Water solubility enhancements of pyrene by both single-surfactant and mixed-surfactant solutions were compared and evaluated. The solubility of pyrene in water was greatly enhanced by each of Triton X-100 (TX100), Tri...Water solubility enhancements of pyrene by both single-surfactant and mixed-surfactant solutions were compared and evaluated. The solubility of pyrene in water was greatly enhanced by each of Triton X-100 (TX100), Triton X-405 (TX405), Brij 35 and SDS, in which the water solubility enhancements increased with increasing surfactant concentrations. The extent of solubility enhancements at surfactant concentrations below. the CMC is the order of TX100 > Brij 35 > TX405 > SDS; the sequence at surfactant concentrations above the CMC is TX100 > Brij 35 > SDS > TX405. Pyrene was solubilized synergistically by anionic-nonionic mixed surfactant solutions, especially at low surfactant concentrations. The synergistic power of the mixed surfactants is SDS-TX405 > SDS-Brij 35 > SDS-TX100. The synergism as noted is attributed to increasing Kmc and/or decreasing the CMC of the mixed surfactant solution. For SDS-TX405 and SDS-Brij 35 mixed surfactant solutions, an increase in Kmc is coupled with a decrease in the CMC; for SDS-TX100, only a decreased in the CMC value is noted. Mixed-surfactant solutions may improve the performance of the surfactant-enhanced remediation (SER) of soils by increasing the bioavailability and biodegradation of non-aqueous-phase organic pollutants and reducing the level of surfactant pollution and remediation expenses.展开更多
Runoff and soil losses from agricultural fields are investigated as major nonpoint sources of phosphorus (P) entering lakes of Eastern China. There is relatively little information on P transport from ricefield and cr...Runoff and soil losses from agricultural fields are investigated as major nonpoint sources of phosphorus (P) entering lakes of Eastern China. There is relatively little information on P transport from ricefield and cropland of Lake Taihu watershed in Eastern China. Soil and P in surface runoff from a series of plots in the watershed were evaluated under simulated rainfall conditions. The objectives of this study were to evaluate the effects of crop cover, slope, and fertilizer application on P concentrations in surface runoff and eroded soil. Accumulated sediment yields varied from 7.1 to 300 g/m2 for croplands, depending on management practices. For all experiment plots, weighted average concentrations of total-P (TP), dissolved P (DP) and particulate P (PP) are much higher than 0.02 mg/L, the limiting concentration for lake water. This result showed the potential contamination of lake water from agricultural surface runoff. Accumulated TP losses were 3.8 and 18.8 mg/m2 for ricefield and cropland, respectively. The estimated annual loss of TP was 0.74 kg/(hm2 · a) for cropland. Most of P loss is in the PP form, which accounts for more than 90% of TP loss for cropland.展开更多
Besides competing with algae for light and mineral nutrients (i. e. N, P, etc.), the root system of Acorus tatarinowii excretes some chemical substances, which injure and eliminate alga cells, to inhibit the growth of...Besides competing with algae for light and mineral nutrients (i. e. N, P, etc.), the root system of Acorus tatarinowii excretes some chemical substances, which injure and eliminate alga cells, to inhibit the growth of the algae. When the algae cells were treated in 'A. tatarinowii water', some of the chlorophyll a were destroyed and the photosynthetic rate of algae decreased markedly and the ability of alga cells to deoxidize triphenyltetrazolium chloride (TTC) reduced greatly. Then alga cells turned from bright red to bluish green under fluorescence microscope. These showed that the allelopathic effects of A. tatarinowii on algae were obvious and planting A. tatarinowii can control some green algae. The experiment on the extractions of the secretions of the root system showed that the inhibitory effect had a concentration effect. If the concentration of the root secretion was below 30 μl/disc, the inhibitory rate was negative; if it was over 45 μl/disc, the inhibitory rate was positive. This proved that the influence of the root secretion on the same acceptor was a kind of concentration effect. When the concentration of the root secretion was low, it promoted the growth of algae; when the concentration reached a definite threshold value, it restrained the growth of algae. In present case, the threshold value was between 30 μl/disc and 45 μl/disc.展开更多
The decolorization of Direct Black 22 by Aspergillus ficuum has been studied. It was found that Aspergillus ficuum could effectively decolorize Direct Black 22 especially when grown as pelleted mycelia. Results showed...The decolorization of Direct Black 22 by Aspergillus ficuum has been studied. It was found that Aspergillus ficuum could effectively decolorize Direct Black 22 especially when grown as pelleted mycelia. Results showed that the media containing Direct Black 22 at 50 mg/L could be decolorized by 98.05% of the initial color in 24 h. The optimum pH and temperature of decolorization are 4.0 and 33 °C respectively. Aeration was quite beneficial to decolorization. Medium composition and the concentration of Direct Black 22 could affect the rate of decolorization. The dye degraded products assayed by UV-visible spectrophotometer and macroscopic observation showed that the decolorization of Direct Black 22 by mycelial pellets includes two important processes: bioadsorption and biodegradation. The degradation experiment agree with the Michaelis-Menten kinetics equation.展开更多
The application of atrazine in China during the last ten years has led to some environmental problems. In this paper, the multimedia model of atrazine in soil-plant-groundwater system at Baiyangdian Lake area in North...The application of atrazine in China during the last ten years has led to some environmental problems. In this paper, the multimedia model of atrazine in soil-plant-groundwater system at Baiyangdian Lake area in Northern China was established using a fugacity approach, and verified with observed values. The model involved 7 environmental compartments which are air, groundwater, soil, corn roots, corn stem, corn leaf and kernel of corn. The results showed that the relative errors between calculated and observed values have a mean value of 24.7%, the highest value is 48% and the lowest value is 1.4%. All these values indicated that this multimedia model can be used to simulate the environmental fate of atrazine. Both the calculated and observed values of concentrations of atrazine in plant compartments are in the following order: in corn roots > in corn stem > in kernel of corn > in corn leaf, it exhibited a good regularity. The prediction results indicated that concentrations of atrazine in the groundwater and kernel of corn will override the limitation of 3 μg/L and 0.05 mg/kg respectively.展开更多
The accumulation of undesirable deposits on the heat exchange surface represents a critical issue in industrial heat exchangers.Taking experimental measurements of the fouling is relatively difficult and,often,this me...The accumulation of undesirable deposits on the heat exchange surface represents a critical issue in industrial heat exchangers.Taking experimental measurements of the fouling is relatively difficult and,often,this method does not lead to precise results.To overcome these problems,in the present study,a new approach based on an Artificial Neural Network(ANN)is used to predict the fouling resistance as a function of specific measurable variables in the phosphoric acid concentration process.These include:the phosphoric acid inlet and outlet temperatures,the steam temperature,the phosphoric acid density,the phosphoric acid volume flow rate circulating in the loop.Some statistical accuracy indices are employed simultaneously to justify the interrelation between these independent variables and the fouling resistance and to select the best training algorithm allowing the determination of the optimal number of hidden neurons.In particular,the BFGS quasi-Newton back-propagation approach is found to be the most performing of the considered training algorithms.Furthermore,the best topology ANN for the shell and tube heat exchanger is obtained with a network consisting of one hidden layer with 13 neurons using a tangent sigmoid transfer function for the hidden and output layers.This model predicts the experimental values of the fouling resistance with AARD%=0.065,MSE=2.168×10^(−11),RMSE=4.656×10^(−6)and r^(2)=0.994.展开更多
Radial basis function neural network(RBFNN) is an effective algorithm in nonlinear system identification. How to properly adjust the structure and parameters of RBFNN is quite challenging. To solve this problem, a dis...Radial basis function neural network(RBFNN) is an effective algorithm in nonlinear system identification. How to properly adjust the structure and parameters of RBFNN is quite challenging. To solve this problem, a distance concentration immune algorithm(DCIA) is proposed to self-organize the structure and parameters of the RBFNN in this paper. First, the distance concentration algorithm, which increases the diversity of antibodies, is used to find the global optimal solution. Secondly,the information processing strength(IPS) algorithm is used to avoid the instability that is caused by the hidden layer with neurons split or deleted randomly. However, to improve the forecasting accuracy and reduce the computation time, a sample with the most frequent occurrence of maximum error is proposed to regulate the parameters of the new neuron. In addition, the convergence proof of a self-organizing RBF neural network based on distance concentration immune algorithm(DCIA-SORBFNN) is applied to guarantee the feasibility of algorithm. Finally, several nonlinear functions are used to validate the effectiveness of the algorithm. Experimental results show that the proposed DCIASORBFNN has achieved better nonlinear approximation ability than that of the art relevant competitors.展开更多
The coupled numerical simulation on fluid flow, heat transfer, and mass transfer in the process of laser cladding is undertaken on the basis of the continuum model. In the simulation of mass transfer in the laser molt...The coupled numerical simulation on fluid flow, heat transfer, and mass transfer in the process of laser cladding is undertaken on the basis of the continuum model. In the simulation of mass transfer in the laser molten pool, the concentration distribution in the regions on different sides of the interface between cladding layer and substrate is calculated separately and coupled at the co-boundary. The non-equilibrium solute partition coefficient is obtained from equilibrium solute partition coefficient according to the Sobolev model. By using the developed software which is based on the commercial software PHOENICS 1.4, the distribution of Fe in laser molten pool in an experiment of cladding Stellite 6 on 12CrMoV is calculated. The obtained results well coincide with the experimental ones.展开更多
The photo-acoustic (PA) spectrum of nitrogen dioxide (NO2) in the range of 420 - 520 nm with a Nd:YAG pumped optical parametric generator and amplifier as radiation source is presented. The spectrum has a charact...The photo-acoustic (PA) spectrum of nitrogen dioxide (NO2) in the range of 420 - 520 nm with a Nd:YAG pumped optical parametric generator and amplifier as radiation source is presented. The spectrum has a characteristic of banded structure superimposed on continuum. The banded structure of the spectrum can be assigned to NO2 B2B1← X^2A1 transition. While the continual one comes from the chaos states of the first excited state A^2B2 and the high vibration levels of the ground state X^2A1. The relationship of PA signal with buffer gas pressure and NO2 concentration is measured. The PA signal intensity increases with buffer gas pressure and almost is invariable when the buffer gas pressure is more than 3.00 × 10^4 Pa. The PA signal intensity has linearity with NO2 concentration. The detection limit is about 2×10^-5 on the basis of SNR = 1, however lower value of the detection limit can be expected by improving the apparatus properties.展开更多
The two-dimensional(2D) compound parabolic concentrator's(CPC) characteristics are analyzed.It is shown that CPC's height is taller and its light collecting ability is stronger with the CPC's field of view decr...The two-dimensional(2D) compound parabolic concentrator's(CPC) characteristics are analyzed.It is shown that CPC's height is taller and its light collecting ability is stronger with the CPC's field of view decreasing when the bottom radius is unchanged.According to the ZEMAX analysis,CPC is good at collecting optical signal,and the antenna combining CPC with hemispherical lens can gather more optical signal than a single CPC or CPCs combined in series.The light propagation of scattering optical communication based on multiple scattering is simulated by Monte Carlo method,and the results show that using CPC as receiving antenna can strengthen communication system's signal collecting ability and increase its communication distance.展开更多
The current-voltage (I-V) characteristics of 4H-SiC metal-semiconductor-metal (MSM) ultraviolet photodetector with different finger widths and spacings, different carrier concentrations and thicknesses of n-type e...The current-voltage (I-V) characteristics of 4H-SiC metal-semiconductor-metal (MSM) ultraviolet photodetector with different finger widths and spacings, different carrier concentrations and thicknesses of n-type epitaxial layer are simulated. The simulation results indicate that the dark current and the photocurrent both increase when the finger width increases. But the effect of finger width on the dark current is more significant. On the other hand, the effect of finger spacing on the photocurrent is more significant. When the finger spacing increases, the photocurrent decreases and the dark current is almost changeless. In addition, it is found that the smaller the carrier concentration of n-type epitaxial layer is, the smaller the dark current and the larger the photocurrent will be. It is also found that I-V characteristics of MSM detector also depend on the epitaxial layer thickness. The dark current of detector is smaller and the photocurrent is larger when the epitaxial layer thickness is about 3μm.展开更多
Selected milestones in the development and use of electrical tomography in powder conveying, slurry processing and multi-phase flow are highlighted. The ability to map concentration in opaque mixtures under process-re...Selected milestones in the development and use of electrical tomography in powder conveying, slurry processing and multi-phase flow are highlighted. The ability to map concentration in opaque mixtures under process-realistic conditions was a major innovation for the method and has had far reaching implications. Subsequent developments have enabled velocity information to be abstracted resulting in the ability to measure component flux and motion.展开更多
The response time and transmittivity of the magnetic fluid (MF) for different concentrations at room temperature were investigated in this letter. The volume fraction of the investigated sample ranged from 0.44% to ...The response time and transmittivity of the magnetic fluid (MF) for different concentrations at room temperature were investigated in this letter. The volume fraction of the investigated sample ranged from 0.44% to 6.47%. It was found that the transmittivity decreased with increasing concentration under a given magnetic field, and the evolution time was changed with different concentrations. Moreover the light intensity decreased rapidly at the beginning and then became stable when the magnetic field was applied.展开更多
The Raman spectrum intensity can be enhanced in liquid core optical fiber (LCOF) of CCl4 solution. We dissolved liquid CCl4 into CS2 and got solutions of different concentrations. There is an optimum concentration a...The Raman spectrum intensity can be enhanced in liquid core optical fiber (LCOF) of CCl4 solution. We dissolved liquid CCl4 into CS2 and got solutions of different concentrations. There is an optimum concentration at which the maximum Raman intensity can be obtained. There exists an optimum fiber length of 2 m. The experimental result is in good agreement with the theoretical calculation. The Raman intensity becomes powerful with the increase of the pump power and Raman linewidth becomes narrower with the decrease of the CCl4 concentration.展开更多
The Zn1-xMgxO thin films were deposited on sapphire substrates by reactive electron beam evaporation deposition (REBED). The X-ray diffraction (XRD) measurement demonstrates that these films undergo phase transiti...The Zn1-xMgxO thin films were deposited on sapphire substrates by reactive electron beam evaporation deposition (REBED). The X-ray diffraction (XRD) measurement demonstrates that these films undergo phase transition from hexagonal to cubic with increasing the Mg concentration. Absorption coefficients at 532 nm of the samples were obtained from the absorption spectra. Using optical Kerr effect, the thirdorder susceptibilities of the ternary films over a wide range of Mg concentrations were determined. The magnitude of X^(3) of the ternary Zn1-xMgxO films is order of 10^-11 esu at λ = 532 nm. The sample with phase mixture of both hexagonal and cubic structures shows the largest third-order susceptibility. The difference observed in the magnitude of X^(3) of Zn1-xMgxO films is attributed to the different microstructures of the ternary films, such as crystalline phase separation and crystal grains that enhance stimulated scattering.展开更多
A novel measurement method for chemical solubility determination is brought forward, in which the advantages of two kinds of traditional methods are united. The results show that the concentration of unsolved particle...A novel measurement method for chemical solubility determination is brought forward, in which the advantages of two kinds of traditional methods are united. The results show that the concentration of unsolved particles suspending in the solution can be determined by measuring I/I0 (ratio of the transmission intensity to the incident intensity) of the laser beam permeating through the solution according to Lamben-Beer law. The biggest relative deviation for the solubility data determined is less than 1.5% for the sparingly soluble substances and 0.3% for the opulently soluble substances. By comparison of the experimental solubility data with previous data, the light extinction method is demonstrated to be stable and reliable.展开更多
The clusters of Eu^3+ ion in Eu(DBM)3Phen-doped polymethyl methacrylate (PMMA) have been studied by three means. The relative fluorescence intensity ratio of the ^5D0 → ^7F2 to ^5D0 → ^7F1 transitions with diff...The clusters of Eu^3+ ion in Eu(DBM)3Phen-doped polymethyl methacrylate (PMMA) have been studied by three means. The relative fluorescence intensity ratio of the ^5D0 → ^7F2 to ^5D0 → ^7F1 transitions with different concentrations of Eu^3+ in Eu(DBM)3Phen-doped PMMA and metastable-state (^5D0) lifetime dependence on Eu^3+ concentration axe analyzed. The analysis indicates that there axe no clustering effects in Eu^3+ ions of Eu(DBM)3Phen-doped PMMA when the Eu^3+ doping concentration is up to 1.0 wt.-%. At the same time, the clustering effect has not been observed by the scanning neax-field optical microscopy (SNOM) in Eu(DBM)3Phen-doped PMMA with 1.0 wt.-% of Eu^3+ ions. The analysis reveals that a high concentration of Eu^3+ can be incorporated into polymer optical fiber (POF) without clustering effect.展开更多
文摘Water solubility enhancements of pyrene by both single-surfactant and mixed-surfactant solutions were compared and evaluated. The solubility of pyrene in water was greatly enhanced by each of Triton X-100 (TX100), Triton X-405 (TX405), Brij 35 and SDS, in which the water solubility enhancements increased with increasing surfactant concentrations. The extent of solubility enhancements at surfactant concentrations below. the CMC is the order of TX100 > Brij 35 > TX405 > SDS; the sequence at surfactant concentrations above the CMC is TX100 > Brij 35 > SDS > TX405. Pyrene was solubilized synergistically by anionic-nonionic mixed surfactant solutions, especially at low surfactant concentrations. The synergistic power of the mixed surfactants is SDS-TX405 > SDS-Brij 35 > SDS-TX100. The synergism as noted is attributed to increasing Kmc and/or decreasing the CMC of the mixed surfactant solution. For SDS-TX405 and SDS-Brij 35 mixed surfactant solutions, an increase in Kmc is coupled with a decrease in the CMC; for SDS-TX100, only a decreased in the CMC value is noted. Mixed-surfactant solutions may improve the performance of the surfactant-enhanced remediation (SER) of soils by increasing the bioavailability and biodegradation of non-aqueous-phase organic pollutants and reducing the level of surfactant pollution and remediation expenses.
文摘Runoff and soil losses from agricultural fields are investigated as major nonpoint sources of phosphorus (P) entering lakes of Eastern China. There is relatively little information on P transport from ricefield and cropland of Lake Taihu watershed in Eastern China. Soil and P in surface runoff from a series of plots in the watershed were evaluated under simulated rainfall conditions. The objectives of this study were to evaluate the effects of crop cover, slope, and fertilizer application on P concentrations in surface runoff and eroded soil. Accumulated sediment yields varied from 7.1 to 300 g/m2 for croplands, depending on management practices. For all experiment plots, weighted average concentrations of total-P (TP), dissolved P (DP) and particulate P (PP) are much higher than 0.02 mg/L, the limiting concentration for lake water. This result showed the potential contamination of lake water from agricultural surface runoff. Accumulated TP losses were 3.8 and 18.8 mg/m2 for ricefield and cropland, respectively. The estimated annual loss of TP was 0.74 kg/(hm2 · a) for cropland. Most of P loss is in the PP form, which accounts for more than 90% of TP loss for cropland.
基金TheNationalNaturalScienceFoundationofChinaandthe"Ninth five"significantBitem (No .KZ 95 1 B1 2 0 1)oftheChineseAcademyofScie
文摘Besides competing with algae for light and mineral nutrients (i. e. N, P, etc.), the root system of Acorus tatarinowii excretes some chemical substances, which injure and eliminate alga cells, to inhibit the growth of the algae. When the algae cells were treated in 'A. tatarinowii water', some of the chlorophyll a were destroyed and the photosynthetic rate of algae decreased markedly and the ability of alga cells to deoxidize triphenyltetrazolium chloride (TTC) reduced greatly. Then alga cells turned from bright red to bluish green under fluorescence microscope. These showed that the allelopathic effects of A. tatarinowii on algae were obvious and planting A. tatarinowii can control some green algae. The experiment on the extractions of the secretions of the root system showed that the inhibitory effect had a concentration effect. If the concentration of the root secretion was below 30 μl/disc, the inhibitory rate was negative; if it was over 45 μl/disc, the inhibitory rate was positive. This proved that the influence of the root secretion on the same acceptor was a kind of concentration effect. When the concentration of the root secretion was low, it promoted the growth of algae; when the concentration reached a definite threshold value, it restrained the growth of algae. In present case, the threshold value was between 30 μl/disc and 45 μl/disc.
文摘The decolorization of Direct Black 22 by Aspergillus ficuum has been studied. It was found that Aspergillus ficuum could effectively decolorize Direct Black 22 especially when grown as pelleted mycelia. Results showed that the media containing Direct Black 22 at 50 mg/L could be decolorized by 98.05% of the initial color in 24 h. The optimum pH and temperature of decolorization are 4.0 and 33 °C respectively. Aeration was quite beneficial to decolorization. Medium composition and the concentration of Direct Black 22 could affect the rate of decolorization. The dye degraded products assayed by UV-visible spectrophotometer and macroscopic observation showed that the decolorization of Direct Black 22 by mycelial pellets includes two important processes: bioadsorption and biodegradation. The degradation experiment agree with the Michaelis-Menten kinetics equation.
基金TheNationalNaturalScienceFoundationofChina (No .2 97770 2 6 )andtheMajorProjectFoundationoftheChineseAcademyofSciences (KZ95 1
文摘The application of atrazine in China during the last ten years has led to some environmental problems. In this paper, the multimedia model of atrazine in soil-plant-groundwater system at Baiyangdian Lake area in Northern China was established using a fugacity approach, and verified with observed values. The model involved 7 environmental compartments which are air, groundwater, soil, corn roots, corn stem, corn leaf and kernel of corn. The results showed that the relative errors between calculated and observed values have a mean value of 24.7%, the highest value is 48% and the lowest value is 1.4%. All these values indicated that this multimedia model can be used to simulate the environmental fate of atrazine. Both the calculated and observed values of concentrations of atrazine in plant compartments are in the following order: in corn roots > in corn stem > in kernel of corn > in corn leaf, it exhibited a good regularity. The prediction results indicated that concentrations of atrazine in the groundwater and kernel of corn will override the limitation of 3 μg/L and 0.05 mg/kg respectively.
文摘The accumulation of undesirable deposits on the heat exchange surface represents a critical issue in industrial heat exchangers.Taking experimental measurements of the fouling is relatively difficult and,often,this method does not lead to precise results.To overcome these problems,in the present study,a new approach based on an Artificial Neural Network(ANN)is used to predict the fouling resistance as a function of specific measurable variables in the phosphoric acid concentration process.These include:the phosphoric acid inlet and outlet temperatures,the steam temperature,the phosphoric acid density,the phosphoric acid volume flow rate circulating in the loop.Some statistical accuracy indices are employed simultaneously to justify the interrelation between these independent variables and the fouling resistance and to select the best training algorithm allowing the determination of the optimal number of hidden neurons.In particular,the BFGS quasi-Newton back-propagation approach is found to be the most performing of the considered training algorithms.Furthermore,the best topology ANN for the shell and tube heat exchanger is obtained with a network consisting of one hidden layer with 13 neurons using a tangent sigmoid transfer function for the hidden and output layers.This model predicts the experimental values of the fouling resistance with AARD%=0.065,MSE=2.168×10^(−11),RMSE=4.656×10^(−6)and r^(2)=0.994.
基金supported by the National Natural Science Foundation of China(61890930-5,61533002,61603012)the Major Science and Technology Program for Water Pollution Control and Treatment of China(2018ZX07111005)+1 种基金the National Key Research and Development Project(2018YFC1900800-5)Beijing Municipal Education Commission Foundation(KM201710005025)
文摘Radial basis function neural network(RBFNN) is an effective algorithm in nonlinear system identification. How to properly adjust the structure and parameters of RBFNN is quite challenging. To solve this problem, a distance concentration immune algorithm(DCIA) is proposed to self-organize the structure and parameters of the RBFNN in this paper. First, the distance concentration algorithm, which increases the diversity of antibodies, is used to find the global optimal solution. Secondly,the information processing strength(IPS) algorithm is used to avoid the instability that is caused by the hidden layer with neurons split or deleted randomly. However, to improve the forecasting accuracy and reduce the computation time, a sample with the most frequent occurrence of maximum error is proposed to regulate the parameters of the new neuron. In addition, the convergence proof of a self-organizing RBF neural network based on distance concentration immune algorithm(DCIA-SORBFNN) is applied to guarantee the feasibility of algorithm. Finally, several nonlinear functions are used to validate the effectiveness of the algorithm. Experimental results show that the proposed DCIASORBFNN has achieved better nonlinear approximation ability than that of the art relevant competitors.
基金the National Natural Sci-ence Foundation of China under Grant No.59871038the Foundation of State Key Laboratory of Laser Tech-nology,Huazhong University of Science and Technology.
文摘The coupled numerical simulation on fluid flow, heat transfer, and mass transfer in the process of laser cladding is undertaken on the basis of the continuum model. In the simulation of mass transfer in the laser molten pool, the concentration distribution in the regions on different sides of the interface between cladding layer and substrate is calculated separately and coupled at the co-boundary. The non-equilibrium solute partition coefficient is obtained from equilibrium solute partition coefficient according to the Sobolev model. By using the developed software which is based on the commercial software PHOENICS 1.4, the distribution of Fe in laser molten pool in an experiment of cladding Stellite 6 on 12CrMoV is calculated. The obtained results well coincide with the experimental ones.
基金This work was supported by the Natural Science Foundation of Hebei Province under Grant No. 102090
文摘The photo-acoustic (PA) spectrum of nitrogen dioxide (NO2) in the range of 420 - 520 nm with a Nd:YAG pumped optical parametric generator and amplifier as radiation source is presented. The spectrum has a characteristic of banded structure superimposed on continuum. The banded structure of the spectrum can be assigned to NO2 B2B1← X^2A1 transition. While the continual one comes from the chaos states of the first excited state A^2B2 and the high vibration levels of the ground state X^2A1. The relationship of PA signal with buffer gas pressure and NO2 concentration is measured. The PA signal intensity increases with buffer gas pressure and almost is invariable when the buffer gas pressure is more than 3.00 × 10^4 Pa. The PA signal intensity has linearity with NO2 concentration. The detection limit is about 2×10^-5 on the basis of SNR = 1, however lower value of the detection limit can be expected by improving the apparatus properties.
基金supported by the National Natural Science Foundation of China under Grant No.60607013.
文摘The two-dimensional(2D) compound parabolic concentrator's(CPC) characteristics are analyzed.It is shown that CPC's height is taller and its light collecting ability is stronger with the CPC's field of view decreasing when the bottom radius is unchanged.According to the ZEMAX analysis,CPC is good at collecting optical signal,and the antenna combining CPC with hemispherical lens can gather more optical signal than a single CPC or CPCs combined in series.The light propagation of scattering optical communication based on multiple scattering is simulated by Monte Carlo method,and the results show that using CPC as receiving antenna can strengthen communication system's signal collecting ability and increase its communication distance.
基金the National Defense Pre-Research Foundation of China.
文摘The current-voltage (I-V) characteristics of 4H-SiC metal-semiconductor-metal (MSM) ultraviolet photodetector with different finger widths and spacings, different carrier concentrations and thicknesses of n-type epitaxial layer are simulated. The simulation results indicate that the dark current and the photocurrent both increase when the finger width increases. But the effect of finger width on the dark current is more significant. On the other hand, the effect of finger spacing on the photocurrent is more significant. When the finger spacing increases, the photocurrent decreases and the dark current is almost changeless. In addition, it is found that the smaller the carrier concentration of n-type epitaxial layer is, the smaller the dark current and the larger the photocurrent will be. It is also found that I-V characteristics of MSM detector also depend on the epitaxial layer thickness. The dark current of detector is smaller and the photocurrent is larger when the epitaxial layer thickness is about 3μm.
基金support of co-workers in the tomography groups at University of Leeds and the University of Manchester with funding to enable us to develop the frontiers of tomography provided by EPSRC (EP/D031257/1)
文摘Selected milestones in the development and use of electrical tomography in powder conveying, slurry processing and multi-phase flow are highlighted. The ability to map concentration in opaque mixtures under process-realistic conditions was a major innovation for the method and has had far reaching implications. Subsequent developments have enabled velocity information to be abstracted resulting in the ability to measure component flux and motion.
基金the National Natural Science Foundation of China(No.10574092)the National Basic Research Program"973"of China(No.2007CB307000)the Shanghai Leading Academic Discipline Project(No.B201)
文摘The response time and transmittivity of the magnetic fluid (MF) for different concentrations at room temperature were investigated in this letter. The volume fraction of the investigated sample ranged from 0.44% to 6.47%. It was found that the transmittivity decreased with increasing concentration under a given magnetic field, and the evolution time was changed with different concentrations. Moreover the light intensity decreased rapidly at the beginning and then became stable when the magnetic field was applied.
基金This work was supported by the Natural Science Foundation of Zhejiang (No. ZD0102).
文摘The Raman spectrum intensity can be enhanced in liquid core optical fiber (LCOF) of CCl4 solution. We dissolved liquid CCl4 into CS2 and got solutions of different concentrations. There is an optimum concentration at which the maximum Raman intensity can be obtained. There exists an optimum fiber length of 2 m. The experimental result is in good agreement with the theoretical calculation. The Raman intensity becomes powerful with the increase of the pump power and Raman linewidth becomes narrower with the decrease of the CCl4 concentration.
基金This work was supported by the National Natural Sci-ence Foundation of China under Grant No. 10174064and 50472058.
文摘The Zn1-xMgxO thin films were deposited on sapphire substrates by reactive electron beam evaporation deposition (REBED). The X-ray diffraction (XRD) measurement demonstrates that these films undergo phase transition from hexagonal to cubic with increasing the Mg concentration. Absorption coefficients at 532 nm of the samples were obtained from the absorption spectra. Using optical Kerr effect, the thirdorder susceptibilities of the ternary films over a wide range of Mg concentrations were determined. The magnitude of X^(3) of the ternary Zn1-xMgxO films is order of 10^-11 esu at λ = 532 nm. The sample with phase mixture of both hexagonal and cubic structures shows the largest third-order susceptibility. The difference observed in the magnitude of X^(3) of Zn1-xMgxO films is attributed to the different microstructures of the ternary films, such as crystalline phase separation and crystal grains that enhance stimulated scattering.
文摘A novel measurement method for chemical solubility determination is brought forward, in which the advantages of two kinds of traditional methods are united. The results show that the concentration of unsolved particles suspending in the solution can be determined by measuring I/I0 (ratio of the transmission intensity to the incident intensity) of the laser beam permeating through the solution according to Lamben-Beer law. The biggest relative deviation for the solubility data determined is less than 1.5% for the sparingly soluble substances and 0.3% for the opulently soluble substances. By comparison of the experimental solubility data with previous data, the light extinction method is demonstrated to be stable and reliable.
基金This work was supported by the National ScienceFoundation of China (No. 90201013), the Fujian NaturalScience Foundation of China (No. A0510014), and theFujian Educational Department Foundation of China(No. JB03151 and JB04246).
文摘The clusters of Eu^3+ ion in Eu(DBM)3Phen-doped polymethyl methacrylate (PMMA) have been studied by three means. The relative fluorescence intensity ratio of the ^5D0 → ^7F2 to ^5D0 → ^7F1 transitions with different concentrations of Eu^3+ in Eu(DBM)3Phen-doped PMMA and metastable-state (^5D0) lifetime dependence on Eu^3+ concentration axe analyzed. The analysis indicates that there axe no clustering effects in Eu^3+ ions of Eu(DBM)3Phen-doped PMMA when the Eu^3+ doping concentration is up to 1.0 wt.-%. At the same time, the clustering effect has not been observed by the scanning neax-field optical microscopy (SNOM) in Eu(DBM)3Phen-doped PMMA with 1.0 wt.-% of Eu^3+ ions. The analysis reveals that a high concentration of Eu^3+ can be incorporated into polymer optical fiber (POF) without clustering effect.