In this paper, we present reduction algorithms based on the principle of Skowron's discernibility matrix - the ordered attributes method. The completeness of the algorithms for Pawlak reduct and the uniqueness for...In this paper, we present reduction algorithms based on the principle of Skowron's discernibility matrix - the ordered attributes method. The completeness of the algorithms for Pawlak reduct and the uniqueness for a given order of the attributes are proved. Since a discernibility matrix requires the size of the memory of U2, U is a universe of objects, it would be impossible to apply these algorithms directly to a massive object set. In order to solve the problem, a so-called quasi-discernibility matrix and two reduction algorithms are proposed. Although the proposed algorithms are incomplete for Pawlak reduct, their opimal paradigms ensure the completeness as long as they satisfy some conditions. Finally we consider the problem on the reduction of distributive object sets.展开更多
BACKGROUND： Chemical induction has been shown to be effective at promoting the differentiation of bone marrow-derived mesenchymal stem cells （MSCs）. However, these inductors have cytotoxicity side effects that may ...BACKGROUND： Chemical induction has been shown to be effective at promoting the differentiation of bone marrow-derived mesenchymal stem cells （MSCs）. However, these inductors have cytotoxicity side effects that may damage cells over time. Traditional Chinese medicines avoid this disadvantage while still producing effective induction. OBJECTIVE： To investigate the influence of RadixAstragafi （Huangql） on the differentiation of MSCs. DESIGN, TIME AND SETTING： In vitro study of traditional Chinese medicine in neural stem cell differentiation. The experiment was performed at the Central Laboratory of Hebei North University between April and June 2007. MATERIALS： Radix Astragafi solution （lot No. 060105; license No. Z53021585） was purchased from Dali Pharmaceutical Co., Ltd., China; rabbit anti-rat nestin, rabbit anti-rat neuron-specific enolase （NSE）, mouse anti-rat microtubule-associated protein 2, and rabbit anti-rat glial fibrillary acidic protein were purchased from Wuhan Boster, China. METHODS： Whole bone marrow was isolated from the femur and tibia of 6-week-old male Wistar rats and subcultured. The fourth passage of MSCs were harvested and induced by different concentrations （50, 100, 200, 400 g/L） of Radix Astragali. MAIN OUTCOME MEASURES： Hematoxylin-eosin staining was used to observe MSC morphology after 24 hours of induction. Immunocytochemistry was employed to observe the expression of NSE （specific neuronal marker）, nestin （marker of neural stem cell）, glial fibrillary acidic protein and microtubule-associated protein 2 （markers of astrocytes）. RESULTS： Following Radix Astragali treatment, changes occurred in cell morphology including： cell body pyknosis; thin and long processes formed in some cells, with growth corresponding to drug concentration and induction time; and the formation of network-like connections between some cells. With increasing drug concentration and induction time, nestin expression was upregulated, and the number of positive cells incre展开更多
We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance...We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance of the system are systematically analyzed through mathematical methods.A circuit simulation model and a finite element analysis(FEA)simulation model are developed to study the power losses of the system,including copper loss in coils,semiconductor loss in circuits,and eddy current loss in transmission media.The characteristics of the power losses can provide guidelines to improve the efficiency of ICPT systems.Calculation results and simulation results are validated by relevant experiments of the prototype system.The output power of the prototype system is up to 45 W and the efficiency is up to 0.84.The preliminary results indicate that the efficiency will increase as the transmission power is raised by increasing the input voltage.When the output power reaches 500 W,the efficiency is expected to exceed 0.94.The efficiency can be further improved by choosing proper semiconductors and coils.The analysis methods prove effective in predicting the performance of similar ICPT systems and should be useful in designing new systems.展开更多
This paper presents a P-Q coordination based highvoltage ride through(HVRT) control strategy for doubly fed induction generators(DFIGs) based on a combined Q-V control and P-V de-loading control. The active/reactive p...This paper presents a P-Q coordination based highvoltage ride through(HVRT) control strategy for doubly fed induction generators(DFIGs) based on a combined Q-V control and P-V de-loading control. The active/reactive power injection effect of DFIG on transient overvoltage is firstly analyzed and the reactive power capacity evaluation of DFIG considering its de-loading operation is then conducted. In the proposed strategy, the reactive power limit of DFIG can be flexibly extended during the transient process in coordination with its active power adjustment. As a result, the transient overvoltage caused by DC bipolar block can be effectively suppressed. Moreover, key outer loop parameters such as Q-V control coefficient and deloading coefficient can be determined based on the voltage level of point of common coupling(PCC) and the available power capacity of DFIG. Finally, case studies based on MATLAB/Simulink simulation are used to verify the effectiveness of the proposed control strategy.展开更多
In the present study, we aimed to intensively study the chemical constituents, especially organic acids from a medicinal plant Portulaca oleracea L., and screen their anti-inflammatory and quinone reductase （QR, a ph...In the present study, we aimed to intensively study the chemical constituents, especially organic acids from a medicinal plant Portulaca oleracea L., and screen their anti-inflammatory and quinone reductase （QR, a phase II detoxyfication enzyme） inductive activity. A total of 20 compounds were isolated and identified based on spectroscopic methods, as succinic acid （1）, mono-methyl succinate （2）, L-malic acid （3）, L-l-methyl malate （4）, L-4-methyl malate （5）, L-dimethyl malate （6）, L-6-ethyl citrate （7）, L-1-methyl citrate （8）, L-1,5-dimethyl citrate （9）, 4-hydroxy-5-methylfuran-3-carboxylic acid （10）, 5-hydroxymethyl-furoic acid （11）, stearic acid （12）, L-pyroglutamic acid （13）, cyclo-（tyrosine-leucine） （14）, L-isoleucine （15）, （-）-dehydrovomifoliol （16）, （-）-epiloliolide （17）, 3,4-dihydroxyphenylethanol （18）, succinimide （19）, and uracil （20）. Among them, 14 compounds （2, 4-8, 10, 11, 13-18） were isolated from P. oleracea for the first time. Compotmd 18 （12.5 μM） exhibited potent anti-inflammatory effect in lipopolysaccharide （LPS）-induced macrophage cells （RAW264.7） by reducing NO production, and it also increased QR activity in Hepa lclc7 cells. Compound 16 （50 μM） showed weak QR inductive activity. None of other compounds showed anti-inflammatory or QR inductive activities.展开更多
This paper presents a generalized method for updating approximations of a concept incrementally, which can be used as an effective tool to deal with dynamic attribute generalization. By combining this method and the L...This paper presents a generalized method for updating approximations of a concept incrementally, which can be used as an effective tool to deal with dynamic attribute generalization. By combining this method and the LERS inductive learning algorithm, it also introduces a generalized quasi incremental algorithm for learning classification rules from data bases.展开更多
本文充分利用网页数据的超链接关系和文本信息,提出了一种用于网页分类的归纳式半监督学习算法:基于图的Co-training网页分类算法(Graph based Co-training algorithmfor web page classification),简称GCo-training,并从理论上证明了...本文充分利用网页数据的超链接关系和文本信息,提出了一种用于网页分类的归纳式半监督学习算法:基于图的Co-training网页分类算法(Graph based Co-training algorithmfor web page classification),简称GCo-training,并从理论上证明了算法的有效性.GCo-training在Co-training算法框架下,迭代地学习一个基于由超链接信息构造的图的半监督分类器和一个基于文本特征的Bayes分类器.基于图的半监督分类器只利用少量的标记数据,通过挖掘数据间大量的关系信息就可达到比较高的预测精度,可为Bayes分类器提供大量的标记信息;反过来学习大量标记信息后的Bayes分类器也可为基于图的分类器提供有效信息.迭代过程中,二者互相帮助,不断提高各自的性能,而后Bayes分类器可以用来预测大量未见数据的类别.在Web→KB数据集上的实验结果表明,与利用文本特征和锚文本特征的Co-training算法和基于EM的Bayes算法相比,GCo-training算法性能优越.展开更多
Electroreduction of Ni(Ⅱ) to metallic Ni in urea NaBr melt at 373 K is irreversible in one step. Gd(Ⅲ) is not reduced to Gd alone, but can be inductively codeposited with Ni(Ⅱ). The amorphous Gd Ni alloy films were...Electroreduction of Ni(Ⅱ) to metallic Ni in urea NaBr melt at 373 K is irreversible in one step. Gd(Ⅲ) is not reduced to Gd alone, but can be inductively codeposited with Ni(Ⅱ). The amorphous Gd Ni alloy films were obtained by potentiostatic electrolysis and galvanostatic electrolysis. With the cathode potential shift to negative direction and the increase of current density, the content of gadolinium in the alloy increases first, and then drops down gradually. The molar ratio of Gd(Ⅲ) to Ni(Ⅱ) and the time also influence the content of Gd. Crystalline GdNi 3 alloy was obtained after heat treatment of the deposit. [展开更多
文摘In this paper, we present reduction algorithms based on the principle of Skowron's discernibility matrix - the ordered attributes method. The completeness of the algorithms for Pawlak reduct and the uniqueness for a given order of the attributes are proved. Since a discernibility matrix requires the size of the memory of U2, U is a universe of objects, it would be impossible to apply these algorithms directly to a massive object set. In order to solve the problem, a so-called quasi-discernibility matrix and two reduction algorithms are proposed. Although the proposed algorithms are incomplete for Pawlak reduct, their opimal paradigms ensure the completeness as long as they satisfy some conditions. Finally we consider the problem on the reduction of distributive object sets.
文摘BACKGROUND： Chemical induction has been shown to be effective at promoting the differentiation of bone marrow-derived mesenchymal stem cells （MSCs）. However, these inductors have cytotoxicity side effects that may damage cells over time. Traditional Chinese medicines avoid this disadvantage while still producing effective induction. OBJECTIVE： To investigate the influence of RadixAstragafi （Huangql） on the differentiation of MSCs. DESIGN, TIME AND SETTING： In vitro study of traditional Chinese medicine in neural stem cell differentiation. The experiment was performed at the Central Laboratory of Hebei North University between April and June 2007. MATERIALS： Radix Astragafi solution （lot No. 060105; license No. Z53021585） was purchased from Dali Pharmaceutical Co., Ltd., China; rabbit anti-rat nestin, rabbit anti-rat neuron-specific enolase （NSE）, mouse anti-rat microtubule-associated protein 2, and rabbit anti-rat glial fibrillary acidic protein were purchased from Wuhan Boster, China. METHODS： Whole bone marrow was isolated from the femur and tibia of 6-week-old male Wistar rats and subcultured. The fourth passage of MSCs were harvested and induced by different concentrations （50, 100, 200, 400 g/L） of Radix Astragali. MAIN OUTCOME MEASURES： Hematoxylin-eosin staining was used to observe MSC morphology after 24 hours of induction. Immunocytochemistry was employed to observe the expression of NSE （specific neuronal marker）, nestin （marker of neural stem cell）, glial fibrillary acidic protein and microtubule-associated protein 2 （markers of astrocytes）. RESULTS： Following Radix Astragali treatment, changes occurred in cell morphology including： cell body pyknosis; thin and long processes formed in some cells, with growth corresponding to drug concentration and induction time; and the formation of network-like connections between some cells. With increasing drug concentration and induction time, nestin expression was upregulated, and the number of positive cells incre
基金Project supported by the National High-Tech R&D Program of China(No.2013AA09A414)the National Natural Science Foundation of China(No.51221004)the Interdisciplinary Research Foundation of Zhejiang University(No.2012HY003A)
文摘We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance of the system are systematically analyzed through mathematical methods.A circuit simulation model and a finite element analysis(FEA)simulation model are developed to study the power losses of the system,including copper loss in coils,semiconductor loss in circuits,and eddy current loss in transmission media.The characteristics of the power losses can provide guidelines to improve the efficiency of ICPT systems.Calculation results and simulation results are validated by relevant experiments of the prototype system.The output power of the prototype system is up to 45 W and the efficiency is up to 0.84.The preliminary results indicate that the efficiency will increase as the transmission power is raised by increasing the input voltage.When the output power reaches 500 W,the efficiency is expected to exceed 0.94.The efficiency can be further improved by choosing proper semiconductors and coils.The analysis methods prove effective in predicting the performance of similar ICPT systems and should be useful in designing new systems.
基金jointly supported by the National Natural Science Foundation of China (No.51677165,No.51837004)the National Key R&D Program of China (No.2017YFB0902000)。
文摘This paper presents a P-Q coordination based highvoltage ride through(HVRT) control strategy for doubly fed induction generators(DFIGs) based on a combined Q-V control and P-V de-loading control. The active/reactive power injection effect of DFIG on transient overvoltage is firstly analyzed and the reactive power capacity evaluation of DFIG considering its de-loading operation is then conducted. In the proposed strategy, the reactive power limit of DFIG can be flexibly extended during the transient process in coordination with its active power adjustment. As a result, the transient overvoltage caused by DC bipolar block can be effectively suppressed. Moreover, key outer loop parameters such as Q-V control coefficient and deloading coefficient can be determined based on the voltage level of point of common coupling(PCC) and the available power capacity of DFIG. Finally, case studies based on MATLAB/Simulink simulation are used to verify the effectiveness of the proposed control strategy.
基金National Natural Science Foundation of China(Grant No.81073005)Science and Technology Development Program of Shandong Province(Grant No.2014GSF119007)+2 种基金Major Project of Science and Technology of Shandong Province(Grant No.2015ZDJS04001)Young Scholars Program of Shandong University(Grant No.YSPSDU2015WLJH50)China-Australia Centre for Health Sciences Research(2015)
文摘In the present study, we aimed to intensively study the chemical constituents, especially organic acids from a medicinal plant Portulaca oleracea L., and screen their anti-inflammatory and quinone reductase （QR, a phase II detoxyfication enzyme） inductive activity. A total of 20 compounds were isolated and identified based on spectroscopic methods, as succinic acid （1）, mono-methyl succinate （2）, L-malic acid （3）, L-l-methyl malate （4）, L-4-methyl malate （5）, L-dimethyl malate （6）, L-6-ethyl citrate （7）, L-1-methyl citrate （8）, L-1,5-dimethyl citrate （9）, 4-hydroxy-5-methylfuran-3-carboxylic acid （10）, 5-hydroxymethyl-furoic acid （11）, stearic acid （12）, L-pyroglutamic acid （13）, cyclo-（tyrosine-leucine） （14）, L-isoleucine （15）, （-）-dehydrovomifoliol （16）, （-）-epiloliolide （17）, 3,4-dihydroxyphenylethanol （18）, succinimide （19）, and uracil （20）. Among them, 14 compounds （2, 4-8, 10, 11, 13-18） were isolated from P. oleracea for the first time. Compotmd 18 （12.5 μM） exhibited potent anti-inflammatory effect in lipopolysaccharide （LPS）-induced macrophage cells （RAW264.7） by reducing NO production, and it also increased QR activity in Hepa lclc7 cells. Compound 16 （50 μM） showed weak QR inductive activity. None of other compounds showed anti-inflammatory or QR inductive activities.
文摘This paper presents a generalized method for updating approximations of a concept incrementally, which can be used as an effective tool to deal with dynamic attribute generalization. By combining this method and the LERS inductive learning algorithm, it also introduces a generalized quasi incremental algorithm for learning classification rules from data bases.
文摘本文充分利用网页数据的超链接关系和文本信息,提出了一种用于网页分类的归纳式半监督学习算法:基于图的Co-training网页分类算法(Graph based Co-training algorithmfor web page classification),简称GCo-training,并从理论上证明了算法的有效性.GCo-training在Co-training算法框架下,迭代地学习一个基于由超链接信息构造的图的半监督分类器和一个基于文本特征的Bayes分类器.基于图的半监督分类器只利用少量的标记数据,通过挖掘数据间大量的关系信息就可达到比较高的预测精度,可为Bayes分类器提供大量的标记信息;反过来学习大量标记信息后的Bayes分类器也可为基于图的分类器提供有效信息.迭代过程中,二者互相帮助,不断提高各自的性能,而后Bayes分类器可以用来预测大量未见数据的类别.在Web→KB数据集上的实验结果表明,与利用文本特征和锚文本特征的Co-training算法和基于EM的Bayes算法相比,GCo-training算法性能优越.
文摘Electroreduction of Ni(Ⅱ) to metallic Ni in urea NaBr melt at 373 K is irreversible in one step. Gd(Ⅲ) is not reduced to Gd alone, but can be inductively codeposited with Ni(Ⅱ). The amorphous Gd Ni alloy films were obtained by potentiostatic electrolysis and galvanostatic electrolysis. With the cathode potential shift to negative direction and the increase of current density, the content of gadolinium in the alloy increases first, and then drops down gradually. The molar ratio of Gd(Ⅲ) to Ni(Ⅱ) and the time also influence the content of Gd. Crystalline GdNi 3 alloy was obtained after heat treatment of the deposit. [
