Photonic crystal fibers （PCFs） with a stepped raised-core profile and one layer equally spaced holes in the cladding are analyzed. Using effective index method and considering a raised step refractive index differen...Photonic crystal fibers （PCFs） with a stepped raised-core profile and one layer equally spaced holes in the cladding are analyzed. Using effective index method and considering a raised step refractive index difference between the index of the core and the effective index of the cladding, we improve the characteristic parameters such as numerical aperture and V-parameter, and reduce its bending loss to about one tenth of a conventional PCF. Implementing such a structure in PCFs may be one step forward to achieve low loss PCFs for communication applications.展开更多
Aiming at the characteristics of multi-stage and(extremely)small samples of the identification problem of key effectiveness indexes of weapon equipment system-of-systems(WESoS),a Bayesian intelligent identification an...Aiming at the characteristics of multi-stage and(extremely)small samples of the identification problem of key effectiveness indexes of weapon equipment system-of-systems(WESoS),a Bayesian intelligent identification and inference model for system effectiveness assessment indexes based on dynamic grey incidence is proposed.The method uses multi-layer Bayesian techniques,makes full use of historical statistics and empirical information,and determines the Bayesian estima-tion of the incidence degree of indexes,which effectively solves the difficulties of small sample size of effectiveness indexes and difficulty in obtaining incidence rules between indexes.Sec-ondly,The method quantifies the incidence relationship between evaluation indexes and combat effectiveness based on Bayesian posterior grey incidence,and then identifies key system effec-tiveness evaluation indexes.Finally,the proposed method is applied to a case of screening key effectiveness indexes of a missile defensive system,and the analysis results show that the proposed method can fuse multi-moment information and extract multi-stage key indexes,and has good data extraction capability in the case of small samples.展开更多
Based on the quasi analytical technique, an analytical expression for the effective index profile in the depth direction in Ti:LiNbO 3 strip waveguide is theoretically derived. It is very u...Based on the quasi analytical technique, an analytical expression for the effective index profile in the depth direction in Ti:LiNbO 3 strip waveguide is theoretically derived. It is very useful for the research into the propagation characteristics of the strip waveguides with metal clad. From this expression, the field distributions and modal indices in typical waveguides are calculated. In addition, the method of how to get the position where the mode field has the maximum value is yielded in this paper. It is very important to the optical coupling between two waveguides or between the waveguide and the fiber.展开更多
With the cost estimation of military aircraft as the research object, this paper aims to study the contradiction between the choice of explanatory variables in index modeling and the maintaining of model validity. It ...With the cost estimation of military aircraft as the research object, this paper aims to study the contradiction between the choice of explanatory variables in index modeling and the maintaining of model validity. It analyzes and establishes a cost estimation modeling concept based on an Effectiveness Index and studies the way to construct Effectiveness Indexes for the sake of cost estimation modeling. Based on a case study, the paper establishes and analyzes the Effectiveness Index-based cost estimation models and DAPCA （Development And Procurement Costs of Aircraft） models developed by the RAND Corparation . The comparison of these models shows that the Effective- ness Index-based cost parameter models not only comprehensively consider the obvious driving parameter indexes of the cost, but reduces the variables of regressive analysis, hence giving the model a higher reliability.展开更多
The interaction potential index IPI（X） of 16 Br, C1, I, NO2, CN, CHO, COOH, CH3, CH： kinds of substituents X （X---OH, SH, NH2, ：CH2, C-CH, Ph, COCH3, COOCH3） were proposed, which are derived from the experimenta...The interaction potential index IPI（X） of 16 Br, C1, I, NO2, CN, CHO, COOH, CH3, CH： kinds of substituents X （X---OH, SH, NH2, ：CH2, C-CH, Ph, COCH3, COOCH3） were proposed, which are derived from the experimental enthalpies of formation △fHФ （g） values of monosubstituted straight-chain alkanes. Based on the IPI（X） and polarizability effect index, a simple and effective model was constructed to estimate the △fHФ （g） values of monosubstituted alkanes RX （including the branched derivatives）. The present model takes into account not only the contributions of the alkyl R and the substituent X, but also the contribution of the interaction between R and X. Its stability and prediction ability was confirmed by the results of leave-one-out method. Compared with previous reported studies, the obtained equation can be used to estimate enthalpies of formation for much more kinds of monosubstituted alkanes with less parameters. Thus, it is recommended for the calculation of the △fHФ（g） for the RX.展开更多
By replacing leaf area index （LAI） with effective leaf area index （ELAI） through introduction of leaf rolling index （LRI）, the distributions of photosynthetically active radiation （PAR） in the canopies of thre...By replacing leaf area index （LAI） with effective leaf area index （ELAI） through introduction of leaf rolling index （LRI）, the distributions of photosynthetically active radiation （PAR） in the canopies of three hybrid rice combinations, Liangyou E32 with high LRI, Liangyoupeijiu with moderate LRI and Shanyou 63 with non-rolling leaves （normal）, were simulated. The model based on ELAI could predict more accurately than that based on LAI. The PAR interception, conversion and utilization efficiency in the three combinations were studied to evaluate their optimal LRI and LAI. The PAR utilization efficiency of Liangyou E32 was lower due to excessive rolling leaves and less ELAI, and that of Shanyou 63 was also lower because of the faulty PAR interception and lower photosynthetic rate and saturation point at lower layer in canopy. Compared with the above two combinations, Liangyoupeijiu showed more appropriate distribution of PAR interception and conversion efficiency in canopy, and higher PAR utilization efficiency. The optimal LRI and LAI for Liangyoupeijiu were 0.11 and 7.6, respectively, which were close to the observed value, 0.11 and 7.9, respectively. However, the optimum LAI was 9.8 for Liangyou E32 and 6.2 for Shanyou 63, larger or smaller than those under the current plant density, which led to lower efficiency of PAR utilization. Besides, the optimum LRI for Liangyou E32 and Shanyou 63 were 0.12 and 0.08, respectively, which were close to the actual LRI for Liangyoupeijiu （0.11）.展开更多
The damage and even failure of hard brittle rocks has been the most important challenge facing the safety of construction of deep engineering works,so the key to solving this problem is the recognition of the strength...The damage and even failure of hard brittle rocks has been the most important challenge facing the safety of construction of deep engineering works,so the key to solving this problem is the recognition of the strength characteristics and description of the mechanical behavior of hard brittle rocks.Therefore,in view of this problem,in this study,we first analyzed the strength and mechanical response characteristics revealed in tests of,and site excavation in,hard brittle rocks.Second,by analyzing rock-strength envelopes on meridional and deviatoric planes,the generalized polyaxial strain energy(GPSE)strength criterion was applied.This allows description of the effects of the minimum principal stress,intermediate principal stress,hydrostatic pressure,and Lode’s angle of stress on the strength of hard rocks.By establishing evolutionary relationships of strength parameters and dilation parameters with plastic volumetric strain in rock failure,we established an elasto-plastic mechanical constitutive model for hard brittle rocks based on the GPSE criterion.In addition,through use of the failure approach index theory and the dilatancy safety factor,an evaluation index for degree of damage considering dilatant effects of rocks was proposed.Finally,the constitutive model established in this study and the proposed evaluation index were integrated into the numerical simulation method to simulate triaxial tests on rocks and numerical simulation of deformation and fracture of the rocks surrounding the deep-buried auxiliary tunnels in China’s Jinping II Hydropower Station.In this way,the reasonableness of the model and the index was verified.The strength theory and the constitutive model established in this research are applicable to the analysis of high-stress deformation and fracture of hard brittle rock masses,which supports the theoretical work related to deep engineering operations.展开更多
An effective evaluation system can provide specific and practical suggestions to the deep groundwater management. But such kind of evaluation system has not been proposed in China. In this study, an evaluation index s...An effective evaluation system can provide specific and practical suggestions to the deep groundwater management. But such kind of evaluation system has not been proposed in China. In this study, an evaluation index system is specifically developed to evaluate deep groundwater management efficiency. It is composed of three first-level indicators(law enforcement capability, management ability, and management effectiveness) and eleven second-level indicators. The second-level indicators include seven mandatory indicators and four optional indicators. Piecewise linear function is used to normalize the quantitative indicators, and expert scoring method and questionnaire survey method are used to normalize the qualitative indicators. Then a comprehensive indicator weighting evaluation method is used to evaluate the first-level indicators and the target topic. A case study is carried out to evaluate deep groundwater management efficiency in Tianjin City. According to the evaluation score in each period, the management efficiency of every district in Tianjin City gradually improved. The overall evaluation score in the early deep groundwater extraction period is 0.12. After a series of deep groundwater protection efforts, this score reached to 0.61 in 2007, and met the regulation criteria. The evaluation results also showed that the further groundwater management efforts in Tianjin City should be focused on building a dynamic database to collect comprehensive deep well-log data; and on a reasonable design and distribution of the groundwater monitoring network. It demonstrated that the index system is suitable to locate the deficiencies of current groundwater management systems and to guide further improvements. It can then be used to protect deep groundwater.展开更多
The so-called enterprise internal control work is in the daily operation of the enterprise in such a process, by the inside and outside the use of the relevant legal means and rules and regulations of the enterprise i...The so-called enterprise internal control work is in the daily operation of the enterprise in such a process, by the inside and outside the use of the relevant legal means and rules and regulations of the enterprise internal self-restraint and control of such a process. The evaluation of the effectiveness of internal control is also in the daily operation of the enterprise, the special supervision and management of the enterprise uses the effect of self-management. Of course, an excellent enterprise must have a certain sense of internal control to make the corresponding internal control evaluation system constructed successfully. And only with a standardized evaluation system can enterprises can run and develop with higher quality and long-term time. This paper analyzes the construction mode of the internal control effectiveness evaluation system, and provides a certain scientific reference and theoretical basis for the construction of the effectiveness evaluation system of the internal control work.展开更多
Relative tillering rate(RTR)increased linear-ly with the increasing of leaf N concentration(NLV)has been already reported.To testwhether this relationship could be used toquantitatively explain the difference in tille...Relative tillering rate(RTR)increased linear-ly with the increasing of leaf N concentration(NLV)has been already reported.To testwhether this relationship could be used toquantitatively explain the difference in tilleringamong a wide range of N application,field ex- periments were conducted at the IRRI farm,Los Banos,Laguna,the Philippines.Two in- dica cultivars,IR 72 and IR68284H wereused.For each cultivar,12 treatments includ- ing 4 N levels(0,60,120,and 180kgN·ha)and 3 transplanting spacing(30×20,20×20,and 10×20cm)were arranged in a ran-domized split-plot design with 4 replications.The N treatments were designated as mainplots and spacings as subplots.Fourteen-day-old seedlings were transplanted with 3seedlings per hill.The subplot area was 20m~2.Nitrogen fertilizer was applied as basal,atmidtillering,and at panicle initiation in threeequal splits.P,K,and Zn were applied asbasal at normal dosage.The field was flooded.Plant samples were taken every 7-14 d from 14d after transplanting to flower展开更多
Cadmium accumulation in seafood has become a major concern for human health.Recently,there has been an increasing focus on the potential risks associated with food-borne fluorescent carbon dots(CDs)that are formed dur...Cadmium accumulation in seafood has become a major concern for human health.Recently,there has been an increasing focus on the potential risks associated with food-borne fluorescent carbon dots(CDs)that are formed during the thermal processing of seafood.The co-occurrence of cadmium and CDs from cooked seafood become a common phenomenon and co-exposure of them to human has been an inevitable route during long-term seafood consuming.In addition,it has been widely recognized that CDs can be used as nanocarriers for metal ion chelation for their transport into organisms,thereby,they could influence the bioavailability of metal ion.While there have been numerous studies on the toxic effects of cadmium or CDs,none have explored the combined toxicity of food-borne CDs from clams(CCDs)and Cd^(2+).In this study,we investigated the single or co-exposure(combined exposure)of Cd^(2+)and CCDs on PC12 cells to investigate the combined toxicity of them.Our analysis of cell viability revealed that CCDs significantly augmented the cytotoxicity induced by Cd^(2+).More in-depth metabolomics and lipidomics investigation indicated that the combined exposure of Cd^(2+)and CCDs led to significant metabolic disorders,causing an antagonistic effect on energy metabolism,and a synergistic effect on amino acids and lipids metabolism.The disturbance in metabolomics and lipidomics was further supported by the disruption of mitochondrial membrane potential and the accumulation of reactive oxygen species following co-exposure.These findings provide new evidence that support the enhanced cytotoxicity of Cd^(2+)by the CCDs derived from the thermal processing of clams.This study also declares the necessary that prioritize the investigation of the potential impact of other thermal processing hazards originating from heat-processed foods on the toxicity of heavy metal ions.展开更多
We proposed and demonstrated the ultra-compact 1310/1550 nm wavelength multiplexer/demultiplexer assisted by subwavelength grating(SWG)using particle swarm optimization(PSO)algorithm in silicon-on-insulator(SOI)platfo...We proposed and demonstrated the ultra-compact 1310/1550 nm wavelength multiplexer/demultiplexer assisted by subwavelength grating(SWG)using particle swarm optimization(PSO)algorithm in silicon-on-insulator(SOI)platform.Through the self-imaging effect of multimode interference(MMI)coupler,the demultiplexing function for 1310 nm and 1550 nm wavelengths is implemented.After that,three parallel SWG-based slots are inserted into the MMI section so that the effective refractive index of the modes can be engineered and thus the beat length can be adjusted.Importantly,these three SWG slots significantly reduce the length of the device,which is much shorter than the length of traditional MMI-based wavelength demultiplexers.Ultimately,by using the PSO algorithm,the equivalent refractive index and width of the SWG in a certain range are optimized to achieve the best performance of the wavelength demultiplexer.It has been verified that the device footprint is only 2×30.68μm^(2),and 1 dB bandwidths of larger than 120 nm are acquired at 1310 nm and 1550 nm wavelengths.Meanwhile,the transmitted spectrum shows that the insertion loss(IL)values are below 0.47 dB at both wavelengths when the extinction ratio(ER)values are above 12.65 dB.This inverse design approach has been proved to be efficient in increasing bandwidth and reducing device length.展开更多
Improved waveguide designs for 9.0μm GaAs-based quantum cascade laser （QCL） structures are presented. Modal losses and confinement factors are calculated for TM modes with the transfer matrix method （TMM） and eff...Improved waveguide designs for 9.0μm GaAs-based quantum cascade laser （QCL） structures are presented. Modal losses and confinement factors are calculated for TM modes with the transfer matrix method （TMM） and effective index method （EIM）. The thicknesses of the cladding layer and waveguide layer, the ridge-width, and the cavity length are all taken into account. Appropriate thicknesses of epilayers are given with lower threshold gain and more economical material growth time.展开更多
Five types of rare earth/alkaline earth oxide-doped CeO2 superfine-powders were synthesized by a low-temperature combustion technique. The relevant solid electrolyte materials were also sintered by pressureless sinter...Five types of rare earth/alkaline earth oxide-doped CeO2 superfine-powders were synthesized by a low-temperature combustion technique. The relevant solid electrolyte materials were also sintered by pressureless sintering at different temperatures. The results of X-ray diffraction and transmission electron microscopy showed that the grain size of the powders was approximately 20-30 nm, and rare earth/alkaline earth oxides were completely dissolved into ceria-based solid solution with fluorite structure. The electrical conductivities of the SmzO3-CeO2 system were measured by the ac impedance technique in air at temperatures ranging from 513-900℃. The results indicated that the ionic conductivities of Srno.2oCe0.8Ol.875 solid electrolyte increase with increasing sintering temperature, and the relationship between the conductivities and measuring temperature obeys the An＇henius equation. Then the SmzO3-CeO2 material was further doped with other rare earth/alkaline earth oxide, and the conductivities improve with the effective index.展开更多
Doped Ceria nano-powders were synthesized via a Pechini-type gel rout. The specific surface area of Ce_(0.8)Sm_(0.2)O_(1.9) powder measured by the multilayer BET method is 41 m2.g^(-1). The electrical conductivities o...Doped Ceria nano-powders were synthesized via a Pechini-type gel rout. The specific surface area of Ce_(0.8)Sm_(0.2)O_(1.9) powder measured by the multilayer BET method is 41 m2.g^(-1). The electrical conductivities of Sm_2O_(3)-CeO_2 systems were measured by the ac impedance technique in air at temperatures ranging from 513 to 900 ℃. Typical impedance spectra consist of two depressed semicircles at reduced measuring temperature and one depressed semicircle at elevated measuring temperature respectively, from which the grain interior and grain boundary conductivities were calculated. The relationship between the conductivities of Sm_2O_3 doped CeO_2 (SDC) electrolyte and measuring temperature obeys Arrhenius equation. The grain interior conductivity of SDC varies slightly with improving sintering temperature, while the total conductivity increases with enhancing sintering temperature. The effective index has a significant effect on the ionic conductivity of ceria doped based electrolyte. When the effective index improves, the ionic conductivity increases and the apparent conductance activation energy decreases.展开更多
An electrically driven, single-longitudinal-mode GaAs based photonic crystal （PC） ridge waveguide （RWG） laser emitting at around 850 nm is demonstrated. The single-longitudinal-mode lasing characteristic is achiev...An electrically driven, single-longitudinal-mode GaAs based photonic crystal （PC） ridge waveguide （RWG） laser emitting at around 850 nm is demonstrated. The single-longitudinal-mode lasing characteristic is achieved by introducing the PC to the RWG laser. The triangle PC is etched on both sides of the ridge by photolithography and inductive coupled plasma （ICP） etching. The lasing spectra of the RWG lasers with and without the PC are studied, and the result shows that the PC purifies the longitudinal mode. The power per facet versus current and current-voltage characteristics have also been studied and compared.展开更多
We demonstrate a new kind of multi-core photonic liquid crystal fibers (PLCFs) which have six liquid crystal cores arrayed in the ring-type geometry and separated by the air holes. Through analyzing the structure of t...We demonstrate a new kind of multi-core photonic liquid crystal fibers (PLCFs) which have six liquid crystal cores arrayed in the ring-type geometry and separated by the air holes. Through analyzing the structure of this kind of PLCFs, it can be found that they have the ability to resist the structure deformation. Due to the effective index of the liquid crystal can be adjusted by temperature and wavelength, the energy in the six liquid crystal cores is increased with the temperature increasing and wavelength decreasing. The effective index of the PLCFs is decreased, the effective fundamental mode area is increased and the dispersion properties are gently affected with the wavelength increasing and temperature decreasing.展开更多
Based on the Semi-Markov mathematical description, the multiple states of maintenance processes for aviation weapon equipment are studied. Six kinds of maintenance states are determined and the Semi-Markov model of th...Based on the Semi-Markov mathematical description, the multiple states of maintenance processes for aviation weapon equipment are studied. Six kinds of maintenance states are determined and the Semi-Markov model of the maintenance process is given. According to maintenance characteristic, the multiple states maintenance processes are divided into the wait, use and alternate stages. Through using the mathematical model for the different stages, the probability in different states and effective index on different stages are obtained. These results are available to the maintenance practice.展开更多
A new version of the scalar transverse electric(TE) wave equation in the bent waveguide is introduced. Then, TE polarized field in curved single-mode waveguides is analyzed by using the finite-difference beam propagat...A new version of the scalar transverse electric(TE) wave equation in the bent waveguide is introduced. Then, TE polarized field in curved single-mode waveguides is analyzed by using the finite-difference beam propagation method(FD-BPM). The bending loss in bent waveguides is gotten for the optical fields obtained from BPM and comparisons are made among losses of the waveguides with various curvature radiuses, refractive index differences and cross sections. Based on the results, the design of spiral bent waveguide configuration is proposed as follows: refractive index difference being of 0.007, both width and thickness of waveguides being of 6 μm, the curvature radius in the spiral centre being of 4 mm, and the bending loss coefficient of the designed spiral bent waveguide being of 0.302 3 dB/cm.展开更多
Nanocrystalline yttrium vanadate doped with europium ions powders were synthesized via sol-gel method based on decomposition of metal-polymer complex. X-ray diffraction analysis showed that samples had pure tetragonal...Nanocrystalline yttrium vanadate doped with europium ions powders were synthesized via sol-gel method based on decomposition of metal-polymer complex. X-ray diffraction analysis showed that samples had pure tetragonal phase without any impurities. Scanning electron microscopy and static light scattering technique were used to study morphology and size of prepared nanoparticles. Average diameter of the nanoparticles was about 40 nm. The changes in structural and luminescence properties were observed as a function of the first and second calcination temperature. The optimal conditions for synthesis of nanoparticles were determined as Т1=500℃, t1=1 h; Т2=950 ℃, t2=1.5 h. The effect of different media surrounding the nanoparticles on their luminescence properties and lifetime was investigated and discussed in terms of effective refractive index. It was found that the observed lifetime of YVO4：Eu^3＋ 5 at.% nanophosphor was decreased from 0.64 ms in air（nmed=1） to 0.45 ms in chalcogenide glass As39S61（nmed=2.39）.展开更多
文摘Photonic crystal fibers （PCFs） with a stepped raised-core profile and one layer equally spaced holes in the cladding are analyzed. Using effective index method and considering a raised step refractive index difference between the index of the core and the effective index of the cladding, we improve the characteristic parameters such as numerical aperture and V-parameter, and reduce its bending loss to about one tenth of a conventional PCF. Implementing such a structure in PCFs may be one step forward to achieve low loss PCFs for communication applications.
基金supported by the National Natural Science Foundation of China(72271124,72071111).
文摘Aiming at the characteristics of multi-stage and(extremely)small samples of the identification problem of key effectiveness indexes of weapon equipment system-of-systems(WESoS),a Bayesian intelligent identification and inference model for system effectiveness assessment indexes based on dynamic grey incidence is proposed.The method uses multi-layer Bayesian techniques,makes full use of historical statistics and empirical information,and determines the Bayesian estima-tion of the incidence degree of indexes,which effectively solves the difficulties of small sample size of effectiveness indexes and difficulty in obtaining incidence rules between indexes.Sec-ondly,The method quantifies the incidence relationship between evaluation indexes and combat effectiveness based on Bayesian posterior grey incidence,and then identifies key system effec-tiveness evaluation indexes.Finally,the proposed method is applied to a case of screening key effectiveness indexes of a missile defensive system,and the analysis results show that the proposed method can fuse multi-moment information and extract multi-stage key indexes,and has good data extraction capability in the case of small samples.
文摘Based on the quasi analytical technique, an analytical expression for the effective index profile in the depth direction in Ti:LiNbO 3 strip waveguide is theoretically derived. It is very useful for the research into the propagation characteristics of the strip waveguides with metal clad. From this expression, the field distributions and modal indices in typical waveguides are calculated. In addition, the method of how to get the position where the mode field has the maximum value is yielded in this paper. It is very important to the optical coupling between two waveguides or between the waveguide and the fiber.
文摘With the cost estimation of military aircraft as the research object, this paper aims to study the contradiction between the choice of explanatory variables in index modeling and the maintaining of model validity. It analyzes and establishes a cost estimation modeling concept based on an Effectiveness Index and studies the way to construct Effectiveness Indexes for the sake of cost estimation modeling. Based on a case study, the paper establishes and analyzes the Effectiveness Index-based cost estimation models and DAPCA （Development And Procurement Costs of Aircraft） models developed by the RAND Corparation . The comparison of these models shows that the Effective- ness Index-based cost parameter models not only comprehensively consider the obvious driving parameter indexes of the cost, but reduces the variables of regressive analysis, hence giving the model a higher reliability.
基金This work was supported by the National Natural Science Foundation of China （No.21072053 and No.20772028） and the Scientific Research Fund of Hunan Provincial Education Department （No.10K025 and No.09C386）.
文摘The interaction potential index IPI（X） of 16 Br, C1, I, NO2, CN, CHO, COOH, CH3, CH： kinds of substituents X （X---OH, SH, NH2, ：CH2, C-CH, Ph, COCH3, COOCH3） were proposed, which are derived from the experimental enthalpies of formation △fHФ （g） values of monosubstituted straight-chain alkanes. Based on the IPI（X） and polarizability effect index, a simple and effective model was constructed to estimate the △fHФ （g） values of monosubstituted alkanes RX （including the branched derivatives）. The present model takes into account not only the contributions of the alkyl R and the substituent X, but also the contribution of the interaction between R and X. Its stability and prediction ability was confirmed by the results of leave-one-out method. Compared with previous reported studies, the obtained equation can be used to estimate enthalpies of formation for much more kinds of monosubstituted alkanes with less parameters. Thus, it is recommended for the calculation of the △fHФ（g） for the RX.
基金supported by the National High-tech Research and Development Program of China (Grant No.2003AA212040 and No.2006AA100101)
文摘By replacing leaf area index （LAI） with effective leaf area index （ELAI） through introduction of leaf rolling index （LRI）, the distributions of photosynthetically active radiation （PAR） in the canopies of three hybrid rice combinations, Liangyou E32 with high LRI, Liangyoupeijiu with moderate LRI and Shanyou 63 with non-rolling leaves （normal）, were simulated. The model based on ELAI could predict more accurately than that based on LAI. The PAR interception, conversion and utilization efficiency in the three combinations were studied to evaluate their optimal LRI and LAI. The PAR utilization efficiency of Liangyou E32 was lower due to excessive rolling leaves and less ELAI, and that of Shanyou 63 was also lower because of the faulty PAR interception and lower photosynthetic rate and saturation point at lower layer in canopy. Compared with the above two combinations, Liangyoupeijiu showed more appropriate distribution of PAR interception and conversion efficiency in canopy, and higher PAR utilization efficiency. The optimal LRI and LAI for Liangyoupeijiu were 0.11 and 7.6, respectively, which were close to the observed value, 0.11 and 7.9, respectively. However, the optimum LAI was 9.8 for Liangyou E32 and 6.2 for Shanyou 63, larger or smaller than those under the current plant density, which led to lower efficiency of PAR utilization. Besides, the optimum LRI for Liangyou E32 and Shanyou 63 were 0.12 and 0.08, respectively, which were close to the actual LRI for Liangyoupeijiu （0.11）.
基金The work was supported by the National Key Research and Development Project of China(Grant No.2016 YFC 0401804)the Key projects of the Yalong River Joint Fund of the National Natural Science Foundation of China(Grant No.U1865203)+1 种基金the National Natural Science Foundation of China(Grant Nos.51539002 and 51779018)It was also supported by the Basic Research Fund for Central Research Institutes of Public Causes(CKSF 2017054/YT).
文摘The damage and even failure of hard brittle rocks has been the most important challenge facing the safety of construction of deep engineering works,so the key to solving this problem is the recognition of the strength characteristics and description of the mechanical behavior of hard brittle rocks.Therefore,in view of this problem,in this study,we first analyzed the strength and mechanical response characteristics revealed in tests of,and site excavation in,hard brittle rocks.Second,by analyzing rock-strength envelopes on meridional and deviatoric planes,the generalized polyaxial strain energy(GPSE)strength criterion was applied.This allows description of the effects of the minimum principal stress,intermediate principal stress,hydrostatic pressure,and Lode’s angle of stress on the strength of hard rocks.By establishing evolutionary relationships of strength parameters and dilation parameters with plastic volumetric strain in rock failure,we established an elasto-plastic mechanical constitutive model for hard brittle rocks based on the GPSE criterion.In addition,through use of the failure approach index theory and the dilatancy safety factor,an evaluation index for degree of damage considering dilatant effects of rocks was proposed.Finally,the constitutive model established in this study and the proposed evaluation index were integrated into the numerical simulation method to simulate triaxial tests on rocks and numerical simulation of deformation and fracture of the rocks surrounding the deep-buried auxiliary tunnels in China’s Jinping II Hydropower Station.In this way,the reasonableness of the model and the index was verified.The strength theory and the constitutive model established in this research are applicable to the analysis of high-stress deformation and fracture of hard brittle rock masses,which supports the theoretical work related to deep engineering operations.
基金Under the auspices of National Basic Research Program of China(No.2010CB428804)
文摘An effective evaluation system can provide specific and practical suggestions to the deep groundwater management. But such kind of evaluation system has not been proposed in China. In this study, an evaluation index system is specifically developed to evaluate deep groundwater management efficiency. It is composed of three first-level indicators(law enforcement capability, management ability, and management effectiveness) and eleven second-level indicators. The second-level indicators include seven mandatory indicators and four optional indicators. Piecewise linear function is used to normalize the quantitative indicators, and expert scoring method and questionnaire survey method are used to normalize the qualitative indicators. Then a comprehensive indicator weighting evaluation method is used to evaluate the first-level indicators and the target topic. A case study is carried out to evaluate deep groundwater management efficiency in Tianjin City. According to the evaluation score in each period, the management efficiency of every district in Tianjin City gradually improved. The overall evaluation score in the early deep groundwater extraction period is 0.12. After a series of deep groundwater protection efforts, this score reached to 0.61 in 2007, and met the regulation criteria. The evaluation results also showed that the further groundwater management efforts in Tianjin City should be focused on building a dynamic database to collect comprehensive deep well-log data; and on a reasonable design and distribution of the groundwater monitoring network. It demonstrated that the index system is suitable to locate the deficiencies of current groundwater management systems and to guide further improvements. It can then be used to protect deep groundwater.
文摘The so-called enterprise internal control work is in the daily operation of the enterprise in such a process, by the inside and outside the use of the relevant legal means and rules and regulations of the enterprise internal self-restraint and control of such a process. The evaluation of the effectiveness of internal control is also in the daily operation of the enterprise, the special supervision and management of the enterprise uses the effect of self-management. Of course, an excellent enterprise must have a certain sense of internal control to make the corresponding internal control evaluation system constructed successfully. And only with a standardized evaluation system can enterprises can run and develop with higher quality and long-term time. This paper analyzes the construction mode of the internal control effectiveness evaluation system, and provides a certain scientific reference and theoretical basis for the construction of the effectiveness evaluation system of the internal control work.
文摘Relative tillering rate(RTR)increased linear-ly with the increasing of leaf N concentration(NLV)has been already reported.To testwhether this relationship could be used toquantitatively explain the difference in tilleringamong a wide range of N application,field ex- periments were conducted at the IRRI farm,Los Banos,Laguna,the Philippines.Two in- dica cultivars,IR 72 and IR68284H wereused.For each cultivar,12 treatments includ- ing 4 N levels(0,60,120,and 180kgN·ha)and 3 transplanting spacing(30×20,20×20,and 10×20cm)were arranged in a ran-domized split-plot design with 4 replications.The N treatments were designated as mainplots and spacings as subplots.Fourteen-day-old seedlings were transplanted with 3seedlings per hill.The subplot area was 20m~2.Nitrogen fertilizer was applied as basal,atmidtillering,and at panicle initiation in threeequal splits.P,K,and Zn were applied asbasal at normal dosage.The field was flooded.Plant samples were taken every 7-14 d from 14d after transplanting to flower
基金supported by the National Key Research and Development Project of China(2017YFC1600702)the Central Funds Guiding the Local Science and Technology Development of China(2020JH6/10500002).
文摘Cadmium accumulation in seafood has become a major concern for human health.Recently,there has been an increasing focus on the potential risks associated with food-borne fluorescent carbon dots(CDs)that are formed during the thermal processing of seafood.The co-occurrence of cadmium and CDs from cooked seafood become a common phenomenon and co-exposure of them to human has been an inevitable route during long-term seafood consuming.In addition,it has been widely recognized that CDs can be used as nanocarriers for metal ion chelation for their transport into organisms,thereby,they could influence the bioavailability of metal ion.While there have been numerous studies on the toxic effects of cadmium or CDs,none have explored the combined toxicity of food-borne CDs from clams(CCDs)and Cd^(2+).In this study,we investigated the single or co-exposure(combined exposure)of Cd^(2+)and CCDs on PC12 cells to investigate the combined toxicity of them.Our analysis of cell viability revealed that CCDs significantly augmented the cytotoxicity induced by Cd^(2+).More in-depth metabolomics and lipidomics investigation indicated that the combined exposure of Cd^(2+)and CCDs led to significant metabolic disorders,causing an antagonistic effect on energy metabolism,and a synergistic effect on amino acids and lipids metabolism.The disturbance in metabolomics and lipidomics was further supported by the disruption of mitochondrial membrane potential and the accumulation of reactive oxygen species following co-exposure.These findings provide new evidence that support the enhanced cytotoxicity of Cd^(2+)by the CCDs derived from the thermal processing of clams.This study also declares the necessary that prioritize the investigation of the potential impact of other thermal processing hazards originating from heat-processed foods on the toxicity of heavy metal ions.
基金supported by the National Natural Science Foundation of China(No.61505160)the Innovation Capability Support Program of Shaanxi(No.2018KJXX-042)+2 种基金the Natural Science Basic Research Program of Shaanxi(No.2019JM-084)the State Key Laboratory of Transient Optics and Photonics(No.SKLST202108)the Graduate Innovation and Practical Ability Training Project of Xi’an Shiyou University(No.YCS22213190)。
文摘We proposed and demonstrated the ultra-compact 1310/1550 nm wavelength multiplexer/demultiplexer assisted by subwavelength grating(SWG)using particle swarm optimization(PSO)algorithm in silicon-on-insulator(SOI)platform.Through the self-imaging effect of multimode interference(MMI)coupler,the demultiplexing function for 1310 nm and 1550 nm wavelengths is implemented.After that,three parallel SWG-based slots are inserted into the MMI section so that the effective refractive index of the modes can be engineered and thus the beat length can be adjusted.Importantly,these three SWG slots significantly reduce the length of the device,which is much shorter than the length of traditional MMI-based wavelength demultiplexers.Ultimately,by using the PSO algorithm,the equivalent refractive index and width of the SWG in a certain range are optimized to achieve the best performance of the wavelength demultiplexer.It has been verified that the device footprint is only 2×30.68μm^(2),and 1 dB bandwidths of larger than 120 nm are acquired at 1310 nm and 1550 nm wavelengths.Meanwhile,the transmitted spectrum shows that the insertion loss(IL)values are below 0.47 dB at both wavelengths when the extinction ratio(ER)values are above 12.65 dB.This inverse design approach has been proved to be efficient in increasing bandwidth and reducing device length.
文摘Improved waveguide designs for 9.0μm GaAs-based quantum cascade laser （QCL） structures are presented. Modal losses and confinement factors are calculated for TM modes with the transfer matrix method （TMM） and effective index method （EIM）. The thicknesses of the cladding layer and waveguide layer, the ridge-width, and the cavity length are all taken into account. Appropriate thicknesses of epilayers are given with lower threshold gain and more economical material growth time.
文摘Five types of rare earth/alkaline earth oxide-doped CeO2 superfine-powders were synthesized by a low-temperature combustion technique. The relevant solid electrolyte materials were also sintered by pressureless sintering at different temperatures. The results of X-ray diffraction and transmission electron microscopy showed that the grain size of the powders was approximately 20-30 nm, and rare earth/alkaline earth oxides were completely dissolved into ceria-based solid solution with fluorite structure. The electrical conductivities of the SmzO3-CeO2 system were measured by the ac impedance technique in air at temperatures ranging from 513-900℃. The results indicated that the ionic conductivities of Srno.2oCe0.8Ol.875 solid electrolyte increase with increasing sintering temperature, and the relationship between the conductivities and measuring temperature obeys the An＇henius equation. Then the SmzO3-CeO2 material was further doped with other rare earth/alkaline earth oxide, and the conductivities improve with the effective index.
文摘Doped Ceria nano-powders were synthesized via a Pechini-type gel rout. The specific surface area of Ce_(0.8)Sm_(0.2)O_(1.9) powder measured by the multilayer BET method is 41 m2.g^(-1). The electrical conductivities of Sm_2O_(3)-CeO_2 systems were measured by the ac impedance technique in air at temperatures ranging from 513 to 900 ℃. Typical impedance spectra consist of two depressed semicircles at reduced measuring temperature and one depressed semicircle at elevated measuring temperature respectively, from which the grain interior and grain boundary conductivities were calculated. The relationship between the conductivities of Sm_2O_3 doped CeO_2 (SDC) electrolyte and measuring temperature obeys Arrhenius equation. The grain interior conductivity of SDC varies slightly with improving sintering temperature, while the total conductivity increases with enhancing sintering temperature. The effective index has a significant effect on the ionic conductivity of ceria doped based electrolyte. When the effective index improves, the ionic conductivity increases and the apparent conductance activation energy decreases.
基金Project supported by the National Natural Science Foundation of China (Grant No. 91121019)the National Basic Research Program of China (Grant No. 2013CB632105)
文摘An electrically driven, single-longitudinal-mode GaAs based photonic crystal （PC） ridge waveguide （RWG） laser emitting at around 850 nm is demonstrated. The single-longitudinal-mode lasing characteristic is achieved by introducing the PC to the RWG laser. The triangle PC is etched on both sides of the ridge by photolithography and inductive coupled plasma （ICP） etching. The lasing spectra of the RWG lasers with and without the PC are studied, and the result shows that the PC purifies the longitudinal mode. The power per facet versus current and current-voltage characteristics have also been studied and compared.
基金supported by the National Natural Science Foundation of China (Nos.61077047 and 61107059)the Natural Science Foundation of Heilongjiang Province (No.A200914)the Research Fund for the Doctoral Program of Higher Education of China (No.200802171034)
文摘We demonstrate a new kind of multi-core photonic liquid crystal fibers (PLCFs) which have six liquid crystal cores arrayed in the ring-type geometry and separated by the air holes. Through analyzing the structure of this kind of PLCFs, it can be found that they have the ability to resist the structure deformation. Due to the effective index of the liquid crystal can be adjusted by temperature and wavelength, the energy in the six liquid crystal cores is increased with the temperature increasing and wavelength decreasing. The effective index of the PLCFs is decreased, the effective fundamental mode area is increased and the dispersion properties are gently affected with the wavelength increasing and temperature decreasing.
文摘Based on the Semi-Markov mathematical description, the multiple states of maintenance processes for aviation weapon equipment are studied. Six kinds of maintenance states are determined and the Semi-Markov model of the maintenance process is given. According to maintenance characteristic, the multiple states maintenance processes are divided into the wait, use and alternate stages. Through using the mathematical model for the different stages, the probability in different states and effective index on different stages are obtained. These results are available to the maintenance practice.
文摘A new version of the scalar transverse electric(TE) wave equation in the bent waveguide is introduced. Then, TE polarized field in curved single-mode waveguides is analyzed by using the finite-difference beam propagation method(FD-BPM). The bending loss in bent waveguides is gotten for the optical fields obtained from BPM and comparisons are made among losses of the waveguides with various curvature radiuses, refractive index differences and cross sections. Based on the results, the design of spiral bent waveguide configuration is proposed as follows: refractive index difference being of 0.007, both width and thickness of waveguides being of 6 μm, the curvature radius in the spiral centre being of 4 mm, and the bending loss coefficient of the designed spiral bent waveguide being of 0.302 3 dB/cm.
文摘Nanocrystalline yttrium vanadate doped with europium ions powders were synthesized via sol-gel method based on decomposition of metal-polymer complex. X-ray diffraction analysis showed that samples had pure tetragonal phase without any impurities. Scanning electron microscopy and static light scattering technique were used to study morphology and size of prepared nanoparticles. Average diameter of the nanoparticles was about 40 nm. The changes in structural and luminescence properties were observed as a function of the first and second calcination temperature. The optimal conditions for synthesis of nanoparticles were determined as Т1=500℃, t1=1 h; Т2=950 ℃, t2=1.5 h. The effect of different media surrounding the nanoparticles on their luminescence properties and lifetime was investigated and discussed in terms of effective refractive index. It was found that the observed lifetime of YVO4：Eu^3＋ 5 at.% nanophosphor was decreased from 0.64 ms in air（nmed=1） to 0.45 ms in chalcogenide glass As39S61（nmed=2.39）.
