With the rapid development of cloud computing,edge computing,and smart devices,computing power resources indicate a trend of ubiquitous deployment.The traditional network architecture cannot efficiently leverage these...With the rapid development of cloud computing,edge computing,and smart devices,computing power resources indicate a trend of ubiquitous deployment.The traditional network architecture cannot efficiently leverage these distributed computing power resources due to computing power island effect.To overcome these problems and improve network efficiency,a new network computing paradigm is proposed,i.e.,Computing Power Network(CPN).Computing power network can connect ubiquitous and heterogenous computing power resources through networking to realize computing power scheduling flexibly.In this survey,we make an exhaustive review on the state-of-the-art research efforts on computing power network.We first give an overview of computing power network,including definition,architecture,and advantages.Next,a comprehensive elaboration of issues on computing power modeling,information awareness and announcement,resource allocation,network forwarding,computing power transaction platform and resource orchestration platform is presented.The computing power network testbed is built and evaluated.The applications and use cases in computing power network are discussed.Then,the key enabling technologies for computing power network are introduced.Finally,open challenges and future research directions are presented as well.展开更多
In this paper the coefficient and law of the size effect of RPC were studied through experiments and theoretical analysis. The size-effect coefficients for the compressive strength of RPC are deduced through experimen...In this paper the coefficient and law of the size effect of RPC were studied through experiments and theoretical analysis. The size-effect coefficients for the compressive strength of RPC are deduced through experiments.They indicate that RPC without fiber behaves quite the same as normal or high strength concrete.The size effect on compressive strength is more prominent in RPC containing fiber.Bazant's size effect formula of compressive strength applies to RPC.A formula is given to predict the compressive strength of cubic RPC specimens 100 mm on a side where the fiber dosage ranges from 0-2%.展开更多
Lithium production in China mainly depends on hard rock lithium ores,which has a defect in resources,environment,and economy compared with extracting lithium from brine.This paper focuses on the research progress of e...Lithium production in China mainly depends on hard rock lithium ores,which has a defect in resources,environment,and economy compared with extracting lithium from brine.This paper focuses on the research progress of extracting lithium from spodumene,lepidolite,petalite,and zinnwaldite by acid,alkali,salt roasting,and chlorination methods,and analyzes the resource intensity,environmental impact,and production cost of industrial lithium extraction from spodumene and lepidolite.It is found that the sulfuric acid method has a high lithium recovery rate,but with a complicated process and high energy consumption;alkali and chlorination methods can directly react with lithium ores,reducing energy consumption,but need to optimize reaction conditions and safety of equipment and operation;the salt roasting method has large material flux and high energy consumption,so require adjustment of sulfate ratio to increase the lithium yield and reduce production cost.Compared with extracting lithium from brine,extracting lithium from ores,calcination,roasting,purity,and other processes consume more resources and energy;and its environmental impact mainly comes from the pollutants discharged by fossil energy,9.3-60.4 times that of lithium extracted from brine.The processing cost of lithium extraction from lepidolite by sulfate roasting method is higher than that from spodumene by sulfuric acid due to the consumption of high-value sulfate.However,the production costs of both are mainly affected by the price of lithium ores,which is less competitive than that of extracting lithium from brine.Thus,the process of extracting lithium from ores should develop appropriate technology,shorten the process flow,save resources and energy,and increase the recovery rate of related elements to reduce environmental impact and improve the added value of by-products and the economy of the process.展开更多
A novel on-line system composed of supercritical fluid extraction(SFE), dilution line and reverse phase liquid chromatography/mass spectrometry(RPLC/MS) was constructed for on-line extraction and reverse phase separat...A novel on-line system composed of supercritical fluid extraction(SFE), dilution line and reverse phase liquid chromatography/mass spectrometry(RPLC/MS) was constructed for on-line extraction and reverse phase separation of some fat-soluble components in foods. Three columns including a trap column,concentration column and analytical column were used for trapping the fat-soluble components, on-line enrichment and reverse phase separation, respectively. Capsaicinoids were on-line extracted by a CO_2 supercritical fluid, then concentrated and separated by using the C_(18) columns, finally detected by mass spectrometry(MS). Capsaicin eluted at 10.1 min and limit of detection(LOD, S/N=3) for the standard solution is 0.55pg. The linearity was calculated with a value of coefficient of determination(R^2)≥0.998 in the range of 1.1–8.5 ng. Concentrations of capsaicin in the green, yellow, and red bell peppers were determined to be 60.33 ng/g, 31.79 ng/g, 35.38ng/g, respectively.展开更多
The mesoscale eddy and internal wave both are phenomena commonly observed in oceans. It is aimed to investigate how the presence of a mesoscale eddy in the ocean affects wave form deformation of the internal solitary ...The mesoscale eddy and internal wave both are phenomena commonly observed in oceans. It is aimed to investigate how the presence of a mesoscale eddy in the ocean affects wave form deformation of the internal solitary wave propagation. An ocean eddy is produced by a quasi-geostrophic model in f-plane, and the one-dimensional nonlinear variable-coefficient extended Korteweg-de Vries （eKdV） equation is used to simulate an internal solitary wave passing through the mesoscale eddy field. The results suggest that the mode structures of the linear internal wave are modified due to the presence of the mesoscale eddy field. A cyclonic eddy and an anticyclonic eddy have different influences on the background environment of the internal solitary wave propagation. The existence of a mesoscale eddy field has almost no prominent impact on the propagation of a smallamplitude internal solitary wave only based on the first mode vertical structure, but the mesoscale eddy background field exerts a considerable influence on the solitary wave propagation if considering high-mode vertical structures. Furthermore, whether an internal solitary wave first passes through anticyclonic eddy or cyclonic eddy, the deformation of wave profiles is different. Many observations of solitary internal waves in the real oceans suggest the formation of the waves. Apart from topography effect, it is shown that the mesoscale eddy background field is also a considerable factor which influences the internal solitary wave propagation and deformation.展开更多
The propagation and fission process of internal solitary waves （ISWs） with amplitudes of about 170 m are simulated in the northeast of the South China Sea （NSCS） by using the generalized Korteweg-de Vries （KdV） ...The propagation and fission process of internal solitary waves （ISWs） with amplitudes of about 170 m are simulated in the northeast of the South China Sea （NSCS） by using the generalized Korteweg-de Vries （KdV） equation under continuous stratification. More attention is paid to the effects of the ebb and flood background currents on the fission process of ISWs. This kind of background current is provided by the composed results simulated in terms of monthly mean baroclinic circulation and barotropic tidal current. It is found that the obtained relation of the number of fission solitons to the water depth and stratification is roughly in accordance with the fission law derived by Djordjevic and Redekopp in 1978; however, there exists obvious difference between the effects of the ebb and flood background currents on the wave-lengths of fission solitons （defined as the distance between two neighboring peaks of ISWs）. The difference in nonlinearity coefficient a between the ebb and flood background currents is a main cause for the different wave-lengths of fission solitons.展开更多
BACKGROUND The preoperative prediction of peritoneal metastasis(PM)in gastric cancer would prevent unnecessary surgery and promptly indicate an appropriate treatment plan.AIM To explore the predictive value of viscera...BACKGROUND The preoperative prediction of peritoneal metastasis(PM)in gastric cancer would prevent unnecessary surgery and promptly indicate an appropriate treatment plan.AIM To explore the predictive value of visceral fat(VF)parameters obtained from preoperative computed tomography(CT)images for occult PM and to develop an individualized model for predicting occult PM in patients with gastric carcinoma(GC).METHODS A total of 128 confirmed GC cases(84 male and 44 female patients)that underwent CT scans were analyzed and categorized into PM-positive(n=43)and PM-negative(n=85)groups.The clinical characteristics and VF parameters of two regions of interest(ROIs)were collected.Univariate and stratified analyses based on VF volume were performed to screen for predictive characteristics for occult PM.Prediction models with and without VF parameters were established by multivariable logistic regression analysis.RESULTS The mean attenuations of VF_(ROI 1)and VF_(ROI 2)varied significantly between the PM-positive and PMnegative groups(P=0.044 and 0.001,respectively).The areas under the receiver operating characteristic curves(AUCs)of VF_(ROI 1)and VF_(ROI 2)were 0.599 and 0.657,respectively.The mean attenuation of VF_(ROI 2)was included in the final prediction combined model,but not an independent risk factor of PM(P=0.068).No significant difference was observed between the models with and without mean attenuation of VF(AUC:0.749 vs 0.730,P=0.339).CONCLUSION The mean attenuation of VF is a potential auxiliary parameter for predicting occult PM in patients with GC.展开更多
Glaciers are a critical freshwater resource of river recharge in arid areas around the world.In recent decades,glaciers have shown evidence of retreat due to climate change,and the accelerated ablation of glaciers and...Glaciers are a critical freshwater resource of river recharge in arid areas around the world.In recent decades,glaciers have shown evidence of retreat due to climate change,and the accelerated ablation of glaciers and associated impacts on water resources have received widespread attention.Glacier variations result from climate change,so they can serve as an indicator of climate change.Considering the climatic differences in different elevation ranges,it is worthwhile to explore whether different responses exist between glacier area and air temperature in each elevation zone.In this study,we selected a typical arid inland river basin(Sugan Lake Basin)in the western Qilian Mountains of Northwest China to analyze the glacier variations and their response to climate change.The glacier area data from 1989 to 2016 were delineated using Landsat Thematic Mapper(TM),Enhanced TM+(ETM+)and Operational Land Imager(OLI)images.We compared the relationships between glacier area and air temperature at seven meteorological stations in the glacier-covered areas and in the Sugan Lake Basin,and further analyzed the relationship between glacier area and mean air temperature of the glacier surfaces in July–August in the elevation range of 4700–5500 m a.s.l.by the linear regression method and correlation analysis.In addition,based on the linear regression relationship established between glacier area and air temperature in each elevation zone,we predicted glacier areas under future climate scenarios during the periods of 2046–2065 and 2081–2100.The results indicate that the glaciers experienced a remarkable shrinkage from 1989 to 2016 with a shrinkage rate of–1.61 km^2/a(–0.5%/a),and the rising temperature is the decisive factor dominating glacial retreat;there is a significant negative linear correlation between glacier area and mean air temperature of the glacier surfaces in July–August in each elevation zone from 1989 to 2016.The variations in glaciers are far less sensitive to changes in precipitation than to changes in air temperature.Due to the influence of climate and topographic conditions,the distribution of glacier area and the rate of glacier ablation first increased and then decreased in different elevation zones.The trend in glacier shrinkage will continue because air temperature will continue to increase in the future,and the result of glacier retreat in each elevation zone will be slightly slower than that in the entire study area.Quantitative glacier research can more accurately reflect the response of glacier variations to climate change,and the regression relationship can be used to predict the areas of glaciers under future climate scenarios.These conclusions can offer effective references for assessing glacier variations and their response to climate change in arid inland river basins in Northwest China as well as other similar regions in the world.展开更多
This paper highlights the statistical procedure used in developing models that have the ability of capturing and forecasting the traffic of mobile communication network operating in Vietnam. To build such models, we f...This paper highlights the statistical procedure used in developing models that have the ability of capturing and forecasting the traffic of mobile communication network operating in Vietnam. To build such models, we follow Box-Jenkins method to construct a multiplicative seasonal ARIMA model to represent the mean component using the past values of traffic, then incorporate a GARCH model to represent its volatility. The traffic is collected from EVN Telecom mobile communication network. Diagnostic tests and examination of forecast accuracy measures indicate that the multiplicative seasonal ARIMA/GARCH model, i.e. ARIMA (1, 0, 1) × (0, 1, 1)24/GARCH (1, 1) shows a good estimation when dealing with volatility clustering in the data series. This model can be considered to be a flexible model to capture well the characteristics of EVN traffic series and give reasonable forecasting results. Moreover, in such situations that the volatility is not necessary to be taken into account, i.e. short-term prediction, the multiplicative seasonal ARIMA/GARCH model still acts well with the GARCH parameters adjusted to GARCH (0, 0).展开更多
With the development of the Industrial Internet of Things(IIoT),end devices(EDs)are equipped with more functions to capture information.Therefore,a large amount of data is generated at the edge of the network and need...With the development of the Industrial Internet of Things(IIoT),end devices(EDs)are equipped with more functions to capture information.Therefore,a large amount of data is generated at the edge of the network and needs to be processed.However,no matter whether these computing tasks are offloaded to traditional central clusters or mobile edge computing(MEC)devices,the data is short of security and may be changed during transmission.In view of this challenge,this paper proposes a trusted task offloading optimization scheme that can offer low latency and high bandwidth services for IIoT with data security.Blockchain technology is adopted to ensure data consistency.Meanwhile,to reduce the impact of low throughput of blockchain on task offloading performance,we design the processes of consensus and offloading as a Markov decision process(MDP)by defining states,actions,and rewards.Deep reinforcement learning(DRL)algorithm is introduced to dynamically select offloading actions.To accelerate the optimization,we design a novel reward function for the DRL algorithm according to the scale and computational complexity of the task.Experiments demonstrate that compared with methods without optimization,our mechanism performs better when it comes to the number of task offloading and throughput of blockchain.展开更多
In this study, the effect of heat treatment on the room temperature strength of W-core Si C fiber produced by chemical vapor deposition（CVD） was investigated. Thermal exposure in the temperature range of 900–1000？...In this study, the effect of heat treatment on the room temperature strength of W-core Si C fiber produced by chemical vapor deposition（CVD） was investigated. Thermal exposure in the temperature range of 900–1000？C decreases the strength of the Si C fiber. Fracture morphology analysis indicates that failure initiations predominantly take place at the W-core/Si C interface. A reaction layer that formed at the W-core/Si C interface during thermal exposure degraded the fiber strength and an empirical linear relationship of strength vs thickness of the reaction layer can be obtained. The kinetics of the growth of the W-core/Si C reaction layer were determined.展开更多
Restoration of mining soils is important to the vegetation and environment.This study aimed to explore the variations in soil nutrient contents,microbial abundance,and biomass under different gradients of substrate am...Restoration of mining soils is important to the vegetation and environment.This study aimed to explore the variations in soil nutrient contents,microbial abundance,and biomass under different gradients of substrate amendments in mining soils to select effective measures.Soil samples were collected from the Bayan Obo mining region in Inner Mongolia Autonomous Region,China.Contents of soil organic matter(SOM),available nitrogen(AN),available phosphorus(AP),available potassium(AK),microbial biomass carbon/microbial biomass nitrogen(MBC/MBN)ratio,biomass,and bacteria,fungi,and actinomycetes abundance were assessed in Agropyron cristatum L.Gaertn.,Elymus dahuricus Turcz.,and Medicago sativa L.soils with artificial zeolite(AZ)and microbial fertilizer(MF)applied at T0(0 g/kg),T1(5 g/kg),T2(10 g/kg),and T3(20 g/kg).Redundancy analysis(RDA)and technique for order preference by similarity to ideal solution(TOPSIS)were used to identify the main factors controlling the variation of biomass.Results showed that chemical indices and microbial content of restored soils were far greater than those of control.The application of AZ significantly increases SOM,AN,and AP by 20.27%,23.61%,and 40.43%,respectively.AZ significantly increased bacteria,fungi,and actinomycetes abundance by 0.63,3.12,and 1.93 times of control,respectively.RDA indicated that AN,MBC/MBN ratio,and SOM were dominant predictors for biomass across samples with AZ application,explaining 87.6%of the biomass variance.SOM,MBC/MBN ratio,and AK were dominant predictors with MF application,explaining 82.9%of the biomass variance.TOPSIS indicated that T2 was the best dosage and the three plant species could all be used to repair mining soils.AZ and MF application at T2 concentration in the mining soils with M.sativa was found to be the most appropriate measure.展开更多
Light weights wheels improve vehicle performance with respect to road handling, cornering as well providing fuel economy and reduced greenhouse gas emissions. Aluminum wheels are currently used in many models and are ...Light weights wheels improve vehicle performance with respect to road handling, cornering as well providing fuel economy and reduced greenhouse gas emissions. Aluminum wheels are currently used in many models and are produced usually by low pressure assisted gravity casting. Important property requirements are fatigue strength, pressure tightness, tensile strength, impact resistance, and corrosion resistance. Many attempts have been made to convert aluminum road wheels to magnesium. Race cars and some of the high end models (Porsche, Ferrari, etc.) have used magnesium wheels. These wheels have been gravity cast or forged. Viable corrosion protection systems have been developed and magnesium wheels have been used with success on these models. To use magnesium on more modest models is a challenge due to cost issues. Higher productivity casting processes or more cost effective coating systems need to be utilized. The project consists of selecting magnesium alloys for road wheels, examining the possible cost effective casting processes and corrosion protection systems, evaluating the cost per one wheel and comparing it to aluminum wheel costs. The wheels will also be compared with respect to fatigue and impact properties, pressure tightness, and corrosion.展开更多
The MAC layer in IEEE802.16 is designed to differentiate service among traffic categories with different multimedia requirements.In this paper,a scheduling algorithm at MAC layer for multiple connections with diverse ...The MAC layer in IEEE802.16 is designed to differentiate service among traffic categories with different multimedia requirements.In this paper,a scheduling algorithm at MAC layer for multiple connections with diverse QoS requirements is proposed.As for this algorithm,each connection is assigned a priority,which is updated dynamically based on its service status concluding queue characteristic and channel state.A connection with the highest priority is scheduled each time.Analytical model is developed by assuming a Finite State Markov Chain(FSMC)channel model.Simulation results show that the proposed scheduling algorithm can improve the performance of mean waiting time and throughput in broadband wireless networks.展开更多
The ceramic thermal barrier coatings (TBCs) play an increasingly important in advanced gas turbine engines because of their ability to further increase the engine operating temperature and reduce the cooling, thus hel...The ceramic thermal barrier coatings (TBCs) play an increasingly important in advanced gas turbine engines because of their ability to further increase the engine operating temperature and reduce the cooling, thus help achieve future engine low emission, high efficiency and improve the reliability goals. Currently, there are two different processes such as the plasma spraying (PS) and the electron beam-physical vapor deposition (EB-PVD) techniques. The PS coating was selected to test the elastic modulus. Using the nanoindentation and resonant frequency method, the mechanical properties of ceramic top-coat were measured in-situ. According to the theory of the resonant frequency and composite beam, the testing system was set up including the hardware and software. The results show that the accurate characterization of the elastic properties of TBCs is important for stress-strain analysis and failure prediction. The TBCs systems are multi-layer material system. It is difficult to measure the elastic modulus of top-coat by tensile method. The testing data is scatter by nanoindentation method because of the microstructure of the ceramic top-coat. The elastic modulus of the top-coat between 20?1 150 ℃ is obtained. The elastic modulus is from 2 to 70 GPa at room temperature. The elastic modulus changes from 62.5 GPa to 18.6 GPa when the temperature increases from 20 ℃ to 1 150 ℃.展开更多
This paper introduces a new stabilized finite element method for the coupled Stokes and Darcy problem based on the nonconforming Crouzeix-Raviart element. Optimal error estimates for the fluid velocity and pressure ar...This paper introduces a new stabilized finite element method for the coupled Stokes and Darcy problem based on the nonconforming Crouzeix-Raviart element. Optimal error estimates for the fluid velocity and pressure are derived. A numerical example is presented to verify the theoretical predictions.展开更多
In this work the applicability of the micro-channel reactor technique to the production of promising platform chemical 5-hydroxymethyl furan(HMF) from fructose in aqueous solution is systemically investigated by perfo...In this work the applicability of the micro-channel reactor technique to the production of promising platform chemical 5-hydroxymethyl furan(HMF) from fructose in aqueous solution is systemically investigated by performing CFD simulations.Influential factors including solvents,residence time distribution of reaction mixtures,heat transfer conditions and micro-channel configurations are evaluated in terms of the reaction performance indices,i.e.,conversion of fructose,HMF selectivity and yield.A scale-up method from a single channel to a multiple channel reactor is also proposed.It is demonstrated that:1) at the single channel scale,controlling residence times and temperature distribution of the reaction mixture within the channel is crucial for enhancing the reaction performance,while different channel configurations lead to marginal improvements;2) for the scaling-up of the reaction process,a reactor module containing 15 circular parallel channels could be used as module blocks,which can be stacked one by one to meet the required reactor performance and production capacity.The present results show that micro-reactors are quite suitable for HMF production.展开更多
The Sulige gas field is a typical low-pressure low-permeability tight sandstone gas reservoir. The reservoir has poor seepage capacity, strong heterogeneity, high mineralization of formation water and extremely scarce...The Sulige gas field is a typical low-pressure low-permeability tight sandstone gas reservoir. The reservoir has poor seepage capacity, strong heterogeneity, high mineralization of formation water and extremely scarce water resources on the site. These unfavorable factors have brought great difficulties to the on-site mining process. Now, a nano-composite green environmental protection slick water fracturing fluid system CQFR can be quickly dissolved because of the larger specific surface area, and the small molecular size makes the damage to the reservoir less than 5%, and the average drag reduction effect can reach more than 73%. It can quickly and well dissolve and maintain performance under high salinity conditions and fracturing flowback fluids. It responds well to the complex reservoir conditions on the construction site and makes the flowback fluid recyable, which greatly reduces the consumption of water resources on the construction site and effectively improves the construction efficiency and economic benefits.展开更多
To enhance the performance of the artificial bee colony optimization by integrating the quantum computing model into bee colony optimization, we present a quantum-inspired bee colony optimization algorithm. In our met...To enhance the performance of the artificial bee colony optimization by integrating the quantum computing model into bee colony optimization, we present a quantum-inspired bee colony optimization algorithm. In our method, the bees are encoded with the qubits described on the Bloch sphere. The classical bee colony algorithm is used to compute the rotation axes and rotation angles. The Pauli matrices are used to construct the rotation matrices. The evolutionary search is achieved by rotating the qubit about the rotation axis to the target qubit on the Bloch sphere. By measuring with the Pauli matrices, the Bloch coordinates of qubit can be obtained, and the optimization solutions can be presented through the solution space transformation. The proposed method can simultaneously adjust two parameters of a qubit and automatically achieve the best match between two adjustment quantities, which may accelerate the optimization process. The experimental results show that the proposed method is obviously superior to the classical one for some benchmark functions.展开更多
基金supported by the National Science Foundation of China under Grant 62271062 and 62071063by the Zhijiang Laboratory Open Project Fund 2020LCOAB01。
文摘With the rapid development of cloud computing,edge computing,and smart devices,computing power resources indicate a trend of ubiquitous deployment.The traditional network architecture cannot efficiently leverage these distributed computing power resources due to computing power island effect.To overcome these problems and improve network efficiency,a new network computing paradigm is proposed,i.e.,Computing Power Network(CPN).Computing power network can connect ubiquitous and heterogenous computing power resources through networking to realize computing power scheduling flexibly.In this survey,we make an exhaustive review on the state-of-the-art research efforts on computing power network.We first give an overview of computing power network,including definition,architecture,and advantages.Next,a comprehensive elaboration of issues on computing power modeling,information awareness and announcement,resource allocation,network forwarding,computing power transaction platform and resource orchestration platform is presented.The computing power network testbed is built and evaluated.The applications and use cases in computing power network are discussed.Then,the key enabling technologies for computing power network are introduced.Finally,open challenges and future research directions are presented as well.
基金Project 50508005 supported by the National Natural Science Foundations of China
文摘In this paper the coefficient and law of the size effect of RPC were studied through experiments and theoretical analysis. The size-effect coefficients for the compressive strength of RPC are deduced through experiments.They indicate that RPC without fiber behaves quite the same as normal or high strength concrete.The size effect on compressive strength is more prominent in RPC containing fiber.Bazant's size effect formula of compressive strength applies to RPC.A formula is given to predict the compressive strength of cubic RPC specimens 100 mm on a side where the fiber dosage ranges from 0-2%.
基金financially supported by the National Natural Science Foundation of China(71991484,41971265,72088101,and 71991480)the National Key R&D program of China(2021YFC2901801)。
文摘Lithium production in China mainly depends on hard rock lithium ores,which has a defect in resources,environment,and economy compared with extracting lithium from brine.This paper focuses on the research progress of extracting lithium from spodumene,lepidolite,petalite,and zinnwaldite by acid,alkali,salt roasting,and chlorination methods,and analyzes the resource intensity,environmental impact,and production cost of industrial lithium extraction from spodumene and lepidolite.It is found that the sulfuric acid method has a high lithium recovery rate,but with a complicated process and high energy consumption;alkali and chlorination methods can directly react with lithium ores,reducing energy consumption,but need to optimize reaction conditions and safety of equipment and operation;the salt roasting method has large material flux and high energy consumption,so require adjustment of sulfate ratio to increase the lithium yield and reduce production cost.Compared with extracting lithium from brine,extracting lithium from ores,calcination,roasting,purity,and other processes consume more resources and energy;and its environmental impact mainly comes from the pollutants discharged by fossil energy,9.3-60.4 times that of lithium extracted from brine.The processing cost of lithium extraction from lepidolite by sulfate roasting method is higher than that from spodumene by sulfuric acid due to the consumption of high-value sulfate.However,the production costs of both are mainly affected by the price of lithium ores,which is less competitive than that of extracting lithium from brine.Thus,the process of extracting lithium from ores should develop appropriate technology,shorten the process flow,save resources and energy,and increase the recovery rate of related elements to reduce environmental impact and improve the added value of by-products and the economy of the process.
基金supported by the National Natural Science Foundation of China (No. 21621003)
文摘A novel on-line system composed of supercritical fluid extraction(SFE), dilution line and reverse phase liquid chromatography/mass spectrometry(RPLC/MS) was constructed for on-line extraction and reverse phase separation of some fat-soluble components in foods. Three columns including a trap column,concentration column and analytical column were used for trapping the fat-soluble components, on-line enrichment and reverse phase separation, respectively. Capsaicinoids were on-line extracted by a CO_2 supercritical fluid, then concentrated and separated by using the C_(18) columns, finally detected by mass spectrometry(MS). Capsaicin eluted at 10.1 min and limit of detection(LOD, S/N=3) for the standard solution is 0.55pg. The linearity was calculated with a value of coefficient of determination(R^2)≥0.998 in the range of 1.1–8.5 ng. Concentrations of capsaicin in the green, yellow, and red bell peppers were determined to be 60.33 ng/g, 31.79 ng/g, 35.38ng/g, respectively.
基金The National Basic Research Program of China under contract Nos 2011CB403503 and 2012CB955601the Scientific Research Fund of the Second Institute of Oceanography, the State Oceanic Administration of China under contract Nos JG1009, JT1006 and JT0905
文摘The mesoscale eddy and internal wave both are phenomena commonly observed in oceans. It is aimed to investigate how the presence of a mesoscale eddy in the ocean affects wave form deformation of the internal solitary wave propagation. An ocean eddy is produced by a quasi-geostrophic model in f-plane, and the one-dimensional nonlinear variable-coefficient extended Korteweg-de Vries （eKdV） equation is used to simulate an internal solitary wave passing through the mesoscale eddy field. The results suggest that the mode structures of the linear internal wave are modified due to the presence of the mesoscale eddy field. A cyclonic eddy and an anticyclonic eddy have different influences on the background environment of the internal solitary wave propagation. The existence of a mesoscale eddy field has almost no prominent impact on the propagation of a smallamplitude internal solitary wave only based on the first mode vertical structure, but the mesoscale eddy background field exerts a considerable influence on the solitary wave propagation if considering high-mode vertical structures. Furthermore, whether an internal solitary wave first passes through anticyclonic eddy or cyclonic eddy, the deformation of wave profiles is different. Many observations of solitary internal waves in the real oceans suggest the formation of the waves. Apart from topography effect, it is shown that the mesoscale eddy background field is also a considerable factor which influences the internal solitary wave propagation and deformation.
基金supported by the Key Program of National Natural Science Foundation of China under contract No.41030855
文摘The propagation and fission process of internal solitary waves （ISWs） with amplitudes of about 170 m are simulated in the northeast of the South China Sea （NSCS） by using the generalized Korteweg-de Vries （KdV） equation under continuous stratification. More attention is paid to the effects of the ebb and flood background currents on the fission process of ISWs. This kind of background current is provided by the composed results simulated in terms of monthly mean baroclinic circulation and barotropic tidal current. It is found that the obtained relation of the number of fission solitons to the water depth and stratification is roughly in accordance with the fission law derived by Djordjevic and Redekopp in 1978; however, there exists obvious difference between the effects of the ebb and flood background currents on the wave-lengths of fission solitons （defined as the distance between two neighboring peaks of ISWs）. The difference in nonlinearity coefficient a between the ebb and flood background currents is a main cause for the different wave-lengths of fission solitons.
基金Supported by Henan Province 2023 Scientific Research Projects Focused on Higher Education Project,China,No.23A320059.
文摘BACKGROUND The preoperative prediction of peritoneal metastasis(PM)in gastric cancer would prevent unnecessary surgery and promptly indicate an appropriate treatment plan.AIM To explore the predictive value of visceral fat(VF)parameters obtained from preoperative computed tomography(CT)images for occult PM and to develop an individualized model for predicting occult PM in patients with gastric carcinoma(GC).METHODS A total of 128 confirmed GC cases(84 male and 44 female patients)that underwent CT scans were analyzed and categorized into PM-positive(n=43)and PM-negative(n=85)groups.The clinical characteristics and VF parameters of two regions of interest(ROIs)were collected.Univariate and stratified analyses based on VF volume were performed to screen for predictive characteristics for occult PM.Prediction models with and without VF parameters were established by multivariable logistic regression analysis.RESULTS The mean attenuations of VF_(ROI 1)and VF_(ROI 2)varied significantly between the PM-positive and PMnegative groups(P=0.044 and 0.001,respectively).The areas under the receiver operating characteristic curves(AUCs)of VF_(ROI 1)and VF_(ROI 2)were 0.599 and 0.657,respectively.The mean attenuation of VF_(ROI 2)was included in the final prediction combined model,but not an independent risk factor of PM(P=0.068).No significant difference was observed between the models with and without mean attenuation of VF(AUC:0.749 vs 0.730,P=0.339).CONCLUSION The mean attenuation of VF is a potential auxiliary parameter for predicting occult PM in patients with GC.
基金This study was financially supported by the National Key Research and Development Program of China(2016YFC0402405)the National Natural Science Foundation of China(91647109,51179203,51579248,51679257,51779270).
文摘Glaciers are a critical freshwater resource of river recharge in arid areas around the world.In recent decades,glaciers have shown evidence of retreat due to climate change,and the accelerated ablation of glaciers and associated impacts on water resources have received widespread attention.Glacier variations result from climate change,so they can serve as an indicator of climate change.Considering the climatic differences in different elevation ranges,it is worthwhile to explore whether different responses exist between glacier area and air temperature in each elevation zone.In this study,we selected a typical arid inland river basin(Sugan Lake Basin)in the western Qilian Mountains of Northwest China to analyze the glacier variations and their response to climate change.The glacier area data from 1989 to 2016 were delineated using Landsat Thematic Mapper(TM),Enhanced TM+(ETM+)and Operational Land Imager(OLI)images.We compared the relationships between glacier area and air temperature at seven meteorological stations in the glacier-covered areas and in the Sugan Lake Basin,and further analyzed the relationship between glacier area and mean air temperature of the glacier surfaces in July–August in the elevation range of 4700–5500 m a.s.l.by the linear regression method and correlation analysis.In addition,based on the linear regression relationship established between glacier area and air temperature in each elevation zone,we predicted glacier areas under future climate scenarios during the periods of 2046–2065 and 2081–2100.The results indicate that the glaciers experienced a remarkable shrinkage from 1989 to 2016 with a shrinkage rate of–1.61 km^2/a(–0.5%/a),and the rising temperature is the decisive factor dominating glacial retreat;there is a significant negative linear correlation between glacier area and mean air temperature of the glacier surfaces in July–August in each elevation zone from 1989 to 2016.The variations in glaciers are far less sensitive to changes in precipitation than to changes in air temperature.Due to the influence of climate and topographic conditions,the distribution of glacier area and the rate of glacier ablation first increased and then decreased in different elevation zones.The trend in glacier shrinkage will continue because air temperature will continue to increase in the future,and the result of glacier retreat in each elevation zone will be slightly slower than that in the entire study area.Quantitative glacier research can more accurately reflect the response of glacier variations to climate change,and the regression relationship can be used to predict the areas of glaciers under future climate scenarios.These conclusions can offer effective references for assessing glacier variations and their response to climate change in arid inland river basins in Northwest China as well as other similar regions in the world.
文摘This paper highlights the statistical procedure used in developing models that have the ability of capturing and forecasting the traffic of mobile communication network operating in Vietnam. To build such models, we follow Box-Jenkins method to construct a multiplicative seasonal ARIMA model to represent the mean component using the past values of traffic, then incorporate a GARCH model to represent its volatility. The traffic is collected from EVN Telecom mobile communication network. Diagnostic tests and examination of forecast accuracy measures indicate that the multiplicative seasonal ARIMA/GARCH model, i.e. ARIMA (1, 0, 1) × (0, 1, 1)24/GARCH (1, 1) shows a good estimation when dealing with volatility clustering in the data series. This model can be considered to be a flexible model to capture well the characteristics of EVN traffic series and give reasonable forecasting results. Moreover, in such situations that the volatility is not necessary to be taken into account, i.e. short-term prediction, the multiplicative seasonal ARIMA/GARCH model still acts well with the GARCH parameters adjusted to GARCH (0, 0).
基金supported by the Projects of Software of Big Data Processing Tool(TC210804V-1)Big Data Risk Screening Model Procurement(No.S20200).
文摘With the development of the Industrial Internet of Things(IIoT),end devices(EDs)are equipped with more functions to capture information.Therefore,a large amount of data is generated at the edge of the network and needs to be processed.However,no matter whether these computing tasks are offloaded to traditional central clusters or mobile edge computing(MEC)devices,the data is short of security and may be changed during transmission.In view of this challenge,this paper proposes a trusted task offloading optimization scheme that can offer low latency and high bandwidth services for IIoT with data security.Blockchain technology is adopted to ensure data consistency.Meanwhile,to reduce the impact of low throughput of blockchain on task offloading performance,we design the processes of consensus and offloading as a Markov decision process(MDP)by defining states,actions,and rewards.Deep reinforcement learning(DRL)algorithm is introduced to dynamically select offloading actions.To accelerate the optimization,we design a novel reward function for the DRL algorithm according to the scale and computational complexity of the task.Experiments demonstrate that compared with methods without optimization,our mechanism performs better when it comes to the number of task offloading and throughput of blockchain.
基金the Raman Spectroscopy Laboratory of Institute of Metal Research, Chinese Academy of Sciences for the support in the accomplishment of this paper
文摘In this study, the effect of heat treatment on the room temperature strength of W-core Si C fiber produced by chemical vapor deposition（CVD） was investigated. Thermal exposure in the temperature range of 900–1000？C decreases the strength of the Si C fiber. Fracture morphology analysis indicates that failure initiations predominantly take place at the W-core/Si C interface. A reaction layer that formed at the W-core/Si C interface during thermal exposure degraded the fiber strength and an empirical linear relationship of strength vs thickness of the reaction layer can be obtained. The kinetics of the growth of the W-core/Si C reaction layer were determined.
基金supported by the Beijing Forestry University(BJFU),China。
文摘Restoration of mining soils is important to the vegetation and environment.This study aimed to explore the variations in soil nutrient contents,microbial abundance,and biomass under different gradients of substrate amendments in mining soils to select effective measures.Soil samples were collected from the Bayan Obo mining region in Inner Mongolia Autonomous Region,China.Contents of soil organic matter(SOM),available nitrogen(AN),available phosphorus(AP),available potassium(AK),microbial biomass carbon/microbial biomass nitrogen(MBC/MBN)ratio,biomass,and bacteria,fungi,and actinomycetes abundance were assessed in Agropyron cristatum L.Gaertn.,Elymus dahuricus Turcz.,and Medicago sativa L.soils with artificial zeolite(AZ)and microbial fertilizer(MF)applied at T0(0 g/kg),T1(5 g/kg),T2(10 g/kg),and T3(20 g/kg).Redundancy analysis(RDA)and technique for order preference by similarity to ideal solution(TOPSIS)were used to identify the main factors controlling the variation of biomass.Results showed that chemical indices and microbial content of restored soils were far greater than those of control.The application of AZ significantly increases SOM,AN,and AP by 20.27%,23.61%,and 40.43%,respectively.AZ significantly increased bacteria,fungi,and actinomycetes abundance by 0.63,3.12,and 1.93 times of control,respectively.RDA indicated that AN,MBC/MBN ratio,and SOM were dominant predictors for biomass across samples with AZ application,explaining 87.6%of the biomass variance.SOM,MBC/MBN ratio,and AK were dominant predictors with MF application,explaining 82.9%of the biomass variance.TOPSIS indicated that T2 was the best dosage and the three plant species could all be used to repair mining soils.AZ and MF application at T2 concentration in the mining soils with M.sativa was found to be the most appropriate measure.
文摘Light weights wheels improve vehicle performance with respect to road handling, cornering as well providing fuel economy and reduced greenhouse gas emissions. Aluminum wheels are currently used in many models and are produced usually by low pressure assisted gravity casting. Important property requirements are fatigue strength, pressure tightness, tensile strength, impact resistance, and corrosion resistance. Many attempts have been made to convert aluminum road wheels to magnesium. Race cars and some of the high end models (Porsche, Ferrari, etc.) have used magnesium wheels. These wheels have been gravity cast or forged. Viable corrosion protection systems have been developed and magnesium wheels have been used with success on these models. To use magnesium on more modest models is a challenge due to cost issues. Higher productivity casting processes or more cost effective coating systems need to be utilized. The project consists of selecting magnesium alloys for road wheels, examining the possible cost effective casting processes and corrosion protection systems, evaluating the cost per one wheel and comparing it to aluminum wheel costs. The wheels will also be compared with respect to fatigue and impact properties, pressure tightness, and corrosion.
文摘The MAC layer in IEEE802.16 is designed to differentiate service among traffic categories with different multimedia requirements.In this paper,a scheduling algorithm at MAC layer for multiple connections with diverse QoS requirements is proposed.As for this algorithm,each connection is assigned a priority,which is updated dynamically based on its service status concluding queue characteristic and channel state.A connection with the highest priority is scheduled each time.Analytical model is developed by assuming a Finite State Markov Chain(FSMC)channel model.Simulation results show that the proposed scheduling algorithm can improve the performance of mean waiting time and throughput in broadband wireless networks.
文摘The ceramic thermal barrier coatings (TBCs) play an increasingly important in advanced gas turbine engines because of their ability to further increase the engine operating temperature and reduce the cooling, thus help achieve future engine low emission, high efficiency and improve the reliability goals. Currently, there are two different processes such as the plasma spraying (PS) and the electron beam-physical vapor deposition (EB-PVD) techniques. The PS coating was selected to test the elastic modulus. Using the nanoindentation and resonant frequency method, the mechanical properties of ceramic top-coat were measured in-situ. According to the theory of the resonant frequency and composite beam, the testing system was set up including the hardware and software. The results show that the accurate characterization of the elastic properties of TBCs is important for stress-strain analysis and failure prediction. The TBCs systems are multi-layer material system. It is difficult to measure the elastic modulus of top-coat by tensile method. The testing data is scatter by nanoindentation method because of the microstructure of the ceramic top-coat. The elastic modulus of the top-coat between 20?1 150 ℃ is obtained. The elastic modulus is from 2 to 70 GPa at room temperature. The elastic modulus changes from 62.5 GPa to 18.6 GPa when the temperature increases from 20 ℃ to 1 150 ℃.
基金Project supported by the Science and Technology Foundation of Sichuan Province(No. 05GG006-006-2)
文摘This paper introduces a new stabilized finite element method for the coupled Stokes and Darcy problem based on the nonconforming Crouzeix-Raviart element. Optimal error estimates for the fluid velocity and pressure are derived. A numerical example is presented to verify the theoretical predictions.
文摘In this work the applicability of the micro-channel reactor technique to the production of promising platform chemical 5-hydroxymethyl furan(HMF) from fructose in aqueous solution is systemically investigated by performing CFD simulations.Influential factors including solvents,residence time distribution of reaction mixtures,heat transfer conditions and micro-channel configurations are evaluated in terms of the reaction performance indices,i.e.,conversion of fructose,HMF selectivity and yield.A scale-up method from a single channel to a multiple channel reactor is also proposed.It is demonstrated that:1) at the single channel scale,controlling residence times and temperature distribution of the reaction mixture within the channel is crucial for enhancing the reaction performance,while different channel configurations lead to marginal improvements;2) for the scaling-up of the reaction process,a reactor module containing 15 circular parallel channels could be used as module blocks,which can be stacked one by one to meet the required reactor performance and production capacity.The present results show that micro-reactors are quite suitable for HMF production.
文摘The Sulige gas field is a typical low-pressure low-permeability tight sandstone gas reservoir. The reservoir has poor seepage capacity, strong heterogeneity, high mineralization of formation water and extremely scarce water resources on the site. These unfavorable factors have brought great difficulties to the on-site mining process. Now, a nano-composite green environmental protection slick water fracturing fluid system CQFR can be quickly dissolved because of the larger specific surface area, and the small molecular size makes the damage to the reservoir less than 5%, and the average drag reduction effect can reach more than 73%. It can quickly and well dissolve and maintain performance under high salinity conditions and fracturing flowback fluids. It responds well to the complex reservoir conditions on the construction site and makes the flowback fluid recyable, which greatly reduces the consumption of water resources on the construction site and effectively improves the construction efficiency and economic benefits.
文摘To enhance the performance of the artificial bee colony optimization by integrating the quantum computing model into bee colony optimization, we present a quantum-inspired bee colony optimization algorithm. In our method, the bees are encoded with the qubits described on the Bloch sphere. The classical bee colony algorithm is used to compute the rotation axes and rotation angles. The Pauli matrices are used to construct the rotation matrices. The evolutionary search is achieved by rotating the qubit about the rotation axis to the target qubit on the Bloch sphere. By measuring with the Pauli matrices, the Bloch coordinates of qubit can be obtained, and the optimization solutions can be presented through the solution space transformation. The proposed method can simultaneously adjust two parameters of a qubit and automatically achieve the best match between two adjustment quantities, which may accelerate the optimization process. The experimental results show that the proposed method is obviously superior to the classical one for some benchmark functions.
