Coordinating light and nitrogen(N)distribution within a canopy is essential for improving rice yield and resource use efficiency.However,limited research has examined light and N distribution in response to planting d...Coordinating light and nitrogen(N)distribution within a canopy is essential for improving rice yield and resource use efficiency.However,limited research has examined light and N distribution in response to planting density and N rate,and their relationships with grain yield,radiation use efficiency(RUE),and N use efficiency for grain production(NUEg)in rice.A two-year field experiment was conducted with two hybrid varieties under three N levels,0 kg ha^(-1)(N1),90 kg ha^(-1)(N2)and 180 kg ha^(-1)(N3),and two planting densities,22.2 hills m-2(D1)and 33.3 hills m^(-2)(D2).Results showed 3.4%higher yield and 4.4%higher NUEg under N2D2 compared with N3D1.The extinction coefficient for N(K_(N))and light(K_(L))and their ratio(K_(N)/K_(L))at heading stage were significantly influenced by N rate,planting density,and their interaction.K_(N)decreased with the increase of N input or planting density.Compared to N1,K_(N)decreased by 43.5 and 58.8%under N2 and N3,respectively,while K_(N)under D2 decreased by 16.0%compared to D1.Higher K_(L)and K_(N)/K_(L)values occurred under low N rates,with opposite trends under high N rates.Increased planting density led to decreased K_(L)and K_(N)/K_(L)values.N2D2 demonstrated higher K_(L)and K_(N),and thus comparable K_(N)/K_(L),compared to N3D1.Correlation analysis revealed K_(L)negatively correlated with RUE,while K_(N)and K_(N)/K_(L)positively correlated with NUEg.These findings indicate that increasing planting density under reduced N input could maintain rice yield while enhancing resource use efficiency through regulation of canopy light and N distribution.展开更多
The distributions of light and nitrogen within a plant's canopy reflect the growth adaptation of crops to the environment and are conducive to improving the carbon assimilation ability.So can the yield in crop pro...The distributions of light and nitrogen within a plant's canopy reflect the growth adaptation of crops to the environment and are conducive to improving the carbon assimilation ability.So can the yield in crop production be maximized by improving the light and nitrogen distributions without adding any additional inputs?In this study,the effects of different nitrogen application rates and planting densities on the canopy light and nitrogen distributions of two highyielding maize cultivars(XY335 and DH618)and the regulatory effects of canopy physiological characteristics on radiation use efficiency(RUE)and yield were studied based on high-yield field experiments in Qitai,Xinjiang Uygur Autonomous Region,China,during 2019 and 2020.The results showed that the distribution of photosynthetically active photon flux density(PPFD)in the maize canopy decreased from top to bottom,while the vertical distribution of specific leaf nitrogen(SLN)initially increased and then decreased from top to bottom in the canopy.When SLN began to decrease,the PPDF values of XY335 and DH618 were 0.5 and 0.3,respectively,corresponding to 40.6 and49.3%of the total leaf area index(LAI).Nitrogen extinction coefficient(K_(N))/light extinction coefficient(K_(L))ratio in the middle and lower canopy of XY335(0.32)was 0.08 higher than that of DH618(0.24).The yield and RUE of XY335(17.2 t ha^(-1)and 1.8g MJ^(-1))were 7.0%(1.1 t ha^(-1))and 13.7%(0.2 g MJ^(-1))higher than those of DH618(16.1 t ha^(-1)and 1.6 g MJ^(-1)).Therefore,better light conditions(where the proportion of LAI in the upper and middle canopy was small)improved the light distribution when SLN started to decline,thus helping to mobilize the nitrogen distribution and maintain a high K_(N)and K_(N)/K_(L)ratio.In addition,K_(N)/K_(L)was a key parameter for yield improvement when the maize nutrient requirements were met at 360 kg N ha^(-1).At this level,an appropriately optimized high planting density could promote nitrogen utilization and produce higher yields and greater efficiency.The results of this study will be important for achieving high maize yields and the high efficiency cultivation and breeding of maize in the future.展开更多
The objectives of this study were to determine how the distribution of photosynthetically active radiation （PAR） in a maize canopy affected basal internode strength and stalk lodging. The distributions of PAR within...The objectives of this study were to determine how the distribution of photosynthetically active radiation （PAR） in a maize canopy affected basal internode strength and stalk lodging. The distributions of PAR within the canopies of two maize cultivars （Zhongdan 909 and Xinyu 41） were altered by removing whole leaves or half leaves in different canopy layers. The results showed that removing whole leaves or half leaves above the three-ear-leaves （RAE and RAE/2） at flowering sig- nificantly increased. PAR at the ear and interception of PAR （IPAR） from the ear to middle of the ear and soil surface. These changes increased the structural carbohydrate content and rind penetration strength （RPS） of the third basal internode by 5.4-11.6% and reduced lodging by 4.2-7.8%. Removal of the first three leaves below the three-ear-leaves （RBE） before flowering significantly reduced IPAR from the ear to half way below the ear. This reduced the structural carbohydrate con- tent and the RPS of the third basal internode by 9.1-17.4% and increased lodging by 7.0-11.2%. Removal of the three lowest green leaves （RB） in the canopy before flowering increased PAR at the bottom of the canopy, but had no effect on the structural carbohydrate content of the basal internode, the RPS, and the lodging rate. Overall, the results indicated that the key factors affecting the basal internode strength formation and lodging were PAR at the ear and IPAR from the ear to halfway below the ear. Increasing PAR at the ear and IPAR from the ear to halfway below the ear could enhance lodging resistance by increasing the structural carbohydrate content and mechanical strength of the basal internode.展开更多
Plant growth regulators(PGRs)are frequently used to adjust cotton growth and development.The objectives of this study were to determine how PGRs affect plant morphology,light distribution and the spatial distribution ...Plant growth regulators(PGRs)are frequently used to adjust cotton growth and development.The objectives of this study were to determine how PGRs affect plant morphology,light distribution and the spatial distribution of leaves and bolls within the cotton canopy.The field experiments were carried out at Shihezi(Xinjiang Uyghur Autonomous Region,China)in 2014 and 2015.The experiment included two PGR treatments:(i)flumetralin(active ingredient(a.i),N-N-ethy)-2,6-dinitro-4-aniline and(i)mepiquat chloride(ai,1-dimethyl-piperidiniuchloride)plus flumetralin.No PGR(manual topping)was applied in the control treatment.The chemically-topped plants were taller and had more main stem internodes than the manually-topped plants.Furthermore,the PGRs significantly reduced the length of fruiting branches in the upper canopy,resulting in a more compact canopy.The maximum leaf area index was signifcantly greater in the chemically-topped treatments than that in the control.In particular,the PGRs increased leaf area index by 25%in the upper canopy.The leaf area duration was also longer in the chemically-topped treatments than in the control.Compared with the control,the chemically-topped treatments increased canopy diffuse non-interceptance by 35.75%in the upper canopy layer,while reducing the fraction of intercepted photosynthetically active radiation by 14.45%in the upper canopy layer.Light transmittance in the upper and middle canopy layers was greater in the chemically-topped treatments than in the control,which increased boll numbers in both the upper canopy and the middle canopy.However,the chemically-topped treatments resulted in less light-leakage through the lower canopy layer during the late growth stages,which had a tendency to increase boll numbers in the whole canopy.In summary,the PGRs optimized canopy shape,light distribution and the spatial distribution of bolls and leaves.展开更多
Based on the diffusion approximate theory （DA）, a theoretical model about the distribution of the intensity of a narrow collimation beam illuminating on a semi-lnfinite biological tissue is developed. In order to ve...Based on the diffusion approximate theory （DA）, a theoretical model about the distribution of the intensity of a narrow collimation beam illuminating on a semi-lnfinite biological tissue is developed. In order to verify the correctness of the model, a novel method of measuring the distributions of the intensity of light in Intralipid-10% suspension at 650 nm is presented and ts of the distributions of the distance-dependent intensity of scattering light in different directions are made. The investigations show that the results from our diffusion model are in good agreement with the experimental results beyond and in the areas around the light source, and the distance-dependent intensity in the incident direction attenuates approximately in the exponential form. Furthermore, our theoretic results indicate the anisotropic characteristics of the intensity in different directions of scattering light inside the biological tissue.展开更多
Comparing the city-size distribution at the urban agglomeration（UA） scale is important for understanding the processes of urban development. However, comparative studies of city-size distribution among China＇s thre...Comparing the city-size distribution at the urban agglomeration（UA） scale is important for understanding the processes of urban development. However, comparative studies of city-size distribution among China＇s three largest UAs, the Beijing-Tianjin-Hebei agglomeration（BTHA）, the Yangtze River Delta agglomeration（YRDA）, and the Pearl River Delta agglomeration（PRDA）, remain inadequate due to the limitation of data availability. Therefore, using urban data derived from time-series nighttime light data, the common characteristics and distinctive features of city-size distribution among the three UAs from 1992 to 2015 were compared by the Pareto regression and the rank clock method. We identified two common features. First, the city-size distribution became more even. The Pareto exponents increased by 0.17, 0.12, and 0.01 in the YRDA, BTHA, and PRDA, respectively. Second, the average ranks of small cities ascended, being 0.55, 0.08 and 0.04 in the three UAs, respectively. However, the average ranks of large and medium cities in the three UAs experienced different trajectories, which are closely related to the similarities and differences in the driving forces for the development of UAs. Place-based measures are encouraged to promote a coordinated development among cities of differing sizes in the three UAs.展开更多
This paper reported the diurnal variations of photochemical efficiency of PSII, thermaldissipation rate and other physiology process in the low content chlorophyll mutant rice andits wild type under field conditions, ...This paper reported the diurnal variations of photochemical efficiency of PSII, thermaldissipation rate and other physiology process in the low content chlorophyll mutant rice andits wild type under field conditions, and analyzed the difference of absorbed light distributionbetween the two rice varieties in a day. The results showed that the mutant had poor absorbedlight because of its little light absorption coefficient, but higher electron transportg ratecould partly reduce the disadvantageous effect of deficient absorbed light in mutant. Comparedwith wild-type rice, the mutant had less excess excitation energy and the fraction of absorbedlight allocated to photochemical process was more.展开更多
Some equivalent conditions on the classes of lighted-tailed and heavily heavy-tailed and lightly heavy-tailed d.f.s are introduced.The limit behavior of xα(x) and e λx(x) are discussed.Some properties of the subcla...Some equivalent conditions on the classes of lighted-tailed and heavily heavy-tailed and lightly heavy-tailed d.f.s are introduced.The limit behavior of xα(x) and e λx(x) are discussed.Some properties of the subclass DKc and subclass DK 1 are obtained.展开更多
This paper discusses the basic principle and design m ethod for light distribution of car lamp, introduces an important development: h igh efficient and flexible car lamp with reflecting light distribution-segmente d ...This paper discusses the basic principle and design m ethod for light distribution of car lamp, introduces an important development: h igh efficient and flexible car lamp with reflecting light distribution-segmente d reflector (multi-patch) car lamp, and puts out a design method for segmented reflector based on error analysis. Unlike classical car lamp with refractive lig ht distribution, the method of reflecting light distribution gives car lamp desi gn more flexibility. In the case of guarantying the lightness of car lamp and sa tisfying the standard demand for the light distribution, the design of the exter ior of the car lamp has more freedom. The high gradient of car lamp is more suit able for the demand of streamline of the car exterior. The shape of segmented re flector obtained by theory calculating of car lamp reflecting light distribution is only an ideal shape, which usually has considerable differences with the fin al shape and will influences light distribution. There exist difference between the calculated reflector and manufactured reflector. Owing to light reflecting c haracter, the small diversification of the reflector will reduce the big diver sification of the light distribution shape on light distribution screen in 25 -meter place, so light distribution quality can’t be ensured. To ensure the re flector by light distribution calculation accordance to reflector by practical m anufacture, the error effect of surface shape must be reasonably considered name ly the error effect of manufacture tache. The paper establishes error-analyzing model for segmented reflector according to the analysis of error of making proc ess for segmented reflector. Based on this error-analyzing model and by use of the analyzing software developed for segmented reflector light distribution, it could reasonably consider reflector errors made by manufacturing, such as reflec tor surface spray-painting and plating aluminum, which could give out shapes of reflector patches for segmented reflector well and truly, and direct the plan o f making process efficiently. The method put by the paper has successfully appli ed to develop segmented reflector lamp for several type cars and obtained good e ffect for the factory.展开更多
Aming at the problem of the low accuracy of low dynamic vehicle velocity under the environment of uneven distribution of light intensity,an improved adaptive Kalman filter method for the velocity error estimate by the...Aming at the problem of the low accuracy of low dynamic vehicle velocity under the environment of uneven distribution of light intensity,an improved adaptive Kalman filter method for the velocity error estimate by the fusion of optical flow tracking and scale mvaiant feature transform(SIFT)is proposed.The algorithm introduces anonlinear fuzzy membership function and the filter residual for the noise covariance matrix in the adaptive adjustment process.In the process of calculating the velocity of the vehicle,the tracking and matching of the inter-frame displacement a d the vehicle velocity calculation a e carried out by using the optical fow tracing and the SIF'T methods,respectively.Meanwhile,the velocity difference between theoutputs of thesetwo methods is used as the observation of the improved adaptive Kalman filter.Finally,the velocity calculated by the optical fow method is corrected by using the velocity error estimate of the output of the modified adaptive Kalman filter.The results of semi-physical experiments show that the maximum velocityeror of the fusion algorithm is decreased by29%than that of the optical fow method,and the computation time is reduced by80%compared with the SIFT method.展开更多
Two-dimensional （2D） closed-cavity single quantum well （SQW） and multiple quantum well （MQW） structures are proposed based on the traditional 2D open-cavity SQW structures of photonic crystals. The numerical cal...Two-dimensional （2D） closed-cavity single quantum well （SQW） and multiple quantum well （MQW） structures are proposed based on the traditional 2D open-cavity SQW structures of photonic crystals. The numerical calculation results show that the proposed structures can greatly improve the optical characteristics compared with the traditional structures. It is found that the barrier thickness has a great impact on the optical characteristics of the closed-cavity MQW structures： when the barrier thickness is narrower, each resonant peak which appears in the SQW would split, the number of split times is just equal to the number of wells, and each well in the MQW structures is a travelling-wave-well, similar to the well in the open-cavity SQW structures; when the barrier thickness is wider, there is no effect of spectral splitting, and each well in the MQW structures is a standing-wave-well, just like the well in the closed-cavity SQW. The physical origin of different field distributions and the effect of the spectral splitting are provided.展开更多
Measurement of light distribution in biological tissue contributes to selecting strategy and optimizing dose for biomedical application. In this letter, a photoacoustic method combined with Monte Carlo simulation was ...Measurement of light distribution in biological tissue contributes to selecting strategy and optimizing dose for biomedical application. In this letter, a photoacoustic method combined with Monte Carlo simulation was used to estimate the three-dimensional light distribution in biological tissue. The light distribution was produced by a cylindrical diffuser which interposed into tissues. The light profiles obtained by the method were compared to those detected by photo diodes. The experimental results demonstrate the feasibility of this method. The approach can play a significant role for photo-dosimetry in biomedical phototherapy.展开更多
The emergent light distribution of a new type of contact laser scalpel is measured in three different states using a light sensor. The relationship between the angle and the light intensity is analyzed. The results sh...The emergent light distribution of a new type of contact laser scalpel is measured in three different states using a light sensor. The relationship between the angle and the light intensity is analyzed. The results show that the strongest light is emitted from two sides and the front of the scalpel. The light from the front mainly plays a role of cutting. The light from two sides contributes to stanch the wound so as to remain a clear visual field during the surgery. It also helps to increase the cutting efficiency.展开更多
The radiation use efficiency(RUE)is one of the most important functional traits determining crop productivity.The coordination of the vertical distribution of light and leaf nitrogen has been proven to be effective in...The radiation use efficiency(RUE)is one of the most important functional traits determining crop productivity.The coordination of the vertical distribution of light and leaf nitrogen has been proven to be effective in boosting the RUE from both experimental and computational evidence.However,previous simulation studies have primarily assumed that the leaf area is uniformly distributed along the canopy depth,rarely considering the optimization of the leaf area distribution,especially for C4 crops.The present study hypothesizes that the RUE may be maximized by matching the leaf area and leaf nitrogen vertical distributions in the canopy.To test this hypothesis,various virtual maize canopies were generated by combining the leaf inclination angle,vertical leaf area distribution,and vertical leaf nitrogen distribution and were further evaluated by an improved multilayer canopy photosynthesis model.We found that a greater fraction of leaf nitrogen is preferentially allocated to canopy layers with greater leaf areas to maximize the RUE.The coordination of light and nitrogen emerged as a property from the simulations to maximize the RUE in most scenarios,particularly in dense canopies.This study not only facilitates explicit and precise profiling of ideotypes for maximizing the RUE but also represents a primary step toward high-throughput phenotyping and screening of the RUE for massive numbers of inbred lines and cultivars.展开更多
Appressed and non-appressed lamella membranes of Castor bean leaf chloroplasts were separated by non-ionic detergent Triton-X 100.Appressed membranes showed a high oxygen-evolving activity and low chl a/b ratio. Exami...Appressed and non-appressed lamella membranes of Castor bean leaf chloroplasts were separated by non-ionic detergent Triton-X 100.Appressed membranes showed a high oxygen-evolving activity and low chl a/b ratio. Examining with SDS-PTGE and liquid nitrogen temperature fluorescence measurement showed that they contained only PSII and light-harvesting pigment-protein complexes (LHCP),and there was no detectable amount of PSI. Freeze-fracture electromicroscopic observation confirmed that this part was really an appressed lamella membrane. Through divalent cation Mg^(++), the thylakoid membranes were induced to unstack and restack.With the addition of Mg^(++), the fluorescence intensity was changed instantly. We realized that there existed two processes:One was a rapid process which was accomplished within 30 s. The other was a slow process of which the time duration was about 60 min. This dual effects of Mg^(++) had not been reported before.We had analyzed the change of F685/F730 and discussed the possible rneehanis ms of light energy distribution between photosystems.展开更多
A comprehensive numerical model is developed to simulate the growth of microalgae under light/dark cycling conditions.The purpose of this study is to predict the growth rate of Chlorella vulgaris cultivated in photobi...A comprehensive numerical model is developed to simulate the growth of microalgae under light/dark cycling conditions.The purpose of this study is to predict the growth rate of Chlorella vulgaris cultivated in photobioreactors(PBRs)in order to improve the light conditions for microalgae and enhance the photosynthetic efficiency.Computational fluid dynamics(CFD)is used to simulate its internal hydrodynamic behaviors.The Lagrangian method is employed to track the movement of microalgae cells.The radiative transfer equation(RTE)is used to obtain light intensity distribution.The combination of light radiation field and microalgae cell motions is used to construct the light history and they are integrated into the model of the photosynthetic units(PSU)to calculate the microalgae growth rate.The numerical results demonstrate that enhanced light/dark cycling frequency with ordered mixing can promote efficient microalgae cultivation.The effect of the vortex flow field generated by the baffles in an air-lift PBR is analyzed for increasing microalgae growth rate.When using the 1:1 baffle spacing,the biomass production of microalgae is increased by 41.8% compared to the original PBR.展开更多
LED has shown great advantages in poultry husbandry.This study focused on the behavioral preferences and production performance of chicken broilers reared under unevenly distributed yellow LED light.Four pens were div...LED has shown great advantages in poultry husbandry.This study focused on the behavioral preferences and production performance of chicken broilers reared under unevenly distributed yellow LED light.Four pens were divided into two groups adopting respective maximum light intensities(MLIs,60 lx and 30 lx).Because of different distances from the installation position of the LED pipe,each pen was distributed with unevenly distributed light.Each pen consisted of four subzones indicated by their light intensities-high intensity(HI),medium intensity(MI),low intensity(LI)and weak intensity(WI).Four subzones were the same size and provided with a feeder and a drinker,respectively.The broilers moved freely across the four subzones.No significant differences in body weight(BW),uniformity of final BW and feed conversion ratio(FCR)were observed between the two experimental groups.However,greater feed intake and water intake were found in HI than those in other subzones.The drinking preference changed with age for four subzones and was more likely to appear at the later stage,despite substantial fluctuations within the replicates.The feeding preference was more constant than the drinking preference and appeared mainly at the early and middle stages of this study.These findings could provide implications for broiler production reared under unevenly distributed LED light condition.展开更多
基金supported by the Hubei Provincial Science and Technology Project,China(2025CSA039)the National Natural Science Foundation of China(32001467)。
文摘Coordinating light and nitrogen(N)distribution within a canopy is essential for improving rice yield and resource use efficiency.However,limited research has examined light and N distribution in response to planting density and N rate,and their relationships with grain yield,radiation use efficiency(RUE),and N use efficiency for grain production(NUEg)in rice.A two-year field experiment was conducted with two hybrid varieties under three N levels,0 kg ha^(-1)(N1),90 kg ha^(-1)(N2)and 180 kg ha^(-1)(N3),and two planting densities,22.2 hills m-2(D1)and 33.3 hills m^(-2)(D2).Results showed 3.4%higher yield and 4.4%higher NUEg under N2D2 compared with N3D1.The extinction coefficient for N(K_(N))and light(K_(L))and their ratio(K_(N)/K_(L))at heading stage were significantly influenced by N rate,planting density,and their interaction.K_(N)decreased with the increase of N input or planting density.Compared to N1,K_(N)decreased by 43.5 and 58.8%under N2 and N3,respectively,while K_(N)under D2 decreased by 16.0%compared to D1.Higher K_(L)and K_(N)/K_(L)values occurred under low N rates,with opposite trends under high N rates.Increased planting density led to decreased K_(L)and K_(N)/K_(L)values.N2D2 demonstrated higher K_(L)and K_(N),and thus comparable K_(N)/K_(L),compared to N3D1.Correlation analysis revealed K_(L)negatively correlated with RUE,while K_(N)and K_(N)/K_(L)positively correlated with NUEg.These findings indicate that increasing planting density under reduced N input could maintain rice yield while enhancing resource use efficiency through regulation of canopy light and N distribution.
基金supported by the National Natural Science Foundation of China(32172118)the National Key Research and Development Program of China(2016YFD0300110 and 2016YFD0300101)+1 种基金the Basic Scientific Research Fund of Chinese Academy of Agricultural Sciences,China(S2022ZD05)the Agricultural Science and Technology Innovation Program,China(CAAS-ZDRW202004)。
文摘The distributions of light and nitrogen within a plant's canopy reflect the growth adaptation of crops to the environment and are conducive to improving the carbon assimilation ability.So can the yield in crop production be maximized by improving the light and nitrogen distributions without adding any additional inputs?In this study,the effects of different nitrogen application rates and planting densities on the canopy light and nitrogen distributions of two highyielding maize cultivars(XY335 and DH618)and the regulatory effects of canopy physiological characteristics on radiation use efficiency(RUE)and yield were studied based on high-yield field experiments in Qitai,Xinjiang Uygur Autonomous Region,China,during 2019 and 2020.The results showed that the distribution of photosynthetically active photon flux density(PPFD)in the maize canopy decreased from top to bottom,while the vertical distribution of specific leaf nitrogen(SLN)initially increased and then decreased from top to bottom in the canopy.When SLN began to decrease,the PPDF values of XY335 and DH618 were 0.5 and 0.3,respectively,corresponding to 40.6 and49.3%of the total leaf area index(LAI).Nitrogen extinction coefficient(K_(N))/light extinction coefficient(K_(L))ratio in the middle and lower canopy of XY335(0.32)was 0.08 higher than that of DH618(0.24).The yield and RUE of XY335(17.2 t ha^(-1)and 1.8g MJ^(-1))were 7.0%(1.1 t ha^(-1))and 13.7%(0.2 g MJ^(-1))higher than those of DH618(16.1 t ha^(-1)and 1.6 g MJ^(-1)).Therefore,better light conditions(where the proportion of LAI in the upper and middle canopy was small)improved the light distribution when SLN started to decline,thus helping to mobilize the nitrogen distribution and maintain a high K_(N)and K_(N)/K_(L)ratio.In addition,K_(N)/K_(L)was a key parameter for yield improvement when the maize nutrient requirements were met at 360 kg N ha^(-1).At this level,an appropriately optimized high planting density could promote nitrogen utilization and produce higher yields and greater efficiency.The results of this study will be important for achieving high maize yields and the high efficiency cultivation and breeding of maize in the future.
基金support from the National Natural Science Foundation of China (31160261)
文摘The objectives of this study were to determine how the distribution of photosynthetically active radiation （PAR） in a maize canopy affected basal internode strength and stalk lodging. The distributions of PAR within the canopies of two maize cultivars （Zhongdan 909 and Xinyu 41） were altered by removing whole leaves or half leaves in different canopy layers. The results showed that removing whole leaves or half leaves above the three-ear-leaves （RAE and RAE/2） at flowering sig- nificantly increased. PAR at the ear and interception of PAR （IPAR） from the ear to middle of the ear and soil surface. These changes increased the structural carbohydrate content and rind penetration strength （RPS） of the third basal internode by 5.4-11.6% and reduced lodging by 4.2-7.8%. Removal of the first three leaves below the three-ear-leaves （RBE） before flowering significantly reduced IPAR from the ear to half way below the ear. This reduced the structural carbohydrate con- tent and the RPS of the third basal internode by 9.1-17.4% and increased lodging by 7.0-11.2%. Removal of the three lowest green leaves （RB） in the canopy before flowering increased PAR at the bottom of the canopy, but had no effect on the structural carbohydrate content of the basal internode, the RPS, and the lodging rate. Overall, the results indicated that the key factors affecting the basal internode strength formation and lodging were PAR at the ear and IPAR from the ear to halfway below the ear. Increasing PAR at the ear and IPAR from the ear to halfway below the ear could enhance lodging resistance by increasing the structural carbohydrate content and mechanical strength of the basal internode.
基金This study was financially supported by the 948 Program from Ministry of Agriculture of China(2016-X25)the National Key Technology R&D Program of China(2014BAD09B03)The authors are grateful to Dr.William J.Gale(Shihezi University,China)for his helpful revision of the paper especially in English language.
文摘Plant growth regulators(PGRs)are frequently used to adjust cotton growth and development.The objectives of this study were to determine how PGRs affect plant morphology,light distribution and the spatial distribution of leaves and bolls within the cotton canopy.The field experiments were carried out at Shihezi(Xinjiang Uyghur Autonomous Region,China)in 2014 and 2015.The experiment included two PGR treatments:(i)flumetralin(active ingredient(a.i),N-N-ethy)-2,6-dinitro-4-aniline and(i)mepiquat chloride(ai,1-dimethyl-piperidiniuchloride)plus flumetralin.No PGR(manual topping)was applied in the control treatment.The chemically-topped plants were taller and had more main stem internodes than the manually-topped plants.Furthermore,the PGRs significantly reduced the length of fruiting branches in the upper canopy,resulting in a more compact canopy.The maximum leaf area index was signifcantly greater in the chemically-topped treatments than that in the control.In particular,the PGRs increased leaf area index by 25%in the upper canopy.The leaf area duration was also longer in the chemically-topped treatments than in the control.Compared with the control,the chemically-topped treatments increased canopy diffuse non-interceptance by 35.75%in the upper canopy layer,while reducing the fraction of intercepted photosynthetically active radiation by 14.45%in the upper canopy layer.Light transmittance in the upper and middle canopy layers was greater in the chemically-topped treatments than in the control,which increased boll numbers in both the upper canopy and the middle canopy.However,the chemically-topped treatments resulted in less light-leakage through the lower canopy layer during the late growth stages,which had a tendency to increase boll numbers in the whole canopy.In summary,the PGRs optimized canopy shape,light distribution and the spatial distribution of bolls and leaves.
基金Project supported by the National Natural Science Foundation of China （Grant No 60278007）, the Natural Science Foundation of Tianjin （Grant No 033601311） and the Natural Science Foundation of Guangdong Province （Grant No 04011427）.
文摘Based on the diffusion approximate theory （DA）, a theoretical model about the distribution of the intensity of a narrow collimation beam illuminating on a semi-lnfinite biological tissue is developed. In order to verify the correctness of the model, a novel method of measuring the distributions of the intensity of light in Intralipid-10% suspension at 650 nm is presented and ts of the distributions of the distance-dependent intensity of scattering light in different directions are made. The investigations show that the results from our diffusion model are in good agreement with the experimental results beyond and in the areas around the light source, and the distance-dependent intensity in the incident direction attenuates approximately in the exponential form. Furthermore, our theoretic results indicate the anisotropic characteristics of the intensity in different directions of scattering light inside the biological tissue.
基金National Natural Science Foundation of China,No.41621061,No.41501092 Talents Training Program from the Beijing Municipal Commission of Education No.201500002012G058
文摘Comparing the city-size distribution at the urban agglomeration（UA） scale is important for understanding the processes of urban development. However, comparative studies of city-size distribution among China＇s three largest UAs, the Beijing-Tianjin-Hebei agglomeration（BTHA）, the Yangtze River Delta agglomeration（YRDA）, and the Pearl River Delta agglomeration（PRDA）, remain inadequate due to the limitation of data availability. Therefore, using urban data derived from time-series nighttime light data, the common characteristics and distinctive features of city-size distribution among the three UAs from 1992 to 2015 were compared by the Pareto regression and the rank clock method. We identified two common features. First, the city-size distribution became more even. The Pareto exponents increased by 0.17, 0.12, and 0.01 in the YRDA, BTHA, and PRDA, respectively. Second, the average ranks of small cities ascended, being 0.55, 0.08 and 0.04 in the three UAs, respectively. However, the average ranks of large and medium cities in the three UAs experienced different trajectories, which are closely related to the similarities and differences in the driving forces for the development of UAs. Place-based measures are encouraged to promote a coordinated development among cities of differing sizes in the three UAs.
基金supported by the National Natural Science Foundation of China(30300217).
文摘This paper reported the diurnal variations of photochemical efficiency of PSII, thermaldissipation rate and other physiology process in the low content chlorophyll mutant rice andits wild type under field conditions, and analyzed the difference of absorbed light distributionbetween the two rice varieties in a day. The results showed that the mutant had poor absorbedlight because of its little light absorption coefficient, but higher electron transportg ratecould partly reduce the disadvantageous effect of deficient absorbed light in mutant. Comparedwith wild-type rice, the mutant had less excess excitation energy and the fraction of absorbedlight allocated to photochemical process was more.
基金Supported by the National Natural Science Foundation of China( 1 0 2 71 0 87)
文摘Some equivalent conditions on the classes of lighted-tailed and heavily heavy-tailed and lightly heavy-tailed d.f.s are introduced.The limit behavior of xα(x) and e λx(x) are discussed.Some properties of the subclass DKc and subclass DK 1 are obtained.
文摘This paper discusses the basic principle and design m ethod for light distribution of car lamp, introduces an important development: h igh efficient and flexible car lamp with reflecting light distribution-segmente d reflector (multi-patch) car lamp, and puts out a design method for segmented reflector based on error analysis. Unlike classical car lamp with refractive lig ht distribution, the method of reflecting light distribution gives car lamp desi gn more flexibility. In the case of guarantying the lightness of car lamp and sa tisfying the standard demand for the light distribution, the design of the exter ior of the car lamp has more freedom. The high gradient of car lamp is more suit able for the demand of streamline of the car exterior. The shape of segmented re flector obtained by theory calculating of car lamp reflecting light distribution is only an ideal shape, which usually has considerable differences with the fin al shape and will influences light distribution. There exist difference between the calculated reflector and manufactured reflector. Owing to light reflecting c haracter, the small diversification of the reflector will reduce the big diver sification of the light distribution shape on light distribution screen in 25 -meter place, so light distribution quality can’t be ensured. To ensure the re flector by light distribution calculation accordance to reflector by practical m anufacture, the error effect of surface shape must be reasonably considered name ly the error effect of manufacture tache. The paper establishes error-analyzing model for segmented reflector according to the analysis of error of making proc ess for segmented reflector. Based on this error-analyzing model and by use of the analyzing software developed for segmented reflector light distribution, it could reasonably consider reflector errors made by manufacturing, such as reflec tor surface spray-painting and plating aluminum, which could give out shapes of reflector patches for segmented reflector well and truly, and direct the plan o f making process efficiently. The method put by the paper has successfully appli ed to develop segmented reflector lamp for several type cars and obtained good e ffect for the factory.
基金The National Natural Science Foundation of China(No.51375087,51405203)the Transformation Program of Science and Technology Achievements of Jiangsu Province(No.BA2016139)
文摘Aming at the problem of the low accuracy of low dynamic vehicle velocity under the environment of uneven distribution of light intensity,an improved adaptive Kalman filter method for the velocity error estimate by the fusion of optical flow tracking and scale mvaiant feature transform(SIFT)is proposed.The algorithm introduces anonlinear fuzzy membership function and the filter residual for the noise covariance matrix in the adaptive adjustment process.In the process of calculating the velocity of the vehicle,the tracking and matching of the inter-frame displacement a d the vehicle velocity calculation a e carried out by using the optical fow tracing and the SIF'T methods,respectively.Meanwhile,the velocity difference between theoutputs of thesetwo methods is used as the observation of the improved adaptive Kalman filter.Finally,the velocity calculated by the optical fow method is corrected by using the velocity error estimate of the output of the modified adaptive Kalman filter.The results of semi-physical experiments show that the maximum velocityeror of the fusion algorithm is decreased by29%than that of the optical fow method,and the computation time is reduced by80%compared with the SIFT method.
基金supported by the National Natural Science Foundation of China (Grant Nos 60577006 and 50774034)the Hunan Provincial Science Foundation of China (Grant No 06JJ20005)
文摘Two-dimensional （2D） closed-cavity single quantum well （SQW） and multiple quantum well （MQW） structures are proposed based on the traditional 2D open-cavity SQW structures of photonic crystals. The numerical calculation results show that the proposed structures can greatly improve the optical characteristics compared with the traditional structures. It is found that the barrier thickness has a great impact on the optical characteristics of the closed-cavity MQW structures： when the barrier thickness is narrower, each resonant peak which appears in the SQW would split, the number of split times is just equal to the number of wells, and each well in the MQW structures is a travelling-wave-well, similar to the well in the open-cavity SQW structures; when the barrier thickness is wider, there is no effect of spectral splitting, and each well in the MQW structures is a standing-wave-well, just like the well in the closed-cavity SQW. The physical origin of different field distributions and the effect of the spectral splitting are provided.
基金supported by the National Natural Science Foundation of China(No.61178089/81201124)in part by the Natural Science Foundation of Fujian Province(No.2011Y0019)
文摘Measurement of light distribution in biological tissue contributes to selecting strategy and optimizing dose for biomedical application. In this letter, a photoacoustic method combined with Monte Carlo simulation was used to estimate the three-dimensional light distribution in biological tissue. The light distribution was produced by a cylindrical diffuser which interposed into tissues. The light profiles obtained by the method were compared to those detected by photo diodes. The experimental results demonstrate the feasibility of this method. The approach can play a significant role for photo-dosimetry in biomedical phototherapy.
基金supported by the National"973"Program of China(No.2005CB724302)the National Science Fund for Distinguished Young Scholars from the National Natural Science Foundation of China(No.60588101)+1 种基金the 111 Project from the Ministry of Education of China(B08020)the Shanghai Commission of Science and Technology(No.05DZ22318,05DZ22325,04DZ05114,and 064119540).
文摘The emergent light distribution of a new type of contact laser scalpel is measured in three different states using a light sensor. The relationship between the angle and the light intensity is analyzed. The results show that the strongest light is emitted from two sides and the front of the scalpel. The light from the front mainly plays a role of cutting. The light from two sides contributes to stanch the wound so as to remain a clear visual field during the surgery. It also helps to increase the cutting efficiency.
基金supported by the National Key R&D Program of China(2022YFD2001003)the National Natural Science Foundation of China(32330075 and 32001420)+2 种基金the Science and Technology Innovation Special Construction Funded Program of Beijing Academy of Agriculture and Forestry Sciences(KJCX20220401)the Young Elite Scientist Sponsorship Program by BAST(no.BYESS2023204)the earmarked fund for CARS-02 and CARS-54.
文摘The radiation use efficiency(RUE)is one of the most important functional traits determining crop productivity.The coordination of the vertical distribution of light and leaf nitrogen has been proven to be effective in boosting the RUE from both experimental and computational evidence.However,previous simulation studies have primarily assumed that the leaf area is uniformly distributed along the canopy depth,rarely considering the optimization of the leaf area distribution,especially for C4 crops.The present study hypothesizes that the RUE may be maximized by matching the leaf area and leaf nitrogen vertical distributions in the canopy.To test this hypothesis,various virtual maize canopies were generated by combining the leaf inclination angle,vertical leaf area distribution,and vertical leaf nitrogen distribution and were further evaluated by an improved multilayer canopy photosynthesis model.We found that a greater fraction of leaf nitrogen is preferentially allocated to canopy layers with greater leaf areas to maximize the RUE.The coordination of light and nitrogen emerged as a property from the simulations to maximize the RUE in most scenarios,particularly in dense canopies.This study not only facilitates explicit and precise profiling of ideotypes for maximizing the RUE but also represents a primary step toward high-throughput phenotyping and screening of the RUE for massive numbers of inbred lines and cultivars.
文摘Appressed and non-appressed lamella membranes of Castor bean leaf chloroplasts were separated by non-ionic detergent Triton-X 100.Appressed membranes showed a high oxygen-evolving activity and low chl a/b ratio. Examining with SDS-PTGE and liquid nitrogen temperature fluorescence measurement showed that they contained only PSII and light-harvesting pigment-protein complexes (LHCP),and there was no detectable amount of PSI. Freeze-fracture electromicroscopic observation confirmed that this part was really an appressed lamella membrane. Through divalent cation Mg^(++), the thylakoid membranes were induced to unstack and restack.With the addition of Mg^(++), the fluorescence intensity was changed instantly. We realized that there existed two processes:One was a rapid process which was accomplished within 30 s. The other was a slow process of which the time duration was about 60 min. This dual effects of Mg^(++) had not been reported before.We had analyzed the change of F685/F730 and discussed the possible rneehanis ms of light energy distribution between photosystems.
基金supported by Major Program of the National Natural Science Foundation of China(No.52293413)the National Natural Science Foundation of China(No.52076161)。
文摘A comprehensive numerical model is developed to simulate the growth of microalgae under light/dark cycling conditions.The purpose of this study is to predict the growth rate of Chlorella vulgaris cultivated in photobioreactors(PBRs)in order to improve the light conditions for microalgae and enhance the photosynthetic efficiency.Computational fluid dynamics(CFD)is used to simulate its internal hydrodynamic behaviors.The Lagrangian method is employed to track the movement of microalgae cells.The radiative transfer equation(RTE)is used to obtain light intensity distribution.The combination of light radiation field and microalgae cell motions is used to construct the light history and they are integrated into the model of the photosynthetic units(PSU)to calculate the microalgae growth rate.The numerical results demonstrate that enhanced light/dark cycling frequency with ordered mixing can promote efficient microalgae cultivation.The effect of the vortex flow field generated by the baffles in an air-lift PBR is analyzed for increasing microalgae growth rate.When using the 1:1 baffle spacing,the biomass production of microalgae is increased by 41.8% compared to the original PBR.
基金We acknowledge the support from National Key R&D Program of China(Grant No.2017YFB0404000)China Postdoctoral Science Foundation(2018M632470)Postdoctoral Science Foundation of Zhejiang Province.
文摘LED has shown great advantages in poultry husbandry.This study focused on the behavioral preferences and production performance of chicken broilers reared under unevenly distributed yellow LED light.Four pens were divided into two groups adopting respective maximum light intensities(MLIs,60 lx and 30 lx).Because of different distances from the installation position of the LED pipe,each pen was distributed with unevenly distributed light.Each pen consisted of four subzones indicated by their light intensities-high intensity(HI),medium intensity(MI),low intensity(LI)and weak intensity(WI).Four subzones were the same size and provided with a feeder and a drinker,respectively.The broilers moved freely across the four subzones.No significant differences in body weight(BW),uniformity of final BW and feed conversion ratio(FCR)were observed between the two experimental groups.However,greater feed intake and water intake were found in HI than those in other subzones.The drinking preference changed with age for four subzones and was more likely to appear at the later stage,despite substantial fluctuations within the replicates.The feeding preference was more constant than the drinking preference and appeared mainly at the early and middle stages of this study.These findings could provide implications for broiler production reared under unevenly distributed LED light condition.
