In this paper, we analyze the spectral behavior(optical thickness, shape and linewidth) of laser radiation absorption under the correlation heating of ions in an ultracold plasma. The Voigt formula is used to find the...In this paper, we analyze the spectral behavior(optical thickness, shape and linewidth) of laser radiation absorption under the correlation heating of ions in an ultracold plasma. The Voigt formula is used to find the absorption coefficient.The spectral line width is shown to grow with time while the optical thickness reduces. Our modeling results are in good agreement with the experimental findings reported in the literature.展开更多
Soybean [Glycine max (L.) Merr.] growth rate and grain yield are modified by the interception and solar radiation use efficiency. Thus, it is desirable that the most of plant photosynthetic structures intercepting sol...Soybean [Glycine max (L.) Merr.] growth rate and grain yield are modified by the interception and solar radiation use efficiency. Thus, it is desirable that the most of plant photosynthetic structures intercepting solar radiation in order to have increment in carbon fixation and reflection on growth and yield. The goal of this study was to assess if soybean cultivars differ in grain yield in relation to solar radiation interception. Four soybean cultivars were evaluated at stages V6, V9, R2, R4, R6 and R8. To determine the photosynthetically active radiation interception by the canopy, the plants were divided into two parts (upper and lower strata). For grain yield components, the plants were divided into three parts (upper, middle and lower thirds). Of the photosynthetically active radiation intercepted by the vegetative canopy at the reproductive stages, the maximum observed intercept was 5.2% in the lower stratum of the plants. The number of infertile nodes increased in the lower third of plants due to low interception of solar radiation in this plant region. Thus, the soybean cultivars more efficient in intercepting photosynthetically active radiation inside the vegetative canopy showed higher grain yields.展开更多
A perfect solution to the present natural convective flow problem of a vertical transfinite plate owing to the impulsive motion in the ubiety of first ordered chemical reaction, radiation absorption, radiation, Newton...A perfect solution to the present natural convective flow problem of a vertical transfinite plate owing to the impulsive motion in the ubiety of first ordered chemical reaction, radiation absorption, radiation, Newtonian heating and species concentration in its plane is evolved by applying the method of Laplace transforms in closed form at the plate. Exact results for velocity, temperature, concentration fields are prevailed and expressions for heat and mass transfer rates are also found. The effects are analyzed for the respective invariables for both ammonia and water vapor.展开更多
In order to acquire a broadband absorption spectrum in a single shot,a compact radiation source was developed by using a Z-pinch type electric discharge.This paper presents the mechanical and electrical construction o...In order to acquire a broadband absorption spectrum in a single shot,a compact radiation source was developed by using a Z-pinch type electric discharge.This paper presents the mechanical and electrical construction of the source,as well as its electrical and optical characteristics,including the intense continuum of radiation emitted by the source in the UV and visible spectral range.It also shows that the compactness of the source allows direct coupling with the probed medium,enabling broadband absorption measurement in the spectral range of 200e300 nm without use of an optical fiber which strongly attenuates the light in the short wavelength range.Concretely,thanks to this source,broadband spectral absorption of NO molecules around 210 nm and that of OH molecules around 310 nm were recorded in this direct coupling arrangement.Copper atom spectral absorption around 325 nm of the peripheral cold zones of an intense transient arc was also recorded.展开更多
A three-dimensional mathematical model is developed to examine the flow of nonlinear thermal radiation Oldroyd-B nanofluid past a bidirectional linearly stretched surface in a porous medium. The flow is induced by tem...A three-dimensional mathematical model is developed to examine the flow of nonlinear thermal radiation Oldroyd-B nanofluid past a bidirectional linearly stretched surface in a porous medium. The flow is induced by temperature dependent thermal conductivity, chemical reaction and convective heat and mass conditions. Novel characteristics of Brownian motion and thermophoresis are accompanied by magnetohydrodynamic and heat generation/absorption.Self-similar transformations are employed to convert the system of nonlinear partial differential equations to a system of ordinary differential equations with high nonlinearity and are solved by strong analytic technique named as Homotopy Analysis method(HAM). Effects of varied arising parameters on involved distributions are reflected through graphical illustrations. From this study, it is perceived that strong magnetic field hinders the fluid's motion and leads to rise in temperature that eventually lowers heat transfer rate from the surface. Further, decrease in heat transfer rate is also observed for enhanced values of thermal radiation parameter. To validate our results, a comparison with already published paper in limiting case is also given and results are found in excellent oncurrence; hence reliable results are being presented.展开更多
The effects of color centers＇ absorption on fibers and interferometric fiber optical gyroscopes（IFOGs） are studied in the paper. The irradiation induced attenuation（RIA） spectra of three types of polarization-mai...The effects of color centers＇ absorption on fibers and interferometric fiber optical gyroscopes（IFOGs） are studied in the paper. The irradiation induced attenuation（RIA） spectra of three types of polarization-maintaining fibers（PMFs）, i.e.,P-doped, Ge-doped, and pure silica, irradiated at 100 Gy and 1000 Gy are measured in a wavelength range from 1100 nm to1600 nm and decomposed according to the Gaussian model. The relationship of the color centers absorption intensity with radiation dose is investigated based on a power model. Furthermore, the effects of all color centers＇ absorption on RIA and mean wavelength shifts（MWS） at 1300 nm and 1550 nm are discussed respectively. Finally, the random walk coefficient（RWC） degradation induced from RIA and the scale factor error induced by MWS of the IFOG are simulated and tested at a wavelength of 1300 nm. This research will contribute to the applications of the fibers in radiation environments.展开更多
The excitonic optical absorption of GaAs bulk semiconductors under intense terahertz （THz） radiation is investigated numerically. The method of solving initial-value problems, combined with the perfect matched layer...The excitonic optical absorption of GaAs bulk semiconductors under intense terahertz （THz） radiation is investigated numerically. The method of solving initial-value problems, combined with the perfect matched layer technique, is used to calculate the optical susceptibility. In the presence of a driving THz field, in addition to the usual exciton peaks, 2p replica of the dark 2p exciton and even-THz-photon-sidebands of the main exciton resonance emerge in the continuum above the band edge and below the main exciton resonance. Moreover, to understand the shift of the position of the main exciton peak under intense THz radiation, it is necessary to take into consideration both the dynamical Franz-Keldysh effect and ac Stark effect simultaneously. For moderate frequency fields, the main exciton peak decreases and broadens due to the field-induced ionization of the excitons with THz field increasing. However, for high frequency THz fields, the characteristics of the exciton recur even under very strong THz fields, which accords with the recent experimental results qualitatively.展开更多
The production of grain legumes is becoming a popular practice in the humid south western Nigeria. Apart from the decreasing trends observed in rainfall amount and duration as a result of climate change, solar radiati...The production of grain legumes is becoming a popular practice in the humid south western Nigeria. Apart from the decreasing trends observed in rainfall amount and duration as a result of climate change, solar radiation interception also constitutes a limitation to crop production because of persistent cloud cover. A trial was conducted at the University of Ibadan experimental site to determine the effect of different plant densities of Arachis spp. on solar radiation interception, dry matter production and yield in Ibadan, Nigeria with the aim of ascertaining the best practice for groundnut production in the zone. The treatments were three plant spacings (60 cm×20 cm,75 cm×20 cmand75 cm×40 cm), and three Arachis varieties (Samnut 10, Samnut 21 and Pintoi) arranged in a split plot, randomized complete block design with Arachis varieties as the main plot while plant densities formed the subplot and replicated three times. Growth parameters (number of leaves, dry leaf weight and dry stem weight) were measured at two weeks interval while yield parameters (number of pods, dry pod weight, dry seed weight and total dry matter) were determined at harvest. Intercepted radiation by plants (PAR) was also taken along with the growth parameters. The highest light interception from 42 - 105 days after planting (DAP) among the Arachis spp. was recorded by Samnut 10, while at 42 - 87 DAP, plant density of75 cm×20 cmhad the highest light interception. Dry matter production increased with light interception and was highest at 105 DAP when light interception was between 55% and 60% for all Arachis varieties and all plant densities. In terms of pod weight and grain yield, Samnut 10 performed better than Samnut 21 and also recorded the highest Radiation Use Efficiency (RUE) for pod, seed and total dry matter. However, Arachis pintoi, a sterile and forage plant with slower growth rate served as a cover crop capable of replenishing soil nutrients and physical properties.展开更多
The investigation of radiation-absorption,chemical reaction,Hall and ion-slip impacts on unsteady MHD free convective laminar flow of an incompressible viscous,electrically conducting and heat generation/absorbing flu...The investigation of radiation-absorption,chemical reaction,Hall and ion-slip impacts on unsteady MHD free convective laminar flow of an incompressible viscous,electrically conducting and heat generation/absorbing fluid enclosed with a semi-infinite porous plate within a rotating frame has been premeditated.The plate is assumed to be moving with a constant velocity in the direction of fluid movement.A uniform transverse magnetic field is applied at right angles to the porous surface,which is absorbing the fluid with a suction velocity changing with time.The non-dimensional governing equations for present investigation are solved analytically making use of two term harmonic and non-harmonic functions.The graphical results of velocity,temperature and concentration distributions on the analytical solutions are displayed and discussed with reference to pertinent parameters.It is found that the velocity profiles decreased with an increasing in Hartmann number,rotation parameter,the Schmidt number,heat source parameter,while it increased due to an increase in permeability parameter,radiation-absorption parameter,Hall and ion slip parameters.However,the temperature profile is an increasing function of radiation-absorption parameter,whereas an increase in chemical reaction parameter,the Schmidt number Sc or frequency of oscillations decrease the temperature profile on cooling.Also,it is found that the concentration profile is decreased with an escalating in the Schmidt number or the chemical reaction parameter.展开更多
The γ-ray radiation will speed up the discharge of the storedcharge in nonvolatile MNOS structure. The radiation absorptionmechanism to enhance the discharge is discussed. A direct radiationemission model from the in...The γ-ray radiation will speed up the discharge of the storedcharge in nonvolatile MNOS structure. The radiation absorptionmechanism to enhance the discharge is discussed. A direct radiationemission model from the interface traps distributing both in energylevel and in space is given. The theoretical results based on thismodel are in good agreement with experimental measurements.展开更多
The effects of variable electrical conductivity and radiation absorption on high-speed MHD (Magnetohydrodynamics) free convective flow past an exponential accelerated inclined plate with higher order chemical reaction...The effects of variable electrical conductivity and radiation absorption on high-speed MHD (Magnetohydrodynamics) free convective flow past an exponential accelerated inclined plate with higher order chemical reaction have been investigated. The electrical conductivity has been considered as a function of temperature. The chemical reaction has also been considered as the higher order. The usual transformations have been used to obtain the coupled dimensionless momentum, energy and concentration equations. Then the obtained non-dimensional partial differential equations have been solved numerically by explicit finite difference method. For excellent accuracy, stability and convergence test have been carried out. A computer program Compaq Visual FORTRAN 6.6a has been used to calculate the numerical results. The obtained numerical results concerned with the fluid velocity, temperature, concentration, concerned with skin friction, Nusselt number, Sherwood number, streamlines and isotherms are imprinted graphically by Tecplot and discussed in details. It is noticed that increasing of magnetic parameter increases the temperature and decreases the velocity, skin friction and Nusselt number. It is also observed that the temperature profile is increasing with the increasing values of Dufour number. However, the order of the chemical reaction increases the concentration profile.展开更多
Theoretical calculations which account for the complete absorption and intensity for the optical radiation He I (λ= 5875 ?) spectral line with fine structure of the transition 23P2,1,0 - 33D3,2,1 during He nanosecond...Theoretical calculations which account for the complete absorption and intensity for the optical radiation He I (λ= 5875 ?) spectral line with fine structure of the transition 23P2,1,0 - 33D3,2,1 during He nanosecond discharge are presented. For different values of the absorption parameter (χ 0?), the absorption quantity A of the three components distorted as a result of reabsorption multiple process has been numerically obtained and graphically presented. The theoretical results for small values of χ 0? (≤4) give a good agreement with the experimental data in literature.展开更多
When the thermal environment is under heated conditions, short-wavelength solar radiation shows a strong influence on the human body and the heat is accumulated in the human body. In order to demonstrate the effect of...When the thermal environment is under heated conditions, short-wavelength solar radiation shows a strong influence on the human body and the heat is accumulated in the human body. In order to demonstrate the effect of the short-wavelength solar radiation absorptivity of clothing on physiological temperature in an outdoor space, the relationship between the thermal environment evaluation index, ETFe, and the thermal sensory perceptions of the human body was investigated. A significant temperature difference of 2.7°C was shown for an ETFe that was thermally neutral (neither hot nor cold). The effect of short-wavelength solar radiation absorptivity was strongly apparent in ETFe when direct solar radiation was strong and in warmer outdoor spaces. In an outdoor space where the effect of the sky factor and albedo was strong, the setting of the short-wavelength solar radiation absorptivity was demonstrated to greatly impact the estimation of perceived and physiological temperature. When interviewing subjects on clothing in an outdoor space, it is essential to obtain the hue of clothing.展开更多
Lithium-and manganese-rich(LMR)oxide cathode materials are among the most attractive candidates for next-generation energy-storage materials owing to their anomalous capacity.However,severe Mn dissolution that occurs ...Lithium-and manganese-rich(LMR)oxide cathode materials are among the most attractive candidates for next-generation energy-storage materials owing to their anomalous capacity.However,severe Mn dissolution that occurs during long-term cycling,which leads to capacity loss,hinders their application prospects.In this study,nanoscale AlPO_(4)-coated Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LMR@APO)with significantly enhanced electrochemical performance is successfully synthesized using a simple and effective sol–gel method to mitigate Mn dissolution and suppress local structural distortion at high voltages.Because of the complex evolution of the structure and oxidation state of LMR materials during electrochemical cycling,observing and analyzing them using traditional single characterization methods may be difficult.Therefore,we combine various synchrotron-based characterization techniques to conduct a detailed analysis of the electronic and coordination structures of the cathode material from the surface to the bulk.Synchrotron-based hard and soft X-ray spectroscopies are integrated to investigate the differences in O and Mn evolution between the surfaces and bulk of the cathode.Advanced synchrotron-based transmission X-ray microscopy combined with X-ray near-edge absorption-structure technology is utilized to visualize the two-dimensional nanometer-scale reactivity of the LMR cathode.The AlPO_(4)-coating layer can stabilize the surface structure of the LMR material,effectively alleviating irreversible oxygen release on the surface and preventing the dissolution of Mn^(2+)at the interface caused by side reactions after a long cycle.Therefore,the spatial reaction uniformity of Mn is enhanced by the AlPO_(4)-coating layer,and rapid capacity decay caused by Mn deactivation is prevented.The AlPO_(4)-coating method is a facile modification strategy for high-performance LMR materials.展开更多
The aim of this paper is to achieve the radio frequency stealth(RFS) during the course of tracking by controlling the radiation energy and the interval of a radar. Firstly, we build the model of probability of interce...The aim of this paper is to achieve the radio frequency stealth(RFS) during the course of tracking by controlling the radiation energy and the interval of a radar. Firstly, we build the model of probability of interception with the once radiation during the course of tracking. Secondly, we establish the model of the cumulative probability of interception to describe the effect of RFS throughout the tracking process and obtain two solutions that are minimizing the probability of interception and the radiation times to reduce the cumulative probability of interception. Thirdly, we propose a self-adapting radiation energy control method(SARE)to minimize the probability of interception. Fourthly, we propose a self-adapting radiation interval control method(SARI) to minimize radiation times. Fifthly, combining SARE with SARI, we propose a SARE-SARI control method(SAEI) during the course of tracking.Finally, we compare SAEI with two others by simulation, and the results show the effect of RFS of SAEI is better than the other two,but we have to make a trade-off between the ability of RFS and the effect of tracking.展开更多
Healthy and livable living environments,as well as anti-electromagnetic(EM)radiation buildings,are the long-term goals of human beings.The introduction of advanced EM wave absorbing materials into buildings is one of ...Healthy and livable living environments,as well as anti-electromagnetic(EM)radiation buildings,are the long-term goals of human beings.The introduction of advanced EM wave absorbing materials into buildings is one of the most feasible ways to address the increasing EM pollution in building spaces.High-efficiency,broadband,low-cost and good building performance EM wave absorbing materials,as an important support in the field of sustainable building,has gradually become the hotspot research.Here,we review the research progress of building materials with EM wave absorption functions,and comb their classification,including cement,concrete,ceramics,and prefabs,especially highlighting the advanced coating materials.We objectively outline and evaluate the latest technology of building materials with EM wave absorption performance,and discuss the main problems and bottlenecks,highlighting potential research opportunities.展开更多
Relationship between atomic local structures and Curie temperature of NdFeB permanent magnets was investigated semi-quantitatively using synchrotron radiation technique. Fe K-edge X-ray absorption spectroscopy(XAS) wa...Relationship between atomic local structures and Curie temperature of NdFeB permanent magnets was investigated semi-quantitatively using synchrotron radiation technique. Fe K-edge X-ray absorption spectroscopy(XAS) was employed to study the local structure of Fe atoms for samples before and after doping Dy, Tb or Gd. It is found that the bond lengths and coordination numbers are changed. Thus, the exchange interaction between Fe atoms increases with Dy, Tb or Gd doping, resulting in the improvement of Curie temperature of NdFeB permanent magnets. The doping effect is proven by experimental measurement of the magnetic properties. Microstructural characterization using scanning electron microscopy(SEM) was also used to further analyze the effect of different rare earth elements doping on Curie temperature of NdFeB permanent magnets.展开更多
Presence of different terms with various values can alter the thermal behavior of the nanofluids flow over porous surfaces.The aim of this research is to study the influence of nanoparticles volume fraction,nanopartic...Presence of different terms with various values can alter the thermal behavior of the nanofluids flow over porous surfaces.The aim of this research is to study the influence of nanoparticles volume fraction,nanoparticles type,suction or injection,the heat generation or absorption,the Eckert number,thermal and velocity slip parameters,and radiation on the velocity and temperature fields on the flow and heat transfer over a porous flat plate.Four different types of nanoparticles including metal nanoparticles (Cu),metal oxide nanoparticles (Al2O3) and carbon-based nanomaterials (MWCNTs and SWCNTs) which were dispersed in the water (as based fluid) are studied.The governing equations are converted into the ordinary differential equations using similarity solution and solved numerically by the RKF45 algorithm.The results of the simulations showed a contradiction with the results of other researchers who expressed that using nanoparticles with higher thermal conductivity and volume fraction led to increasing heat transfer rate in nanofluids;this study proves that,in some cases,boosting the volume fraction of nanoparticles has a potential to decrease the heat transfer rate due to significant changes in values of some parameters including radiation,heat generation,and viscous dissipation.展开更多
As a reentry vehicle traveling through atmosphere with a very high Mach number, the ultraviolet, visible light and infrared signatures, produced from its head shock-wave layer and wake, are the foundation of detecting...As a reentry vehicle traveling through atmosphere with a very high Mach number, the ultraviolet, visible light and infrared signatures, produced from its head shock-wave layer and wake, are the foundation of detecting and identifying for the ground monitoring and the antimissile controlling and guiding system. At the same time, the gas layer radiation is also an important source of heating flux to the wall. The absorption coefficients of high temperature gas in the head shock-wave layer are basic parameters for calculations of the target ultraviolet, visible light and infrared optical characteristics, the heat shield and the aerodynamic flow-field coupling with thermal radiation. In this paper, after the thermo-chemical non-equilibrium phenomenon of hypersonic rarefied flow during reentry stage is discussed, a three-temperature model (electronic temperature Te, vibrational temperature TV and rotational-transitional temperature TR) is used to characterize energy levels population of non-equilibrium air species in the shock-wave layer and the contribution of 11-species such as N2, N2+, N, N+, O2, O2+, O, O+, NO, NO+ and e- is directly calculated by using the atomic and molecular radiation theory. At last, a model is established, which calculates the absorption coefficient of high-temperature equilibrium or non-equilibrium air. The results are in good agreement with experimentally measured data in the visible region, but are slightly bad in the ultraviolet and infrared regions.展开更多
Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmental biology.A method based on synchrotron radiation X-ray fluorescence and X-ray absorp...Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmental biology.A method based on synchrotron radiation X-ray fluorescence and X-ray absorption near edge structure spectroscopy was established to analyze the sulfur concentration and speciation in mature camphor tree leaves （CTLs）,which were sampled from 5 local fields in Shanghai,China.Annual SO2 concentration,SO42-concentration in atmospheric particulate,SO42-and sulfur concentration in soil were also analyzed to explore the relationship between ambient sulfur sources and the sulfur nutrient cycling in CTLs.Total sulfur concentration in mature camphor tree leaves was 766-1704 mg/kg.The mainly detected sulfur states and their corresponding compounds were ＋6 （sulfate,include inorganic sulfate and organic sulfate）,＋5.2 （sulfonate）,＋2.2 （suloxides）,＋0.6 （thiols and thiothers）,＋0.2 （organic sulfides）.Total sulfur concentration was strongly correlated with sulfate proportion with a linear correlation coefficient up to 0.977,which suggested that sulfur accumulated in CTLs as sulfate form.Reduced sulfur compounds （organic sulfides,thiols,thioethers,sulfoxide and sulfonate） assimilation was sufficed to meet the nutrient requirement for growth at a balanced level around 526 mg/kg.The sulfate accumulation mainly caused by atmospheric sulfur pollution such as SO2 and airborne sulfate particulate instead of soil contamination.From urban to suburb place,sulfate in mature CTLs decreased as the atmospheric sulfur pollution reduced,but a dramatic increase presented near the seashore,where the marine sulfate emission and maritime activity pollution were significant.The sulfur concentration and speciation in mature CTLs effectively represented the long-term biological accumulation of atmospheric sulfur pollution in local environment.展开更多
文摘In this paper, we analyze the spectral behavior(optical thickness, shape and linewidth) of laser radiation absorption under the correlation heating of ions in an ultracold plasma. The Voigt formula is used to find the absorption coefficient.The spectral line width is shown to grow with time while the optical thickness reduces. Our modeling results are in good agreement with the experimental findings reported in the literature.
文摘Soybean [Glycine max (L.) Merr.] growth rate and grain yield are modified by the interception and solar radiation use efficiency. Thus, it is desirable that the most of plant photosynthetic structures intercepting solar radiation in order to have increment in carbon fixation and reflection on growth and yield. The goal of this study was to assess if soybean cultivars differ in grain yield in relation to solar radiation interception. Four soybean cultivars were evaluated at stages V6, V9, R2, R4, R6 and R8. To determine the photosynthetically active radiation interception by the canopy, the plants were divided into two parts (upper and lower strata). For grain yield components, the plants were divided into three parts (upper, middle and lower thirds). Of the photosynthetically active radiation intercepted by the vegetative canopy at the reproductive stages, the maximum observed intercept was 5.2% in the lower stratum of the plants. The number of infertile nodes increased in the lower third of plants due to low interception of solar radiation in this plant region. Thus, the soybean cultivars more efficient in intercepting photosynthetically active radiation inside the vegetative canopy showed higher grain yields.
文摘A perfect solution to the present natural convective flow problem of a vertical transfinite plate owing to the impulsive motion in the ubiety of first ordered chemical reaction, radiation absorption, radiation, Newtonian heating and species concentration in its plane is evolved by applying the method of Laplace transforms in closed form at the plate. Exact results for velocity, temperature, concentration fields are prevailed and expressions for heat and mass transfer rates are also found. The effects are analyzed for the respective invariables for both ammonia and water vapor.
文摘In order to acquire a broadband absorption spectrum in a single shot,a compact radiation source was developed by using a Z-pinch type electric discharge.This paper presents the mechanical and electrical construction of the source,as well as its electrical and optical characteristics,including the intense continuum of radiation emitted by the source in the UV and visible spectral range.It also shows that the compactness of the source allows direct coupling with the probed medium,enabling broadband absorption measurement in the spectral range of 200e300 nm without use of an optical fiber which strongly attenuates the light in the short wavelength range.Concretely,thanks to this source,broadband spectral absorption of NO molecules around 210 nm and that of OH molecules around 310 nm were recorded in this direct coupling arrangement.Copper atom spectral absorption around 325 nm of the peripheral cold zones of an intense transient arc was also recorded.
基金Supported by the Korea Ministry of Trade,Industry and Energy,"Energy Technology Development Work in 2017",Project No.20172010105570
文摘A three-dimensional mathematical model is developed to examine the flow of nonlinear thermal radiation Oldroyd-B nanofluid past a bidirectional linearly stretched surface in a porous medium. The flow is induced by temperature dependent thermal conductivity, chemical reaction and convective heat and mass conditions. Novel characteristics of Brownian motion and thermophoresis are accompanied by magnetohydrodynamic and heat generation/absorption.Self-similar transformations are employed to convert the system of nonlinear partial differential equations to a system of ordinary differential equations with high nonlinearity and are solved by strong analytic technique named as Homotopy Analysis method(HAM). Effects of varied arising parameters on involved distributions are reflected through graphical illustrations. From this study, it is perceived that strong magnetic field hinders the fluid's motion and leads to rise in temperature that eventually lowers heat transfer rate from the surface. Further, decrease in heat transfer rate is also observed for enhanced values of thermal radiation parameter. To validate our results, a comparison with already published paper in limiting case is also given and results are found in excellent oncurrence; hence reliable results are being presented.
基金supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,China
文摘The effects of color centers＇ absorption on fibers and interferometric fiber optical gyroscopes（IFOGs） are studied in the paper. The irradiation induced attenuation（RIA） spectra of three types of polarization-maintaining fibers（PMFs）, i.e.,P-doped, Ge-doped, and pure silica, irradiated at 100 Gy and 1000 Gy are measured in a wavelength range from 1100 nm to1600 nm and decomposed according to the Gaussian model. The relationship of the color centers absorption intensity with radiation dose is investigated based on a power model. Furthermore, the effects of all color centers＇ absorption on RIA and mean wavelength shifts（MWS） at 1300 nm and 1550 nm are discussed respectively. Finally, the random walk coefficient（RWC） degradation induced from RIA and the scale factor error induced by MWS of the IFOG are simulated and tested at a wavelength of 1300 nm. This research will contribute to the applications of the fibers in radiation environments.
基金Project supported by the National Natural Science Foundation of China (Grant No 60777017)the National Basic Research Program of China (Grant No 2007CB310405)+1 种基金China Postdoctoral Scientists Foundation (Grant No 20060390323)K. C.Wong Education Foundation, Hong Kong, China
文摘The excitonic optical absorption of GaAs bulk semiconductors under intense terahertz （THz） radiation is investigated numerically. The method of solving initial-value problems, combined with the perfect matched layer technique, is used to calculate the optical susceptibility. In the presence of a driving THz field, in addition to the usual exciton peaks, 2p replica of the dark 2p exciton and even-THz-photon-sidebands of the main exciton resonance emerge in the continuum above the band edge and below the main exciton resonance. Moreover, to understand the shift of the position of the main exciton peak under intense THz radiation, it is necessary to take into consideration both the dynamical Franz-Keldysh effect and ac Stark effect simultaneously. For moderate frequency fields, the main exciton peak decreases and broadens due to the field-induced ionization of the excitons with THz field increasing. However, for high frequency THz fields, the characteristics of the exciton recur even under very strong THz fields, which accords with the recent experimental results qualitatively.
文摘The production of grain legumes is becoming a popular practice in the humid south western Nigeria. Apart from the decreasing trends observed in rainfall amount and duration as a result of climate change, solar radiation interception also constitutes a limitation to crop production because of persistent cloud cover. A trial was conducted at the University of Ibadan experimental site to determine the effect of different plant densities of Arachis spp. on solar radiation interception, dry matter production and yield in Ibadan, Nigeria with the aim of ascertaining the best practice for groundnut production in the zone. The treatments were three plant spacings (60 cm×20 cm,75 cm×20 cmand75 cm×40 cm), and three Arachis varieties (Samnut 10, Samnut 21 and Pintoi) arranged in a split plot, randomized complete block design with Arachis varieties as the main plot while plant densities formed the subplot and replicated three times. Growth parameters (number of leaves, dry leaf weight and dry stem weight) were measured at two weeks interval while yield parameters (number of pods, dry pod weight, dry seed weight and total dry matter) were determined at harvest. Intercepted radiation by plants (PAR) was also taken along with the growth parameters. The highest light interception from 42 - 105 days after planting (DAP) among the Arachis spp. was recorded by Samnut 10, while at 42 - 87 DAP, plant density of75 cm×20 cmhad the highest light interception. Dry matter production increased with light interception and was highest at 105 DAP when light interception was between 55% and 60% for all Arachis varieties and all plant densities. In terms of pod weight and grain yield, Samnut 10 performed better than Samnut 21 and also recorded the highest Radiation Use Efficiency (RUE) for pod, seed and total dry matter. However, Arachis pintoi, a sterile and forage plant with slower growth rate served as a cover crop capable of replenishing soil nutrients and physical properties.
文摘The investigation of radiation-absorption,chemical reaction,Hall and ion-slip impacts on unsteady MHD free convective laminar flow of an incompressible viscous,electrically conducting and heat generation/absorbing fluid enclosed with a semi-infinite porous plate within a rotating frame has been premeditated.The plate is assumed to be moving with a constant velocity in the direction of fluid movement.A uniform transverse magnetic field is applied at right angles to the porous surface,which is absorbing the fluid with a suction velocity changing with time.The non-dimensional governing equations for present investigation are solved analytically making use of two term harmonic and non-harmonic functions.The graphical results of velocity,temperature and concentration distributions on the analytical solutions are displayed and discussed with reference to pertinent parameters.It is found that the velocity profiles decreased with an increasing in Hartmann number,rotation parameter,the Schmidt number,heat source parameter,while it increased due to an increase in permeability parameter,radiation-absorption parameter,Hall and ion slip parameters.However,the temperature profile is an increasing function of radiation-absorption parameter,whereas an increase in chemical reaction parameter,the Schmidt number Sc or frequency of oscillations decrease the temperature profile on cooling.Also,it is found that the concentration profile is decreased with an escalating in the Schmidt number or the chemical reaction parameter.
文摘The γ-ray radiation will speed up the discharge of the storedcharge in nonvolatile MNOS structure. The radiation absorptionmechanism to enhance the discharge is discussed. A direct radiationemission model from the interface traps distributing both in energylevel and in space is given. The theoretical results based on thismodel are in good agreement with experimental measurements.
文摘The effects of variable electrical conductivity and radiation absorption on high-speed MHD (Magnetohydrodynamics) free convective flow past an exponential accelerated inclined plate with higher order chemical reaction have been investigated. The electrical conductivity has been considered as a function of temperature. The chemical reaction has also been considered as the higher order. The usual transformations have been used to obtain the coupled dimensionless momentum, energy and concentration equations. Then the obtained non-dimensional partial differential equations have been solved numerically by explicit finite difference method. For excellent accuracy, stability and convergence test have been carried out. A computer program Compaq Visual FORTRAN 6.6a has been used to calculate the numerical results. The obtained numerical results concerned with the fluid velocity, temperature, concentration, concerned with skin friction, Nusselt number, Sherwood number, streamlines and isotherms are imprinted graphically by Tecplot and discussed in details. It is noticed that increasing of magnetic parameter increases the temperature and decreases the velocity, skin friction and Nusselt number. It is also observed that the temperature profile is increasing with the increasing values of Dufour number. However, the order of the chemical reaction increases the concentration profile.
文摘Theoretical calculations which account for the complete absorption and intensity for the optical radiation He I (λ= 5875 ?) spectral line with fine structure of the transition 23P2,1,0 - 33D3,2,1 during He nanosecond discharge are presented. For different values of the absorption parameter (χ 0?), the absorption quantity A of the three components distorted as a result of reabsorption multiple process has been numerically obtained and graphically presented. The theoretical results for small values of χ 0? (≤4) give a good agreement with the experimental data in literature.
文摘When the thermal environment is under heated conditions, short-wavelength solar radiation shows a strong influence on the human body and the heat is accumulated in the human body. In order to demonstrate the effect of the short-wavelength solar radiation absorptivity of clothing on physiological temperature in an outdoor space, the relationship between the thermal environment evaluation index, ETFe, and the thermal sensory perceptions of the human body was investigated. A significant temperature difference of 2.7°C was shown for an ETFe that was thermally neutral (neither hot nor cold). The effect of short-wavelength solar radiation absorptivity was strongly apparent in ETFe when direct solar radiation was strong and in warmer outdoor spaces. In an outdoor space where the effect of the sky factor and albedo was strong, the setting of the short-wavelength solar radiation absorptivity was demonstrated to greatly impact the estimation of perceived and physiological temperature. When interviewing subjects on clothing in an outdoor space, it is essential to obtain the hue of clothing.
基金supported by the National Key R&D Program of China(No.2022YFB3807700)National Natural Science Foundation of China(Nos.U20A20248 and 52372247)+1 种基金Shanghai Pujiang Programme(23PJD110)Science and Technology Commission of Shanghai Municipality(No.18DZ2280800)。
文摘Lithium-and manganese-rich(LMR)oxide cathode materials are among the most attractive candidates for next-generation energy-storage materials owing to their anomalous capacity.However,severe Mn dissolution that occurs during long-term cycling,which leads to capacity loss,hinders their application prospects.In this study,nanoscale AlPO_(4)-coated Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LMR@APO)with significantly enhanced electrochemical performance is successfully synthesized using a simple and effective sol–gel method to mitigate Mn dissolution and suppress local structural distortion at high voltages.Because of the complex evolution of the structure and oxidation state of LMR materials during electrochemical cycling,observing and analyzing them using traditional single characterization methods may be difficult.Therefore,we combine various synchrotron-based characterization techniques to conduct a detailed analysis of the electronic and coordination structures of the cathode material from the surface to the bulk.Synchrotron-based hard and soft X-ray spectroscopies are integrated to investigate the differences in O and Mn evolution between the surfaces and bulk of the cathode.Advanced synchrotron-based transmission X-ray microscopy combined with X-ray near-edge absorption-structure technology is utilized to visualize the two-dimensional nanometer-scale reactivity of the LMR cathode.The AlPO_(4)-coating layer can stabilize the surface structure of the LMR material,effectively alleviating irreversible oxygen release on the surface and preventing the dissolution of Mn^(2+)at the interface caused by side reactions after a long cycle.Therefore,the spatial reaction uniformity of Mn is enhanced by the AlPO_(4)-coating layer,and rapid capacity decay caused by Mn deactivation is prevented.The AlPO_(4)-coating method is a facile modification strategy for high-performance LMR materials.
基金supported by the National Natural Science Foundation of China(61472441)
文摘The aim of this paper is to achieve the radio frequency stealth(RFS) during the course of tracking by controlling the radiation energy and the interval of a radar. Firstly, we build the model of probability of interception with the once radiation during the course of tracking. Secondly, we establish the model of the cumulative probability of interception to describe the effect of RFS throughout the tracking process and obtain two solutions that are minimizing the probability of interception and the radiation times to reduce the cumulative probability of interception. Thirdly, we propose a self-adapting radiation energy control method(SARE)to minimize the probability of interception. Fourthly, we propose a self-adapting radiation interval control method(SARI) to minimize radiation times. Fifthly, combining SARE with SARI, we propose a SARE-SARI control method(SAEI) during the course of tracking.Finally, we compare SAEI with two others by simulation, and the results show the effect of RFS of SAEI is better than the other two,but we have to make a trade-off between the ability of RFS and the effect of tracking.
基金supported by National Natural Science Foundation of China(Nos.51977009,11774027,52177014 and 51132002)。
文摘Healthy and livable living environments,as well as anti-electromagnetic(EM)radiation buildings,are the long-term goals of human beings.The introduction of advanced EM wave absorbing materials into buildings is one of the most feasible ways to address the increasing EM pollution in building spaces.High-efficiency,broadband,low-cost and good building performance EM wave absorbing materials,as an important support in the field of sustainable building,has gradually become the hotspot research.Here,we review the research progress of building materials with EM wave absorption functions,and comb their classification,including cement,concrete,ceramics,and prefabs,especially highlighting the advanced coating materials.We objectively outline and evaluate the latest technology of building materials with EM wave absorption performance,and discuss the main problems and bottlenecks,highlighting potential research opportunities.
基金financially supported by State High-Tech Development Plan (No. 2011AA061901)the TechnologyLanding Project of Jiangxi Province (No.KJLD13041)+1 种基金the Science and Technology Plan of Ganzhou (No.[2014]131)the Research Support Plan of Jiangxi University of Science and Technology(No. jxxjbs15001)
文摘Relationship between atomic local structures and Curie temperature of NdFeB permanent magnets was investigated semi-quantitatively using synchrotron radiation technique. Fe K-edge X-ray absorption spectroscopy(XAS) was employed to study the local structure of Fe atoms for samples before and after doping Dy, Tb or Gd. It is found that the bond lengths and coordination numbers are changed. Thus, the exchange interaction between Fe atoms increases with Dy, Tb or Gd doping, resulting in the improvement of Curie temperature of NdFeB permanent magnets. The doping effect is proven by experimental measurement of the magnetic properties. Microstructural characterization using scanning electron microscopy(SEM) was also used to further analyze the effect of different rare earth elements doping on Curie temperature of NdFeB permanent magnets.
文摘Presence of different terms with various values can alter the thermal behavior of the nanofluids flow over porous surfaces.The aim of this research is to study the influence of nanoparticles volume fraction,nanoparticles type,suction or injection,the heat generation or absorption,the Eckert number,thermal and velocity slip parameters,and radiation on the velocity and temperature fields on the flow and heat transfer over a porous flat plate.Four different types of nanoparticles including metal nanoparticles (Cu),metal oxide nanoparticles (Al2O3) and carbon-based nanomaterials (MWCNTs and SWCNTs) which were dispersed in the water (as based fluid) are studied.The governing equations are converted into the ordinary differential equations using similarity solution and solved numerically by the RKF45 algorithm.The results of the simulations showed a contradiction with the results of other researchers who expressed that using nanoparticles with higher thermal conductivity and volume fraction led to increasing heat transfer rate in nanofluids;this study proves that,in some cases,boosting the volume fraction of nanoparticles has a potential to decrease the heat transfer rate due to significant changes in values of some parameters including radiation,heat generation,and viscous dissipation.
基金Chinese N ational Science Fund for Distinguished Young Scholars ( No.5 972 5 6 17) the National Natural Science Foun-dation of China ( No.5 980 6 0 0 3) and F ok Ying Tung Education Foundation ( No.710 5 3)
文摘As a reentry vehicle traveling through atmosphere with a very high Mach number, the ultraviolet, visible light and infrared signatures, produced from its head shock-wave layer and wake, are the foundation of detecting and identifying for the ground monitoring and the antimissile controlling and guiding system. At the same time, the gas layer radiation is also an important source of heating flux to the wall. The absorption coefficients of high temperature gas in the head shock-wave layer are basic parameters for calculations of the target ultraviolet, visible light and infrared optical characteristics, the heat shield and the aerodynamic flow-field coupling with thermal radiation. In this paper, after the thermo-chemical non-equilibrium phenomenon of hypersonic rarefied flow during reentry stage is discussed, a three-temperature model (electronic temperature Te, vibrational temperature TV and rotational-transitional temperature TR) is used to characterize energy levels population of non-equilibrium air species in the shock-wave layer and the contribution of 11-species such as N2, N2+, N, N+, O2, O2+, O, O+, NO, NO+ and e- is directly calculated by using the atomic and molecular radiation theory. At last, a model is established, which calculates the absorption coefficient of high-temperature equilibrium or non-equilibrium air. The results are in good agreement with experimentally measured data in the visible region, but are slightly bad in the ultraviolet and infrared regions.
基金supported by the National Natural Science Foundation of China(No.11079049,11005141,10775150)the Major Project of Knowledge Innovation Program of Chinese Academy of Sciences(No.KJCX3.SYW.N3)
文摘Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmental biology.A method based on synchrotron radiation X-ray fluorescence and X-ray absorption near edge structure spectroscopy was established to analyze the sulfur concentration and speciation in mature camphor tree leaves （CTLs）,which were sampled from 5 local fields in Shanghai,China.Annual SO2 concentration,SO42-concentration in atmospheric particulate,SO42-and sulfur concentration in soil were also analyzed to explore the relationship between ambient sulfur sources and the sulfur nutrient cycling in CTLs.Total sulfur concentration in mature camphor tree leaves was 766-1704 mg/kg.The mainly detected sulfur states and their corresponding compounds were ＋6 （sulfate,include inorganic sulfate and organic sulfate）,＋5.2 （sulfonate）,＋2.2 （suloxides）,＋0.6 （thiols and thiothers）,＋0.2 （organic sulfides）.Total sulfur concentration was strongly correlated with sulfate proportion with a linear correlation coefficient up to 0.977,which suggested that sulfur accumulated in CTLs as sulfate form.Reduced sulfur compounds （organic sulfides,thiols,thioethers,sulfoxide and sulfonate） assimilation was sufficed to meet the nutrient requirement for growth at a balanced level around 526 mg/kg.The sulfate accumulation mainly caused by atmospheric sulfur pollution such as SO2 and airborne sulfate particulate instead of soil contamination.From urban to suburb place,sulfate in mature CTLs decreased as the atmospheric sulfur pollution reduced,but a dramatic increase presented near the seashore,where the marine sulfate emission and maritime activity pollution were significant.The sulfur concentration and speciation in mature CTLs effectively represented the long-term biological accumulation of atmospheric sulfur pollution in local environment.
