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
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
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
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
Oasis effect can improve the regional climate and habitability of an arid region. In this study, we explored the cold island effects of oases distributed along the edge of Tarim Basin by analyzing the oasis cold islan...Oasis effect can improve the regional climate and habitability of an arid region. In this study, we explored the cold island effects of oases distributed along the edge of Tarim Basin by analyzing the oasis cold island effect (OCIE) intensity, spatial-temporal variation of OCIE, factors influencing the OCIE and impacts of OCIE on air temperature using geographical statistics and GIS methods based on the MODIS land surface temperature, land use/cover change (LUCC) and observed air temperature data. Results showed that all the oases in the Tarim Basin exhibited cold island effects, with the OCIE intensity highest in summer (-9.08℃), followed by autumn (-4.24℃) and spring (-3.85℃). The total area of oasis cold island (OCI) and the comprehensive OCIE index showed the same seasonal change trend as the OCIE intensity. However, the changing trends in areas of OCI with strong, medium and weak OCIEs were inconsistent across different seasons. Farmland and water areas were found to be the key contributors that affected the OCIE, and the area and aggregation metrics of these two land use/cover types directly contributed to the OCIE. By contrast, natural vegetation, such as forest and grassland, almost had no contribution to the OCIE. Simulation of observed air temperature data showed that if farmland is replaced by forest or grassland in the oasis, the mean, maximum and minimum air temperatures will increase significantly. This heating effect will be higher in summer (reaching 1.14℃ to 2.08℃) and lower in spring and autumn. Moreover, the heating effect of farmland being replaced by forest will be higher than that of farmland being replaced by grassland. These results can provide a basis for understanding the cold island effect of oases in arid regions.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
Research on the diffusion characteristics of swells contributes positively to wave energy forecasting, swell monitoring, and early warning. In this work, the South Indian Ocean westerly index(SIWI) and Indian Ocean sw...Research on the diffusion characteristics of swells contributes positively to wave energy forecasting, swell monitoring, and early warning. In this work, the South Indian Ocean westerly index(SIWI) and Indian Ocean swell diffusion effect index(IOSDEI) are defined on the basis of the 45-year(September 1957–August 2002) ERA-40 wave reanalysis data from the European Centre for Medium-Range Weather Forecasts(ECMWF) to analyze the impact of the South Indian Ocean westerlies on the propagation of swell acreage. The following results were obtained: 1) The South Indian Ocean swell mainly propagates from southwest to northeast. The swell also spreads to the Arabian Sea upon reaching low-latitude waters. The 2.0-meter contour of the swell can reach northward to Sri Lankan waters. 2) The size of the IOSDEI is determined by the SIWI strength. The IOSDEI requires approximately 2–3.5 days to fully respond to the SIWI. The correlations between SIWI and IOSDEI show obvious seasonal differences, with the highest correlations found in December–January–February(DJF) and the lowest correlations observed in June–July–August(JJA). 3) The SIWI and IOSDEI have a common period of approximately 1 week in JJA and DJF. The SIWI leads by approximately 2–3 days in this common period.展开更多
The dispersion properties in the short wavelength region of total internal reflective photonic crystal fiber have been studied by using the models of the equivalent twin waveguide soliton coupling,effective refractive...The dispersion properties in the short wavelength region of total internal reflective photonic crystal fiber have been studied by using the models of the equivalent twin waveguide soliton coupling,effective refractive index,effective normalized frequency and dispersion management solitons.It is shown that the dispersion in the cladding waveguide of the total internal reflective photonic crystal fiber is a positive dispersion,and the dispersion of its core waveguide is a negative dispersion.The method of the compensated probing laser diffraction by the phase hole induced by the stationary pumping laser in the cladding waveguide enables the average dispersion value of the total internal reflective photonic crystal fiber to be close to zero and the zero dispersion point to shift to the short wavelength region.展开更多
The dispersion properties in the short wavelength region of total internal reflective photonic crystal fiber(TIRPCF) in Compton scattering have been studied by using the model of the equivalent twin waveguide soliton ...The dispersion properties in the short wavelength region of total internal reflective photonic crystal fiber(TIRPCF) in Compton scattering have been studied by using the model of the equivalent twin waveguide soliton coupling, dispersion management solitons and effective refractive index. It is shown that the positive dispersion of the cladding waveguide of TIRPCF and the negative dispersion of its core waveguide are quickly increased by the square of the collision non-elastic composition between the electron and photons, and they are lessened by the increase of the electron absorption photon number. Under the one-photon nonlinear Compton scattering, the method of the compensated probing laser diffraction by the phase hole induced by the stationary pumping laser in the cladding waveguide enables the average dispersion value of TIRPCF to be close to zero, and the zero dispersion point quickly shifts to the short wavelength region.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
Surface plasmon resonance of noble metal nanoparticles leads to the optical absorption enhancement effects,which have great potential applications in solar cell.By using the general numerical method of discrete dipole...Surface plasmon resonance of noble metal nanoparticles leads to the optical absorption enhancement effects,which have great potential applications in solar cell.By using the general numerical method of discrete dipole approximation (DDA),we study the absorption and scattering properties of two-dimensional square silver nanodisks (2D SSN) arrays on the single crystal silicon solar cell.Based on the effective reflective index model of the single crystal silicon solar cell,we investigate the optical enhancement absorption of light energy by varying the light incident direction,particle size,aspect ratio,and interparticle spacing of the silver nanodisks.The peak values and position of the optical extinction spectra of the 2D square arrays of noble metal nanodisks are obtained with the different array structures.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
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
Temporal changes in structure and refractive index distribution of adipose tissue at photo-dynamic/photothermal treatment were studied with OCT in vitro.Ethanol-water solutions of indocyanine green(ICG)and brilliant g...Temporal changes in structure and refractive index distribution of adipose tissue at photo-dynamic/photothermal treatment were studied with OCT in vitro.Ethanol-water solutions of indocyanine green(ICG)and brilliant green(BG)were used for fat tissue staining.CW laser diode(808 nm)and LED light source(442 and 597 nm)were used for ir adiation of stained tissue slices.The data received supporting the hypothesis that photodynamic/photothermal treatment,induces fat cell lipolysis during a certain period of time after light exposure.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
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
Last years the most profitable line of activity in agriculture is considered with milk production. The-effectiveness of this project depends primarily on the direct costs and the obtained of purchase price. Therefore ...Last years the most profitable line of activity in agriculture is considered with milk production. The-effectiveness of this project depends primarily on the direct costs and the obtained of purchase price. Therefore the aim of this work was to analyze the financial results of dairy farms in the east part of Mazovia region. Completing the research in 2010, to the owners of 36 farms were sent a questionnaire containing 18 questions. The obtained data were used to characterize the various research facilities. And then the whole population was devoted on the 6 production groups, depend on the number of physical units of dairy cows. Moreover, based on survey data, an analysis of the profitability of milk production was done. It was the following economic values: direct costs, revenue, gross margin and the index of production profitability. Also the statistical analysis by calculating the Pearson linear correlation coefficient (r) and coefficient of determination (R2) was done. The study showed that the highest annual yield of milk from a cow at the level of 7500 kg, reached the farmers with the area of l 9.7 ha of with the density of 1.82 BFU/ha and with 8 years of cow utilization. Respondents from this group also received the highest value of effectiveness index (184.60%). In addition, the performed regression analysis showed significant positive correlation between the effectiveness index and the surface agricultural lands occurring in the farms, density of agricultural lands, and efficiency from a cow and the price of milk.展开更多
[Objective] The paper was to explore safe fungicides with high efficiency and long persistence against eucalyptus purple blotch. [Method]10%Difenoconazole WG,500 g /L thiophanate-methyl SC and 50% carbendazim WP were ...[Objective] The paper was to explore safe fungicides with high efficiency and long persistence against eucalyptus purple blotch. [Method]10%Difenoconazole WG,500 g /L thiophanate-methyl SC and 50% carbendazim WP were evaluated through experiment in forest,and clear water was used as CK. [Result]Three fungicides all had relatively good control effect against eucalyptus purple blotch. Most eucalyptus trees were able to restore growth and sprout new shoots after continuous three times of administration with the interval of 10 d. 10% Difenoconazole WG possessed the best control effect against eucalyptus purple blotch,with the disease index of 25. 24 and the control effect of 40. 24%; followed by 500 g /L thiophanate-methyl SC 600 times dilution,with the disease index of 27. 09 and the control effect of 35. 87%; 50% carbendazim WP 500 times dilution had the poorest control effect,with the disease index of 32. 21 and the control effect of23. 74%. The disease index of CK was 42. 24. [Conclusion]The above fungicides were safe to eucalyptus,and could be used to control eucalyptus purple blotch.展开更多
As a variant index, variation has an inherent shortcoming that it can only reflect the static fluctuation of the crop. This paper makes complementary analysis about it on the basis of the comment on Miranda's approac...As a variant index, variation has an inherent shortcoming that it can only reflect the static fluctuation of the crop. This paper makes complementary analysis about it on the basis of the comment on Miranda's approach of β index and goes on to analyze the β index approach under the condition of three kinds of crop insurance plans, β index approach has the advantage that it can dynamically reflect the risk transfer effect of crop insurance plan. At the same insurance level, the smaller the β index is, the better the corresponding risk transfer effect of crop insurance plan is; And vice versa.展开更多
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.
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.
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.
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funded by the National Natural Science Foundation of China(41571109)
文摘Oasis effect can improve the regional climate and habitability of an arid region. In this study, we explored the cold island effects of oases distributed along the edge of Tarim Basin by analyzing the oasis cold island effect (OCIE) intensity, spatial-temporal variation of OCIE, factors influencing the OCIE and impacts of OCIE on air temperature using geographical statistics and GIS methods based on the MODIS land surface temperature, land use/cover change (LUCC) and observed air temperature data. Results showed that all the oases in the Tarim Basin exhibited cold island effects, with the OCIE intensity highest in summer (-9.08℃), followed by autumn (-4.24℃) and spring (-3.85℃). The total area of oasis cold island (OCI) and the comprehensive OCIE index showed the same seasonal change trend as the OCIE intensity. However, the changing trends in areas of OCI with strong, medium and weak OCIEs were inconsistent across different seasons. Farmland and water areas were found to be the key contributors that affected the OCIE, and the area and aggregation metrics of these two land use/cover types directly contributed to the OCIE. By contrast, natural vegetation, such as forest and grassland, almost had no contribution to the OCIE. Simulation of observed air temperature data showed that if farmland is replaced by forest or grassland in the oasis, the mean, maximum and minimum air temperatures will increase significantly. This heating effect will be higher in summer (reaching 1.14℃ to 2.08℃) and lower in spring and autumn. Moreover, the heating effect of farmland being replaced by forest will be higher than that of farmland being replaced by grassland. These results can provide a basis for understanding the cold island effect of oases in arid regions.
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supported by the National Key R&D Program (No.2017YFC1405103)the Joint Funds of the National Natural Science Foundation of China (No.U170 6220)+1 种基金the National Natural Science Foundation of China (Nos.41901006, 41471005, and 41271016)the Natural Science Foundation of Shandong Province (No.ZR 2019BD005)。
文摘Research on the diffusion characteristics of swells contributes positively to wave energy forecasting, swell monitoring, and early warning. In this work, the South Indian Ocean westerly index(SIWI) and Indian Ocean swell diffusion effect index(IOSDEI) are defined on the basis of the 45-year(September 1957–August 2002) ERA-40 wave reanalysis data from the European Centre for Medium-Range Weather Forecasts(ECMWF) to analyze the impact of the South Indian Ocean westerlies on the propagation of swell acreage. The following results were obtained: 1) The South Indian Ocean swell mainly propagates from southwest to northeast. The swell also spreads to the Arabian Sea upon reaching low-latitude waters. The 2.0-meter contour of the swell can reach northward to Sri Lankan waters. 2) The size of the IOSDEI is determined by the SIWI strength. The IOSDEI requires approximately 2–3.5 days to fully respond to the SIWI. The correlations between SIWI and IOSDEI show obvious seasonal differences, with the highest correlations found in December–January–February(DJF) and the lowest correlations observed in June–July–August(JJA). 3) The SIWI and IOSDEI have a common period of approximately 1 week in JJA and DJF. The SIWI leads by approximately 2–3 days in this common period.
文摘The dispersion properties in the short wavelength region of total internal reflective photonic crystal fiber have been studied by using the models of the equivalent twin waveguide soliton coupling,effective refractive index,effective normalized frequency and dispersion management solitons.It is shown that the dispersion in the cladding waveguide of the total internal reflective photonic crystal fiber is a positive dispersion,and the dispersion of its core waveguide is a negative dispersion.The method of the compensated probing laser diffraction by the phase hole induced by the stationary pumping laser in the cladding waveguide enables the average dispersion value of the total internal reflective photonic crystal fiber to be close to zero and the zero dispersion point to shift to the short wavelength region.
文摘The dispersion properties in the short wavelength region of total internal reflective photonic crystal fiber(TIRPCF) in Compton scattering have been studied by using the model of the equivalent twin waveguide soliton coupling, dispersion management solitons and effective refractive index. It is shown that the positive dispersion of the cladding waveguide of TIRPCF and the negative dispersion of its core waveguide are quickly increased by the square of the collision non-elastic composition between the electron and photons, and they are lessened by the increase of the electron absorption photon number. Under the one-photon nonlinear Compton scattering, the method of the compensated probing laser diffraction by the phase hole induced by the stationary pumping laser in the cladding waveguide enables the average dispersion value of TIRPCF to be close to zero, and the zero dispersion point quickly shifts to the short wavelength region.
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 under Grant No. G050104011004024the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No. A0901040110018512026
文摘Surface plasmon resonance of noble metal nanoparticles leads to the optical absorption enhancement effects,which have great potential applications in solar cell.By using the general numerical method of discrete dipole approximation (DDA),we study the absorption and scattering properties of two-dimensional square silver nanodisks (2D SSN) arrays on the single crystal silicon solar cell.Based on the effective reflective index model of the single crystal silicon solar cell,we investigate the optical enhancement absorption of light energy by varying the light incident direction,particle size,aspect ratio,and interparticle spacing of the silver nanodisks.The peak values and position of the optical extinction spectra of the 2D square arrays of noble metal nanodisks are obtained with the different array structures.
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.
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.
基金supported by grant No 224014 PHOTONICS4LIFE of FP7-ICT-2007-2,project No 1.4.09,RF Governmental con-tracts 11.519.11.2035,14.B37.21.0728,and 14.B37.21.0563FiDiPro,TEKES Program(40111/11),Finland+1 种基金SCOPES EC,Uzb/Switz/RF,Swiss NSF,IZ74ZO 137423/1RF President's grant 1177.2012.2"Scientific Schools"。
文摘Temporal changes in structure and refractive index distribution of adipose tissue at photo-dynamic/photothermal treatment were studied with OCT in vitro.Ethanol-water solutions of indocyanine green(ICG)and brilliant green(BG)were used for fat tissue staining.CW laser diode(808 nm)and LED light source(442 and 597 nm)were used for ir adiation of stained tissue slices.The data received supporting the hypothesis that photodynamic/photothermal treatment,induces fat cell lipolysis during a certain period of time after light exposure.
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Last years the most profitable line of activity in agriculture is considered with milk production. The-effectiveness of this project depends primarily on the direct costs and the obtained of purchase price. Therefore the aim of this work was to analyze the financial results of dairy farms in the east part of Mazovia region. Completing the research in 2010, to the owners of 36 farms were sent a questionnaire containing 18 questions. The obtained data were used to characterize the various research facilities. And then the whole population was devoted on the 6 production groups, depend on the number of physical units of dairy cows. Moreover, based on survey data, an analysis of the profitability of milk production was done. It was the following economic values: direct costs, revenue, gross margin and the index of production profitability. Also the statistical analysis by calculating the Pearson linear correlation coefficient (r) and coefficient of determination (R2) was done. The study showed that the highest annual yield of milk from a cow at the level of 7500 kg, reached the farmers with the area of l 9.7 ha of with the density of 1.82 BFU/ha and with 8 years of cow utilization. Respondents from this group also received the highest value of effectiveness index (184.60%). In addition, the performed regression analysis showed significant positive correlation between the effectiveness index and the surface agricultural lands occurring in the farms, density of agricultural lands, and efficiency from a cow and the price of milk.
基金Supported by Fundamental Research Project of Chongqing Academy of Forestry"Control Technologies against Major Pests and Diseases in Eucalyptus Planta-tion"(BB1102)Project of Chongqing Science and Technology Commission"Chongqing Key Laboratory of the Three Gorges Area Forest Ecology Protectionand Restoration"(CSTC,2007CA1001)
文摘[Objective] The paper was to explore safe fungicides with high efficiency and long persistence against eucalyptus purple blotch. [Method]10%Difenoconazole WG,500 g /L thiophanate-methyl SC and 50% carbendazim WP were evaluated through experiment in forest,and clear water was used as CK. [Result]Three fungicides all had relatively good control effect against eucalyptus purple blotch. Most eucalyptus trees were able to restore growth and sprout new shoots after continuous three times of administration with the interval of 10 d. 10% Difenoconazole WG possessed the best control effect against eucalyptus purple blotch,with the disease index of 25. 24 and the control effect of 40. 24%; followed by 500 g /L thiophanate-methyl SC 600 times dilution,with the disease index of 27. 09 and the control effect of 35. 87%; 50% carbendazim WP 500 times dilution had the poorest control effect,with the disease index of 32. 21 and the control effect of23. 74%. The disease index of CK was 42. 24. [Conclusion]The above fungicides were safe to eucalyptus,and could be used to control eucalyptus purple blotch.
文摘As a variant index, variation has an inherent shortcoming that it can only reflect the static fluctuation of the crop. This paper makes complementary analysis about it on the basis of the comment on Miranda's approach of β index and goes on to analyze the β index approach under the condition of three kinds of crop insurance plans, β index approach has the advantage that it can dynamically reflect the risk transfer effect of crop insurance plan. At the same insurance level, the smaller the β index is, the better the corresponding risk transfer effect of crop insurance plan is; And vice versa.