Dipole Shear-Wave Reflection Survey(DSRS)has gained wide application in identifying unconventional reservoirs in anisotropic formations.Previous investigations have illuminated how boreholes complicate the distributio...Dipole Shear-Wave Reflection Survey(DSRS)has gained wide application in identifying unconventional reservoirs in anisotropic formations.Previous investigations have illuminated how boreholes complicate the distribution of acoustic energy.However,these models have not accounted for the anisotropic context,rendering them insufficient for analyzing acoustic energy distribution and radiation efficiency in anisotropic formations.We derive expressions for energy flux and radiation efficiency from a borehole dipole source in the vertical-transverse isotropic(VTI)media using the Umov-Poynting vector and steepest-descent solution.Utilizing this approach,we systematically evaluate the sensitivity of anisotropic parameters to energy flux and radiation efficiency,unveiling intricate variations of these properties across frequency and anisotropic parameters.Our findings emphasize the substantial influence of formation anisotropy on energy distribution from a dipole source inside the borehole.Due to energy conversion between wave modes,five radiation wave modes are elicited by the dipole source,with the SH wave retaining its status as the prime candidate for DSRS in fast formations owing to its elevated radiation efficiency.Conversely,the qP-qP wave exhibits advantages over S waves in unconsolidated formations.A key distinction between isotropic and anisotropic media is the presence of dominant excitation frequencies in the low-frequency domain.The significance of dominant excitation-frequency bands is validated by field data,emphasizing their pivotal role.These results offer valuable insights for designing DSRS measurement strategies,which have broad application expectations for unconventional oil and gas exploration.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
Poor nitrogen use efficiency in rice production is a critical issue in China. Site-specific N managements （SSNM） such as real-time N management （RTNM） and fixed-time adjustable-dose N management （FTNM） improve f...Poor nitrogen use efficiency in rice production is a critical issue in China. Site-specific N managements （SSNM） such as real-time N management （RTNM） and fixed-time adjustable-dose N management （FTNM） improve fertilizer-N use efficiency of irrigated rice. This study was aimed to compare the different nitrogen （N） rates and application methods （FFP, SSNM, and RTNM methods） under with- and without-fungicide application conditions on grain yield, yield components, solar radiation use efficiency （RUE）, agronomic-nitrogen use efficiency （AEN）, and sheath blight disease intensity. Field experiments were carried out at Liuyang County, Hunan Province, China, during 2006 and 2007. A super hybrid rice Liangyou 293 （LY293） was used as experimental material. The results showed that RTNM and SSNM have great potential for improving agronomic-nitrogen use efficiency without sacrificing the grain yield. There were significant differences in light interception rate, sheath blight disease incidence （DI） and the disease index （ShBI）, and total dry matter among the different nitrogen management methods. The radiation use efficiency was increased in a certain level of applied N. But, the harvest index （HI） decreased with the increase in applied N. There is a quadratic curve relationship between grain yield and applied N rates. With the same N fertilizer rate, different fertilizer-N application methods affected the RUE and grain yield. The fungicide application not only improved the canopy light interception rate, RUE, grain filling, and harvest index, but also reduced the degree of sheath blight disease. The treatment of RTNM under the SPAD threshold value 40 obtained the highest yield. While the treatment of SSNM led to the highest nitrogen agronomic efficiency and higher rice yield, and decreased the infestation of sheath blight disease dramatically as well. Nitrogen application regimes and diseases control in rice caused obvious effects on light interception rate, RUE, and HI. Optimal N rate is helpful to get higher light interception rate, RUE, and HI. Disease control with fungicide application decreased and delayed the negative effects of the high N on rice yield formation. SSNM and RTNM under the proper SPAD threshold value obtained high-yield with high efficiency and could alleviate environmental pollution in rice production.展开更多
Knowledge about crop growth processes in relation to N limitation is necessary to optimize N management in farming system. Plant-based diagnostic method, for instance nitrogen nutrition index （NNI） were used to dete...Knowledge about crop growth processes in relation to N limitation is necessary to optimize N management in farming system. Plant-based diagnostic method, for instance nitrogen nutrition index （NNI） were used to determine the crop nitrogen status. This study determines the relationship of NNI with agronomic nitrogen use efficiency （AEN）, tuber yield, radiation use efficiency （RUE） and leaf parameters including leaf area index （LAI）, areal leaf N content （NJ and leaf N concentration （N0. Potatoes were grown in field at three N levels： no N （N 1）, 150 kg N ha^-1 （N2）, 300 kg N ha^-1 （N3）. N deficiency was quantified by NNI and RUE was generally calculated by estimating of the light absorbance on leaf area. NNI was used to evaluate the N effect on tuber yield, RUE, LAI, NAL, and NL. The results showed that NNI was negatively correlated with AEN, N deficiencies （NNI〈 1） which occurred for N 1 and N2 significantly reduced LAI, NL and tuber yield; whereas the N deficiencies had a relative small effect on NAL and RUE. To remove any effect other than N on these parameters, the actual ratio to maximum values were calculated for each developmental linear relationships were obtained between NNI and tuber RUE to NNI. stage of potatoes. When the NNI ranged from 0.4 to 1, positive yield, LAI, NL, while a nonlinear regression fitted the response of展开更多
Double-cropping rice in South China continues to break the total yield record,but the yield potential of singlecropping rice is not being realized.Radiation use efficiency(RUE)has been singled out as an important dete...Double-cropping rice in South China continues to break the total yield record,but the yield potential of singlecropping rice is not being realized.Radiation use efficiency(RUE)has been singled out as an important determinant of grain yield in many cereal species.However,there is no information on whether the yield gaps in doublecropping rice involve differences in RUE.Field experiments were performed over two years to evaluate the effects of intercepted radiation(IP)and RUE on the above-ground biomass production,crop growth rate(CGR),and harvest index(HI),in four representative rice varieties,i.e.,Xiangyaxiangzhan(XYXZ),Meixiangzhan 2(MXZ2),Nanjingxiangzhan(NJXZ),and Ruanhuayoujinsi(RHYJS),during the early and late seasons of rice cultivation in South China.The results revealed that grain yield in the early season was 8.2%higher than in the late season.The yield advantage in the early season was primarily due to higher spikelets per panicle and above-ground biomass resulting from a higher RUE.The spikelets per panicle in the early season were 6.5,8.3,6.9,and 8.5%higher in XYXZ,MXZ2,NJXZ,and RHYJS,respectively,than in the late season.The higher early season grain yield was more closely related to RUE in the middle tillering stage(R^(2)=0.34),panicle initiation(R^(2)=0.16),and maturation stage(R^(2)=0.28),and the intercepted photosynthetically active radiation(IPAR)in the maturation stage(R^(2)=0.28),while the late season grain yield was more dependent on IPAR in the middle tillering stage(R^(2)=0.31)and IPAR at panicle initiation(R^(2)=0.23).The results of this study conclusively show that higher RUE contributes to the yield progress of early season rice,while the yield improvement of late season rice is attributed to higher radiation during the early reproductive stage.Rationally allocating the RUE of double-cropping rice with high RUE varieties or adjustments of the sowing period merits further study.展开更多
It has been shown that adding biochar to soil can improve nitrogen(N)uptake and utilization in rice(Oryza sativa L.).However,there is a lack of research on the physiological alterations of rice as a result of the chan...It has been shown that adding biochar to soil can improve nitrogen(N)uptake and utilization in rice(Oryza sativa L.).However,there is a lack of research on the physiological alterations of rice as a result of the changes in nitrogen uptake due to the addition of biochar.This study conducted field experiments in 2015 and 2016 with the goal of testing the hypothesis that the application of biochar would enhance radiation use efficiency(RUE)of rice by improving the plant’s ability to take in and utilize nitrogen.Our results demonstrated that the application of biochar(20 t ha−1)induced no significant effects on pre-heading specific leaf weight(SLW),nitrogen uptake(NUpre),and leaf area index(LAI)at heading,the ratios of LAI/NUpre and SLW/Nupre,or pre-heading RUE.How-ever,biochar application significantly increased post-heading nitrogen uptake(NUpost),ratios of NUpost/SLWand NUpost/LAI,and post-heading RUE.These results indicate that the application of biochar can improve the plant’s nitrogen uptake and RUE in field-grown rice during the post-heading period,which confirms our hypothesis.展开更多
A new type of AC PDP(alternating current plasma display panel) cell with a five-electrode structure is developed to improve the luminous efficiency of AC PDP.The discharge efficiency of this new cell structure is inve...A new type of AC PDP(alternating current plasma display panel) cell with a five-electrode structure is developed to improve the luminous efficiency of AC PDP.The discharge efficiency of this new cell structure is investigated by a 2D fluid simulation. Continuity equations and flux density equations for charged particles and excited atoms, energy balance equation for electrons are included in the model. The discharge gas is He+5%Xe. The reactions of ionization, excitation, recombination, and radiation are taken into account. The vacuum ultraviolet radiation efficiency of the five-electrode cell structure is about 20% higher than that of a conventional three-electrode cell structure.展开更多
Sound radiation of thin plates is a common problem in engineering. Hashimoto proposed the discrete calculation method(DCM) to deal with the problem. The calculation of the radiation impedance of the rectangular elemen...Sound radiation of thin plates is a common problem in engineering. Hashimoto proposed the discrete calculation method(DCM) to deal with the problem. The calculation of the radiation impedance of the rectangular element is more cumbersome than that of the circular one, so the discrete rectangular radiation element is approximated by the circular one. However, error is also introduced. The formula developed by Sha has been employed to get self- and mutual-radiation impedances of rectangular radiation element. Numerical study was performed to verify error introduced by the approximation Hashimoto adopted. Experimental researches on sound radiation of a 2 mm-thick and a 4 mm-thick magnesium alloy plates were also carried out to evaluate the errors introduced by the approximation. The experimental results indicate that the circular approximation Hashimoto adopted overestimates the sound radiation efficiency. The maximum error levels of the radiation efficiencies of the2 mm-thick and 4 mm-thick magnesium alloy plates are up to 0.15 and 0.12, respectively. The effect of element aspect ratio on the sound radiation efficiency is also remarkable.展开更多
Northeast China (NEC) is one of the major maize production areas in China.Agro-climatic resources have obviously changed,which will seriously affect crop growth and development in this region.It is important to invest...Northeast China (NEC) is one of the major maize production areas in China.Agro-climatic resources have obviously changed,which will seriously affect crop growth and development in this region.It is important to investigate the contribution of climate change adaptation measures to the yield and resource use efficiency to improve our understanding of how we can effectively ensure high yield and high efficiency in the future.In this study,we divided the study area into five accumulated temperature zones (ATZs) based on growing degree days (GDD).Based on the meteorological data,maize data (from agrometeorological stations) and the validated APSIM-Maize Model,we first investigated the spatial distributions and temporal trends of maize potential yield of actual planted cultivars,and revealed the radiation use efficiency (RUE) and heat resource use efficiency (HUE) from 1981 to 2017.Then according to the potential growing seasons and actual growing seasons,we identified the utilization percentages of radiation (P_R) resource and heat resource (P_H) for each ATZ under potential production from 1981 to 2017.Finally,we quantified the contributions of cultivar changings to yield,P_R and P_H of maize.The results showed that during the past 37 years,the estimated mean potential yield of actual planted cultivars was 13 649 kg ha^(–1),ranged from 11 205 to 15 257 kg ha^(–1),and increased by 140 kg ha^(–1) per decade.For potential production,the mean values of RUE and HUE for the actual planted maize cultivars were 1.22 g MJ^(–1) and 8.58 kg (℃ d)^(–1) ha^(–1).RUE showed an increasing tendency,while HUE showed a decreasing tendency.The lengths of the potential growing season and actual growing season were 158 and 123 d,and increased by 2 and 1 d per decade.P_R and P_H under potential production were 82 and 86%,respectively and showed a decreasing tendency during the past 37 years.This indicates that actual planted cultivars failed to make full use of climate resources.However,results from the adaptation assessments indicate that,adoption of cultivars with growing season increased by 2–11 d among ATZs caused increase in yield,P_R and P_H of 0.6–1.7%,1.1–7.6% and 1.5–8.9%,respectively.Therefore,introduction of cultivars with longer growing season can effectively increase the radiation and heat utilization percentages and potential yield.展开更多
Ridge-furrow film mulching has been widely used as a water-saving and yield-increasing planting pattern in arid and semiarid regions.Planting density is also a vitally important factor influencing crop yield,and the o...Ridge-furrow film mulching has been widely used as a water-saving and yield-increasing planting pattern in arid and semiarid regions.Planting density is also a vitally important factor influencing crop yield,and the optimal planting density will vary in different environments(such as ridge-furrow film mulching).How the combination of film mulching and planting density will affect the growth,physiology,yield,and water and radiation use efficiencies of winter oilseed rape is not clear yet.Therefore,a three-year field experiment was conducted from 2017 to 2020 to explore the responses of leaf chlorophyll(Chl)content,net photosynthetic rate(P_(n)),leaf area index(LAI),aboveground dry matter(ADM),root growth and distribution,yield,evapotranspiration(ET),water use efficiency(WUE),and radiation use efficiency(RUE)of winter oilseed rape to different film mulching patterns(F,ridge-furrow planting with plastic film mulching over the ridges;N,flat planting without mulching)and planting densities(LD,100,000 plants ha^(-1);MD,150,000 plants ha^(-1);HD,200,000 plants ha^(-1)).The results showed that the F treatments led to significantly greater leaf Chl contents,P_(n),LAI,and ADM,and a stronger root system than treatments without film mulching throughout the whole winter rapeseed growing seasons.Winter oilseed rape in the MD treatments had better physiological(leaf Chl contents and P_(n))and growth(LAI,ADM,taproot,and lateral root)conditions than in LD and HD at the late growth period after stem-elongation.Grain yield in FMD was the greatest,and it was significantly greater by 34.8-46.0%,6.7-9.6%,87.8-108.3%,38.7-50.3%,and 50.2-61.8%compared to those of FLD,FHD,NLD,NMD,and NHD,respectively.Furthermore,the ET in FMD was equivalent to FLD and FHD,but was markedly lower by 12.2-18.4%,14.5-20.3%,and 14.6-20.4%than in NLD,NMD,and NHD.Finally,the WUE and RUE in FMD were significantly improved by 88.5-94.0%and 29.0-41.8%compared to NHD(the local conventional planting pattern and planting density for winter rapeseed).In summary,FMD is a favorable cultivation management strategy to save water,increase yield and improve resource utilization efficiencies in winter oilseed rape in Northwest China.展开更多
In this work,a novel compact wideband reconfigurable circularly polarised(CP)dielectric resonator antenna(DRA)is presented.The L-shaped Dielectric resonator antenna is excited by an inverted question mark shaped feed....In this work,a novel compact wideband reconfigurable circularly polarised(CP)dielectric resonator antenna(DRA)is presented.The L-shaped Dielectric resonator antenna is excited by an inverted question mark shaped feed.This arrangement of feed-line helps to generate two orthogonal modes inside the DR,which makes the design circularly polarised.A thin micro-strip line placed on the defected ground plane not only helps to generate a wideband response but also assist in the positioning of the two diode switches.These switches located at the left and right of the micro-strip line helps in performing two switching operations.The novel compact design offers the reconfigurability between 2.9–3.8 GHz which can be used for different important wireless applications.For the switching operation I,the achieved impedance bandwidth is 24%while axial ratio bandwidth(ARBW)is 42%.For this switching state,the design has 100%CP performance.Similarly,the switching operation II achieves 60%impedance bandwidth and 58.88%ARBW with 76.36%CP performance.The proposed design has a maximum measured gain of 3.4 dBi and 93%radiation efficiency.The proposed design is novel in terms of compactness and performance parameters.The prototype is fabricated for the performance analysis which shows that the simulated and measured results are in close agreement.展开更多
With co-seismic surface rupture slip displacements provided by the field observation for the 2001 MS8.1 West Kunlun Mountain Pass earthquake, this paper estimates the rupture speed on the main faulting segment with a ...With co-seismic surface rupture slip displacements provided by the field observation for the 2001 MS8.1 West Kunlun Mountain Pass earthquake, this paper estimates the rupture speed on the main faulting segment with a long straight fault trace on the surface based on a simple slip-weakening rupture model, in which the frictional overshoot or undershoot are involved in consideration of energy partition during the earthquake faulting. In contrast to the study of Bouchon and Vallée, in which the rupture propagation along the main fault could exceed the local shear-wave speed, perhaps reach the P-wave speed on a certain section of fault, our results show that, under a slip-weakening assumption combined with a frictional undershoot (partial stress drop model), average rupture speed should be equal to or less than the Rayleigh wave speed with a high seismic radiation efficiency, which is consistent with the result derived by waveform inversion and the result estimated from source stress field. Associated with the surface rupture mechanism, such as partial stress drop (frictional undershoot) associated with the apparent stress, an alternative rupture mechanism based on the slip-weakening model has also been discussed.展开更多
During the ruptures of an earthquake, the strain energy, AE, will be transferred into, at least, three parts, i.e., the seismic radiation energy （Es）, fracture energy （Eg）, and frictional energy （Ef）, that is, A...During the ruptures of an earthquake, the strain energy, AE, will be transferred into, at least, three parts, i.e., the seismic radiation energy （Es）, fracture energy （Eg）, and frictional energy （Ef）, that is, AE = Es ＋ Eg ＋ El. Friction, which is represented by a velocity- and state-de- pendent friction law by some researchers, controls the three parts. One of the main parameters of the law is the char- acteristic slip displacement, De. It is significant and nec- essary to evaluate the reliable value of Dc from observed and inverted seismic data. Since Dc controls the radiation efficiency, ηR = Es/（Es ＋ Eg）, the value of qR is a good constraint of estimating Dc. Integrating observed data and inverted results of source parameters from recorded seis- mograms, the values of Es and Eg of an earthquake can be measured, thus leading to the value of ηR. The constraint used to estimate the reliable value of Dc will be described in this work. An example of estimates of Dc based on the observed and inverted values of source parameters of the September 20, 1999 Ms 7.6 Chi-Chi （Ji-Ji）, Taiwan region, earthquake will be presented.展开更多
We present the design, fabrication, and characterization of two new types of terahertz photoconductive emitters. One has an asymmetric four-contact electrode structure and the other has an arc-shaped electrode structu...We present the design, fabrication, and characterization of two new types of terahertz photoconductive emitters. One has an asymmetric four-contact electrode structure and the other has an arc-shaped electrode structure, which are all modified from a traditional strip line antenna. Numerical simulations and real experiments confirm the good performance of the proposed antennas. An amplitude increase of about 40% is experimentally observed for the terahertz signals generated from the new structures. The special electrode structure and its induced local bias field enhancement are responsible for this radiation efficiency improvement. Our work demonstrates the feasibility of developing highly efficient terahertz photoconductive emitters by optimizing the electrode structure.展开更多
Climate change is making the lands a harsher environment all over the world including Pakistan. It is expected to oppose us with three main challenges： increase in temperature up to 2-5℃ （heat stress）, increasing ...Climate change is making the lands a harsher environment all over the world including Pakistan. It is expected to oppose us with three main challenges： increase in temperature up to 2-5℃ （heat stress）, increasing water stress and severe malnourishment due to climate change. It has been foreseen that there will be a 10% increase of dryland areas with climate change in the world, with more variability and incidences of short periods of extreme events （drought and heat stress）. Pearl millet is a hardy, climate smart grain crop, idyllic for environments prone to drought and heat stresses. The crop continues to produce highly nutritious grain sustainably, thereby encouraging the fight against poverty and food insecurity due to its resilience. The crop is more responsive to good production options （planting time, planting density, inter/intra row spacing, nitrogen application and irrigation）. It has high crop growth rate, large leaf area index and high radiation use efficiency that confers its high potential yield. In most of the cases, pearl millet is remained our agricultural answer to the climate calamity that we are facing, because it is selected as water saving, drought tolerant and climate change complaint crop. In view of circumstances, pearl millet cultivation must be retrieved by recognizing production options in context to changing climate scenarios of Pakistan using crop modeling techniques.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
基金supported by the National Natural Science Foundation of China(grant No.42074137,42204126,41821002,U21B2064)Laoshan National Laboratory Science and Technology Innovation Project(grant No.LSKJ202203407)China Scholarship Council State Scholarship Fund(202206450061)。
文摘Dipole Shear-Wave Reflection Survey(DSRS)has gained wide application in identifying unconventional reservoirs in anisotropic formations.Previous investigations have illuminated how boreholes complicate the distribution of acoustic energy.However,these models have not accounted for the anisotropic context,rendering them insufficient for analyzing acoustic energy distribution and radiation efficiency in anisotropic formations.We derive expressions for energy flux and radiation efficiency from a borehole dipole source in the vertical-transverse isotropic(VTI)media using the Umov-Poynting vector and steepest-descent solution.Utilizing this approach,we systematically evaluate the sensitivity of anisotropic parameters to energy flux and radiation efficiency,unveiling intricate variations of these properties across frequency and anisotropic parameters.Our findings emphasize the substantial influence of formation anisotropy on energy distribution from a dipole source inside the borehole.Due to energy conversion between wave modes,five radiation wave modes are elicited by the dipole source,with the SH wave retaining its status as the prime candidate for DSRS in fast formations owing to its elevated radiation efficiency.Conversely,the qP-qP wave exhibits advantages over S waves in unconsolidated formations.A key distinction between isotropic and anisotropic media is the presence of dominant excitation frequencies in the low-frequency domain.The significance of dominant excitation-frequency bands is validated by field data,emphasizing their pivotal role.These results offer valuable insights for designing DSRS measurement strategies,which have broad application expectations for unconventional oil and gas exploration.
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the National Natural Science Foundation of China (30671219)the Ministry of Science and Technology of China (2009CB118 603)
文摘Poor nitrogen use efficiency in rice production is a critical issue in China. Site-specific N managements （SSNM） such as real-time N management （RTNM） and fixed-time adjustable-dose N management （FTNM） improve fertilizer-N use efficiency of irrigated rice. This study was aimed to compare the different nitrogen （N） rates and application methods （FFP, SSNM, and RTNM methods） under with- and without-fungicide application conditions on grain yield, yield components, solar radiation use efficiency （RUE）, agronomic-nitrogen use efficiency （AEN）, and sheath blight disease intensity. Field experiments were carried out at Liuyang County, Hunan Province, China, during 2006 and 2007. A super hybrid rice Liangyou 293 （LY293） was used as experimental material. The results showed that RTNM and SSNM have great potential for improving agronomic-nitrogen use efficiency without sacrificing the grain yield. There were significant differences in light interception rate, sheath blight disease incidence （DI） and the disease index （ShBI）, and total dry matter among the different nitrogen management methods. The radiation use efficiency was increased in a certain level of applied N. But, the harvest index （HI） decreased with the increase in applied N. There is a quadratic curve relationship between grain yield and applied N rates. With the same N fertilizer rate, different fertilizer-N application methods affected the RUE and grain yield. The fungicide application not only improved the canopy light interception rate, RUE, grain filling, and harvest index, but also reduced the degree of sheath blight disease. The treatment of RTNM under the SPAD threshold value 40 obtained the highest yield. While the treatment of SSNM led to the highest nitrogen agronomic efficiency and higher rice yield, and decreased the infestation of sheath blight disease dramatically as well. Nitrogen application regimes and diseases control in rice caused obvious effects on light interception rate, RUE, and HI. Optimal N rate is helpful to get higher light interception rate, RUE, and HI. Disease control with fungicide application decreased and delayed the negative effects of the high N on rice yield formation. SSNM and RTNM under the proper SPAD threshold value obtained high-yield with high efficiency and could alleviate environmental pollution in rice production.
基金supported by the National Key Technology R&D Program (2011BAD12B03)
文摘Knowledge about crop growth processes in relation to N limitation is necessary to optimize N management in farming system. Plant-based diagnostic method, for instance nitrogen nutrition index （NNI） were used to determine the crop nitrogen status. This study determines the relationship of NNI with agronomic nitrogen use efficiency （AEN）, tuber yield, radiation use efficiency （RUE） and leaf parameters including leaf area index （LAI）, areal leaf N content （NJ and leaf N concentration （N0. Potatoes were grown in field at three N levels： no N （N 1）, 150 kg N ha^-1 （N2）, 300 kg N ha^-1 （N3）. N deficiency was quantified by NNI and RUE was generally calculated by estimating of the light absorbance on leaf area. NNI was used to evaluate the N effect on tuber yield, RUE, LAI, NAL, and NL. The results showed that NNI was negatively correlated with AEN, N deficiencies （NNI〈 1） which occurred for N 1 and N2 significantly reduced LAI, NL and tuber yield; whereas the N deficiencies had a relative small effect on NAL and RUE. To remove any effect other than N on these parameters, the actual ratio to maximum values were calculated for each developmental linear relationships were obtained between NNI and tuber RUE to NNI. stage of potatoes. When the NNI ranged from 0.4 to 1, positive yield, LAI, NL, while a nonlinear regression fitted the response of
基金funded by the National Natural Science Foundation of China(31971843)the Modern Agroindustrial Technology System of Guangdong Province,China(2021KJ105)the Guangzhou Science and Technology Project,China(202103000075 and 202102100008)。
文摘Double-cropping rice in South China continues to break the total yield record,but the yield potential of singlecropping rice is not being realized.Radiation use efficiency(RUE)has been singled out as an important determinant of grain yield in many cereal species.However,there is no information on whether the yield gaps in doublecropping rice involve differences in RUE.Field experiments were performed over two years to evaluate the effects of intercepted radiation(IP)and RUE on the above-ground biomass production,crop growth rate(CGR),and harvest index(HI),in four representative rice varieties,i.e.,Xiangyaxiangzhan(XYXZ),Meixiangzhan 2(MXZ2),Nanjingxiangzhan(NJXZ),and Ruanhuayoujinsi(RHYJS),during the early and late seasons of rice cultivation in South China.The results revealed that grain yield in the early season was 8.2%higher than in the late season.The yield advantage in the early season was primarily due to higher spikelets per panicle and above-ground biomass resulting from a higher RUE.The spikelets per panicle in the early season were 6.5,8.3,6.9,and 8.5%higher in XYXZ,MXZ2,NJXZ,and RHYJS,respectively,than in the late season.The higher early season grain yield was more closely related to RUE in the middle tillering stage(R^(2)=0.34),panicle initiation(R^(2)=0.16),and maturation stage(R^(2)=0.28),and the intercepted photosynthetically active radiation(IPAR)in the maturation stage(R^(2)=0.28),while the late season grain yield was more dependent on IPAR in the middle tillering stage(R^(2)=0.31)and IPAR at panicle initiation(R^(2)=0.23).The results of this study conclusively show that higher RUE contributes to the yield progress of early season rice,while the yield improvement of late season rice is attributed to higher radiation during the early reproductive stage.Rationally allocating the RUE of double-cropping rice with high RUE varieties or adjustments of the sowing period merits further study.
基金This work was supported by the Natural Science Foundation of Hunan Province of China(2019JJ50241)the Scientific Research Fund of Hunan Provincial Education Department(18C0158)the National Natural Science Foundation of China(31460332).
文摘It has been shown that adding biochar to soil can improve nitrogen(N)uptake and utilization in rice(Oryza sativa L.).However,there is a lack of research on the physiological alterations of rice as a result of the changes in nitrogen uptake due to the addition of biochar.This study conducted field experiments in 2015 and 2016 with the goal of testing the hypothesis that the application of biochar would enhance radiation use efficiency(RUE)of rice by improving the plant’s ability to take in and utilize nitrogen.Our results demonstrated that the application of biochar(20 t ha−1)induced no significant effects on pre-heading specific leaf weight(SLW),nitrogen uptake(NUpre),and leaf area index(LAI)at heading,the ratios of LAI/NUpre and SLW/Nupre,or pre-heading RUE.How-ever,biochar application significantly increased post-heading nitrogen uptake(NUpost),ratios of NUpost/SLWand NUpost/LAI,and post-heading RUE.These results indicate that the application of biochar can improve the plant’s nitrogen uptake and RUE in field-grown rice during the post-heading period,which confirms our hypothesis.
基金The project supported by 2002 project for Science and Technology of Ministry of Education
文摘A new type of AC PDP(alternating current plasma display panel) cell with a five-electrode structure is developed to improve the luminous efficiency of AC PDP.The discharge efficiency of this new cell structure is investigated by a 2D fluid simulation. Continuity equations and flux density equations for charged particles and excited atoms, energy balance equation for electrons are included in the model. The discharge gas is He+5%Xe. The reactions of ionization, excitation, recombination, and radiation are taken into account. The vacuum ultraviolet radiation efficiency of the five-electrode cell structure is about 20% higher than that of a conventional three-electrode cell structure.
基金the National Technology Research and Development Program in the 12th Five Year Plan of China(No.2011BAE22B05)the Canada-ChinaUSA Collaborative Research and Development Project(No.2011DFA50900)
文摘Sound radiation of thin plates is a common problem in engineering. Hashimoto proposed the discrete calculation method(DCM) to deal with the problem. The calculation of the radiation impedance of the rectangular element is more cumbersome than that of the circular one, so the discrete rectangular radiation element is approximated by the circular one. However, error is also introduced. The formula developed by Sha has been employed to get self- and mutual-radiation impedances of rectangular radiation element. Numerical study was performed to verify error introduced by the approximation Hashimoto adopted. Experimental researches on sound radiation of a 2 mm-thick and a 4 mm-thick magnesium alloy plates were also carried out to evaluate the errors introduced by the approximation. The experimental results indicate that the circular approximation Hashimoto adopted overestimates the sound radiation efficiency. The maximum error levels of the radiation efficiencies of the2 mm-thick and 4 mm-thick magnesium alloy plates are up to 0.15 and 0.12, respectively. The effect of element aspect ratio on the sound radiation efficiency is also remarkable.
基金supported by the National Key Research and Development Program of China(2016YFD0300101-03)。
文摘Northeast China (NEC) is one of the major maize production areas in China.Agro-climatic resources have obviously changed,which will seriously affect crop growth and development in this region.It is important to investigate the contribution of climate change adaptation measures to the yield and resource use efficiency to improve our understanding of how we can effectively ensure high yield and high efficiency in the future.In this study,we divided the study area into five accumulated temperature zones (ATZs) based on growing degree days (GDD).Based on the meteorological data,maize data (from agrometeorological stations) and the validated APSIM-Maize Model,we first investigated the spatial distributions and temporal trends of maize potential yield of actual planted cultivars,and revealed the radiation use efficiency (RUE) and heat resource use efficiency (HUE) from 1981 to 2017.Then according to the potential growing seasons and actual growing seasons,we identified the utilization percentages of radiation (P_R) resource and heat resource (P_H) for each ATZ under potential production from 1981 to 2017.Finally,we quantified the contributions of cultivar changings to yield,P_R and P_H of maize.The results showed that during the past 37 years,the estimated mean potential yield of actual planted cultivars was 13 649 kg ha^(–1),ranged from 11 205 to 15 257 kg ha^(–1),and increased by 140 kg ha^(–1) per decade.For potential production,the mean values of RUE and HUE for the actual planted maize cultivars were 1.22 g MJ^(–1) and 8.58 kg (℃ d)^(–1) ha^(–1).RUE showed an increasing tendency,while HUE showed a decreasing tendency.The lengths of the potential growing season and actual growing season were 158 and 123 d,and increased by 2 and 1 d per decade.P_R and P_H under potential production were 82 and 86%,respectively and showed a decreasing tendency during the past 37 years.This indicates that actual planted cultivars failed to make full use of climate resources.However,results from the adaptation assessments indicate that,adoption of cultivars with growing season increased by 2–11 d among ATZs caused increase in yield,P_R and P_H of 0.6–1.7%,1.1–7.6% and 1.5–8.9%,respectively.Therefore,introduction of cultivars with longer growing season can effectively increase the radiation and heat utilization percentages and potential yield.
基金supported by the National Natural Science Foundation of China(52479049 and 51909221)the National Key R&D Program of China(2021YFD1900700)+1 种基金the Key R&D Program of Shaanxi Province,China(2024NC-ZDCYL-02-08)the Key Laboratory of Crop Water Use and Regulation,Ministry of Agriculture and Rural Affairs,China(IFI-CWUR202402).
文摘Ridge-furrow film mulching has been widely used as a water-saving and yield-increasing planting pattern in arid and semiarid regions.Planting density is also a vitally important factor influencing crop yield,and the optimal planting density will vary in different environments(such as ridge-furrow film mulching).How the combination of film mulching and planting density will affect the growth,physiology,yield,and water and radiation use efficiencies of winter oilseed rape is not clear yet.Therefore,a three-year field experiment was conducted from 2017 to 2020 to explore the responses of leaf chlorophyll(Chl)content,net photosynthetic rate(P_(n)),leaf area index(LAI),aboveground dry matter(ADM),root growth and distribution,yield,evapotranspiration(ET),water use efficiency(WUE),and radiation use efficiency(RUE)of winter oilseed rape to different film mulching patterns(F,ridge-furrow planting with plastic film mulching over the ridges;N,flat planting without mulching)and planting densities(LD,100,000 plants ha^(-1);MD,150,000 plants ha^(-1);HD,200,000 plants ha^(-1)).The results showed that the F treatments led to significantly greater leaf Chl contents,P_(n),LAI,and ADM,and a stronger root system than treatments without film mulching throughout the whole winter rapeseed growing seasons.Winter oilseed rape in the MD treatments had better physiological(leaf Chl contents and P_(n))and growth(LAI,ADM,taproot,and lateral root)conditions than in LD and HD at the late growth period after stem-elongation.Grain yield in FMD was the greatest,and it was significantly greater by 34.8-46.0%,6.7-9.6%,87.8-108.3%,38.7-50.3%,and 50.2-61.8%compared to those of FLD,FHD,NLD,NMD,and NHD,respectively.Furthermore,the ET in FMD was equivalent to FLD and FHD,but was markedly lower by 12.2-18.4%,14.5-20.3%,and 14.6-20.4%than in NLD,NMD,and NHD.Finally,the WUE and RUE in FMD were significantly improved by 88.5-94.0%and 29.0-41.8%compared to NHD(the local conventional planting pattern and planting density for winter rapeseed).In summary,FMD is a favorable cultivation management strategy to save water,increase yield and improve resource utilization efficiencies in winter oilseed rape in Northwest China.
基金supported by the National Science Foundation of China Grant funded by the Chinese Government(No.61861043).
文摘In this work,a novel compact wideband reconfigurable circularly polarised(CP)dielectric resonator antenna(DRA)is presented.The L-shaped Dielectric resonator antenna is excited by an inverted question mark shaped feed.This arrangement of feed-line helps to generate two orthogonal modes inside the DR,which makes the design circularly polarised.A thin micro-strip line placed on the defected ground plane not only helps to generate a wideband response but also assist in the positioning of the two diode switches.These switches located at the left and right of the micro-strip line helps in performing two switching operations.The novel compact design offers the reconfigurability between 2.9–3.8 GHz which can be used for different important wireless applications.For the switching operation I,the achieved impedance bandwidth is 24%while axial ratio bandwidth(ARBW)is 42%.For this switching state,the design has 100%CP performance.Similarly,the switching operation II achieves 60%impedance bandwidth and 58.88%ARBW with 76.36%CP performance.The proposed design has a maximum measured gain of 3.4 dBi and 93%radiation efficiency.The proposed design is novel in terms of compactness and performance parameters.The prototype is fabricated for the performance analysis which shows that the simulated and measured results are in close agreement.
基金National Natural Science Foundation of China (40574022)the Central Public Affair Program Award for the Specific Academic Research (ZDJ2007-1)One-Hundred Individual Program of Chinese Academy of Sciences (99T3004WAZ)
文摘With co-seismic surface rupture slip displacements provided by the field observation for the 2001 MS8.1 West Kunlun Mountain Pass earthquake, this paper estimates the rupture speed on the main faulting segment with a long straight fault trace on the surface based on a simple slip-weakening rupture model, in which the frictional overshoot or undershoot are involved in consideration of energy partition during the earthquake faulting. In contrast to the study of Bouchon and Vallée, in which the rupture propagation along the main fault could exceed the local shear-wave speed, perhaps reach the P-wave speed on a certain section of fault, our results show that, under a slip-weakening assumption combined with a frictional undershoot (partial stress drop model), average rupture speed should be equal to or less than the Rayleigh wave speed with a high seismic radiation efficiency, which is consistent with the result derived by waveform inversion and the result estimated from source stress field. Associated with the surface rupture mechanism, such as partial stress drop (frictional undershoot) associated with the apparent stress, an alternative rupture mechanism based on the slip-weakening model has also been discussed.
基金financially supported by Academia Sinica and Ministry of Science and Technology under Grand Nos.of MOST 103-2116-M-001-010 and MOST 104-2116-M001-007
文摘During the ruptures of an earthquake, the strain energy, AE, will be transferred into, at least, three parts, i.e., the seismic radiation energy （Es）, fracture energy （Eg）, and frictional energy （Ef）, that is, AE = Es ＋ Eg ＋ El. Friction, which is represented by a velocity- and state-de- pendent friction law by some researchers, controls the three parts. One of the main parameters of the law is the char- acteristic slip displacement, De. It is significant and nec- essary to evaluate the reliable value of Dc from observed and inverted seismic data. Since Dc controls the radiation efficiency, ηR = Es/（Es ＋ Eg）, the value of qR is a good constraint of estimating Dc. Integrating observed data and inverted results of source parameters from recorded seis- mograms, the values of Es and Eg of an earthquake can be measured, thus leading to the value of ηR. The constraint used to estimate the reliable value of Dc will be described in this work. An example of estimates of Dc based on the observed and inverted values of source parameters of the September 20, 1999 Ms 7.6 Chi-Chi （Ji-Ji）, Taiwan region, earthquake will be presented.
基金supported by the National Science and Technology Support Program of China under Grant No.2013BAK14B03
文摘We present the design, fabrication, and characterization of two new types of terahertz photoconductive emitters. One has an asymmetric four-contact electrode structure and the other has an arc-shaped electrode structure, which are all modified from a traditional strip line antenna. Numerical simulations and real experiments confirm the good performance of the proposed antennas. An amplitude increase of about 40% is experimentally observed for the terahertz signals generated from the new structures. The special electrode structure and its induced local bias field enhancement are responsible for this radiation efficiency improvement. Our work demonstrates the feasibility of developing highly efficient terahertz photoconductive emitters by optimizing the electrode structure.
文摘Climate change is making the lands a harsher environment all over the world including Pakistan. It is expected to oppose us with three main challenges： increase in temperature up to 2-5℃ （heat stress）, increasing water stress and severe malnourishment due to climate change. It has been foreseen that there will be a 10% increase of dryland areas with climate change in the world, with more variability and incidences of short periods of extreme events （drought and heat stress）. Pearl millet is a hardy, climate smart grain crop, idyllic for environments prone to drought and heat stresses. The crop continues to produce highly nutritious grain sustainably, thereby encouraging the fight against poverty and food insecurity due to its resilience. The crop is more responsive to good production options （planting time, planting density, inter/intra row spacing, nitrogen application and irrigation）. It has high crop growth rate, large leaf area index and high radiation use efficiency that confers its high potential yield. In most of the cases, pearl millet is remained our agricultural answer to the climate calamity that we are facing, because it is selected as water saving, drought tolerant and climate change complaint crop. In view of circumstances, pearl millet cultivation must be retrieved by recognizing production options in context to changing climate scenarios of Pakistan using crop modeling techniques.
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.
