AIM： To compare the volumetric-modulated arc ther- apy （VMAT） plans with conventional sliding window intensity-modulated radiotherapy （c-IMRT） plans in esophageal cancer （EC）. METHODS： Twenty patients with EC ...AIM： To compare the volumetric-modulated arc ther- apy （VMAT） plans with conventional sliding window intensity-modulated radiotherapy （c-IMRT） plans in esophageal cancer （EC）. METHODS： Twenty patients with EC were selected, including 5 cases located in the cervical, the upper, the middle and the lower thorax, respectively. Five plans were generated with the eclipse planning sys- tem： three using c-IMRT with 5 fields （5F）, 7 fields （7F） and 9 fields （gF）, and two using VMAT with a single arc （1A） and double arcs （2A）. The treatment plans were designed to deliver a dose of 60 Gy to the plan-ning target volume （PTV） with the same constrains in a 2.0 Gy daily fraction, 5 d a week. Plans were normal- ized to 95% of the PTV that received 100% of the pre- scribed dose. We examined the dose-volume histogram parameters of PTV and the organs at risk （OAR） such as lungs, spinal cord and heart. Monitor units （MU） and normal tissue complication probability （NTCP） of OAR were also reported. RESULTS： Both c-IMRT and VMAT plans resulted in abundant dose coverage of PTV for EC of different Io- cations. The dose conformity to PTV was improved as the number of field in c-IMRT or rotating arc in VMAT was increased. The doses to PTV and OAR in VMAT plans were not statistically different in comparison with c-IMRT plans, with the following exceptions： in cervical and upper thoracic EC, the conformity index （CI） was higher in VMAT （1A 0.78 and 2A 0.8） than in c-IMRT （5F 0.62, 7F 0.66 and 9F 0.73） and homogeneity was slightly better in c-IMRT （7F 1.09 and 9F 1.07） than in VMAT （1A 1,1 and 2A 1.09）, Lung V30 was lower in VMAT （1A 12.52 and 2A 12.29） than in c-IMRT （7F 14.35 and 9F 14.81）. The humeral head doses were significantly increased in VMAT as against c-IMRT. In the middle and lower thoracic EC, CI in VMAT （1A 0.76 and 2A 0.74） was higher than in c-IMRT （5F 0.63 Gy and 7F 0.67 Gy）, and homogeneity was almost similar between VMAT and c-IMRT展开更多
Bi is a promising candidate for energy storage materials because of its high volumetric capacity, stability in moisture/air, and facile preparation. In this study, the electrochemical performance of nanosized-Bi-embed...Bi is a promising candidate for energy storage materials because of its high volumetric capacity, stability in moisture/air, and facile preparation. In this study, the electrochemical performance of nanosized-Bi-embedded one-dimensional （1D） carbon nanofibers （Bi/C nanofibers） as anodes for Li-ion batteries （LIBs） and Na-ion batteries （NIBs） was systematically investigated. The Bi/C nanofibers were prepared using a single-nozzle electrospinning method with a specified Bi source followed by carbothermal reduction. Abundant Bi nanoparticles with diameters of approximately 20 nm were homogeneously dispersed and embedded in the 1D carbon nanofibers, as confirmed by structural and morphological characterization. Electrochemical measurements indicate that the Bi/C nanofiber anodes could deliver a long cycle life for LIBs and a preferable rate performance for NIBs. The superior electrochemical performances of the Bi/C nanofiber anodes are attributed to the 1D carbon nanofiber structure and uniform distribution of Bi nanoparticles embedded in the carbon matrix. This unique embedded structure provides a favorable electron carrier and buffering matrix for the effective release of mechanical stress caused by volume change and prevents the aggregation of Bi nanoparticles.展开更多
The soil water index （SWI） from satellite remote sensing and the observational soil moisture from agricultural meteorological stations in eastern China are used to retrieve soil moisture. The analysis of correlation...The soil water index （SWI） from satellite remote sensing and the observational soil moisture from agricultural meteorological stations in eastern China are used to retrieve soil moisture. The analysis of correlation coefficient （CORR）, root-mean-square-error （RMSE） and bias （BIAS） shows that the retrieved soil moisture is convincible and close to the observation. The method can overcome the difficulties in soil moisture observation on a large scale and the retrieved soil moisture may reflect the distribution of the real soil moisture objectively. The retrieved soil moisture is used as an initial scheme to replace initial conditions of soil moisture （NCEP） in the model MM5V3 to simulate the heavy rainfall in 1998. Three heavy rainfall processes during 13-14 June, 18-22 June, and 21-26 July 1998 in the Yangtze River valley are analyzed. The first two processes show that the intensity and location of simulated precipitation from SWI are better than those from NCEP and closer to the observed values. The simulated heavy rainfall for 21-26 July shows that the update of soil moisture initial conditions can improve the model＇s performance. The relationship between soil moisture and rainfall may explain that the stronger rainfall intensity for SWI in the Yangtze River valley is the result of the greater simulated soil moisture from SWI prior to the heavy rainfall date than that from NCEP, and leads to the decline of temperature in the corresponding area in the heavy rainfall days. Detailed analysis of the heavy rainfall on 13-14 June shows that both land-atmosphere interactions and atmospheric circulation were responsible for the heavy ralnfall, and it shows how the SWI simulation improves the simulation. The development of mesoscale systems plays an important role in the simulation regarding the change of initial soil moisture for SWI.展开更多
To fully extract and mine the multi-scale features of reservoirs and geologic structures in time/depth and space dimensions, a new 3D multi-scale volumetric curvature （MSVC） methodology is presented in this paper. W...To fully extract and mine the multi-scale features of reservoirs and geologic structures in time/depth and space dimensions, a new 3D multi-scale volumetric curvature （MSVC） methodology is presented in this paper. We also propose a fast algorithm for computing 3D volumetric curvature. In comparison to conventional volumetric curvature attributes, its main improvements and key algorithms introduce multi-frequency components expansion in time-frequency domain and the corresponding multi-scale adaptive differential operator in the wavenumber domain, into the volumetric curvature calculation. This methodology can simultaneously depict seismic multi-scale features in both time and space. Additionally, we use data fusion of volumetric curvatures at various scales to take full advantage of the geologic features and anomalies extracted by curvature measurements at different scales. The 3D MSVC can highlight geologic anomalies and reduce noise at the same time. Thus, it improves the interpretation efficiency of curvature attributes analysis. The 3D MSVC is applied to both land and marine 3D seismic data. The results demonstrate that it can indicate the spatial distribution of reservoirs, detect faults and fracture zones, and identify their multi-scale properties.展开更多
Low volumetric energy density is a bottleneck for the application of lithium-sulfur (Li-S)battery.The low- density sulfur cooperated with the light-weight carbon sub- strate realizes electrochemical cycle stability,bu...Low volumetric energy density is a bottleneck for the application of lithium-sulfur (Li-S)battery.The low- density sulfur cooperated with the light-weight carbon sub- strate realizes electrochemical cycle stability,but leads to worse volumetric energy density.Here,nickel ferrite (NiFe2O4)nanofibers as novel substrate for sulfur not only anchor lithium polysulfides to enhance the cycle stability of sulfur cathode,but also contribute to the high volumetric capacity of the S/nickel ferrite composite.Specifically,the S/ nickel ferrite composite presents an initial volumetric capacity of 1,281.7mA h cm^-3-composite at 0.1C rate,1.9times higher than that of S/carbon nanotubes,due to the high tap density of the S/nickel ferrite composite.展开更多
Holographic data storage system （HDSS） has been a good candidate for a volumetric recording technology, due to their large storage capacities and high transfer rates, and have been researched for tens of years after...Holographic data storage system （HDSS） has been a good candidate for a volumetric recording technology, due to their large storage capacities and high transfer rates, and have been researched for tens of years after the principle of holography was first proposed. However, these systems, called conventional 2-axis holography, still have essential issues for commercialization of products. Collinear HDSS, in which the information and reference beams are modulated co-axially by the same spatial light modulator （SLM）, as a new read/write method for HDSS are very promising. With this unique configuration, the optical pickup can be designed as small as DVDs, and can be placed on one side of the recording media （disc）. In the disc structure, the preformatted reflective layer is used for the focus/tracking servo and reading address information, and a dichroic mirror layer is used for detecting holographic recording information without interfering with the preformatted information. A 2-dimensional digital page data format is used and the shift-multiplexing method is employed to increase recording density. As servo technologies are being introduced to control the objective lens to be maintained precisely to the disc in the recording and reconstructing process, a vibration isolator is no longer necessary. Collinear holography can produce a small, practical HDSS more easily than conventional 2-axis holography. In this paper, we introduced the principle of the collinear holography and its media structure of disc. Some results of experimental and theoretical studies suggest that it is a very effective method. We also discussed some methods to increase the recording density and data transfer rates of collinear holography.展开更多
The seepage evolution characteristic of brittle rock materials is very significant for the stability and safety of rock engineering. In this research, a series of conventional triaxial compression and gas seepage test...The seepage evolution characteristic of brittle rock materials is very significant for the stability and safety of rock engineering. In this research, a series of conventional triaxial compression and gas seepage tests were carded out on sandstone specimens with a rock mechanics servo-controlled testing system. Based on the experimental results, the relationship between permeability and deformation is firstly analyzed in detail. The results show that the permeabilityaxial strain curve can be divided into the following five phases： the phase of micro-defects closure, the phase of linear elastic deformation, the phase of nonlinear deformation, the phase of post-peak stress softening and the phase of residual strength. The seepage evolution characteristic is also closely correlated with the volumetric deformation according to the relationship between permeability and volumetric strain. It is found that the gas seepage pressure has a great effect on the permeability evolution, i.e. permeability coefficients increase with increasing gas seepage pressures. Finally, the influence of gas seepage pressures on the failure behavior of brittle sandstone specimens is discussed.展开更多
Volumetric particle image velocimetry(VPIV) refers to a PIV-based technique which can obtain full velocity components in a three-dimensional measurement volume.A new VPIV method with a single lens was developed.A thre...Volumetric particle image velocimetry(VPIV) refers to a PIV-based technique which can obtain full velocity components in a three-dimensional measurement volume.A new VPIV method with a single lens was developed.A three-vision prism was used to make viewing from different angles using one camera.The technique was tested and successfully applied to a three-dimensional three-component(3D3C) measurement of a zero-net-mass-flux jet flow.The accuracy of the measurement was investigated,specifically in steps of calibration,self-calibration and particle triangulation.Time sequence of a vortex ring development was presented.It was shown that the measurement has high accuracy with validation rate of velocity vector reaching about 95%.The flow with vortex ring passing the measurement volume was studied using both swirl strength and vorticity magnitude criteria.Through comparison,the swirl criterion was found to be superior to the criterion of vorticity in differentiating the rotation motion and the free shear.展开更多
It is of great significance for safety reason to obtain the triaxial compressive properties of cemented tailings backfill(CTB).The influence of cement content,curing age and confining pressure on strength and deformat...It is of great significance for safety reason to obtain the triaxial compressive properties of cemented tailings backfill(CTB).The influence of cement content,curing age and confining pressure on strength and deformation properties of CTB was examined and discussed.Results indicate that the triaxial compressive and deformation behavior of CTB is strongly affected by the cement content,curing age and confining pressure.The increase in cement content,curing age and confining pressure leads to a change in stress−strain behavior and an increase in the axial strain at failure and post-peak strength loss.The cohesion of CTB rises as the curing age and cement content increase.However,the enhancement in internal friction angle is trivial and negligible.It should be noted that the failure pattern of CTB samples in triaxial compression is mainly along a shear plane,the confining pressure restrains the lateral expansion and the bulging failure pattern is dominantly detected in CTB samples as curing age length and cement content increase.The results will help to better understand the triaxial mechanical and deformation behavior of CTB.展开更多
Objective: A dosimetric study was performed to evaluate the performance of volumetric modulated arc radiotherapy with RapidArc on locally advanced nasopharyngeal carcinoma (NPC). Methods: The CT scan data sets of 20 p...Objective: A dosimetric study was performed to evaluate the performance of volumetric modulated arc radiotherapy with RapidArc on locally advanced nasopharyngeal carcinoma (NPC). Methods: The CT scan data sets of 20 patients of locally advanced NPC were selected randomly. The plans were managed using volumetric modulated arc with RapidArc and fixed nine-field coplanar dynamic intensity-modulated radiotherapy (IMRT) for these patients. The dosimetry of the planning target volumes (PTV), the organs at risk (OARs) and the healthy tissue were evaluated. The dose prescription was set to 70 Gy to the primary tumor and 60 Gy to the clinical target volumes (CTV) in 33 fractions. Each fraction applied daily, five fractions per week. The monitor unit (MU) values and the delivery time were scored to evaluate the expected treatment efficiency. Results: Both techniques had reached clinical treatment’s requirement. The mean dose (Dmean), maximum dose (Dmax) and minimum dose (Dmin) in RapidArc and fixed field IMRT for PTV were 68.4±0.6 Gy, 74.8±0.9 Gy and 56.8±1.1 Gy; and 67.6±0.6 Gy, 73.8±0.4 Gy and 57.5±0.6 Gy (P<0.05), respectively. Homogeneity index was 78.85±1.29 in RapidArc and 80.34±0.54 (P<0.05) in IMRT. The conformity index (CI: 95%) was 0.78±0.01 for both techniques (P>0.05). Compared to IMRT, RapidArc allowed a reduction of Dmean to the brain stem, mandible and optic nerves of 14.1% (P<0.05), 5.6% (P<0.05) and 12.2% (P<0.05), respectively. For the healthy tissue and the whole absorbed dose, Dmean of RapidArc was reduced by 3.6% (P<0.05), and 3.7% (P<0.05), respectively. The Dmean to the parotids, the spinal cord and the lens had no statistical difference among them. The mean MU values of RapidArc and IMRT were 550 and 1,379. The mean treatment time of RapidArc and IMRT was 165 s and 447 s. Compared to IMRT, the delivery time and the MU values of RapidArc were reduced by 63% and 60%, respectively. Conclusion: For locally advanced NPC, both RapidArc and IMRT reached the clinic requirement. The target volume 展开更多
It is highly desirable to design and synthesize two-dimensional nanostructured electrode materials with high electrical conductivity,large electrolyte-accessible surface area and more exposed active sites for energy s...It is highly desirable to design and synthesize two-dimensional nanostructured electrode materials with high electrical conductivity,large electrolyte-accessible surface area and more exposed active sites for energy storage applications.Herein,MXene/Co Al-LDH heterostructure has been prepared through electrostatic ordered hetero-assembly of monolayer MXene and edge-rich Co Al-LDH nanosheets in a faceto-face manner on molecular-scale for supercapacitor applications.Benefiting from the unique structure,strong interfacial interaction and synergistic effects between MXene and Co Al-LDH nanosheets,the electrical conductivity and exposed electrolyte-accessible active sites are significantly enhanced.The asprepared MXene/Co Al-LDH-80%(ML-80)film exhibits high volumetric capacity of 2472 C cm-3 in 3 M KOH electrolyte with high rate capability of 70.6%at 20 A g-1.Notably,to the best of our knowledge,the high volumetric capacity is the highest among other previously reported values for supercapacitors in aqueous electrolytes.Furthermore,our asymmetric supercapacitor device fabricated with ML-80 and MXene/graphene composite as cathode and anode,respectively,exhibits impressive volumetric energy density of 85.4 Wh L-1 with impressive cycling stability of 94.4%retention ratio after 30,000 continuous charge/discharge cycles.展开更多
An efficient voxelization algorithm is presented for polygonal models by using the hardware support for the 2 D rasterization algorithm and the GPU programmable function to satisfy the volumetric display system. The v...An efficient voxelization algorithm is presented for polygonal models by using the hardware support for the 2 D rasterization algorithm and the GPU programmable function to satisfy the volumetric display system. The volume is sampled into slices by the rendering hardware and then slices are rasterated into a series of voxels. A composed buffer is used to record encoded voxels of the target volume to reduce the graphic memory requirement. In the algorithm, dynamic vertexes and index buffers are used to improve the voxelization efficiency. Experimental results show that the algorithm is efficient for a true 3-D display system.展开更多
The marine diatom Phaeodactylum tricornutum is a polymorphological, ecologically significant, and well-studied model of unicellular microalga. This diatom can accumulate diverse important metabolites. Herein, we cultu...The marine diatom Phaeodactylum tricornutum is a polymorphological, ecologically significant, and well-studied model of unicellular microalga. This diatom can accumulate diverse important metabolites. Herein, we cultured P. tricornutum in an internally installed tie-piece flat-plate photobioreactor under 14.5 m mol L^(-1)(high nitrogen, HN) and 2.9 m mol L^(-1)(low nitrogen, LN) of KNO_3 and assessed its time-resolved changes in biochemical compositions. The results showed that HN was inductive to accumulate high biomass(4.1 g L^(-1)). However, the LN condition could accelerate lipid accumulation in P. tricornutum. The maximum total lipid(TL) content under LN was up to 42.5% of biomass on day 12. Finally, neutral lipids(NLs) were 63.8% and 75.7% of TLs under HN and LN, respectively. The content of EPA ranged from 2.3% to 1.5% of dry weight during the growth period under the two culture conditions. Peak volumetric lipid productivity of 128.4 mg L^(-1)d^(-1) was achieved in the HN group(on day 9). The highest volumetric productivity values of EPA, chrysolaminarin, and fucoxanthin were obtained in the exponential phase(on day 6) under HN, which were 9.6, 93.6, and 4.7 mg L^(-1)d^(-1), respectively. In conclusion, extractable amounts of lipids, EPA, fucoxanthin, and chrysolaminarin could be obtained from P. tricornutum by regulating the culture conditions.展开更多
In this paper,the content and density of adsorbed water in fine-grained soil are determined.According to the test results,the calculation method of compaction degree of the solid-phase and void ration of soil is impro...In this paper,the content and density of adsorbed water in fine-grained soil are determined.According to the test results,the calculation method of compaction degree of the solid-phase and void ration of soil is improved.Four kinds of fine-grained soils from different regions in China were selected,and the adsorbed water content and density of four kinds of fine-grained soils were determined by thermogravimetry and volumetric flask method.Furthermore,SEM and XRD experiments were used to analyze the differences in the ability of each soil sample to absorb water.In order to study the compression characteristics of adsorbed water,four saturated soil samples were tested by consolidation method.The results show that the desorption temperature range of the adsorbed water and its density were equal to 100−115℃and 1.30 g/cm^(3),respectively.Adsorbed water plays a positive role in keeping the compressibility of fine-grained soil at a low rate when it has high water content.Besides,adsorbed water can be a stable parameter and is difficult to discharge during the operation period of subgrade.The settlement of fine-grained soil embankment is predicted by engineering example,and compared with the result of conventional calculation method.The results show that it is more close to the field monitoring results by using the improved void ratio of soil as the parameter.展开更多
Porous volumetric solar receivers are one type of solar receivers that can volumetrically absorb solar radiation and achieve efficient solar-to-thermal energy conversion.Porous volumetric solar receivers have been dev...Porous volumetric solar receivers are one type of solar receivers that can volumetrically absorb solar radiation and achieve efficient solar-to-thermal energy conversion.Porous volumetric solar receivers have been developed since 1980s.In this review,we focus on the development progress of the atmospheric and pressurized porous volumetric solar receivers,in which the structural designs,the material selections,the experimental research methods,the comparison of thermal performance,and the transient response characteristic of the receivers were reviewed.On the other hand,the theoretical research methods including the direct pore-scale and volume averaging simulations were introduced.The pore-scale reconstruction method and the procedure to investigate the fluid flow and heat transfer processes at the pore-scale were presented.For the volume averaging method,detailed descriptions for the selection of empirical parameters in the governing equations to be solved were summarized.Typical research results based on these methods were presented and research limitations were also pointed out.Furthermore,the methods for the enhancement of volumetric absorption and the improvement of thermal efficiency of the receivers have been comprehensively reviewed.Two methods including geometrical parameters optimization and spectrally selective absorption were presented in detail.This review will provide a better understanding of the development and research methods for porous volumetric solar receivers,and inspire future studies for the performance improvement of the receivers.展开更多
基金Supported by The National Natural Science Foundation of China, No. 30870738
文摘AIM： To compare the volumetric-modulated arc ther- apy （VMAT） plans with conventional sliding window intensity-modulated radiotherapy （c-IMRT） plans in esophageal cancer （EC）. METHODS： Twenty patients with EC were selected, including 5 cases located in the cervical, the upper, the middle and the lower thorax, respectively. Five plans were generated with the eclipse planning sys- tem： three using c-IMRT with 5 fields （5F）, 7 fields （7F） and 9 fields （gF）, and two using VMAT with a single arc （1A） and double arcs （2A）. The treatment plans were designed to deliver a dose of 60 Gy to the plan-ning target volume （PTV） with the same constrains in a 2.0 Gy daily fraction, 5 d a week. Plans were normal- ized to 95% of the PTV that received 100% of the pre- scribed dose. We examined the dose-volume histogram parameters of PTV and the organs at risk （OAR） such as lungs, spinal cord and heart. Monitor units （MU） and normal tissue complication probability （NTCP） of OAR were also reported. RESULTS： Both c-IMRT and VMAT plans resulted in abundant dose coverage of PTV for EC of different Io- cations. The dose conformity to PTV was improved as the number of field in c-IMRT or rotating arc in VMAT was increased. The doses to PTV and OAR in VMAT plans were not statistically different in comparison with c-IMRT plans, with the following exceptions： in cervical and upper thoracic EC, the conformity index （CI） was higher in VMAT （1A 0.78 and 2A 0.8） than in c-IMRT （5F 0.62, 7F 0.66 and 9F 0.73） and homogeneity was slightly better in c-IMRT （7F 1.09 and 9F 1.07） than in VMAT （1A 1,1 and 2A 1.09）, Lung V30 was lower in VMAT （1A 12.52 and 2A 12.29） than in c-IMRT （7F 14.35 and 9F 14.81）. The humeral head doses were significantly increased in VMAT as against c-IMRT. In the middle and lower thoracic EC, CI in VMAT （1A 0.76 and 2A 0.74） was higher than in c-IMRT （5F 0.63 Gy and 7F 0.67 Gy）, and homogeneity was almost similar between VMAT and c-IMRT
文摘Bi is a promising candidate for energy storage materials because of its high volumetric capacity, stability in moisture/air, and facile preparation. In this study, the electrochemical performance of nanosized-Bi-embedded one-dimensional （1D） carbon nanofibers （Bi/C nanofibers） as anodes for Li-ion batteries （LIBs） and Na-ion batteries （NIBs） was systematically investigated. The Bi/C nanofibers were prepared using a single-nozzle electrospinning method with a specified Bi source followed by carbothermal reduction. Abundant Bi nanoparticles with diameters of approximately 20 nm were homogeneously dispersed and embedded in the 1D carbon nanofibers, as confirmed by structural and morphological characterization. Electrochemical measurements indicate that the Bi/C nanofiber anodes could deliver a long cycle life for LIBs and a preferable rate performance for NIBs. The superior electrochemical performances of the Bi/C nanofiber anodes are attributed to the 1D carbon nanofiber structure and uniform distribution of Bi nanoparticles embedded in the carbon matrix. This unique embedded structure provides a favorable electron carrier and buffering matrix for the effective release of mechanical stress caused by volume change and prevents the aggregation of Bi nanoparticles.
基金This study was supported by the 973 Project(Grant No.2001CB309404)the National Natural Science Foundation of China(Grant No.40333031).
文摘The soil water index （SWI） from satellite remote sensing and the observational soil moisture from agricultural meteorological stations in eastern China are used to retrieve soil moisture. The analysis of correlation coefficient （CORR）, root-mean-square-error （RMSE） and bias （BIAS） shows that the retrieved soil moisture is convincible and close to the observation. The method can overcome the difficulties in soil moisture observation on a large scale and the retrieved soil moisture may reflect the distribution of the real soil moisture objectively. The retrieved soil moisture is used as an initial scheme to replace initial conditions of soil moisture （NCEP） in the model MM5V3 to simulate the heavy rainfall in 1998. Three heavy rainfall processes during 13-14 June, 18-22 June, and 21-26 July 1998 in the Yangtze River valley are analyzed. The first two processes show that the intensity and location of simulated precipitation from SWI are better than those from NCEP and closer to the observed values. The simulated heavy rainfall for 21-26 July shows that the update of soil moisture initial conditions can improve the model＇s performance. The relationship between soil moisture and rainfall may explain that the stronger rainfall intensity for SWI in the Yangtze River valley is the result of the greater simulated soil moisture from SWI prior to the heavy rainfall date than that from NCEP, and leads to the decline of temperature in the corresponding area in the heavy rainfall days. Detailed analysis of the heavy rainfall on 13-14 June shows that both land-atmosphere interactions and atmospheric circulation were responsible for the heavy ralnfall, and it shows how the SWI simulation improves the simulation. The development of mesoscale systems plays an important role in the simulation regarding the change of initial soil moisture for SWI.
基金supported by the National Natural Science Foundation of China (No. 41004054) Research Fund for the Doctoral Program of Higher Education of China (No. 20105122120002)Natural Science Key Project, Sichuan Provincial Department of Education (No. 092A011)
文摘To fully extract and mine the multi-scale features of reservoirs and geologic structures in time/depth and space dimensions, a new 3D multi-scale volumetric curvature （MSVC） methodology is presented in this paper. We also propose a fast algorithm for computing 3D volumetric curvature. In comparison to conventional volumetric curvature attributes, its main improvements and key algorithms introduce multi-frequency components expansion in time-frequency domain and the corresponding multi-scale adaptive differential operator in the wavenumber domain, into the volumetric curvature calculation. This methodology can simultaneously depict seismic multi-scale features in both time and space. Additionally, we use data fusion of volumetric curvatures at various scales to take full advantage of the geologic features and anomalies extracted by curvature measurements at different scales. The 3D MSVC can highlight geologic anomalies and reduce noise at the same time. Thus, it improves the interpretation efficiency of curvature attributes analysis. The 3D MSVC is applied to both land and marine 3D seismic data. The results demonstrate that it can indicate the spatial distribution of reservoirs, detect faults and fracture zones, and identify their multi-scale properties.
基金supported by the New Energy Project for Electric Vehicles in National Key Research and Development Program (2016YFB0100200)the National Natural Science Foundation of China (21573114 and 51502145)
文摘Low volumetric energy density is a bottleneck for the application of lithium-sulfur (Li-S)battery.The low- density sulfur cooperated with the light-weight carbon sub- strate realizes electrochemical cycle stability,but leads to worse volumetric energy density.Here,nickel ferrite (NiFe2O4)nanofibers as novel substrate for sulfur not only anchor lithium polysulfides to enhance the cycle stability of sulfur cathode,but also contribute to the high volumetric capacity of the S/nickel ferrite composite.Specifically,the S/ nickel ferrite composite presents an initial volumetric capacity of 1,281.7mA h cm^-3-composite at 0.1C rate,1.9times higher than that of S/carbon nanotubes,due to the high tap density of the S/nickel ferrite composite.
文摘Holographic data storage system （HDSS） has been a good candidate for a volumetric recording technology, due to their large storage capacities and high transfer rates, and have been researched for tens of years after the principle of holography was first proposed. However, these systems, called conventional 2-axis holography, still have essential issues for commercialization of products. Collinear HDSS, in which the information and reference beams are modulated co-axially by the same spatial light modulator （SLM）, as a new read/write method for HDSS are very promising. With this unique configuration, the optical pickup can be designed as small as DVDs, and can be placed on one side of the recording media （disc）. In the disc structure, the preformatted reflective layer is used for the focus/tracking servo and reading address information, and a dichroic mirror layer is used for detecting holographic recording information without interfering with the preformatted information. A 2-dimensional digital page data format is used and the shift-multiplexing method is employed to increase recording density. As servo technologies are being introduced to control the objective lens to be maintained precisely to the disc in the recording and reconstructing process, a vibration isolator is no longer necessary. Collinear holography can produce a small, practical HDSS more easily than conventional 2-axis holography. In this paper, we introduced the principle of the collinear holography and its media structure of disc. Some results of experimental and theoretical studies suggest that it is a very effective method. We also discussed some methods to increase the recording density and data transfer rates of collinear holography.
基金supported by the National Natural Science Foundation of China (Grant 41272344)the National Basic Research Program (973) of China (Grant 2014CB046905)+3 种基金the Natural Science Foundation of Jiangsu Province of China (Grant BK2012568)the Team Project Funded by 2014 Jiangsu Innovation and Entrepreneurship Programthe Fundamental Research Funds for the Central Universities (China University of Mining and Technology) (Grants 2014YC10 and 2014XT03)Outstanding Innovation Team Project in China University of Mining and Technology (Grant 2014QN002)
文摘The seepage evolution characteristic of brittle rock materials is very significant for the stability and safety of rock engineering. In this research, a series of conventional triaxial compression and gas seepage tests were carded out on sandstone specimens with a rock mechanics servo-controlled testing system. Based on the experimental results, the relationship between permeability and deformation is firstly analyzed in detail. The results show that the permeabilityaxial strain curve can be divided into the following five phases： the phase of micro-defects closure, the phase of linear elastic deformation, the phase of nonlinear deformation, the phase of post-peak stress softening and the phase of residual strength. The seepage evolution characteristic is also closely correlated with the volumetric deformation according to the relationship between permeability and volumetric strain. It is found that the gas seepage pressure has a great effect on the permeability evolution, i.e. permeability coefficients increase with increasing gas seepage pressures. Finally, the influence of gas seepage pressures on the failure behavior of brittle sandstone specimens is discussed.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11102013,10832001)the "Weishi" Foundation of Beijing University of Aeronautics and Astronautics (Grant No. YWF-12-RHRS-008)
文摘Volumetric particle image velocimetry(VPIV) refers to a PIV-based technique which can obtain full velocity components in a three-dimensional measurement volume.A new VPIV method with a single lens was developed.A three-vision prism was used to make viewing from different angles using one camera.The technique was tested and successfully applied to a three-dimensional three-component(3D3C) measurement of a zero-net-mass-flux jet flow.The accuracy of the measurement was investigated,specifically in steps of calibration,self-calibration and particle triangulation.Time sequence of a vortex ring development was presented.It was shown that the measurement has high accuracy with validation rate of velocity vector reaching about 95%.The flow with vortex ring passing the measurement volume was studied using both swirl strength and vorticity magnitude criteria.Through comparison,the swirl criterion was found to be superior to the criterion of vorticity in differentiating the rotation motion and the free shear.
基金Projects(2018YFC0808403,2018YFE0123000)supported by the National Key Technologies Research&Development Program of ChinaProject(800015Z1185)supported by the Yueqi Young Scholar Project,ChinaProject(2020YJSNY04)supported by the Fundamental Research Funds for the Central Universities,China。
文摘It is of great significance for safety reason to obtain the triaxial compressive properties of cemented tailings backfill(CTB).The influence of cement content,curing age and confining pressure on strength and deformation properties of CTB was examined and discussed.Results indicate that the triaxial compressive and deformation behavior of CTB is strongly affected by the cement content,curing age and confining pressure.The increase in cement content,curing age and confining pressure leads to a change in stress−strain behavior and an increase in the axial strain at failure and post-peak strength loss.The cohesion of CTB rises as the curing age and cement content increase.However,the enhancement in internal friction angle is trivial and negligible.It should be noted that the failure pattern of CTB samples in triaxial compression is mainly along a shear plane,the confining pressure restrains the lateral expansion and the bulging failure pattern is dominantly detected in CTB samples as curing age length and cement content increase.The results will help to better understand the triaxial mechanical and deformation behavior of CTB.
文摘Objective: A dosimetric study was performed to evaluate the performance of volumetric modulated arc radiotherapy with RapidArc on locally advanced nasopharyngeal carcinoma (NPC). Methods: The CT scan data sets of 20 patients of locally advanced NPC were selected randomly. The plans were managed using volumetric modulated arc with RapidArc and fixed nine-field coplanar dynamic intensity-modulated radiotherapy (IMRT) for these patients. The dosimetry of the planning target volumes (PTV), the organs at risk (OARs) and the healthy tissue were evaluated. The dose prescription was set to 70 Gy to the primary tumor and 60 Gy to the clinical target volumes (CTV) in 33 fractions. Each fraction applied daily, five fractions per week. The monitor unit (MU) values and the delivery time were scored to evaluate the expected treatment efficiency. Results: Both techniques had reached clinical treatment’s requirement. The mean dose (Dmean), maximum dose (Dmax) and minimum dose (Dmin) in RapidArc and fixed field IMRT for PTV were 68.4±0.6 Gy, 74.8±0.9 Gy and 56.8±1.1 Gy; and 67.6±0.6 Gy, 73.8±0.4 Gy and 57.5±0.6 Gy (P<0.05), respectively. Homogeneity index was 78.85±1.29 in RapidArc and 80.34±0.54 (P<0.05) in IMRT. The conformity index (CI: 95%) was 0.78±0.01 for both techniques (P>0.05). Compared to IMRT, RapidArc allowed a reduction of Dmean to the brain stem, mandible and optic nerves of 14.1% (P<0.05), 5.6% (P<0.05) and 12.2% (P<0.05), respectively. For the healthy tissue and the whole absorbed dose, Dmean of RapidArc was reduced by 3.6% (P<0.05), and 3.7% (P<0.05), respectively. The Dmean to the parotids, the spinal cord and the lens had no statistical difference among them. The mean MU values of RapidArc and IMRT were 550 and 1,379. The mean treatment time of RapidArc and IMRT was 165 s and 447 s. Compared to IMRT, the delivery time and the MU values of RapidArc were reduced by 63% and 60%, respectively. Conclusion: For locally advanced NPC, both RapidArc and IMRT reached the clinic requirement. The target volume
基金supported by the financial support from the National Natural Science Foundation of China(21571040)the Young Top-Notch Talent of National Ten Thousand Talent Program+1 种基金Heilongjiang Touyan Innovation Team ProgramFundamental Research Funds for the Central Universities。
文摘It is highly desirable to design and synthesize two-dimensional nanostructured electrode materials with high electrical conductivity,large electrolyte-accessible surface area and more exposed active sites for energy storage applications.Herein,MXene/Co Al-LDH heterostructure has been prepared through electrostatic ordered hetero-assembly of monolayer MXene and edge-rich Co Al-LDH nanosheets in a faceto-face manner on molecular-scale for supercapacitor applications.Benefiting from the unique structure,strong interfacial interaction and synergistic effects between MXene and Co Al-LDH nanosheets,the electrical conductivity and exposed electrolyte-accessible active sites are significantly enhanced.The asprepared MXene/Co Al-LDH-80%(ML-80)film exhibits high volumetric capacity of 2472 C cm-3 in 3 M KOH electrolyte with high rate capability of 70.6%at 20 A g-1.Notably,to the best of our knowledge,the high volumetric capacity is the highest among other previously reported values for supercapacitors in aqueous electrolytes.Furthermore,our asymmetric supercapacitor device fabricated with ML-80 and MXene/graphene composite as cathode and anode,respectively,exhibits impressive volumetric energy density of 85.4 Wh L-1 with impressive cycling stability of 94.4%retention ratio after 30,000 continuous charge/discharge cycles.
文摘An efficient voxelization algorithm is presented for polygonal models by using the hardware support for the 2 D rasterization algorithm and the GPU programmable function to satisfy the volumetric display system. The volume is sampled into slices by the rendering hardware and then slices are rasterated into a series of voxels. A composed buffer is used to record encoded voxels of the target volume to reduce the graphic memory requirement. In the algorithm, dynamic vertexes and index buffers are used to improve the voxelization efficiency. Experimental results show that the algorithm is efficient for a true 3-D display system.
基金supported by the Natural Science Foundation of China (No. 31170337)the National High Technology Research and Development Program of China (863 Program) (No. 2013AA 065805)+1 种基金the National Basic Research Program of China (973 Program) (No. 2011CB2009001)the Special Program for Low-Carbon, Reform and Development Commission of Guangdong Province (No. 2011-051)
文摘The marine diatom Phaeodactylum tricornutum is a polymorphological, ecologically significant, and well-studied model of unicellular microalga. This diatom can accumulate diverse important metabolites. Herein, we cultured P. tricornutum in an internally installed tie-piece flat-plate photobioreactor under 14.5 m mol L^(-1)(high nitrogen, HN) and 2.9 m mol L^(-1)(low nitrogen, LN) of KNO_3 and assessed its time-resolved changes in biochemical compositions. The results showed that HN was inductive to accumulate high biomass(4.1 g L^(-1)). However, the LN condition could accelerate lipid accumulation in P. tricornutum. The maximum total lipid(TL) content under LN was up to 42.5% of biomass on day 12. Finally, neutral lipids(NLs) were 63.8% and 75.7% of TLs under HN and LN, respectively. The content of EPA ranged from 2.3% to 1.5% of dry weight during the growth period under the two culture conditions. Peak volumetric lipid productivity of 128.4 mg L^(-1)d^(-1) was achieved in the HN group(on day 9). The highest volumetric productivity values of EPA, chrysolaminarin, and fucoxanthin were obtained in the exponential phase(on day 6) under HN, which were 9.6, 93.6, and 4.7 mg L^(-1)d^(-1), respectively. In conclusion, extractable amounts of lipids, EPA, fucoxanthin, and chrysolaminarin could be obtained from P. tricornutum by regulating the culture conditions.
基金Project(51978085)supported by the National Natural Science Foundation of ChinaProject(K2019G045)supported by the Science and Technology Research and Development Plan of China National Railway Group Co.,Ltd.Project(201808430102)supported by the China Scholarship Council。
文摘In this paper,the content and density of adsorbed water in fine-grained soil are determined.According to the test results,the calculation method of compaction degree of the solid-phase and void ration of soil is improved.Four kinds of fine-grained soils from different regions in China were selected,and the adsorbed water content and density of four kinds of fine-grained soils were determined by thermogravimetry and volumetric flask method.Furthermore,SEM and XRD experiments were used to analyze the differences in the ability of each soil sample to absorb water.In order to study the compression characteristics of adsorbed water,four saturated soil samples were tested by consolidation method.The results show that the desorption temperature range of the adsorbed water and its density were equal to 100−115℃and 1.30 g/cm^(3),respectively.Adsorbed water plays a positive role in keeping the compressibility of fine-grained soil at a low rate when it has high water content.Besides,adsorbed water can be a stable parameter and is difficult to discharge during the operation period of subgrade.The settlement of fine-grained soil embankment is predicted by engineering example,and compared with the result of conventional calculation method.The results show that it is more close to the field monitoring results by using the improved void ratio of soil as the parameter.
基金supported by the National Key Research and Development Program of China(2022YFB3304001)the Key R&D Program of Shaanxi province of China(No.2022GXLH-01-04).
文摘Porous volumetric solar receivers are one type of solar receivers that can volumetrically absorb solar radiation and achieve efficient solar-to-thermal energy conversion.Porous volumetric solar receivers have been developed since 1980s.In this review,we focus on the development progress of the atmospheric and pressurized porous volumetric solar receivers,in which the structural designs,the material selections,the experimental research methods,the comparison of thermal performance,and the transient response characteristic of the receivers were reviewed.On the other hand,the theoretical research methods including the direct pore-scale and volume averaging simulations were introduced.The pore-scale reconstruction method and the procedure to investigate the fluid flow and heat transfer processes at the pore-scale were presented.For the volume averaging method,detailed descriptions for the selection of empirical parameters in the governing equations to be solved were summarized.Typical research results based on these methods were presented and research limitations were also pointed out.Furthermore,the methods for the enhancement of volumetric absorption and the improvement of thermal efficiency of the receivers have been comprehensively reviewed.Two methods including geometrical parameters optimization and spectrally selective absorption were presented in detail.This review will provide a better understanding of the development and research methods for porous volumetric solar receivers,and inspire future studies for the performance improvement of the receivers.
