As a promising material in the aircraft industry,2A97 Al-Cu-Li alloy exhibits high corrosion susceptibility that may limit its application.In the present work,to illustrate the influences of precipitate and grain-stor...As a promising material in the aircraft industry,2A97 Al-Cu-Li alloy exhibits high corrosion susceptibility that may limit its application.In the present work,to illustrate the influences of precipitate and grain-stored energy on localized corrosion evolution in 2A97 Al-Cu-Li alloy,cold working and artificial aging were carried out to produce 2A97 Al-Cu-Li alloys under different thermomechanical conditions.Quasi-in-situ analysis,traditional immersion test and electrochemical measurement were then conducted to examine the corrosion behavior of 2A97 alloys.It is revealed that precipitate significantly affects Cu enrichment at corrosion fronts,which determines corrosion susceptibility of alloys,whereas grain-stored energy distribution is closely associated with localized corrosion propagation.It is also indicated that quasi-in-situ analysis exhibits a consistent corrosion evolution with traditional immersion tests,which is regarded as a proper method to explore localized corrosion mechanisms by providing local microstructural information with enhanced time and spatial resolutions.展开更多
Acoustic emission(AE)source localization is a fundamental element of rock fracture damage imaging.To improve the efficiency and accuracy of AE source localization,this paper proposes a joint method comprising a three-...Acoustic emission(AE)source localization is a fundamental element of rock fracture damage imaging.To improve the efficiency and accuracy of AE source localization,this paper proposes a joint method comprising a three-dimensional(3D)AE source localization simplex method and grid search scanning.Using the concept of the geometry of simplexes,tetrahedral iterations were first conducted to narrow down the suspected source region.This is followed by a process of meshing the region and node searching to scan for optimal solutions,until the source location is determined.The resulting algorithm was tested using the artificial excitation source localization and uniaxial compression tests,after which the localization results were compared with the simplex and exhaustive methods.The results revealed that the localization obtained using the proposed method is more stable and can be effectively avoided compared with the simplex localization method.Furthermore,compared with the global scanning method,the proposed method is more efficient,with an average time of 10%–20%of the global scanning localization algorithm.Thus,the proposed algorithm is of great significance for laboratory research focused on locating rupture damages sustained by large-sized rock masses or test blocks.展开更多
Powder mixture of pure A1 and oxidized SiC was consolidated into 10% (mass fraction) SiCp/AI composites at 523 K by equal channel angular pressing and torsion (ECAP-T). The interfacial bonding of the composites wa...Powder mixture of pure A1 and oxidized SiC was consolidated into 10% (mass fraction) SiCp/AI composites at 523 K by equal channel angular pressing and torsion (ECAP-T). The interfacial bonding of the composites was characterized by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The selected area electron diffraction (SAED) for the interface was investigated. The elements at the interface were scanned by energy dispersive spectroscopy (EDS) and the EDS mapping was also obtained. X-ray diffraction (XRD) analysis was carried out for the composites fabricated by 1 pass, 2 passes and 4 passes ECAP-T. According to the XRD analysis, the influences of ECAP-T pass on the Bragg angle and interplanar spacing for AI crystalline planes were studied. The results show that after ECAP-T, the interface between A1 and SiC within the composites is a belt of amorphous SiO2 containing a trace of A1, Si and C which diffused from the matrix and the reinforcement. With the growing ECAP-T pass, the Bragg angle decreases and interplanar spacing increases for A1 crystalline planes, due to the accumulated lattice strain. The increasing lattice strain of A1 grains also boosts the density of the dislocation within A1 grains.展开更多
A capacity model of multi-phase signalized intersections is derived by a stopping-line method. It is simplified with two normal situations: one situation involves one straight lane and one left-turn lane; the other s...A capacity model of multi-phase signalized intersections is derived by a stopping-line method. It is simplified with two normal situations: one situation involves one straight lane and one left-turn lane; the other situation involves two straight lanes and one left-turn lane. The results show that the capacity is mainly relative to signal cycle length, phase length, intersection layout and following time. With regard to the vehicles arrival rates, the optimal model is derived based on each phase's remaining time balance, and it is solved by Lagrange multipliers. Therefore, the calculation models of the optimal signal cycle length and phase lengths are derived and simplified. Compared to the existing models, the proposed model is more convenient and practical. Finally, a practical intersection is chosen and its signal cycles and phase lengths are calculated by the proposed model.展开更多
In this paper, direct sequence spread spectrum multiple access (DS/SSMA) communication system employing serially concatenated trellis coded modulation (TCM) and continuous phase modulation (CPM) over flat Rayleigh fa...In this paper, direct sequence spread spectrum multiple access (DS/SSMA) communication system employing serially concatenated trellis coded modulation (TCM) and continuous phase modulation (CPM) over flat Rayleigh fading channel are presented. The performance of this concatenated TCM/CPM DS/SSMA system is exploited by the theoretical analysis and numerical simulations. The results demonstrate that significant improvements in error probability of this DS/SSMA system over the system with single TCM or CPM of different modulation indices can be achieved under the same conditions.展开更多
This paper is to construct a “digital local, regional, region” information framework based on the technology of “SIG” and its significance and application to the regional sustainable development evaluation system....This paper is to construct a “digital local, regional, region” information framework based on the technology of “SIG” and its significance and application to the regional sustainable development evaluation system. First, the concept of the “grid computing” and “SIG” is interpreted and discussed, then the relationship between the “grid computing” and “digital region” is analyzed, and the framework of the “digital region” is put forward. Finally, the significance and application of “grid computing” to the “region sustainable development evaluation system” are discussed.展开更多
In view of the relative positioning problem between non-regular quadrilateral grids and regular rectangle grid nodes in the wave front construction method, concrete realization problems with four grid positioning meth...In view of the relative positioning problem between non-regular quadrilateral grids and regular rectangle grid nodes in the wave front construction method, concrete realization problems with four grid positioning methods (vector cross product judgment, angle sum, intersection-point, and signs comparison algorithms) in wave front construction which are commonly used in computer graphics are compared and analyzed in this paper. Based on the stability analysis of the location method, the calculation examples show that the vector cross product judgment method is faster and more accurate than other methods in the realization of the relative positioning between non-regular quadrilateral grids and regular rectangle grid nodes in wave front construction. It provides precise grid point attribute values for the next steps of migration and demigration.展开更多
Texture,geochemistry,and in-situ Pb isotope of galena were investigated to probe the origin of anomalous Ag enrichment in the Dayingezhuang Au(-Ag)deposit.Silver enrichment postdates the main Au mineralization and occ...Texture,geochemistry,and in-situ Pb isotope of galena were investigated to probe the origin of anomalous Ag enrichment in the Dayingezhuang Au(-Ag)deposit.Silver enrichment postdates the main Au mineralization and occurs in the south of the Dayingezhuang deposit.It is primarily associated with galena and the exsolution of Ag-rich sulfosalts(e.g.,matildite)in distal vein-ores related to steeply dipping brittle fractures.Silver-rich galena is characterized by the least radiogenic Pb isotope signature(^(206)Pb/^(204)Pb 17.195–17.258 and ^(208)Pb/^(204)Pb 37.706–37.793),possibly indicating a metasomatized lithospheric mantle or modified lower crustal source for Pb and Ag.Both of these mafic and ultramafic source regions have been previously suggested as Au reservoirs for other Jiaodong Au deposits,implying that the metal reservoir has only a weak control on the uneven Ag-enrichment.Since the Ag-enrichment areas are located in the footwalls of both the Dayingezhuang and Zhaoping faults,the enrichment was most likely dominated by local rotational stress during coeval movements of the two faults in a NE–SW compression and NW−SE extension regime.This work highlights the shallow-crust structural deformation responsible for controlling the flow of late ore-forming fluid resulting in local anomalous metal enrichment.展开更多
The flow and the temperature in the threestream mixing flow of the lobed nozzle mixer-ejector with double-wall diffuser are numerically investigated. The domain of computation is divided into sub-domalns according to ...The flow and the temperature in the threestream mixing flow of the lobed nozzle mixer-ejector with double-wall diffuser are numerically investigated. The domain of computation is divided into sub-domalns according to the shapes of the double-plate and lobed nozzle. The three-dimensional body-fitted coordinated grids are generated respectively in these sub-domains by solving Lapalace's equations. Grids are dense on the boundaries and orthogonal at the lobe. The grids of all sub-domains compose the whole grid of the domain. In order to avoid the divergence of the computation as the serious non-orthogonality of the grid from the lobe, the co-located grid, SIMPLEC and Chen-Kim modified k-εturbulence model are applied. The great viscosity, the linear and simultaneous cooperation under-relaxation factors are used to solve the coupling of the fluid and solid. Results show that the air is ejected into the double wall section to form the cooling flow. The wall temperature of the double-wall diffuser is lower than that of the single-wall diffuser. The average wall temperature goes down as the diffuser angle increases at the range of 0~5°,otherwise, the result at the range of 5~10°is opposite.展开更多
AIM:To develop orthotopic gastric cancer mouse models from different cell lines and characterize the tumor features to assist further in preclinical trials and clinical treatment strategies.METHODS:Human gastric cance...AIM:To develop orthotopic gastric cancer mouse models from different cell lines and characterize the tumor features to assist further in preclinical trials and clinical treatment strategies.METHODS:Human gastric cancer SGC-7901 and BGC823 cell suspensions were injected subcutaneously into nude mice to develop solid tumors,and tumor tissue pieces were then implanted under the serous coat of the stomach.An autopsy was performed on all animals of the SGC-7901 and BGC-823 models to observe the primary tumor growth and metastases using pathological and immunohistochemical methods.RESULTS:Both models showed large tumors in situ resulting in pressure and infiltration of the adjacent organs.The gastric cavity became smaller,along with stenosis of the cardia or pylorus.There were biological and statistical differences between the two models.The metastasis rate in involved organs (lymph nodes,kidney,spleen,testis) was significantly higher in the BGC-823 model compared to the SGC-7901 model (P < 0.05 or P < 0.01).The median survival of the BGC-823 model was shorter than that of SGC-7901 (23 d vs 84 d,P < 0.05).Histopathologically,the primary tumor and metastatic lesions of the two models showed obvious atypia and mucus in the cytoplasm.Compared with the SGC-7901 model,BGC-823 appeared more poorly differentiated (absence of adenoid structure),had a smaller volume,and richer capillary structure.Immunohistochemical staining revealed cytokeratin 20 and epithelial membrane antigen expression was positive in the SGC-7901 tumors,while negative in BGC-823 ones.CONCLUSION:Models using the SGC-7901 and BGC-823 cell lines were established which could function in gastric cancer research on carcinogenesis mechanism and drug discovery.The two models showed different tumor behavior and the latter was more malignant than the former.展开更多
In a manufacturing company, certain departments can be characterized as production departments and others as service departments. This paper expands and simplifies the results by the author and his co-author (Lowenth...In a manufacturing company, certain departments can be characterized as production departments and others as service departments. This paper expands and simplifies the results by the author and his co-author (Lowenthal & Malek, 2005; 2013), by explaining in a simple way how to obtain the fair-price per unit to pay to external suppliers that replace service departments. The paper also proves that replacing several service departments at once produces exactly the same fair-price per unit if they were replaced sequentially.展开更多
By analyzing the relationship among government, market driving forces, distribution orientation of banking industry, service opportunity equality and spatial patterns, this paper proposes that it is distribution orien...By analyzing the relationship among government, market driving forces, distribution orientation of banking industry, service opportunity equality and spatial patterns, this paper proposes that it is distribution orientation that lead to the formation and evolution of spatial pattern of banking industry. The difference of the distribution orientation leads to the separation of the spatial pattern of banking industry, and the change of the distribution orientation leads to the change of spatial pattern. The degree of spatial pattern change is subject to the degree of change of distribution orientation, and the scale of bank resources in the regions, which supports the distribution orientation variation. Based on these theoretical frameworks, some indicators were designed to analyze the pattern change of China′s banking industry and its effects since 1995 under the change of the distribution orientation. This paper finds that the orientation of economic benefit maximization driven by market causes the banking industry to concentrate in economically developed regions.The government, which does not follow the orientation of economic benefit maximization, plays a role of stabilizer. Since the bank branches in the regions with the greatest change in bank branch distribution are too few, and regions with the greatest change in bank loan allocation are the regions with lots of loans, the pattern change of the banking industry in physical form is not as notable as that in economic form.展开更多
The present work aims to evaluate the increase in the number of spot welds in the 16 × 16 type fuel assembly structure that connects guide thimbles and spacer grids, in order to provide a proper joint for this co...The present work aims to evaluate the increase in the number of spot welds in the 16 × 16 type fuel assembly structure that connects guide thimbles and spacer grids, in order to provide a proper joint for this connection. This new and improved process can provide more stiffness to the whole structure, since the number of spots raised from four to eight. A 3-D geometric model of a guide thimble section was generated in a CAD (computer aided design) program (SolidWorks). After that, the geometric model was imported to a CAE (computer aided engineering) program (ANSYS Mechanical APDL, Release 14.0), where the finite element model was built, considering the guide thimble geometry assembled with the spacer grid through the welded connections. Boundaries conditions were implemented in the model in order to simulate the correct physical behavior due to the operation of the fuel assembly inside the reactor. The analysis covered specific loads and displacements acting on the entire structure. The method used to solve this finite element analysis was a linear static simulation in order to perform the connection between a spacer grid cell and a guide thimble section. Hence, four models was evaluated, differing on the spot weld number in the spacer grid and guide thimble connection. The rotational stiffness results of each model were compared. The results acquired from four and eight spot weld were validated with physical test results. The behavior of the structure under the acting force/displacement and the related results of the analysis, mainly the stiffness, were satisfied. The results of this analysis were used to prove that the increasing spot welds number is an improvement in the dimensional stability when submitted to loads and displacements required on the fuel assembly design. This analysis aid to get more information of extreme importance such as, the pursuance to develop better manufacturing process and to improve the fuel assembly performance due to the increasing of the bum-up.展开更多
In advanced nuclear fuel design, the outer strap of a spacer grid plays an important role on fuel assembly mechanical and thermal-hydraulic performance, e.g., precluding the risk of hang-up and improvement on the mixi...In advanced nuclear fuel design, the outer strap of a spacer grid plays an important role on fuel assembly mechanical and thermal-hydraulic performance, e.g., precluding the risk of hang-up and improvement on the mixing of the coolant. The communication of the outer strap affects the hydraulic force exerted by the spacer grid of the fuel assembly which could induce fuel assembly bow. In present study, in order to understand the influencing factors of hydraulic force exerted by the spacer grid, outer straps with various flow opening design features, different location and size are investigated by a commercially CFD (computational fluid dynamics) code, ANSYS CFX 12.1. Three dimensional rod bundles including the outer strap without and with different openings are modelled for simulation. The analysis results show that the openings on the spacer grid outer strap can reduce the lateral hydraulic loadings perpendicular to the centerline of the fuel rods exerted by the spacer grids obviously because of the pressures inside and outside the spacer grids being balanced. Besides, influences of the opening design features on the hydraulic force, resistance characteristics and lateral flow factor are investigated in details.展开更多
Abstract: The Tigris and Euphrates Rivers are the main sources of water in Iraq. Iraq used to receive 33×109 m^3 of river water per year at Hit, 200 km downstream from the Syrian border before the 1970s. In 1980...Abstract: The Tigris and Euphrates Rivers are the main sources of water in Iraq. Iraq used to receive 33×109 m^3 of river water per year at Hit, 200 km downstream from the Syrian border before the 1970s. In 1980s, the discharge decreased to as little as 8 × 10^9 m^3 per year at Hit. The decreasing of discharge and water level in the Euphrates River causes problems of both quantity and quality, such as the increasing salinity in the internal delta downstream, the TDS (total dissolves salinity) at Hit has increased from less than 500 ppm to about 700 ppm. By 1989, the Euphrates' salinity at A1 Qaim reached 1,000 ppm. Currently, the TDS of the river, at AI Qaim, is greater than 1,000 ppm. The problem of control salinity has received considerable attention particularly when the surface water is extremely limited with poorly available ground water supply. The field measurement has achieved for TDS, pH (hydrogen ion), EC (electric conductivity), coliform content and heavy metal for three sectors in the Euphrates River basin in Iraq as well as the lakes of Tharthar, Habbaniya, and AI-Razzaza. The statistical analysis was made to relate these parameter with discharge and water level, which are refered to the important effect of the flow in river on the water quality of Euphrates River. The storage of water in the lakes Al-tharthar, Al-habbanya, and A1-Razzaza has a negative effects on the water quality, and shows that the best method for storage water is the reservoirs along river stream.展开更多
A series of three‐dimensionally ordered macroporous(3DOM)SnO2‐based catalysts modified by the cations Ce4+,Mn3+,and Cu2+have been prepared by using a colloidal crystal templating method and tested for soot combustio...A series of three‐dimensionally ordered macroporous(3DOM)SnO2‐based catalysts modified by the cations Ce4+,Mn3+,and Cu2+have been prepared by using a colloidal crystal templating method and tested for soot combustion under loose contact condition.XRD and STEM mapping results confirm that all the secondary metal cations have entered the lattice matrix of tetragonal rutile SnO2 to form non‐continuous solid solutions,thus impeding crystallization and improving the surface areas and pore volumes of the modified catalysts.In comparison with regular SnO2 nanoparticles,the 3DOM SnO2 displays evidently improved activity,testifying that the formation of the 3DOM structure can anchor the soot particulates in the macro‐pores,which ensures that the contact of the soot particles with the active sites on the 3DOM skeleton is more easily formed,thus benefiting the target reaction.With the incorporation of the secondary metal cations,the activity of the catalyst can be further improved due to the formation of more abundant mobile oxygen species.In summary,these effects are believed to be the major factors responsible for the activity of the catalyst.展开更多
We evaluated 2011-2015 mobile relative gravity data from the Hexi monitoring network that covers the epicenter of the 2016 Menyuan Ms6.4 earthquake, Qinghai Province, China and examined the spatiotemporal characterist...We evaluated 2011-2015 mobile relative gravity data from the Hexi monitoring network that covers the epicenter of the 2016 Menyuan Ms6.4 earthquake, Qinghai Province, China and examined the spatiotemporal characteristics of the gravity field at the focal depth. In addition, we assessed the regional gravity field and its variation the half-year before the earthquake. We use first different interpolation algorithms to build a grid for the gravity data and then introduce potential field interpolation-cutting separation techniques and adaptive noise filtering. The results suggest that the gravity filed at the focal depth of 11.12 km separated from the total gravity field at about -400-150 ×10^-8 m/s^2 in the second half of 2015, which is larger than that in the same period in 2011 to 2014 (±30×10^-8 m/s^2). Moreover, at the same time, the gravity field changed fast from September 2014 to May 2015 and May 2015 to September 2015, reflecting to some extent material migration deep in the crust before the Menyuan earthquake.展开更多
We study s-wave pion-pion scattering length in lattice QCD for pion masses ranging from 330 MeV to 466 MeV. In the "Asqtad" improved staggered fermion formulation, we measure full ππ four-point correlators for iso...We study s-wave pion-pion scattering length in lattice QCD for pion masses ranging from 330 MeV to 466 MeV. In the "Asqtad" improved staggered fermion formulation, we measure full ππ four-point correlators for isospin I = 0 and 2 channels, and use chiral perturbation theory at next-to-leading order to extrapolate our simulation results. Extrapolating to the physical pion mass yields scattering lengths as mna01=2 = -0.041 6(2) and mna01= 0.186(2) for isospin I = 2 and 0 channels, respectively. Our lattice simulation for ππ scattering length in I = 0 channel is an exploratory study, where we include the disconnected contribution, and our preliminary result is near to its experimental value. These simulations are carried out with MILC 2 + 1 flavor gauge configurations at lattice spacing a ≈0.15 fm.展开更多
The Arctic sea ice minimum records appeared in the Septembers of 2007 and 2012, followed by high snow cover areas in the Northern Hemisphere winters. The snow cover distributions show different spatial patterns in the...The Arctic sea ice minimum records appeared in the Septembers of 2007 and 2012, followed by high snow cover areas in the Northern Hemisphere winters. The snow cover distributions show different spatial patterns in these two years: increased snow cover in Central Asia and Central North America in 2007, while increased snow cover in East Asia and northwestern Europe in 2012. The high snow cover anomaly shifted to higher latitudes in winter of 2012 compared to 2007. It is noticed that the snow cover had positive anomaly in 2007 and 2012 with the following conditions: the negative geopotential height and the related cyclonic wind anomaly were favorable for upwelling, and, with the above conditions, the low troposphere and surface air temperature anomaly and water vapor anomaly were favorable for the formation and maintenance of snowfalls. The negative geopotential height, cyclonic wind and low air temperature conditions were satisfied in different locations in 2007 and 2012, resulting in different spatial snow cover patterns. The cross section of lower air temperature move to higher latitudes in winter of 2012 compared to 2007.展开更多
基金supports from the National Natural Science Foundation of China(Nos.52371065,52001128)the Hubei Provincial Natural Science Foundation of China(No.2023AFB637)。
文摘As a promising material in the aircraft industry,2A97 Al-Cu-Li alloy exhibits high corrosion susceptibility that may limit its application.In the present work,to illustrate the influences of precipitate and grain-stored energy on localized corrosion evolution in 2A97 Al-Cu-Li alloy,cold working and artificial aging were carried out to produce 2A97 Al-Cu-Li alloys under different thermomechanical conditions.Quasi-in-situ analysis,traditional immersion test and electrochemical measurement were then conducted to examine the corrosion behavior of 2A97 alloys.It is revealed that precipitate significantly affects Cu enrichment at corrosion fronts,which determines corrosion susceptibility of alloys,whereas grain-stored energy distribution is closely associated with localized corrosion propagation.It is also indicated that quasi-in-situ analysis exhibits a consistent corrosion evolution with traditional immersion tests,which is regarded as a proper method to explore localized corrosion mechanisms by providing local microstructural information with enhanced time and spatial resolutions.
基金supported by the Natural Science Foundation of Henan Province(No.222300420596)China Railway Science and Technology Innovation Program Funded Project(CZ02-Special-03)Science and Technology Innovation Project funded by China Railway Tunnel Group(Tunnel Research 2021-03)。
文摘Acoustic emission(AE)source localization is a fundamental element of rock fracture damage imaging.To improve the efficiency and accuracy of AE source localization,this paper proposes a joint method comprising a three-dimensional(3D)AE source localization simplex method and grid search scanning.Using the concept of the geometry of simplexes,tetrahedral iterations were first conducted to narrow down the suspected source region.This is followed by a process of meshing the region and node searching to scan for optimal solutions,until the source location is determined.The resulting algorithm was tested using the artificial excitation source localization and uniaxial compression tests,after which the localization results were compared with the simplex and exhaustive methods.The results revealed that the localization obtained using the proposed method is more stable and can be effectively avoided compared with the simplex localization method.Furthermore,compared with the global scanning method,the proposed method is more efficient,with an average time of 10%–20%of the global scanning localization algorithm.Thus,the proposed algorithm is of great significance for laboratory research focused on locating rupture damages sustained by large-sized rock masses or test blocks.
基金Project(51175138) supported by the National Natural Science Foundation of ChinaProjects(2012HGZX0030,2013HGCH0011) supported by the Fundamental Research Funds for the Central Universities,China
文摘Powder mixture of pure A1 and oxidized SiC was consolidated into 10% (mass fraction) SiCp/AI composites at 523 K by equal channel angular pressing and torsion (ECAP-T). The interfacial bonding of the composites was characterized by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The selected area electron diffraction (SAED) for the interface was investigated. The elements at the interface were scanned by energy dispersive spectroscopy (EDS) and the EDS mapping was also obtained. X-ray diffraction (XRD) analysis was carried out for the composites fabricated by 1 pass, 2 passes and 4 passes ECAP-T. According to the XRD analysis, the influences of ECAP-T pass on the Bragg angle and interplanar spacing for AI crystalline planes were studied. The results show that after ECAP-T, the interface between A1 and SiC within the composites is a belt of amorphous SiO2 containing a trace of A1, Si and C which diffused from the matrix and the reinforcement. With the growing ECAP-T pass, the Bragg angle decreases and interplanar spacing increases for A1 crystalline planes, due to the accumulated lattice strain. The increasing lattice strain of A1 grains also boosts the density of the dislocation within A1 grains.
基金China Postdoctoral Science Foundation(No.2004035208)Jiangsu Communication Science Foundation (No.06Y36)
文摘A capacity model of multi-phase signalized intersections is derived by a stopping-line method. It is simplified with two normal situations: one situation involves one straight lane and one left-turn lane; the other situation involves two straight lanes and one left-turn lane. The results show that the capacity is mainly relative to signal cycle length, phase length, intersection layout and following time. With regard to the vehicles arrival rates, the optimal model is derived based on each phase's remaining time balance, and it is solved by Lagrange multipliers. Therefore, the calculation models of the optimal signal cycle length and phase lengths are derived and simplified. Compared to the existing models, the proposed model is more convenient and practical. Finally, a practical intersection is chosen and its signal cycles and phase lengths are calculated by the proposed model.
文摘In this paper, direct sequence spread spectrum multiple access (DS/SSMA) communication system employing serially concatenated trellis coded modulation (TCM) and continuous phase modulation (CPM) over flat Rayleigh fading channel are presented. The performance of this concatenated TCM/CPM DS/SSMA system is exploited by the theoretical analysis and numerical simulations. The results demonstrate that significant improvements in error probability of this DS/SSMA system over the system with single TCM or CPM of different modulation indices can be achieved under the same conditions.
文摘This paper is to construct a “digital local, regional, region” information framework based on the technology of “SIG” and its significance and application to the regional sustainable development evaluation system. First, the concept of the “grid computing” and “SIG” is interpreted and discussed, then the relationship between the “grid computing” and “digital region” is analyzed, and the framework of the “digital region” is put forward. Finally, the significance and application of “grid computing” to the “region sustainable development evaluation system” are discussed.
基金This research work is supported by the Projects of National Science Foundation of China (Grant No, 40574052 and 40437018) and National Basic Research Program of China (973 Program) (Grant No. 2007CB209603).Acknowledgements We wish to thank Researcher Xu Tao for his advice and comment. We also thank Mrs. Wang Kun for her help in the process of translation.
文摘In view of the relative positioning problem between non-regular quadrilateral grids and regular rectangle grid nodes in the wave front construction method, concrete realization problems with four grid positioning methods (vector cross product judgment, angle sum, intersection-point, and signs comparison algorithms) in wave front construction which are commonly used in computer graphics are compared and analyzed in this paper. Based on the stability analysis of the location method, the calculation examples show that the vector cross product judgment method is faster and more accurate than other methods in the realization of the relative positioning between non-regular quadrilateral grids and regular rectangle grid nodes in wave front construction. It provides precise grid point attribute values for the next steps of migration and demigration.
基金financial support for studying at Lakehead University by the CSU Special Scholarship for Study Abroad from Central South Universitysupported by the National Natural Science Foundation of China (Nos. 42030809, 41772349, 41972309, 42072325)the National Key R&D Program of China (No. 2017YFC0601503)
文摘Texture,geochemistry,and in-situ Pb isotope of galena were investigated to probe the origin of anomalous Ag enrichment in the Dayingezhuang Au(-Ag)deposit.Silver enrichment postdates the main Au mineralization and occurs in the south of the Dayingezhuang deposit.It is primarily associated with galena and the exsolution of Ag-rich sulfosalts(e.g.,matildite)in distal vein-ores related to steeply dipping brittle fractures.Silver-rich galena is characterized by the least radiogenic Pb isotope signature(^(206)Pb/^(204)Pb 17.195–17.258 and ^(208)Pb/^(204)Pb 37.706–37.793),possibly indicating a metasomatized lithospheric mantle or modified lower crustal source for Pb and Ag.Both of these mafic and ultramafic source regions have been previously suggested as Au reservoirs for other Jiaodong Au deposits,implying that the metal reservoir has only a weak control on the uneven Ag-enrichment.Since the Ag-enrichment areas are located in the footwalls of both the Dayingezhuang and Zhaoping faults,the enrichment was most likely dominated by local rotational stress during coeval movements of the two faults in a NE–SW compression and NW−SE extension regime.This work highlights the shallow-crust structural deformation responsible for controlling the flow of late ore-forming fluid resulting in local anomalous metal enrichment.
文摘The flow and the temperature in the threestream mixing flow of the lobed nozzle mixer-ejector with double-wall diffuser are numerically investigated. The domain of computation is divided into sub-domalns according to the shapes of the double-plate and lobed nozzle. The three-dimensional body-fitted coordinated grids are generated respectively in these sub-domains by solving Lapalace's equations. Grids are dense on the boundaries and orthogonal at the lobe. The grids of all sub-domains compose the whole grid of the domain. In order to avoid the divergence of the computation as the serious non-orthogonality of the grid from the lobe, the co-located grid, SIMPLEC and Chen-Kim modified k-εturbulence model are applied. The great viscosity, the linear and simultaneous cooperation under-relaxation factors are used to solve the coupling of the fluid and solid. Results show that the air is ejected into the double wall section to form the cooling flow. The wall temperature of the double-wall diffuser is lower than that of the single-wall diffuser. The average wall temperature goes down as the diffuser angle increases at the range of 0~5°,otherwise, the result at the range of 5~10°is opposite.
基金Supported by A grant from the Natural Science Foundation of China,No.30830040
文摘AIM:To develop orthotopic gastric cancer mouse models from different cell lines and characterize the tumor features to assist further in preclinical trials and clinical treatment strategies.METHODS:Human gastric cancer SGC-7901 and BGC823 cell suspensions were injected subcutaneously into nude mice to develop solid tumors,and tumor tissue pieces were then implanted under the serous coat of the stomach.An autopsy was performed on all animals of the SGC-7901 and BGC-823 models to observe the primary tumor growth and metastases using pathological and immunohistochemical methods.RESULTS:Both models showed large tumors in situ resulting in pressure and infiltration of the adjacent organs.The gastric cavity became smaller,along with stenosis of the cardia or pylorus.There were biological and statistical differences between the two models.The metastasis rate in involved organs (lymph nodes,kidney,spleen,testis) was significantly higher in the BGC-823 model compared to the SGC-7901 model (P < 0.05 or P < 0.01).The median survival of the BGC-823 model was shorter than that of SGC-7901 (23 d vs 84 d,P < 0.05).Histopathologically,the primary tumor and metastatic lesions of the two models showed obvious atypia and mucus in the cytoplasm.Compared with the SGC-7901 model,BGC-823 appeared more poorly differentiated (absence of adenoid structure),had a smaller volume,and richer capillary structure.Immunohistochemical staining revealed cytokeratin 20 and epithelial membrane antigen expression was positive in the SGC-7901 tumors,while negative in BGC-823 ones.CONCLUSION:Models using the SGC-7901 and BGC-823 cell lines were established which could function in gastric cancer research on carcinogenesis mechanism and drug discovery.The two models showed different tumor behavior and the latter was more malignant than the former.
文摘In a manufacturing company, certain departments can be characterized as production departments and others as service departments. This paper expands and simplifies the results by the author and his co-author (Lowenthal & Malek, 2005; 2013), by explaining in a simple way how to obtain the fair-price per unit to pay to external suppliers that replace service departments. The paper also proves that replacing several service departments at once produces exactly the same fair-price per unit if they were replaced sequentially.
基金Under the auspices of Key Program of National Natural Science Foundation of China(No.40830741)
文摘By analyzing the relationship among government, market driving forces, distribution orientation of banking industry, service opportunity equality and spatial patterns, this paper proposes that it is distribution orientation that lead to the formation and evolution of spatial pattern of banking industry. The difference of the distribution orientation leads to the separation of the spatial pattern of banking industry, and the change of the distribution orientation leads to the change of spatial pattern. The degree of spatial pattern change is subject to the degree of change of distribution orientation, and the scale of bank resources in the regions, which supports the distribution orientation variation. Based on these theoretical frameworks, some indicators were designed to analyze the pattern change of China′s banking industry and its effects since 1995 under the change of the distribution orientation. This paper finds that the orientation of economic benefit maximization driven by market causes the banking industry to concentrate in economically developed regions.The government, which does not follow the orientation of economic benefit maximization, plays a role of stabilizer. Since the bank branches in the regions with the greatest change in bank branch distribution are too few, and regions with the greatest change in bank loan allocation are the regions with lots of loans, the pattern change of the banking industry in physical form is not as notable as that in economic form.
文摘The present work aims to evaluate the increase in the number of spot welds in the 16 × 16 type fuel assembly structure that connects guide thimbles and spacer grids, in order to provide a proper joint for this connection. This new and improved process can provide more stiffness to the whole structure, since the number of spots raised from four to eight. A 3-D geometric model of a guide thimble section was generated in a CAD (computer aided design) program (SolidWorks). After that, the geometric model was imported to a CAE (computer aided engineering) program (ANSYS Mechanical APDL, Release 14.0), where the finite element model was built, considering the guide thimble geometry assembled with the spacer grid through the welded connections. Boundaries conditions were implemented in the model in order to simulate the correct physical behavior due to the operation of the fuel assembly inside the reactor. The analysis covered specific loads and displacements acting on the entire structure. The method used to solve this finite element analysis was a linear static simulation in order to perform the connection between a spacer grid cell and a guide thimble section. Hence, four models was evaluated, differing on the spot weld number in the spacer grid and guide thimble connection. The rotational stiffness results of each model were compared. The results acquired from four and eight spot weld were validated with physical test results. The behavior of the structure under the acting force/displacement and the related results of the analysis, mainly the stiffness, were satisfied. The results of this analysis were used to prove that the increasing spot welds number is an improvement in the dimensional stability when submitted to loads and displacements required on the fuel assembly design. This analysis aid to get more information of extreme importance such as, the pursuance to develop better manufacturing process and to improve the fuel assembly performance due to the increasing of the bum-up.
文摘In advanced nuclear fuel design, the outer strap of a spacer grid plays an important role on fuel assembly mechanical and thermal-hydraulic performance, e.g., precluding the risk of hang-up and improvement on the mixing of the coolant. The communication of the outer strap affects the hydraulic force exerted by the spacer grid of the fuel assembly which could induce fuel assembly bow. In present study, in order to understand the influencing factors of hydraulic force exerted by the spacer grid, outer straps with various flow opening design features, different location and size are investigated by a commercially CFD (computational fluid dynamics) code, ANSYS CFX 12.1. Three dimensional rod bundles including the outer strap without and with different openings are modelled for simulation. The analysis results show that the openings on the spacer grid outer strap can reduce the lateral hydraulic loadings perpendicular to the centerline of the fuel rods exerted by the spacer grids obviously because of the pressures inside and outside the spacer grids being balanced. Besides, influences of the opening design features on the hydraulic force, resistance characteristics and lateral flow factor are investigated in details.
文摘Abstract: The Tigris and Euphrates Rivers are the main sources of water in Iraq. Iraq used to receive 33×109 m^3 of river water per year at Hit, 200 km downstream from the Syrian border before the 1970s. In 1980s, the discharge decreased to as little as 8 × 10^9 m^3 per year at Hit. The decreasing of discharge and water level in the Euphrates River causes problems of both quantity and quality, such as the increasing salinity in the internal delta downstream, the TDS (total dissolves salinity) at Hit has increased from less than 500 ppm to about 700 ppm. By 1989, the Euphrates' salinity at A1 Qaim reached 1,000 ppm. Currently, the TDS of the river, at AI Qaim, is greater than 1,000 ppm. The problem of control salinity has received considerable attention particularly when the surface water is extremely limited with poorly available ground water supply. The field measurement has achieved for TDS, pH (hydrogen ion), EC (electric conductivity), coliform content and heavy metal for three sectors in the Euphrates River basin in Iraq as well as the lakes of Tharthar, Habbaniya, and AI-Razzaza. The statistical analysis was made to relate these parameter with discharge and water level, which are refered to the important effect of the flow in river on the water quality of Euphrates River. The storage of water in the lakes Al-tharthar, Al-habbanya, and A1-Razzaza has a negative effects on the water quality, and shows that the best method for storage water is the reservoirs along river stream.
基金the Natural Science Foundation of China(21567016,21503106)the Natural Science Foundation of Jiangxi Province(20171BAB213013)+3 种基金the Education Department Foundation of Jiangxi Province(KJLD14005)National Key Research and Development Program of China(2016YFC0209302)the Innovation Fund Designated for Graduate Students of Jiangxi Province(YC2015-B017)the Innovation Fund Designated for Undergraduate Students of China(201701035)~~
文摘A series of three‐dimensionally ordered macroporous(3DOM)SnO2‐based catalysts modified by the cations Ce4+,Mn3+,and Cu2+have been prepared by using a colloidal crystal templating method and tested for soot combustion under loose contact condition.XRD and STEM mapping results confirm that all the secondary metal cations have entered the lattice matrix of tetragonal rutile SnO2 to form non‐continuous solid solutions,thus impeding crystallization and improving the surface areas and pore volumes of the modified catalysts.In comparison with regular SnO2 nanoparticles,the 3DOM SnO2 displays evidently improved activity,testifying that the formation of the 3DOM structure can anchor the soot particulates in the macro‐pores,which ensures that the contact of the soot particles with the active sites on the 3DOM skeleton is more easily formed,thus benefiting the target reaction.With the incorporation of the secondary metal cations,the activity of the catalyst can be further improved due to the formation of more abundant mobile oxygen species.In summary,these effects are believed to be the major factors responsible for the activity of the catalyst.
基金supported by the Science for Earthquake Resilience(No.XH17058Y)Science and Technology Innovation Fund of the First Crust Monitoring and Application Center,CEA(No.FMC2016004)Special Program for Basic Work of the Ministry of Science and Technology,China(No.2015FY210403)
文摘We evaluated 2011-2015 mobile relative gravity data from the Hexi monitoring network that covers the epicenter of the 2016 Menyuan Ms6.4 earthquake, Qinghai Province, China and examined the spatiotemporal characteristics of the gravity field at the focal depth. In addition, we assessed the regional gravity field and its variation the half-year before the earthquake. We use first different interpolation algorithms to build a grid for the gravity data and then introduce potential field interpolation-cutting separation techniques and adaptive noise filtering. The results suggest that the gravity filed at the focal depth of 11.12 km separated from the total gravity field at about -400-150 ×10^-8 m/s^2 in the second half of 2015, which is larger than that in the same period in 2011 to 2014 (±30×10^-8 m/s^2). Moreover, at the same time, the gravity field changed fast from September 2014 to May 2015 and May 2015 to September 2015, reflecting to some extent material migration deep in the crust before the Menyuan earthquake.
基金Supported by Fundamental Research Funds for the Central Universities under Grant No. 2010SCU23002the Startup Grant fromthe Institute of Nuclear Science and Technology of Sichuan University
文摘We study s-wave pion-pion scattering length in lattice QCD for pion masses ranging from 330 MeV to 466 MeV. In the "Asqtad" improved staggered fermion formulation, we measure full ππ four-point correlators for isospin I = 0 and 2 channels, and use chiral perturbation theory at next-to-leading order to extrapolate our simulation results. Extrapolating to the physical pion mass yields scattering lengths as mna01=2 = -0.041 6(2) and mna01= 0.186(2) for isospin I = 2 and 0 channels, respectively. Our lattice simulation for ππ scattering length in I = 0 channel is an exploratory study, where we include the disconnected contribution, and our preliminary result is near to its experimental value. These simulations are carried out with MILC 2 + 1 flavor gauge configurations at lattice spacing a ≈0.15 fm.
基金supported by the Project of Comprehensive Evaluation of Polar Areas on Global and Regional Climate Changes (CHINARE2015-04-04)the National Natural Science Foundation of China (Grant No. 41406027)+1 种基金the NSFC-Shandong Joint Fund for Marine Science Research Centers (Grant No. U1406404)the international cooperation project of Indo-Pacific ocean environment variation and air-sea interaction (Grant No. GASI-03-IPOVAI-05)
文摘The Arctic sea ice minimum records appeared in the Septembers of 2007 and 2012, followed by high snow cover areas in the Northern Hemisphere winters. The snow cover distributions show different spatial patterns in these two years: increased snow cover in Central Asia and Central North America in 2007, while increased snow cover in East Asia and northwestern Europe in 2012. The high snow cover anomaly shifted to higher latitudes in winter of 2012 compared to 2007. It is noticed that the snow cover had positive anomaly in 2007 and 2012 with the following conditions: the negative geopotential height and the related cyclonic wind anomaly were favorable for upwelling, and, with the above conditions, the low troposphere and surface air temperature anomaly and water vapor anomaly were favorable for the formation and maintenance of snowfalls. The negative geopotential height, cyclonic wind and low air temperature conditions were satisfied in different locations in 2007 and 2012, resulting in different spatial snow cover patterns. The cross section of lower air temperature move to higher latitudes in winter of 2012 compared to 2007.