Antarctic krill (Euphausia superba) were collected from the Prydz Bay region during the austral summer of 1999/2000. The sample - collection was made at 15 sites in 3 longitudinal transects. Although krill were encoun...Antarctic krill (Euphausia superba) were collected from the Prydz Bay region during the austral summer of 1999/2000. The sample - collection was made at 15 sites in 3 longitudinal transects. Although krill were encountered at 14 sites, the abundance was comparatively low in general. The main component of the krill population was of post -larval stages. The mean numerical and weight density of krill integrated for all sampling stations in the survey area were 16. 17 ind. 1000 m -3and 12.02 g 1000 m -3 , respectively. In the survey area, stations with larger krill density are mainly located in the slope zone, except that the largest sample was collected in the open sea zone. No krill occurred in the only station of the shelf zone during our investigation. Krill collected from the slope zone were under better growth condition than those from the open sea zone, but when the survey area is considered as a whole, the growth condition is normal. The results of the comprehensive analysis of the environmental factors show that the three large sample stations seem to be related with the cold water mass at 75 m depth and the confluence area between the high and low Chla centers at the depth of 25 m.展开更多
Root cause analysis （RCA） of abnormal aluminum electrolysis cell condition has long been a challenging industrial issue due to its inherent complexity in analyzing based on multi-source knowledge. In addition, accur...Root cause analysis （RCA） of abnormal aluminum electrolysis cell condition has long been a challenging industrial issue due to its inherent complexity in analyzing based on multi-source knowledge. In addition, accurate RCA of abnormal aluminum electrolysis cell condition is the precondition of improving current efficiency. RCA of abnormal condition is a complex work of multi-source knowledge fusion, which is difficult to ensure the RCA accuracy of abnormal cell condition because of dwindling and frequent flow of experienced technicians. In view of this, a method based on Fuzzy- Bayesian network to construct multi-source knowledge solidification reasoning model is proposed. The method can effectively fuse and solidify the knowledge, which is used to analyze the cause of abnormal condition by technicians providing a clear and intuitive framework to this complex task, and also achieve the result of root cause automatically. The proposed method was verified under 20 sets of abnormal cell conditions, and implements root cause analysis by finding the abnormal state of root node, which has a maximum posterior probability by Bayesian diagnosis reasoning. The accuracy of the test results is up to 95%, which shows that the knowledge reasoning feasibility for RCA of aluminum electrolysis cell.展开更多
In this paper we study zero-sum stochastic games. The optimality criterion is the long-run expected average criterion, and the payoff function may have neither upper nor lower bounds. We give a new set of conditions f...In this paper we study zero-sum stochastic games. The optimality criterion is the long-run expected average criterion, and the payoff function may have neither upper nor lower bounds. We give a new set of conditions for the existence of a value and a pair of optimal stationary strategies. Our conditions are slightly weaker than those in the previous literature, and some new sufficient conditions for the existence of a pair of optimal stationary strategies are imposed on the primitive data of the model. Our results are illustrated with a queueing system, for which our conditions are satisfied but some of the conditions in some previous literatures fail to hold.展开更多
Selective catalytic reduction of NOχ by H2 in the presence of oxygen has been investigated over Pt/ A12O3 catalysts pre-treated under different conditions. Catalyst preparation conditions exert significant influence ...Selective catalytic reduction of NOχ by H2 in the presence of oxygen has been investigated over Pt/ A12O3 catalysts pre-treated under different conditions. Catalyst preparation conditions exert significant influence on the catalytic performance, and the catalyst pre-treated by HE or H2 then followed by O2 is much more active than that pre-treated by air. The higher surface area and the presence of metallic Pt over Pt/A12O3 pre-treated by HE or pretreated by H2 then followed by O2 can contribute to the formation of NO2, which then promotes the reaction to proceed at low temperatures.展开更多
Effect of the device fabrication conditions on photovoltaic performance of the polymer solar cells based on poly（3-hexylthiophene） （P3HT） as donor and indene-C70 bisadduct （IC70BA） as acceptor was studied system...Effect of the device fabrication conditions on photovoltaic performance of the polymer solar cells based on poly（3-hexylthiophene） （P3HT） as donor and indene-C70 bisadduct （IC70BA） as acceptor was studied systematically. The device fabrication conditions we studied include pre-thermal annealing temperature, active layer thickness, and the P3HT ： IC70BA weight ratios. For devices with a 188-nm-thick active layer of P3HT ： ICToBA （1 ： 1, w ＇ w） blend film and pre-thermal annealing at 150 ℃C for 10 rain, maximum power conversion efficiency （PCE） reached 5.82% with Voc of 0.81 V, Isc of 11.37 mA/cm2, and FF of 64.0% under the illumination of AM1.5G, 100 mW/cm2.展开更多
A study on the effects of Navier slip, in conjunction with other flow parameters, on unsteady flow of reactive variable viscosity third-grade fluid through a porous saturated medium with asymmetric convective boundary...A study on the effects of Navier slip, in conjunction with other flow parameters, on unsteady flow of reactive variable viscosity third-grade fluid through a porous saturated medium with asymmetric convective boundary conditions is presented. The channel walls are assumed to be subjected to asymmetric convective heat exchange with the ambient, and exothermic chemical reactions take place within the flow system. The heat exchange with the ambient obeys Newton＇s law of cooling. The coupled equations, arising from the law of conservation of momentum and the first law of thermodynamics, then the derived system are non- dimensionalised and solved using a semi-implicit finite difference scheme. The lower wall slip parameter is observed to increase the fluid velocity profiles, whereas the upper wall slip parameter retards them because of backflow at the upper channel wall. Heat pro- duction in the fluid is seen to increase with the slip parameters. The wall shear stress increases with the slip parameters while the wall heat transfer rate is largely unaltered by the lower wall slip parameter but marginally increased by the upper wall slip parameter.展开更多
The crystallization behavior of silica-filled polydimethylsiloxane(PDMS)was investigated in detail by^(1)H solid-state nuclear magnetic resonance(^(1)H SS-NMR)in combination with synchrotron radiation wide-angle X-ray...The crystallization behavior of silica-filled polydimethylsiloxane(PDMS)was investigated in detail by^(1)H solid-state nuclear magnetic resonance(^(1)H SS-NMR)in combination with synchrotron radiation wide-angle X-ray scattering(WAXS),and temperature-modulated differential scanning calorimetry(TMDSC)techniques.For neat PDMS,no apparent difference is observed for the crystallinity characterized by^(1)H SS-NMR and WAXS at low-temperature regions.However,upon filler addition,a 15%-35%lower difference in crystallinity is observed measured by^(1)H SS-NMR compared to WAXS.The origin of such mismatch was explored through multi-component structural,dynamics,and chain-order analysis of PDMS samples with different filler fractions.The 1D integrated WAXS results of PDMS with different filler fractions at different temperatures show that the packing structure as well as crystal size basically remain unchanged,but as the filler fraction increases from 0 phr to 60 phr,the rigid component’s dynamics order parameter S_(r)obtained by^(1)H SS-NMR decreases from 0.70 to 0.55.The filler fraction-dependent crystallinity calculated based on S_(r)was compared with experimental values,revealing a behavior of decreasing order in the crystalline region.Combining with the results of accelerated chain dynamics in crystalline region as reflected by T_(2)values,the molecular origin is attributed to the formation of CONDIS crystals,whose conformational order is lost but the position and orientation orders are kept.Such hypothesis is further supported by the TMDSC results,where,as the filler fraction increases from 0 phr to 60 phr,the melting range widens from 8.77 K to 14.56 K,representing a growth of166%.In addition to previous reports related to the condition for forming CONDIS mesophase,i.e.,temperature,pressure,and stretching,the nano-sized filler could also introduce the local conformational disorder for chain packing.展开更多
目的视网膜眼底图像广泛用于临床筛查和诊断眼科疾病,但由于散焦、光线条件不佳等引起的眼底图像模糊,导致医生无法正确诊断,且现有图像增强方法恢复的图像仍存在模糊、高频信息缺失以及噪点增多问题。本文提出了一个卷积字典扩散模型,...目的视网膜眼底图像广泛用于临床筛查和诊断眼科疾病,但由于散焦、光线条件不佳等引起的眼底图像模糊,导致医生无法正确诊断,且现有图像增强方法恢复的图像仍存在模糊、高频信息缺失以及噪点增多问题。本文提出了一个卷积字典扩散模型,将卷积字典学习的去噪能力与条件扩散模型的灵活性相结合,从而解决了上述问题。方法算法主要包括两个过程:扩散过程和去噪过程。首先向输入图像中逐步添加随机噪声,得到趋于纯粹噪声的图像;然后训练一个神经网络逐渐将噪声从图像中移除,直到获得一幅清晰图像。本文利用卷积网络来实现卷积字典学习并获取图像稀疏表示,该算法充分利用图像的先验信息,有效避免重建图像高频信息缺失和噪点增多的问题。结果将本文模型在EyePACS数据集上进行训练,并分别在合成数据集DRIVE(dgital retinal images for vessel extraction)、CHASEDB1(child heart and health study in England)、ROC(retinopathy online challenge)和真实数据集RF(real fundus)、HRF(high-resolution fundus)上进行测试,验证了所提方法在图像增强任务上的性能及跨数据集的泛化能力,其评价指标峰值信噪比(peak signal-to-noise ratio,PSNR)和学习感知图像块相似度(learned perceptual image patch similarity,LPIPS)与原始扩散模型(learning enhancement from degradation,Led)相比平均分别提升了1.9929 dB和0.0289。此外,将本文方法用于真实眼科图像下游任务的前处理能够有效提升下游任务的表现,在含有分割标签的DRIVE数据集上进行的视网膜血管分割实验结果显示,相较于原始扩散模型,其分割指标对比其受试者工作特征曲线下面积(area under the curve,AUC),准确率(accuracy,Acc)和敏感性(sensitivity,Sen)平均分别提升0.0314,0.0030和0.0738。结论提出的方法能够在保留真实眼底特征的同时去除模糊、恢复更丰富的细节,从而有利于临床图像的分析和应用。展开更多
基金This study was supported by the CAS know ledge innov ation program KZCX2-303.
文摘Antarctic krill (Euphausia superba) were collected from the Prydz Bay region during the austral summer of 1999/2000. The sample - collection was made at 15 sites in 3 longitudinal transects. Although krill were encountered at 14 sites, the abundance was comparatively low in general. The main component of the krill population was of post -larval stages. The mean numerical and weight density of krill integrated for all sampling stations in the survey area were 16. 17 ind. 1000 m -3and 12.02 g 1000 m -3 , respectively. In the survey area, stations with larger krill density are mainly located in the slope zone, except that the largest sample was collected in the open sea zone. No krill occurred in the only station of the shelf zone during our investigation. Krill collected from the slope zone were under better growth condition than those from the open sea zone, but when the survey area is considered as a whole, the growth condition is normal. The results of the comprehensive analysis of the environmental factors show that the three large sample stations seem to be related with the cold water mass at 75 m depth and the confluence area between the high and low Chla centers at the depth of 25 m.
文摘Root cause analysis （RCA） of abnormal aluminum electrolysis cell condition has long been a challenging industrial issue due to its inherent complexity in analyzing based on multi-source knowledge. In addition, accurate RCA of abnormal aluminum electrolysis cell condition is the precondition of improving current efficiency. RCA of abnormal condition is a complex work of multi-source knowledge fusion, which is difficult to ensure the RCA accuracy of abnormal cell condition because of dwindling and frequent flow of experienced technicians. In view of this, a method based on Fuzzy- Bayesian network to construct multi-source knowledge solidification reasoning model is proposed. The method can effectively fuse and solidify the knowledge, which is used to analyze the cause of abnormal condition by technicians providing a clear and intuitive framework to this complex task, and also achieve the result of root cause automatically. The proposed method was verified under 20 sets of abnormal cell conditions, and implements root cause analysis by finding the abnormal state of root node, which has a maximum posterior probability by Bayesian diagnosis reasoning. The accuracy of the test results is up to 95%, which shows that the knowledge reasoning feasibility for RCA of aluminum electrolysis cell.
文摘In this paper we study zero-sum stochastic games. The optimality criterion is the long-run expected average criterion, and the payoff function may have neither upper nor lower bounds. We give a new set of conditions for the existence of a value and a pair of optimal stationary strategies. Our conditions are slightly weaker than those in the previous literature, and some new sufficient conditions for the existence of a pair of optimal stationary strategies are imposed on the primitive data of the model. Our results are illustrated with a queueing system, for which our conditions are satisfied but some of the conditions in some previous literatures fail to hold.
文摘Selective catalytic reduction of NOχ by H2 in the presence of oxygen has been investigated over Pt/ A12O3 catalysts pre-treated under different conditions. Catalyst preparation conditions exert significant influence on the catalytic performance, and the catalyst pre-treated by HE or H2 then followed by O2 is much more active than that pre-treated by air. The higher surface area and the presence of metallic Pt over Pt/A12O3 pre-treated by HE or pretreated by H2 then followed by O2 can contribute to the formation of NO2, which then promotes the reaction to proceed at low temperatures.
基金This work was supported by the National Natural Science Foundation of China （Nos. 20821120293 and 50933003） and Chinese Academy of Sciences.
文摘Effect of the device fabrication conditions on photovoltaic performance of the polymer solar cells based on poly（3-hexylthiophene） （P3HT） as donor and indene-C70 bisadduct （IC70BA） as acceptor was studied systematically. The device fabrication conditions we studied include pre-thermal annealing temperature, active layer thickness, and the P3HT ： IC70BA weight ratios. For devices with a 188-nm-thick active layer of P3HT ： ICToBA （1 ： 1, w ＇ w） blend film and pre-thermal annealing at 150 ℃C for 10 rain, maximum power conversion efficiency （PCE） reached 5.82% with Voc of 0.81 V, Isc of 11.37 mA/cm2, and FF of 64.0% under the illumination of AM1.5G, 100 mW/cm2.
文摘A study on the effects of Navier slip, in conjunction with other flow parameters, on unsteady flow of reactive variable viscosity third-grade fluid through a porous saturated medium with asymmetric convective boundary conditions is presented. The channel walls are assumed to be subjected to asymmetric convective heat exchange with the ambient, and exothermic chemical reactions take place within the flow system. The heat exchange with the ambient obeys Newton＇s law of cooling. The coupled equations, arising from the law of conservation of momentum and the first law of thermodynamics, then the derived system are non- dimensionalised and solved using a semi-implicit finite difference scheme. The lower wall slip parameter is observed to increase the fluid velocity profiles, whereas the upper wall slip parameter retards them because of backflow at the upper channel wall. Heat pro- duction in the fluid is seen to increase with the slip parameters. The wall shear stress increases with the slip parameters while the wall heat transfer rate is largely unaltered by the lower wall slip parameter but marginally increased by the upper wall slip parameter.
基金financially supported by NSAF Joint Fund of China(No.U2030203)the National Natural Science Foundation of China(Nos.51973207 and 51903230)。
文摘The crystallization behavior of silica-filled polydimethylsiloxane(PDMS)was investigated in detail by^(1)H solid-state nuclear magnetic resonance(^(1)H SS-NMR)in combination with synchrotron radiation wide-angle X-ray scattering(WAXS),and temperature-modulated differential scanning calorimetry(TMDSC)techniques.For neat PDMS,no apparent difference is observed for the crystallinity characterized by^(1)H SS-NMR and WAXS at low-temperature regions.However,upon filler addition,a 15%-35%lower difference in crystallinity is observed measured by^(1)H SS-NMR compared to WAXS.The origin of such mismatch was explored through multi-component structural,dynamics,and chain-order analysis of PDMS samples with different filler fractions.The 1D integrated WAXS results of PDMS with different filler fractions at different temperatures show that the packing structure as well as crystal size basically remain unchanged,but as the filler fraction increases from 0 phr to 60 phr,the rigid component’s dynamics order parameter S_(r)obtained by^(1)H SS-NMR decreases from 0.70 to 0.55.The filler fraction-dependent crystallinity calculated based on S_(r)was compared with experimental values,revealing a behavior of decreasing order in the crystalline region.Combining with the results of accelerated chain dynamics in crystalline region as reflected by T_(2)values,the molecular origin is attributed to the formation of CONDIS crystals,whose conformational order is lost but the position and orientation orders are kept.Such hypothesis is further supported by the TMDSC results,where,as the filler fraction increases from 0 phr to 60 phr,the melting range widens from 8.77 K to 14.56 K,representing a growth of166%.In addition to previous reports related to the condition for forming CONDIS mesophase,i.e.,temperature,pressure,and stretching,the nano-sized filler could also introduce the local conformational disorder for chain packing.
文摘模块化多电平换流器(modular multilevel converter,MMC)近年来得到了广泛的发展与应用。电容器是MMC中子模块(sub-module,SM)的重要组成部分与关键元件,承担直流支撑与储能工作。为保证MMC系统的安全可靠运行,有必要对子模块电容器状态监测方法展开研究。基于MMC系统运行特性,提出一种在工频周期内对子模块电压进行多相位点采样,并结合系统控制侧开关信号、调制比与交流侧电流电压幅值、相位等信息构建电压电流状态方程,以求解电容值与等效串联电阻(equivalent series resistance,ESR)值等状态特征参量的子模块电容器状态监测方法。随后搭建单相七电平MMC系统仿真平台与半实物仿真平台,对上述方法的可行性与准确性进行验证。仿真结果表明子模块电容器C值监测误差绝对值小于0.03%,ESR值监测误差绝对值小于0.5%。实验结果表明C值监测误差绝对值小于1.5%,ESR值监测误差小于10%,满足子模块电容器状态监测要求。
文摘目的视网膜眼底图像广泛用于临床筛查和诊断眼科疾病,但由于散焦、光线条件不佳等引起的眼底图像模糊,导致医生无法正确诊断,且现有图像增强方法恢复的图像仍存在模糊、高频信息缺失以及噪点增多问题。本文提出了一个卷积字典扩散模型,将卷积字典学习的去噪能力与条件扩散模型的灵活性相结合,从而解决了上述问题。方法算法主要包括两个过程:扩散过程和去噪过程。首先向输入图像中逐步添加随机噪声,得到趋于纯粹噪声的图像;然后训练一个神经网络逐渐将噪声从图像中移除,直到获得一幅清晰图像。本文利用卷积网络来实现卷积字典学习并获取图像稀疏表示,该算法充分利用图像的先验信息,有效避免重建图像高频信息缺失和噪点增多的问题。结果将本文模型在EyePACS数据集上进行训练,并分别在合成数据集DRIVE(dgital retinal images for vessel extraction)、CHASEDB1(child heart and health study in England)、ROC(retinopathy online challenge)和真实数据集RF(real fundus)、HRF(high-resolution fundus)上进行测试,验证了所提方法在图像增强任务上的性能及跨数据集的泛化能力,其评价指标峰值信噪比(peak signal-to-noise ratio,PSNR)和学习感知图像块相似度(learned perceptual image patch similarity,LPIPS)与原始扩散模型(learning enhancement from degradation,Led)相比平均分别提升了1.9929 dB和0.0289。此外,将本文方法用于真实眼科图像下游任务的前处理能够有效提升下游任务的表现,在含有分割标签的DRIVE数据集上进行的视网膜血管分割实验结果显示,相较于原始扩散模型,其分割指标对比其受试者工作特征曲线下面积(area under the curve,AUC),准确率(accuracy,Acc)和敏感性(sensitivity,Sen)平均分别提升0.0314,0.0030和0.0738。结论提出的方法能够在保留真实眼底特征的同时去除模糊、恢复更丰富的细节,从而有利于临床图像的分析和应用。
