Solid-liquid hydrocyclones are mainly used to separate large particles, such as the particles of drilling fluid in petroleum industry, and large mineral particles. Till now the hydrocyclonic separation for fine partic...Solid-liquid hydrocyclones are mainly used to separate large particles, such as the particles of drilling fluid in petroleum industry, and large mineral particles. Till now the hydrocyclonic separation for fine particles is still a big problem. Basic separation principle of hydrocyclones and experimental research facility are simply introduced. The difficulty of separating fine particle is analyzed. Based on a solid-liquid hydrocyclone used for separating fine particles, relationships of dimensionless pressure characteristic parameters, i.e. Euler number and pressure drop ratio, with several main dimensionless parameters, such as split ratio, swirl number and gas-liquid ratio, were experimentally studied in detail. The research was carried out by using the hydrocyclonic separation experimental rig at the University of Bradford. It is shown that the less the size of particle, the less the value of radius of the balance orbit occupied by the particle, and then the more difficult for the particle to be separated. Experiments indicate that Euler number of the tested hydrocyclone increases with the rise of Reynolds number, split ratio, swirl number and gas-liquid ratio respectively, and the pressure drop ratio falls with the increase of Reynolds number, split ratio and swirl number respectively. It is concluded that the most effective way to decrease the unit energy dissipation of hydrocyclone is to reduce swirl number or gas-liquid ratio of the mixed media.展开更多
Programs take on changing behavior at nmtime in a simultaneous multithreading (SMT) environment. How reasonably common resources are distributed among the threads significantly determines the throughput and fairness...Programs take on changing behavior at nmtime in a simultaneous multithreading (SMT) environment. How reasonably common resources are distributed among the threads significantly determines the throughput and fairness performance in SMT processors. Existing resource distribution methods either mainly rely on the front-end fetch policy, or make distribution decisions according to the limited information from the pipeline. It is difficult for them to efficiently catch the various resource requirements of the threads. This work presents a spatially triggered dissipative resource distribution (SDRD) policy for SMT processors, its two parts, the self-organization mechanism that is driven by the real-time instructions per cycle (IPC) performance and the introduction of chaos that tries to control the diversity Of trial resource distributions, work together to supply sustaining resource distribution optimization for changing program behavior. Simulation results show that SDRD with fine-grained diversity controlling is more effective than that with a coarse-grained one. And SDRD benefits much from its two well-coordinated parts, providing potential fairness gains as well as good throughput gains. Meanings and settings of important SDRD parameters are also discussed.展开更多
A defined mesophilic consortium including an iron oxidizing bacterium and a sulfur oxidizing bacterium was constructed to evaluate its ability for bioleaching a flotation concentrate from Andacollo mine in Neuqué...A defined mesophilic consortium including an iron oxidizing bacterium and a sulfur oxidizing bacterium was constructed to evaluate its ability for bioleaching a flotation concentrate from Andacollo mine in Neuquén,Argentina.Experiments were performed in shake flasks with a pulp density of10%(w/v),using a basal salt medium containing ferrous iron at pH1.8.The leaching solutions were analyzed for pH,redox potential(using specifics electrodes),ferrous iron(by UV-Vis spectrophotometry)and metal concentrations(by atomic absorption spectroscopy).The results showed that the consortium was able to reduce the refractory behavior of the concentrate,allowing91.6%of gold recovery;at the same time,high dissolution of copper and zinc was reached.These dissolutions followed a shrinking core kinetic model.According to this model,the copper solubilization was controlled by diffusion through a product layer(mainly jarosite),while zinc dissolution did not show a defined control step.This designed consortium,composed of bacterial strains with specific physiological abilities,could be useful not only to optimize gold recovery but also to decrease the leachates metallic charge,which would be an environmental advantage.展开更多
Pulsed signal experiment was carried out to determine the hydrodynamic behaviours of lateral flow biological aerated filter(LBAF). With the analysis of experimental results, LBAF is viewed as an approximate plug flow ...Pulsed signal experiment was carried out to determine the hydrodynamic behaviours of lateral flow biological aerated filter(LBAF). With the analysis of experimental results, LBAF is viewed as an approximate plug flow reactor, and hydraulic retention time distribution function was derived based on LBAF. The results show that flow rate and aeration strength are two critical factors which influence flow patterns in LBAF reactor. The hydrodynamic behaviour analysis of LBAF is the theoretical basis of future research on improving capacity factor and developing kinetic model for the reactor.展开更多
Cross-media retrieval is an interesting research topic,which seeks to remove the barriers among different modalities.To enable cross-media retrieval,it is needed to find the correlation measures between heterogeneous ...Cross-media retrieval is an interesting research topic,which seeks to remove the barriers among different modalities.To enable cross-media retrieval,it is needed to find the correlation measures between heterogeneous low-level features and to judge the semantic similarity.This paper presents a novel approach to learn cross-media correlation between visual features and auditory features for image-audio retrieval.A semi-supervised correlation preserving mapping(SSCPM)method is described to construct the isomorphic SSCPM subspace where canonical correlations between the original visual and auditory features are further preserved.Subspace optimization algorithm is proposed to improve the local image cluster and audio cluster quality in an interactive way.A unique relevance feedback strategy is developed to update the knowledge of cross-media correlation by learning from user behaviors,so retrieval performance is enhanced in a progressive manner.Experimental results show that the performance of our approach is effective.展开更多
There is a growing awareness among industry players of reaping the benefits of mobile-cloud convergence by extending today's unmodified cloud to a decentralized two-level cloud-cloudlet architecture based on emerg...There is a growing awareness among industry players of reaping the benefits of mobile-cloud convergence by extending today's unmodified cloud to a decentralized two-level cloud-cloudlet architecture based on emerging mobile-edge computing(MEC) capabilities. In light of future 5G mobile networks moving toward decentralization based on cloudlets, intelligent base stations, and MEC, the inherent distributed processing and storage capabilities of radio-and-fiber(R&F) networks may be exploited for new applications, e.g., cognitive assistance, augmented reality, or cloud robotics. In this paper, we first revisit fiber-wireless(Fi Wi) networks in the context of conventional clouds and emerging cloudlets, thereby highlighting the limitations of conventional radio-overfiber(Ro F) networks such as China Mobile's centralized cloud radio access network(C-RAN) to meet the aforementioned trends. Furthermore, we pay close attention to the specific design challenges of data center networks and revisit our switchless arrayedwaveguide grating(AWG) based network with efficient support of east-west flows and enhanced scalability.展开更多
Cu-15Ni-8Sn-0.3Nb alloy rods were prepared by means of powder metallurgy followed by hot extrusion.Element maps obtained by electron probe micro analyzer(EPMA)showed that Nb-rich phases were formed and distributed wit...Cu-15Ni-8Sn-0.3Nb alloy rods were prepared by means of powder metallurgy followed by hot extrusion.Element maps obtained by electron probe micro analyzer(EPMA)showed that Nb-rich phases were formed and distributed within grains and at grain boundaries of the Cu-15Ni-8Sn-0.3Nb alloy.Transmission electron microscope(TEM)results indicated that there was no obvious orientation relationship between these phases and the matrix.Spinodal decomposition and ordering transformation appeared at early stages of aging at400°C and caused significant strengthening.Cu-15Ni-8Sn-0.3Nb alloy exhibited both higher strength(ultimate tensile strength>1030MPa)and higher tensile ductility(elongation>9.1%)than Cu-15Ni-8Sn alloy after aging treatment.The improvement was caused by Nb-rich phases at grain boundaries which led o the refinement of grain size and postponed the growth of discontinuous precipitates during aging.展开更多
A combined first and second-order model, which includes bulk decay and wall decay, was developed to describe chlorine decay in water distribution systems. In the model the bulk decay has complex relationships with tot...A combined first and second-order model, which includes bulk decay and wall decay, was developed to describe chlorine decay in water distribution systems. In the model the bulk decay has complex relationships with total organic carbon (TOC), the initial chlorine concentration and the temperature. Except for the initial stages they can be simplified into a linear increase with TOC, a linear decrease with initial chlorine concentration and an exponential relationship with the temperature. The model also explains why chlorine decays rapidly in the initial stages. The parameters of model are determined by deriving the best fitness with experimental data. And the accuracy of model has been verified by using the experimental data and the monitoring data in a distribution system.展开更多
Based on the advantages of the wavelet to separate regional field and local anomalies in MATLAB environment,a high-precision regional-residual separation was finally realized. Analytical continuation and trend surface...Based on the advantages of the wavelet to separate regional field and local anomalies in MATLAB environment,a high-precision regional-residual separation was finally realized. Analytical continuation and trend surface analysis are conventional methods for gravity anomaly separation. But the wavelet packet analysis in analyzing gravity data can make the gravity anomaly to be computed at a higher precision. In this paper,wavelet packet method is used to process gravity anomaly data obtained in Laos,and the separation result is good. Daubechies wavelet series has a higher precision in the wavelet packet.展开更多
To study the physical and mechanical properties of coal rock after treatment at different temperatures under impact loading, dynamic compression experiments were conducted by using a split Hopkinson pressure bar(SHPB)...To study the physical and mechanical properties of coal rock after treatment at different temperatures under impact loading, dynamic compression experiments were conducted by using a split Hopkinson pressure bar(SHPB). The stress–strain curves of specimens under impact loading were obtained, and then four indexes affected by temperature were analyzed in the experiment: the longitudinal wave velocity, elastic modulus, peak stress and peak strain. Among these indexes, the elastic modulus was utilized to express the specimens' damage characteristics. The results show that the stress–strain curves under impact loading lack the stage of micro-fissure closure and the slope of the elastic deformation stage is higher than that under static loading. Due to the dynamic loading effect, the peak stress increases while peak strain decreases. The dynamic mechanical properties of coal rock show obvious temperature effects. The longitudinal wave velocity, elastic modulus and peak stress all decrease to different extents with increasing temperature, while the peak strain increases continuously. During the whole heating process, the thermal damage value continues to increase linearly, which indicates that the internal structure of coal rock is gradually damaged by high temperature.展开更多
One of the bottle-neck problems to the commercial development of supercritlcal water oxidation (SCWO) is high operation cost. In this study the condition to realize an energetically self-sufficient SCWO process is a...One of the bottle-neck problems to the commercial development of supercritlcal water oxidation (SCWO) is high operation cost. In this study the condition to realize an energetically self-sufficient SCWO process is analyzed. The reaction heat is recovered by means of Organic Rankine Circle. The process of SCWO for phenol is simulated with the Aspen Plus~ process simulator, and the results show that the influence of temperature on reaction heat is small at a constant pressure. It is reasonable to neglect the effect of temperature and to estimate the heat of reaction with average temperature when the temperature changes in a small range. The necessary condition to realize an energetically self-sufficient SCWO process is that the released energy is not less than consumed one. Whether a waste system with given chemical composition is energeticallyself-sufficient can be estimated by ^QR^QH 〉 W The thermodynamics analysis shows that energetically self-sufficient SCWO process with an Organic Rankine Cycle is a feasible technology for the recovery of SCWO reaction heat,and the energy balance point for phenol is 2wt%.展开更多
The adsorption capacity of powdered active carbons, used in a water treatment facility, for the removal of the triazine herbicides propazine, prometryn and prometon, was evaluated. Kinetic studies showed that some of ...The adsorption capacity of powdered active carbons, used in a water treatment facility, for the removal of the triazine herbicides propazine, prometryn and prometon, was evaluated. Kinetic studies showed that some of the carbon samples used could be suitable in the practice for the treatment of moderate contents of the herbicides in contaminated waters. Equilibrium studies showed that the data fit the Frumkin isotherm. The results show that in the adsorption process there are repulsive lateral interactions that depend mainly of the adsorbate molecules rather than the nature or distribution of adsorption sites. Such lateral interactions seem to be established mainly between the isopropyl groups of adjacent molecules, being of the same order for the three molecules. The effectiveness of the active carbons was evaluated by determining the percentage of reduction achieved by each product.展开更多
The ability of some Tunisian sand-clays in rural wastewater treatment was investigated in this study. The sand-clays were characterized by studying the mineralogical and geochemical characteristics using X-ray diffrac...The ability of some Tunisian sand-clays in rural wastewater treatment was investigated in this study. The sand-clays were characterized by studying the mineralogical and geochemical characteristics using X-ray diffractometer and atomic absorption spectrophotometer (AAS), respectively. Performance efficiency studies were conducted to determine the best combination ratio of sand-clay/pebbles. Sand-clay fortified with pebbles in the ratio 3:1 gave the optimum water purification while combination ratio 1:3 gave the least. The fortified sand-clays were used in the treatment of wastewater from rural locality. On the other hand, bacteria play an important role in determining the properties and behavior of clay minerals in natural environments and such interactions have great potential for creating stable biofilms and carbon storage sites in soils, but our knowledge of these interactions are far from complete. The purpose of this study was to understand better the effects of bacteria-generated biofilms on clay interlayer expansion. Mixtures of a colloidal, 2-water smectite clay and Pseudomonas aereginosae in a minimal media suspension evolve into a polysaccharide-rich biofilm aggregate in time-series experiments lasting up to 1 week. X-ray diffraction analysis reveals that upon aggregation, the clay undergoes an initial interlayer contraction.展开更多
The solution of linear equation group can be applied to the oil exploration, the structure vibration analysis, the computational fluid dynamics, and other fields. When we make the in-depth analysis of some large or ve...The solution of linear equation group can be applied to the oil exploration, the structure vibration analysis, the computational fluid dynamics, and other fields. When we make the in-depth analysis of some large or very large complicated structures, we must use the parallel algorithm with the aid of high-performance computers to solve complex problems. This paper introduces the implementation process having the parallel with sparse linear equations from the perspective of sparse linear equation group.展开更多
Neural information processing is tightly coupled to both energy consumption and derivation from substrates.In this study,the energy function of the neuron during the action potential(AP)is described and analyzed.It ha...Neural information processing is tightly coupled to both energy consumption and derivation from substrates.In this study,the energy function of the neuron during the action potential(AP)is described and analyzed.It has been observed that energy consumption during the AP does not match predictions of the conventional theory of neural energy dynamics.On short time scales,neural energy expenditure shifts between positive and negative phases.During the AP,the energy source switches from neuronal stores(positive expenditure or net consumption)to exploitation of external substrates,specifically the glucose and oxygen carried in cerebral blood(the negative consumption phase).Based on the idea of reductionism,this paper demonstrates how ion channels,membrane pumps and transporters,ionotropic and metabotropic receptor signaling pathways,astrocyte glycolysis and the production lactate,and the glutamate-glutamine cycle all serve to relate cerebral blood flow and neuronal metabolism to neuronal activity and so maintain neuronal energy charge during the AP.展开更多
Shale gas has been discovered in the Upper Triassic Yanchang Formation, Ordos Basin, China. Due to the weak tectonic activities in which the shale plays, core observations indicate abundant random non-tectonic micro- ...Shale gas has been discovered in the Upper Triassic Yanchang Formation, Ordos Basin, China. Due to the weak tectonic activities in which the shale plays, core observations indicate abundant random non-tectonic micro- fractures in the producing shales. The non-tectonic micro-fractures are different from tectonic fractures and are characterized by being irregular, curved, discontinuous, and randomly distributed. The role of micro-fractures in hydraulic fracturing for shale gas development is currently poorly understood yet potentially critical. Two-dimensional computational modeling studies have been used in an initial attempt toward understanding how naturally random fractured reservoirs respond during hydraulic fracturing. The aim of the paper is to investigate the effect of random non-tectonic fractures on hydraulic fracturing. The numerical models with random non-tectonic micro-fractures are built by extracting the fractures of rock blocks after repeated heating and cooling, using a digital image process. Simulations were conducted as a function of:(1) the in-situ stress ratio;(2) internal friction angle of random fractures;(3) cohesion of random fractures;(4) operational variables such as injection rate; and(5) variable injection rate technology. A sensitivity study reveals a number of interesting observations resulting from these parameters on the shear stimulation in a natural fracture system. Three types of fracturing networks were observed from the studied simulations, and the results also show that variable injection rate technology is most promising for producing complex fracturing networks. This work strongly links the production technology and geomechanical evaluation. It can aid in the understanding and optimization of hydraulic fracturing simulations in naturally random fractured reservoirs.展开更多
Mental imagery generation is essential in the retrieval and storage of knowledge.Previous studies have indicated that the holistic properties of mental imagery generation can be evaluated more easily than the partial ...Mental imagery generation is essential in the retrieval and storage of knowledge.Previous studies have indicated that the holistic properties of mental imagery generation can be evaluated more easily than the partial properties.However,the relationship between partial and holistic mental imagery generations has not been clearly demonstrated.To address this issue,we designed a task to investigate the changes in the spectrum of the electroencephalogram (EEG) during partial or holistic imagery generation.EEG signals were obtained from 18 healthy subjects,and a statistical measure of spectral dynamics between two EEG signals in per frequency band was performed.Additionally,a bicoherence spectrum analysis was used to detect the phase coupling within these two imagery conditions.Our results indicated that EEG of the partial imagery appeared earlier and stronger than that of the holistic imagery in the theta (5–8 Hz) range in a time window around 220 to 300 ms after cue onset,and a slight decrease in the alpha (8–12 Hz) band was observed at around 270 ms.The scalp topography of these changes in the theta and alpha bands distributed overall significantly in the frontal and central-temporal areas.The significant phase coupling within two conditions was remarkable at high frequency.From these results,we infer that there are complex relations between partial and holistic imageries.The generation of partial mental imagery is not a subprocess of holistic imagery,but it is relevant to holistic imagery and requires correct modification from the holistic information.展开更多
This paper aims to study the Earth's temporal inertia moment and its influence on length of day (LOD). First, the GRACE data are processed by wavelet analysis to remove abnormal jumps and noises. Then the theoreti...This paper aims to study the Earth's temporal inertia moment and its influence on length of day (LOD). First, the GRACE data are processed by wavelet analysis to remove abnormal jumps and noises. Then the theoretical impacts of the second-order potential coefficients on the inertia moment and LOD are studied. Finally, the processed GRACE data are applied and results show that mass redistribution has led to decreasing tendencies of inertia moment and LOD as well as some unexpected seasonal oscillations in the recent 6 years.展开更多
文摘Solid-liquid hydrocyclones are mainly used to separate large particles, such as the particles of drilling fluid in petroleum industry, and large mineral particles. Till now the hydrocyclonic separation for fine particles is still a big problem. Basic separation principle of hydrocyclones and experimental research facility are simply introduced. The difficulty of separating fine particle is analyzed. Based on a solid-liquid hydrocyclone used for separating fine particles, relationships of dimensionless pressure characteristic parameters, i.e. Euler number and pressure drop ratio, with several main dimensionless parameters, such as split ratio, swirl number and gas-liquid ratio, were experimentally studied in detail. The research was carried out by using the hydrocyclonic separation experimental rig at the University of Bradford. It is shown that the less the size of particle, the less the value of radius of the balance orbit occupied by the particle, and then the more difficult for the particle to be separated. Experiments indicate that Euler number of the tested hydrocyclone increases with the rise of Reynolds number, split ratio, swirl number and gas-liquid ratio respectively, and the pressure drop ratio falls with the increase of Reynolds number, split ratio and swirl number respectively. It is concluded that the most effective way to decrease the unit energy dissipation of hydrocyclone is to reduce swirl number or gas-liquid ratio of the mixed media.
基金the Hi-Tech Research and Development Pro-gram (863) of China (No. 2006AA01Z431) the Key Science andTechnology Program of Zhejiang Province (Nos. 2007C11068 and2007C11088), China
文摘Programs take on changing behavior at nmtime in a simultaneous multithreading (SMT) environment. How reasonably common resources are distributed among the threads significantly determines the throughput and fairness performance in SMT processors. Existing resource distribution methods either mainly rely on the front-end fetch policy, or make distribution decisions according to the limited information from the pipeline. It is difficult for them to efficiently catch the various resource requirements of the threads. This work presents a spatially triggered dissipative resource distribution (SDRD) policy for SMT processors, its two parts, the self-organization mechanism that is driven by the real-time instructions per cycle (IPC) performance and the introduction of chaos that tries to control the diversity Of trial resource distributions, work together to supply sustaining resource distribution optimization for changing program behavior. Simulation results show that SDRD with fine-grained diversity controlling is more effective than that with a coarse-grained one. And SDRD benefits much from its two well-coordinated parts, providing potential fairness gains as well as good throughput gains. Meanings and settings of important SDRD parameters are also discussed.
基金supported by PIP 0368 from CONICET and PICT 0630 and 0623 from ANPCyT
文摘A defined mesophilic consortium including an iron oxidizing bacterium and a sulfur oxidizing bacterium was constructed to evaluate its ability for bioleaching a flotation concentrate from Andacollo mine in Neuquén,Argentina.Experiments were performed in shake flasks with a pulp density of10%(w/v),using a basal salt medium containing ferrous iron at pH1.8.The leaching solutions were analyzed for pH,redox potential(using specifics electrodes),ferrous iron(by UV-Vis spectrophotometry)and metal concentrations(by atomic absorption spectroscopy).The results showed that the consortium was able to reduce the refractory behavior of the concentrate,allowing91.6%of gold recovery;at the same time,high dissolution of copper and zinc was reached.These dissolutions followed a shrinking core kinetic model.According to this model,the copper solubilization was controlled by diffusion through a product layer(mainly jarosite),while zinc dissolution did not show a defined control step.This designed consortium,composed of bacterial strains with specific physiological abilities,could be useful not only to optimize gold recovery but also to decrease the leachates metallic charge,which would be an environmental advantage.
基金Project(2001BA604A01) supported by the Key Project of National"Tenth Five Year"Science & Technology of China
文摘Pulsed signal experiment was carried out to determine the hydrodynamic behaviours of lateral flow biological aerated filter(LBAF). With the analysis of experimental results, LBAF is viewed as an approximate plug flow reactor, and hydraulic retention time distribution function was derived based on LBAF. The results show that flow rate and aeration strength are two critical factors which influence flow patterns in LBAF reactor. The hydrodynamic behaviour analysis of LBAF is the theoretical basis of future research on improving capacity factor and developing kinetic model for the reactor.
基金Project supported by the National Natural Science Foundation of China (Nos. 60533090 and 60773051)the Natural Science Foundation of Zhejiang Province (No. Y105395),China
文摘Cross-media retrieval is an interesting research topic,which seeks to remove the barriers among different modalities.To enable cross-media retrieval,it is needed to find the correlation measures between heterogeneous low-level features and to judge the semantic similarity.This paper presents a novel approach to learn cross-media correlation between visual features and auditory features for image-audio retrieval.A semi-supervised correlation preserving mapping(SSCPM)method is described to construct the isomorphic SSCPM subspace where canonical correlations between the original visual and auditory features are further preserved.Subspace optimization algorithm is proposed to improve the local image cluster and audio cluster quality in an interactive way.A unique relevance feedback strategy is developed to update the knowledge of cross-media correlation by learning from user behaviors,so retrieval performance is enhanced in a progressive manner.Experimental results show that the performance of our approach is effective.
文摘There is a growing awareness among industry players of reaping the benefits of mobile-cloud convergence by extending today's unmodified cloud to a decentralized two-level cloud-cloudlet architecture based on emerging mobile-edge computing(MEC) capabilities. In light of future 5G mobile networks moving toward decentralization based on cloudlets, intelligent base stations, and MEC, the inherent distributed processing and storage capabilities of radio-and-fiber(R&F) networks may be exploited for new applications, e.g., cognitive assistance, augmented reality, or cloud robotics. In this paper, we first revisit fiber-wireless(Fi Wi) networks in the context of conventional clouds and emerging cloudlets, thereby highlighting the limitations of conventional radio-overfiber(Ro F) networks such as China Mobile's centralized cloud radio access network(C-RAN) to meet the aforementioned trends. Furthermore, we pay close attention to the specific design challenges of data center networks and revisit our switchless arrayedwaveguide grating(AWG) based network with efficient support of east-west flows and enhanced scalability.
基金Project (2016YFB0301400) supported by the National Key Research and Development Program of ChinaProject (9140A12040515QT48167) supported by the Pre-research Fund of the General Armaments Department of ChinaProject (CSU20151024) supported by the Innovation-driven Plan of Central South University,China
文摘Cu-15Ni-8Sn-0.3Nb alloy rods were prepared by means of powder metallurgy followed by hot extrusion.Element maps obtained by electron probe micro analyzer(EPMA)showed that Nb-rich phases were formed and distributed within grains and at grain boundaries of the Cu-15Ni-8Sn-0.3Nb alloy.Transmission electron microscope(TEM)results indicated that there was no obvious orientation relationship between these phases and the matrix.Spinodal decomposition and ordering transformation appeared at early stages of aging at400°C and caused significant strengthening.Cu-15Ni-8Sn-0.3Nb alloy exhibited both higher strength(ultimate tensile strength>1030MPa)and higher tensile ductility(elongation>9.1%)than Cu-15Ni-8Sn alloy after aging treatment.The improvement was caused by Nb-rich phases at grain boundaries which led o the refinement of grain size and postponed the growth of discontinuous precipitates during aging.
基金Sponsored by Fok Ying Tung Education Foundation (No. 94004)
文摘A combined first and second-order model, which includes bulk decay and wall decay, was developed to describe chlorine decay in water distribution systems. In the model the bulk decay has complex relationships with total organic carbon (TOC), the initial chlorine concentration and the temperature. Except for the initial stages they can be simplified into a linear increase with TOC, a linear decrease with initial chlorine concentration and an exponential relationship with the temperature. The model also explains why chlorine decays rapidly in the initial stages. The parameters of model are determined by deriving the best fitness with experimental data. And the accuracy of model has been verified by using the experimental data and the monitoring data in a distribution system.
文摘Based on the advantages of the wavelet to separate regional field and local anomalies in MATLAB environment,a high-precision regional-residual separation was finally realized. Analytical continuation and trend surface analysis are conventional methods for gravity anomaly separation. But the wavelet packet analysis in analyzing gravity data can make the gravity anomaly to be computed at a higher precision. In this paper,wavelet packet method is used to process gravity anomaly data obtained in Laos,and the separation result is good. Daubechies wavelet series has a higher precision in the wavelet packet.
基金Projects(41272304,51304241,51204068)supported by the National Natural Science Foundation of ChinaProject(2014M552164)supported by the Postdoctoral Science Foundation of ChinaProject(20130162120015)supported by the PhD Programs Foundation of Ministry of Education of China
文摘To study the physical and mechanical properties of coal rock after treatment at different temperatures under impact loading, dynamic compression experiments were conducted by using a split Hopkinson pressure bar(SHPB). The stress–strain curves of specimens under impact loading were obtained, and then four indexes affected by temperature were analyzed in the experiment: the longitudinal wave velocity, elastic modulus, peak stress and peak strain. Among these indexes, the elastic modulus was utilized to express the specimens' damage characteristics. The results show that the stress–strain curves under impact loading lack the stage of micro-fissure closure and the slope of the elastic deformation stage is higher than that under static loading. Due to the dynamic loading effect, the peak stress increases while peak strain decreases. The dynamic mechanical properties of coal rock show obvious temperature effects. The longitudinal wave velocity, elastic modulus and peak stress all decrease to different extents with increasing temperature, while the peak strain increases continuously. During the whole heating process, the thermal damage value continues to increase linearly, which indicates that the internal structure of coal rock is gradually damaged by high temperature.
文摘One of the bottle-neck problems to the commercial development of supercritlcal water oxidation (SCWO) is high operation cost. In this study the condition to realize an energetically self-sufficient SCWO process is analyzed. The reaction heat is recovered by means of Organic Rankine Circle. The process of SCWO for phenol is simulated with the Aspen Plus~ process simulator, and the results show that the influence of temperature on reaction heat is small at a constant pressure. It is reasonable to neglect the effect of temperature and to estimate the heat of reaction with average temperature when the temperature changes in a small range. The necessary condition to realize an energetically self-sufficient SCWO process is that the released energy is not less than consumed one. Whether a waste system with given chemical composition is energeticallyself-sufficient can be estimated by ^QR^QH 〉 W The thermodynamics analysis shows that energetically self-sufficient SCWO process with an Organic Rankine Cycle is a feasible technology for the recovery of SCWO reaction heat,and the energy balance point for phenol is 2wt%.
文摘The adsorption capacity of powdered active carbons, used in a water treatment facility, for the removal of the triazine herbicides propazine, prometryn and prometon, was evaluated. Kinetic studies showed that some of the carbon samples used could be suitable in the practice for the treatment of moderate contents of the herbicides in contaminated waters. Equilibrium studies showed that the data fit the Frumkin isotherm. The results show that in the adsorption process there are repulsive lateral interactions that depend mainly of the adsorbate molecules rather than the nature or distribution of adsorption sites. Such lateral interactions seem to be established mainly between the isopropyl groups of adjacent molecules, being of the same order for the three molecules. The effectiveness of the active carbons was evaluated by determining the percentage of reduction achieved by each product.
文摘The ability of some Tunisian sand-clays in rural wastewater treatment was investigated in this study. The sand-clays were characterized by studying the mineralogical and geochemical characteristics using X-ray diffractometer and atomic absorption spectrophotometer (AAS), respectively. Performance efficiency studies were conducted to determine the best combination ratio of sand-clay/pebbles. Sand-clay fortified with pebbles in the ratio 3:1 gave the optimum water purification while combination ratio 1:3 gave the least. The fortified sand-clays were used in the treatment of wastewater from rural locality. On the other hand, bacteria play an important role in determining the properties and behavior of clay minerals in natural environments and such interactions have great potential for creating stable biofilms and carbon storage sites in soils, but our knowledge of these interactions are far from complete. The purpose of this study was to understand better the effects of bacteria-generated biofilms on clay interlayer expansion. Mixtures of a colloidal, 2-water smectite clay and Pseudomonas aereginosae in a minimal media suspension evolve into a polysaccharide-rich biofilm aggregate in time-series experiments lasting up to 1 week. X-ray diffraction analysis reveals that upon aggregation, the clay undergoes an initial interlayer contraction.
文摘The solution of linear equation group can be applied to the oil exploration, the structure vibration analysis, the computational fluid dynamics, and other fields. When we make the in-depth analysis of some large or very large complicated structures, we must use the parallel algorithm with the aid of high-performance computers to solve complex problems. This paper introduces the implementation process having the parallel with sparse linear equations from the perspective of sparse linear equation group.
基金supported by the National Natural Science Foundation of China(Grant Nos.1123200511002055)the Ministry of Education Doctoral Foundation(Grant No.20120074110020)
文摘Neural information processing is tightly coupled to both energy consumption and derivation from substrates.In this study,the energy function of the neuron during the action potential(AP)is described and analyzed.It has been observed that energy consumption during the AP does not match predictions of the conventional theory of neural energy dynamics.On short time scales,neural energy expenditure shifts between positive and negative phases.During the AP,the energy source switches from neuronal stores(positive expenditure or net consumption)to exploitation of external substrates,specifically the glucose and oxygen carried in cerebral blood(the negative consumption phase).Based on the idea of reductionism,this paper demonstrates how ion channels,membrane pumps and transporters,ionotropic and metabotropic receptor signaling pathways,astrocyte glycolysis and the production lactate,and the glutamate-glutamine cycle all serve to relate cerebral blood flow and neuronal metabolism to neuronal activity and so maintain neuronal energy charge during the AP.
基金supported by the National Natural Science Foundation of China(Grant Nos.4122790141330643&41502294)+2 种基金China Postdoctoral Science Foundation Funded Project(Grants No.2015M571118)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grants Nos.XDB10030000XDB10030300&XDB10050400)
文摘Shale gas has been discovered in the Upper Triassic Yanchang Formation, Ordos Basin, China. Due to the weak tectonic activities in which the shale plays, core observations indicate abundant random non-tectonic micro- fractures in the producing shales. The non-tectonic micro-fractures are different from tectonic fractures and are characterized by being irregular, curved, discontinuous, and randomly distributed. The role of micro-fractures in hydraulic fracturing for shale gas development is currently poorly understood yet potentially critical. Two-dimensional computational modeling studies have been used in an initial attempt toward understanding how naturally random fractured reservoirs respond during hydraulic fracturing. The aim of the paper is to investigate the effect of random non-tectonic fractures on hydraulic fracturing. The numerical models with random non-tectonic micro-fractures are built by extracting the fractures of rock blocks after repeated heating and cooling, using a digital image process. Simulations were conducted as a function of:(1) the in-situ stress ratio;(2) internal friction angle of random fractures;(3) cohesion of random fractures;(4) operational variables such as injection rate; and(5) variable injection rate technology. A sensitivity study reveals a number of interesting observations resulting from these parameters on the shear stimulation in a natural fracture system. Three types of fracturing networks were observed from the studied simulations, and the results also show that variable injection rate technology is most promising for producing complex fracturing networks. This work strongly links the production technology and geomechanical evaluation. It can aid in the understanding and optimization of hydraulic fracturing simulations in naturally random fractured reservoirs.
基金Project supported by the National Natural Science Foundation of China (No. 60971096)the National Basic Research Program (973) of China (No. 2006CB504100)
文摘Mental imagery generation is essential in the retrieval and storage of knowledge.Previous studies have indicated that the holistic properties of mental imagery generation can be evaluated more easily than the partial properties.However,the relationship between partial and holistic mental imagery generations has not been clearly demonstrated.To address this issue,we designed a task to investigate the changes in the spectrum of the electroencephalogram (EEG) during partial or holistic imagery generation.EEG signals were obtained from 18 healthy subjects,and a statistical measure of spectral dynamics between two EEG signals in per frequency band was performed.Additionally,a bicoherence spectrum analysis was used to detect the phase coupling within these two imagery conditions.Our results indicated that EEG of the partial imagery appeared earlier and stronger than that of the holistic imagery in the theta (5–8 Hz) range in a time window around 220 to 300 ms after cue onset,and a slight decrease in the alpha (8–12 Hz) band was observed at around 270 ms.The scalp topography of these changes in the theta and alpha bands distributed overall significantly in the frontal and central-temporal areas.The significant phase coupling within two conditions was remarkable at high frequency.From these results,we infer that there are complex relations between partial and holistic imageries.The generation of partial mental imagery is not a subprocess of holistic imagery,but it is relevant to holistic imagery and requires correct modification from the holistic information.
基金Supported by the Open Fund of Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, China (No.08-02-02)the Special Project Fund of State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing (China)the National 863 Program of China (No.2006AA12Z211)
文摘This paper aims to study the Earth's temporal inertia moment and its influence on length of day (LOD). First, the GRACE data are processed by wavelet analysis to remove abnormal jumps and noises. Then the theoretical impacts of the second-order potential coefficients on the inertia moment and LOD are studied. Finally, the processed GRACE data are applied and results show that mass redistribution has led to decreasing tendencies of inertia moment and LOD as well as some unexpected seasonal oscillations in the recent 6 years.