CHI Statistical Text Feature Selection Method Based on Information Entropy Optimization

Guohua Wu,Sen Li,Lin Han,Mengmeng Zhao 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.11

CHI statistical text feature selection method based on information entropy optimization is presented in this paper. In the text categorization process of feature selection, considering the results of effect of the distribution within categories and among categories, we introduce the frequency of features information entropy among categories, the information entropy within categories, information within category to optimize the CHI statistical methods. The experimental results show that the classification accuracy of the optimized CHI method is significantly higher than that the traditional CHI statistical methods.

Research on rapid source term estimation in nuclear accident emergency decision for pressurized water reactor based on Bayesian network

Wu, Guohua,Tong, Jiejuan,Zhang, Liguo,Yuan, Diping,Xiao, Yiqing Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.8

Nuclear emergency preparedness and response is an essential part to ensure the safety of nuclear power plant (NPP). Key support technologies of nuclear emergency decision-making usually consist of accident diagnosis, source term estimation, accident consequence assessment, and protective action recommendation. Source term estimation is almost the most difficult part among them. For example, bad communication, incomplete information, as well as complicated accident scenario make it hard to determine the reactor status and estimate the source term timely in the Fukushima accident. Subsequently, it leads to the hard decision on how to take appropriate emergency response actions. Hence, this paper aims to develop a method for rapid source term estimation to support nuclear emergency decision making in pressurized water reactor NPP. The method aims to make our knowledge on NPP provide better support nuclear emergency. Firstly, this paper studies how to build a Bayesian network model for the NPP based on professional knowledge and engineering knowledge. This paper presents a method transforming the PRA model (event trees and fault trees) into a corresponding Bayesian network model. To solve the problem that some physical phenomena which are modeled as pivotal events in level 2 PRA, cannot find sensors associated directly with their occurrence, a weighted assignment approach based on expert assessment is proposed in this paper. Secondly, the monitoring data of NPP are provided to the Bayesian network model, the real-time status of pivotal events and initiating events can be determined based on the junction tree algorithm. Thirdly, since PRA knowledge can link the accident sequences to the possible release categories, the proposed method is capable to find the most likely release category for the candidate accidents scenarios, namely the source term. The probabilities of possible accident sequences and the source term are calculated. Finally, the prototype software is checked against several sets of accident scenario data which are generated by the simulator of AP1000-NPP, including large loss of coolant accident, loss of main feedwater, main steam line break, and steam generator tube rupture. The results show that the proposed method for rapid source term estimation under nuclear emergency decision making is promising.

Propagation Properties of Electromagnetic Multi-Gaussian Schell Model Beams Propagating Through Atmospheric Turbulence

Guohua Wu,He Zhou,Tonggang Zhao,Hongzhan Liu,Zhengda Li,Xin Zhao 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.6

A model for electromagnetic multi-Gaussian Schell-model beams is introduced. An analyticalexpression for the cross-spectral density matrix of electromagnetic multi-Gausssian Schell-model(EMGSM) beams propagating through non-Kolmogorov turbulence is derived based on the extendedHuygens-Fresnel principle. With help of this expression, the average intensity, degree of coherence(DOC) and degree of polarization (DOP) of EMGSM beams are investigated in detail. Our resultsshow that by suitable choices of the source parameters, the distance that preserve a flat profile canbe prolonged. The effects of M and exponent value on DOC and DOP of EMGSM beams arestudied in detail.

A Fingerprint Feature Extraction Algorithm based on Optimal Decision for Text Copy Detection

Guohua Wu,Mengmeng Zhao,Lin Han,Sen Li 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.11

Fingerprint feature-based text copy detection can rapidly identify the plagiarism, but suffers from the excessive fingerprint density. To resolve the problem, we propose a fingerprint feature extraction algorithm based on the optimal decision, combined with Winnowing algorithm and optimal decision model, and it can extract fingerprint feature from the hash values in the sliding window. The experimental results demonstrate that our algorithm can reduce the fingerprint density when the windows’ fingerprint feature is too adjacent, and the selected fingerprints can represent the text feature on the premise of the accuracy of the text copy and the algorithm.

Differential Frost Tolerance and Enzymatic Activities in the Leaves and Immature Fruits of Loquat (Eriobotrya japonica Lindl.)

Guohua Zheng,Xianqian Niu,Jinbiao Zhang,Hanwen Wu,Xiuxiang Lin,Dongming Pan 한국원예학회 2015 원예과학기술지 Vol.33 No.3

In this experiment, five commercial cultivars and one wild species of loquat were used to investigate frost tolerance and enzymatic activities in leaves and young fruits under cold stress at -3℃. The frost injury, malondialdehyde (MDA) content, and oxygen-scavenging enzyme activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were studied. This results showed that the wild species ‘Wild Oak-leaf’ loquat was the most frost tolerant among accessions tested, followed by the cultivar ‘Golden Block’. Other cultivars, ‘Wu Gong Bai’, ‘Taicheng 4’, ‘Xiangzhong 11’ and ‘Zaozhong 6’, were relatively weak in frost tolerance. The enzymatic activities of SOD, POD and CAT increased initially and then decreased as the exposure time increased. However, the enzymatic peak occurred later in the frost-tolerant accession than in the frost-sensitive accession. The correlation coefficients of MDA contents between leaves and immature fruits were from 0.93 to 0.99 in the five commercial loquat cultivars. For the ‘Wild Oak-leaf’ loquat, the correlation coefficients of MDA and POD were 0.98 and 0.95, respectively, but the coefficients for SOD, CAT and APX were relatively low. In general, there were good correlations between loquat leaves and immature fruits in MDA content and enzyme activities. These results indicate that analysis of these physiological and biochemical activities in loquat leaves could potentially be used to predict the cold tolerance in loquat at immature fruit stage and to accelerate breeding programs for cold tolerance in loquat.

Optimizations of Canny Edge Detection in Ghost Imaging

Guohua Wu,Dongyue Yang,Chen Chang,Longfei Yin,Bin Luo,Hong Guo 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.3

An optimization of the Canny edge detector’s application in ghost imaging is presented. Based on the pseudo-thermal light ghost imaging scheme with a binary object, a thin and accurate edge map can be extracted by using a Gaussian-filtering-optimized Canny edge detector. The scale of the Gaussian filter in Canny edge detection algorithm is the dominate factor in the performance of the edge detector, and can be evaluated by the bit error rate of reconstructed binary image based on the edge map. Simulation results indicate the optimal window size of Gaussian filter for ghost imaging is proportional to the full width at half maximum of the self-correlation function in the idler arm samples without any priori knowledge of the object. Experimental results show that, with an appropriate Gaussian filter, the reconstructed binary image can approach the original binary object with the minimum bit error rate, which means the edge detection result is optimal.

Uncertainty analysis of containment dose rate for core damage assessment in nuclear power plants

Guohua Wu,Jiejuan Tong,Yan Gao,Liguo Zhang,Yunfei Zhao 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.5

One of the most widely used methods to estimate core damage during a nuclear power plant accident iscontainment radiation measurement. The evolution of severe accidents is extremely complex, leading touncertainty in the containment dose rate (CDR). Therefore, it is difficult to accurately determine coredamage. This study proposes to conduct uncertainty analysis of CDR for core damage assessment. First,based on source term estimation, the Monte Carlo (MC) and point-kernel integration methods were usedto estimate the probability density function of the CDR under different extents of core damage in accidentscenarios with late containment failure. Second, the results were verified by comparing the resultsof both methods. The point-kernel integration method results were more dispersed than the MC results,and the MC method was used for both quantitative and qualitative analyses. Quantitative analysisindicated a linear relationship, rather than the expected proportional relationship, between the CDR andcore damage fraction. The CDR distribution obeyed a logarithmic normal distribution in accidents with asmall break in containment, but not in accidents with a large break in containment. A possible applicationof our analysis is a real-time core damage estimation program based on the CDR

Differential Frost Tolerance and Enzymatic Activities in the Leaves and Immature Fruits of Loquat (Eriobotrya japonica Lindl.)

Zheng, Guohua,Niu, Xianqian,Zhang, Jinbiao,Wu, Hanwen,Lin, Xiuxiang,Pan, Dongming Korean Society of Horticultural Science 2015 원예과학기술지 Vol.33 No.3

In this experiment, five commercial cultivars and one wild species of loquat were used to investigate frost tolerance and enzymatic activities in leaves and young fruits under cold stress at $-3^{\circ}C$. The frost injury, malondialdehyde (MDA) content, and oxygen-scavenging enzyme activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were studied. This results showed that the wild species 'Wild Oak-leaf' loquat was the most frost tolerant among accessions tested, followed by the cultivar 'Golden Block'. Other cultivars, 'Wu Gong Bai', 'Taicheng 4', 'Xiangzhong 11' and 'Zaozhong 6', were relatively weak in frost tolerance. The enzymatic activities of SOD, POD and CAT increased initially and then decreased as the exposure time increased. However, the enzymatic peak occurred later in the frost-tolerant accession than in the frost-sensitive accession. The correlation coefficients of MDA contents between leaves and immature fruits were from 0.93 to 0.99 in the five commercial loquat cultivars. For the 'Wild Oak-leaf' loquat, the correlation coefficients of MDA and POD were 0.98 and 0.95, respectively, but the coefficients for SOD, CAT and APX were relatively low. In general, there were good correlations between loquat leaves and immature fruits in MDA content and enzyme activities. These results indicate that analysis of these physiological and biochemical activities in loquat leaves could potentially be used to predict the cold tolerance in loquat at immature fruit stage and to accelerate breeding programs for cold tolerance in loquat.

Changes in Cell Ca 2+ Distribution in Loquat Leaves and Its Effects on Cold Tolerance

Guohua Zheng,Dongming Pan,Xianqian Niu,Hanwen Wu,Jinbiao Zhang 한국원예학회 2014 원예과학기술지 Vol.32 No.5

Calcium has been associated with improved cold tolerance in many crops. The aim of this study was to investigatethe changes in leaf cell Ca2+distribution and cell organelle ultrastructure of loquat (Eriobotrya japonica Lindl.) plants in responseto cold stress at -3°C, using transmission electron microscopy (TEM). Two loquat accessions, Zaozhong 6 (a commercial cultivar)and oakleaf loquat (a wild relative) were used. Cold tolerance, as measured by leaf browning rate, was higher in oakleaf plants,and calcium treatment improved cold tolerance in both species. Cold stress first induced inward transport of Ca2+from theintracellular space. Then, the imported Ca2+was aggregated around the chloroplast membrane, finally entering the chloroplast. This pattern of Ca2+distribution in leaf cells occurred earlier in Zaozhong 6 than in the wild loquat. With increasing time ofcold exposure, the chloroplast membranes of Zaozhong 6 leaves were damaged, blurred and even disappeared, while those ofwild oakleaf loquat leaves maintained their structure longer. In Zaozhong 6, cold stress induced a clear cavity between poorlystructured granal thylakoids and vesicles appearing inside the chloroplast, while in oakleaf leaves cold stress had little effecton the ultrastructure of chloroplasts (although chloroplast membranes looked blurred). Loquat leaves accumulated free calciumions around chloroplasts in response to cold stress, with earlier calcium accumulation occurring in the cold-sensitive cultivarZaozhong 6 than in wild oakleaf loquat. These results demonstrate that these two loquat species have differences in both coldtolerance and calcium accumulation dynamics.

rGO/VNTs as cathodes for high performance sodium ion batteries with good cycling performance

Guohua Gao,Mingze Ji,Kun Zhang,Guangming Wu 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.1

Using the ex-situ composite method, we have prepared grapheme coating vanadium oxide nanotubes (VNT) by using vanadium oxide nanotubes, cationic surfactant cetyltrimethylammonium bromide (CTAB) and graphene oxide (GO) aqueous solution. The surface of the vanadium oxide nanotube was modified by CTAB, so that vanadium oxide nanotubes were combined with graphene oxide via electrostatic interaction. The introduction of graphene provides an effective protective layer for vanadium oxide nanotubes, alleviates the volume change caused by sodium ion insertion and extraction during charge and discharge process, and enhances the stability of vanadium oxide nanotube structure. The electrochemical test show that the capacity retention of VNTs after 50 cycles was only 18%, while the capacity retention rate of VNTs/rGO was as high as 74%. In addition, we made a detailed analysis of the morphology, structure and formation mechanism of the materials.