiang (NDC) Bridge are two super high-speed railway 3-trusses composite bridges. This is the first time of using three trusses in such large bridges in the world. These two types of railway floor systems of the two bridges have never been used in China before. The problem how to conform the deformations and stress levels of the railway floor system of WTC Bridge was studied. After finite element analysis and comparison,the plan of arranging one expansion stringer every two panels in railway floor system were proposed and good effect was obtained. Because of the application of three trusses,the allocation of the loads acted on the deck in three trusses is different and varies in different places of NDC Bridge. This problem was studied by model experiment and 3D finite element analysis. The results of 3D FEM analysis coincide with the model test results. The allocation rule of the loads acting on the deck in three trusses was presented. Because of the application of monolithic decks,the stiffness and structural integrity of NDC Bridge are high.展开更多
A three-dimensional transient numerical simulation was conducted to study the pressure fluctuations in low-specific-speed centrifugal pumps. The characteristics of the inner flow were investigated using the SST k-ω t...A three-dimensional transient numerical simulation was conducted to study the pressure fluctuations in low-specific-speed centrifugal pumps. The characteristics of the inner flow were investigated using the SST k-ω turbulence model. The distributions of pressure fluctuations in the impeller and the volute were recorded, and the pressure fluctuation intensity was analyzed comprehensively, at the design condition, using statistical methods. The results show that the pressure fluctuation intensity increases along the impeller streamline from the leading edge to the trailing edge. In the impeller passage, the intensity near the shroud is much higher than that near the hub at thc inlet. However, the intensity at the middle passage is almost equal to the intensity at the outlet. The pressure fluctuation intensity is the highest at the trailing edge on the pressure side and near the tongue because of the rotor-stator interaction. The distribution of pressure fluctuation intensity is symmetrical in the axial cross sections of the volute channel. However, this intensity decreases with increasing radial distance. Hence, the pressure fluctuation intensity can be reduced by modifying the geometry of the leading edge in the impeller and the tongue in the volute.展开更多
For the interaction relation between geological object and engineering object in some fields related to water conservancy and hydropower, a unified modeling idea was proposed. On the basis of summarizing both advantag...For the interaction relation between geological object and engineering object in some fields related to water conservancy and hydropower, a unified modeling idea was proposed. On the basis of summarizing both advantages and disadvantages of existing modeling methods, an automatic unified modeling method of both engineering and geological objects based on tri-prism(TP) model was presented. Through the lossless correction algorithm of deviated drill holes contained in this method, the real deviated drill holes could be corrected into the equivalent virtual vertical ones. And the correction accuracy fully meets the requirements of unified modeling. With the virtual vertical drilling data, TIN construction of both cover layer and other stratums would be built in order to obtain the 3D geological model. Then, the engineering design data would be introduced into the 3D geological model for achieving unified modeling. For this process, the volume subdividing and restructuring principles were introduced to deal with the spatial relationships between engineering object and geological object. In order to improve the efficiency of unified modeling, the reconstruction of TIN based on constraint information was also applied in this method. At last, the feasibility and validation of the unified modeling method as well as its relevant key algorithms were verified by specific experiments and analysis of results.展开更多
A three-DOF (degree of freedom) planar robot completely restrained and positioned parallel pulled by four wires was studied. The wire driving properties were analyzed through experiments. The restrained three-DOF plan...A three-DOF (degree of freedom) planar robot completely restrained and positioned parallel pulled by four wires was studied. The wire driving properties were analyzed through experiments. The restrained three-DOF planar platform was established based on slippery course and bearing, and dSPACE real-time control system was used to perform the platform's motion control experiment on robot. Based on the kinematic equation and mechanical balance equation of moving platform, the stiffness of the robot system was analyzed and the calibration scheme of the system considering wire tension was put forward. Position servo control experiments were carried out, position servo tracking precision was analyzed, and real-time wire tension was detected. The results show that the moving error of the moving platform tracking is small (the maximum difference is about 3%), and the rotation error is large (the maximum difference is about 12%). The wire tension has wave properties (the wire tension fluctuation is about 10 N).展开更多
Wind tunnel tests were carried out to investigate the aerodynamic interference between a triple-box girder and trains,involving static aerodynamic forces and vortex-induced vibrations(VIVs).Static and dynamic sectiona...Wind tunnel tests were carried out to investigate the aerodynamic interference between a triple-box girder and trains,involving static aerodynamic forces and vortex-induced vibrations(VIVs).Static and dynamic sectional models of the girder and trains were employed for aerodynamic force measurement and VIV test,respectively.Results indicate that the aerodynamic interference effect on static aerodynamic forces of both the girder and trains is remarkable.When a single train exists,the horizontal position of the train has a small effect on aerodynamic coefficients of the girder.When two trains meet on the girder,the drag coefficient of the girder is significantly reduced compared with that of without train or with a single train;besides,during the whole meeting process,aerodynamic forces of the leeward train first drop and then increase suddenly.The fluctuation of aerodynamic force could cause redundant vibration of the train,which is unfavorable for safety and comfort.A train on the girder could worsen the girder VIV performance:a new vertical VIV appears in the triple-box girder when a train is on the girder,and the torsional VIV amplitude increases significantly when the train is on the windward side.展开更多
The strategies that minimize the overall solution time of multiple linear systems in 3D finite element method (FEM) modeling of direct current (DC) resistivity were discussed. A global stiff matrix is assembled and st...The strategies that minimize the overall solution time of multiple linear systems in 3D finite element method (FEM) modeling of direct current (DC) resistivity were discussed. A global stiff matrix is assembled and stored in two parts separately. One part is associated with the volume integral and the other is associated with the subsurface boundary integral. The equivalent multiple linear systems with closer right-hand sides than the original systems were constructed. A recycling Krylov subspace technique was employed to solve the multiple linear systems. The solution of the seed system was used as an initial guess for the subsequent systems. The results of two numerical experiments show that the improved algorithm reduces the iterations and CPU time by almost 50%, compared with the classical preconditioned conjugate gradient method.展开更多
文摘Several tritylodontid taxa have been reported from the Upper Jurassic of the Wucaiwan area in the Junggar Basin of Xinjiang,northwestern China,including Yuanotherium minor.The original study described the partially preserved postcanine teeth in the middle of the left upper maxilla.After detailed re-examination of the specimen and by CT scanning,3D reconstruction,and scanning electron microscopy observations,we provided a more detailed description of the osteology,neurosensory,and tooth wear pattern for all the bones preserved in this specimen and clarified some characters.Based on new information about the cusp wear pattern,the chewing movement pattern of the dentition and detailed cusp morphology,we discussed the cuspal homology of upper cheek teeth of tritylodontids and postulate a standardized method for cusp identification.We hypothesize that the unique maxilla characteristics furnish the evidence for transitional stages about the evolution of the upper jaw-palate structure in tritylodontids.
文摘A controversial taxon,Hipparion plocodus,is reviewed in the present study.Hi.plocodus has been confirmed to be a valid species with definite diagnostic characteristics,represented by cranial specimens from Baode,Shanxi Province.The phylogenetic analysis performed in the present study,with a new matrix,shows that Hi.plocodus forms a monophyletic group with a European species,Hippotherium malpassii.Actually,no close relationship between so-called Hm.malpassii and the genus Hippotherium has been identified,and the record of stratigraphic range of this genus in late stage of Late Miocene is currently absent.Herein previously Hi.plocodus and Hm.malpassii have both attributed into“Hipparion”before the discovery of better material.Evolutionary stages and correlative absolute age showed that these two species should derive independently from some primitive clade.During the late stage of the Late Miocene,the development of the Asian summer monsoon enhanced the humidity of China,with forest and wood habitats expanding considerably under this setting.As the result,one Eurasian closed-habitat lineage thus extended its range into China,which had become very suited for it,give rise to“Hi.”plocodus.
文摘Perleididae is a group of stem neopterygian fishes known only from the Triassic.Here,we report the discovery of a new perleidid,Teffichthys wui sp.nov.,based on six well-preserved specimens from the late Smithian(Olenekian,Early Triassic)marine deposits of Jurong,Jiangsu and Chaohu,Anhui,China.This new discovery documents the third and youngest species of Teffichthys,which is slightly younger than the Dienerian(Induan)T.elegans from Guizhou and the early Smithian T.madagascariensis from Madagascar.The new species shows diagnostic features of Teffichthys(presence of a spiracular,38-41 lateral line scales,and no more than three epaxial rays in the caudal fin)but differs from T.madagascariensis and T.elegans in some autapomorphies(e.g.,a horizontal opercle/subopercle contact and smooth scales with a nearly straight posterior margin).The diagnostic features for the genus Teffichthys and the family Perleididae are emended based on detailed comparisons of the new taxon with other perleidids.The phylogenetic relationships of perleidids with other stem neopterygians are discussed using a cladistic approach,and the results provide new insights into the phylogeny and classification of main stem neopterygian clades.
基金Projects(41506080,41702162)supported by the National Natural Science Foundation of ChinaProjects(DD20160152,DD20160147,GZH200800503)supported by China Geological Survey+1 种基金Projects(XQ-2005-01,2009GYXQ10)supported by China Ministry of Land and ResourcesProject(201602004)supported by the Postdoctoral Innovation Foundation of Shandong Province,China
文摘In the South Yellow Sea Basin,Mesozoic–Paleozoic marine strata are generally well developed with large thickness,and no substantial breakthroughs have been made in hydrocarbon exploration.Through research,it is believed that the Upper Permian–Lower Triassic can be regarded as a long-term base-level cycle.Based on drilling data,characteristics of the lithology–electric property combination cyclicity,and the special lithology,the long-term base-level cycle was divided into five medium-term base-level cycles(MC1–MC5).On this basis,the Permian–Triassic sedimentary systems and their filling model were analyzed in accordance with the change of base-level cycle and transition of sedimentary environment,as well as characteristics of the drilling sedimentary facies and seismic facies.The results show that there were six sedimentary systems(fluvial,delta,tidal flat,open platform,restricted platform,and continental shelf)developed in the Upper Permian–Lower Triassic,the sedimentary systems were distributed such that the water was deep in the northwest and shallow in the southeast,and there were two base-level cycle filling models(a relatively stable tidal flat facies and a rapidly transgressive continental shelf facies to stable platform facies)developed in the Upper Permian–Lower Triassic.These models can provide a basis for evaluation of the Mesozoic–Paleozoic hydrocarbon geology in the South Yellow Sea Basin.
基金Project(2012CB214803)supported by the Major State Basic Research Development Program,ChinaProject(2011ZX5017-001-HZO2)supported by the National Science & Technology Special Project,China+1 种基金Project(2011D-5006-0105)supported by the PetroChina Research Fund,ChinaProject(SZD0414)supported by the Key Subject Construction Project of Sichuan Province,China
文摘A series of marine natural gas fields were recently discovered in oolitic dolomites of the Lower Triassic Feixianguan formation, northeastern Sichuan Basin, southwest China. The mechanism forming these reservoir dolomites is debatable, limiting the ability to characterize these reservoir successfully. Based on the investigation of the representative Dukouhe, Luojiazhai, and Puguang areas, this issue was addressed by examining the distribution, petrology, and geochemistry of the dolomites, the most comprehensive study to date was provided. Dolomitization occurred at a very early stage of diagenesis, as shown by the petrological features of the rock fabric. Vadose silt, which is composed primarily of dolomitic clasts, is found in the primary and secondary pores of the oolitic dolomite. This indicates that the overlying strata were subjected to dolomitization when the Feixianguan formation was located in the vadose zone. Therefore, it may be inferred that the dolomitization which occurred before the formation was exposed to meteoric conditions. The spatial distribution and geochemical characteristics of the dolomite indicate that dolomitization occurred as a result of seepage reflux. The degree of dolomitization decreases with increasing distance from the evaporative lagoon. Furthermore, the type and porosity of the dolomite vary in different zones of the upward-shoaling sequence, with the porosity gradually decreasing from the highest layer to the lowest layer. This reflects a close relationship between dolomitization and seawater evaporation during the formation of the dolomite. Geochemical analysis provided further evidence for the relationship between the dolomitization fluid and the coeval seawater. The 87Sr/86Sr and 813C isotopes, as well as the abundances of trace elements, Fe and Mn, indicate that seawater concentrated by evaporation acted as the dolomitization fluid. These results also show that dolomitization most likely occurred in a semi-closed diagenetic environment. Therefore, the main mechanism of oolitic dolomite formation is seepage reflux, which occurred at an early stage of diagenesis.
文摘A special experiment setup was designed to observe the interaction between bubbles and particle in flotation cell and to analyze the bubble characteristics such as bubble size, distribution and bubble-loading efficiency. Bubbles in water-gas system and three-phase system were measured. The results indicate that with the current setup the bubbles as small as 10 μm can be easily distinguished. The average size of the bubbles generated under the given conditions in two-phase system is 410 μm at frother concentration of 0.004%, which is in good correspondence with the results of other works. The effect of frother on bubble size was probed. Increasing frother concentration from 0 to 0.004% causes a reduction of bubble size from 700 to 400 μm. The bubble loading efficiency was reported. The result indicates that the fine particle is more easily entrapped than the coarse particle. Some factors, which have effect on measurement accuracy were discussed. The aeration speed has a significant effect on the accuracy of results, if it surpasses 30 mL/s, and the image becomes unclear due to the entrapment of fine particle. Another factor, which can affect observing results, is the sampling position. At a wrong sampling position, the images become unclear.
基金Project(2015KTCL01-09)supported by the Innovation Project of Science and Technology of Shaanxi Province,ChinaProject(2015M582699)supported by the China Postdoctoral Science Foundation+1 种基金Project(2016JQ4022)supported by the Natural Science Foundation Research Project of Shaanxi Province,ChinaProject(41702146)supported by the National Natural Science Foundation of China
文摘Actual sandstone micromodel was used in this work to conduct the microscopic waterflooding experiment of ultra-low sandstone reservoir,since the inside seepage characteristics of microscopic waterflooding process of Chang 8 ultra-low permeability sandstone reservoir of Upper Triassic Yanchang formation in Huaqing region of the Ordos Basin,China is difficult to observe directly.Combined with physical property,casting thin sections,constant-rate mercury injection capillary pressure and nuclear magnetic resonance,the influence of reservoir property on the waterflooding characteristics in pores were analyzed and evaluated.Seepage paths of waterflooding characteristics were divided into four types:homogeneous seepage,reticular-homogeneous seepage,finger-reticular seepage and finger-like seepage,the waterflooding efficiency of which decreases in turn.More than 70%of residual oil occurs as flowing-around seepage and oil film.Physical property,pore structure and movable fluid characteristics are all controlled by digenesis and their impacts on waterflooding efficiency are in accordance.Generally,the pore throat radius size and distribution and movable fluid percentage are closely related to waterflooding law.
基金Projects(2007AA04Z194, 2007AA041401) supported by the National High-Tech Research and Development Program of China
文摘To simulate the process of electrode operation, a dynamic model describing the electrode system of three-phase electric arc furnace was developed. This new model can be divided into three submodels in terms of the practical situation. They are the power supply system model the electric arc model and the hydraulic actuator system model. According to the basic circuit theory, the power supply system model where the high voltage transmission circuit and mutual inductances were considered, was set up. The electric arc model, which was novel for the electrode control, served as the electrical load and was connected to the power supply system model. The hydraulic actuator system model consists of the proportional valve part that is modeled to capture the dead-zone nonlinear characteristics and the hydraulic cylinder part where the impact of the load force is taken into account. By comparing simulation data and actual data, the results show that the electrode system model is proved to be accurate.
基金Project(50774094) supported by the National Natural Science Foundation of ChinaProject(2010CB630905) supported by the National Basic Research Program of China
文摘Two reagents including salicylhydroxamic acid(SHA) and tributyl phosphate(TBP) were tested as collectors either separately or together for electro-flotation of fine cassiterite(<10 μm).Subsequently,the flotation mechanism of the fine cassiterite was investigated by adsorbance determination,electrophoretic mobility measurements and Fourier transform infra-red(FT-IR) spectrum checking.Results of the flotation experiments show that with SHA as a collector,the collecting performance is remarkably impacted by the pulp pH value as the floatability of cassiterite varies sharply when the pH changes,and flotation with SHA gives distinct maximum at about pH 6.5.Additionally,the floatability of cassiterite is determined by using SHA and TBP as collectors.The range of pulp pH for good floatability is broadened in the presence of TBP as auxiliary collector,and the utilization of TBP improves the recovery of cassiterite modestly.Moreover,the optimum pH value for cassiterite flotation is associated with adsorbance.The results of FT-IR spectrum and the electrophoretic mobility measurements indicate that the adsorption interaction between the collectors and the cassiterite is dominantly a kind of chemical bonding in the form of one or two cycle chelate rings due to the coordination of carbonyl group,hydroxamate and P=O group to the metal tin atoms,where the oxygen atoms contained in carbonyl group,hydroxamate and P=O group of the polar groups have the stereo conditions to form five-membered rings.In addition,the adsorption interactions of SHA and TBP on the surfaces of cassiterite are also dominated by means of hydrogen bonds.
基金supported by the grant of the Korean Ministry of Education, Science and Technology (The Regional Core Research Program/Chungbuk BIT Research-Oriented University Consortium)
文摘An efficient calibration algorithm for an ambulatory audiometric test system is proposed. This system utilizes a personal digital assistant (PDA) device to generate the correct sound pressure level (SPL) from an audiometric transducer such as an earphone. The calibrated sound intensities for an audio-logical examination can be obtained in terms of the sound pressure levels of pure-tonal sinusoidal signals in eight-banded frequency ranges (250, 500, 1 000, 2 000, 3 000, 4 000, 6 000 and 8 000 Hz), and with mapping of the input sound pressure levels by the weight coefficients that are tuned by the delta learning rule. With this scheme, the sound intensities, which evoke eight-banded sound pressure levels by 5 dB steps from a minimum of 25 dB to a maximum of 80 dB, can be generated without volume displacement. Consequently, these sound intensities can be utilized to accurately determine the hearing threshold of a subject in the ambulatory audiometric testing environment.
基金Projects(2004G028, 2004G016) supported by the Science and Technology Development Program of Railways Department, China
文摘Wuhan Tianxingzhou Changjiang (WTC) Bridge and Nanjing Dashengguan Changjiang (NDC) Bridge are two super high-speed railway 3-trusses composite bridges. This is the first time of using three trusses in such large bridges in the world. These two types of railway floor systems of the two bridges have never been used in China before. The problem how to conform the deformations and stress levels of the railway floor system of WTC Bridge was studied. After finite element analysis and comparison,the plan of arranging one expansion stringer every two panels in railway floor system were proposed and good effect was obtained. Because of the application of three trusses,the allocation of the loads acted on the deck in three trusses is different and varies in different places of NDC Bridge. This problem was studied by model experiment and 3D finite element analysis. The results of 3D FEM analysis coincide with the model test results. The allocation rule of the loads acting on the deck in three trusses was presented. Because of the application of monolithic decks,the stiffness and structural integrity of NDC Bridge are high.
基金Projects(51239005,51009072) supported by the National Natural Science Foundation of ChinaProject(2011BAF14B04) supported by the National Science&Technology Pillar Program of ChinaProject(13JDG084) supported by the Research Foundation for Advanced Talents of Jiansu University,China
文摘A three-dimensional transient numerical simulation was conducted to study the pressure fluctuations in low-specific-speed centrifugal pumps. The characteristics of the inner flow were investigated using the SST k-ω turbulence model. The distributions of pressure fluctuations in the impeller and the volute were recorded, and the pressure fluctuation intensity was analyzed comprehensively, at the design condition, using statistical methods. The results show that the pressure fluctuation intensity increases along the impeller streamline from the leading edge to the trailing edge. In the impeller passage, the intensity near the shroud is much higher than that near the hub at thc inlet. However, the intensity at the middle passage is almost equal to the intensity at the outlet. The pressure fluctuation intensity is the highest at the trailing edge on the pressure side and near the tongue because of the rotor-stator interaction. The distribution of pressure fluctuation intensity is symmetrical in the axial cross sections of the volute channel. However, this intensity decreases with increasing radial distance. Hence, the pressure fluctuation intensity can be reduced by modifying the geometry of the leading edge in the impeller and the tongue in the volute.
基金Project(BK2012812)supported by the Natural Science Foundation of Jiangsu Province,ChinaProject(51079053)supported by the National Natural Science Foundation of China+2 种基金Project(KYLX_0493)supported by the Scientific Research and Innovation Program for College Graduates of Jiangsu Province,ChinaProject(2014B38814)supported by the Fundamental Research Funds for Central Universities,ChinaProject(2014.1526)supported by the Open Research Fund Program of Key Laboratory of Geological Information of Ministry of Land and Resources,China
文摘For the interaction relation between geological object and engineering object in some fields related to water conservancy and hydropower, a unified modeling idea was proposed. On the basis of summarizing both advantages and disadvantages of existing modeling methods, an automatic unified modeling method of both engineering and geological objects based on tri-prism(TP) model was presented. Through the lossless correction algorithm of deviated drill holes contained in this method, the real deviated drill holes could be corrected into the equivalent virtual vertical ones. And the correction accuracy fully meets the requirements of unified modeling. With the virtual vertical drilling data, TIN construction of both cover layer and other stratums would be built in order to obtain the 3D geological model. Then, the engineering design data would be introduced into the 3D geological model for achieving unified modeling. For this process, the volume subdividing and restructuring principles were introduced to deal with the spatial relationships between engineering object and geological object. In order to improve the efficiency of unified modeling, the reconstruction of TIN based on constraint information was also applied in this method. At last, the feasibility and validation of the unified modeling method as well as its relevant key algorithms were verified by specific experiments and analysis of results.
基金Project(20102304120007) supported by the Research Fund for the Doctoral Program of Higher Education of ChinaProject(QC2010009)supported by the Natural Science Foundation of Heilongjiang Province, China+1 种基金Projects(20110491030, LBH-Z10219) supported by China Postdoctoral Science FoundationProject(HEUCF120706) supported by the Fundamental Research Funds for the Central Universities of China
文摘A three-DOF (degree of freedom) planar robot completely restrained and positioned parallel pulled by four wires was studied. The wire driving properties were analyzed through experiments. The restrained three-DOF planar platform was established based on slippery course and bearing, and dSPACE real-time control system was used to perform the platform's motion control experiment on robot. Based on the kinematic equation and mechanical balance equation of moving platform, the stiffness of the robot system was analyzed and the calibration scheme of the system considering wire tension was put forward. Position servo control experiments were carried out, position servo tracking precision was analyzed, and real-time wire tension was detected. The results show that the moving error of the moving platform tracking is small (the maximum difference is about 3%), and the rotation error is large (the maximum difference is about 12%). The wire tension has wave properties (the wire tension fluctuation is about 10 N).
基金Project(52025082) supported by the National Natural Science Foundation for Distinguished Young Scholars of ChinaProject(CX20190288) supported by Hunan Provincial Innovation Foundation for Postgraduate,China。
文摘Wind tunnel tests were carried out to investigate the aerodynamic interference between a triple-box girder and trains,involving static aerodynamic forces and vortex-induced vibrations(VIVs).Static and dynamic sectional models of the girder and trains were employed for aerodynamic force measurement and VIV test,respectively.Results indicate that the aerodynamic interference effect on static aerodynamic forces of both the girder and trains is remarkable.When a single train exists,the horizontal position of the train has a small effect on aerodynamic coefficients of the girder.When two trains meet on the girder,the drag coefficient of the girder is significantly reduced compared with that of without train or with a single train;besides,during the whole meeting process,aerodynamic forces of the leeward train first drop and then increase suddenly.The fluctuation of aerodynamic force could cause redundant vibration of the train,which is unfavorable for safety and comfort.A train on the girder could worsen the girder VIV performance:a new vertical VIV appears in the triple-box girder when a train is on the girder,and the torsional VIV amplitude increases significantly when the train is on the windward side.
基金Projects(40974077,41164004)supported by the National Natural Science Foundation of ChinaProject(2007AA06Z134)supported by the National High Technology Research and Development Program of China+2 种基金Projects(2011GXNSFA018003,0832263)supported by the Natural Science Foundation of Guangxi Province,ChinaProject supported by Program for Excellent Talents in Guangxi Higher Education Institution,ChinaProject supported by the Foundation of Guilin University of Technology,China
文摘The strategies that minimize the overall solution time of multiple linear systems in 3D finite element method (FEM) modeling of direct current (DC) resistivity were discussed. A global stiff matrix is assembled and stored in two parts separately. One part is associated with the volume integral and the other is associated with the subsurface boundary integral. The equivalent multiple linear systems with closer right-hand sides than the original systems were constructed. A recycling Krylov subspace technique was employed to solve the multiple linear systems. The solution of the seed system was used as an initial guess for the subsequent systems. The results of two numerical experiments show that the improved algorithm reduces the iterations and CPU time by almost 50%, compared with the classical preconditioned conjugate gradient method.
