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Zhihua Sun,Lei Gao,Dong Wang,Lingjie Liu,Chensheng Qiu,Shaopo Wang 대한환경공학회 2024 Environmental Engineering Research Vol.29 No.5
Membrane fouling caused by effluent organic matter (EfOM) limits its further application in wastewater reuse. In this study, the effect of UV/chlorine pretreatment on membrane fouling was investigated in treating secondary effluent by ultrafiltration (UF) process. The relation between organic matter changes and fouling alleviation after UV/chlorine pretreatment was also studied according to the molecular weight (MW) changes in various resin fractions derived from EfOM. Results showed that UV/chlorine pretreatment effectively alleviated irreversible fouling, whereas chlorine pre-oxidation primarily mitigated reversible fouling. UV/chlorine pre-oxidation reduced 18% of reversible membrane fouling and 38% of irreversible membrane fouling at a chlorine dosage of 8 mg/L, indicating better performance in membrane fouling mitigation than chlorine pre-oxidation. UV/chlorine pre-oxidation also decreased dissolved organic matter in the UF permeate. The hydrophobic acidic (HPO-A) fraction caused dominant membrane fouling, while the hydrophilic (HPI) fraction contained most of high MW organic matter. Pre-oxidation changed the polarity of organic matter in the HPO-A fraction and decomposed the organics of high MW in the HPI fraction, which alleviated membrane fouling. These results showed that UV/chlorine pre-oxidation was a prospective pretreatment process prior to UF in wastewater reclamation.
Bacthing Auditing of Data in Multicloud Storage
Zhihua Xia,Xinhui Wang,Xingming Sun,Yafeng Zhu,Peng Ji,Jin Wang 보안공학연구지원센터 2014 International Journal of Database Theory and Appli Vol.7 No.6
Cloud storage enables users to outsource their data to cloud servers and enjoy the on-demand services. However, this new paradigm also introduces integrity threats toward user’ outsourced data. This paper develops an efficient auditing mechanism, which support batch auditing for multiple data files in multi-cloud environment. By constructing a sequence-enforced Merkle Hash Tree, the proposed protocol can resist the replace attack. By using the bilinear map, the proposed protocol achieves stateless and transparent verification. By putting the computation of intermediate values of the verification on cloud servers, our method can greatly reduce the computing burden of the auditor. The performance analysis proves the good efficiency of the proposed protocol.
Model diagnostics of parametric Tobit model based on cumulative residuals
Sun Zhihua,Guo Yuanyuan,Xie Tianfa,Wang Miaomiao 한국통계학회 2021 Journal of the Korean Statistical Society Vol.50 No.1
In this paper, we investigate the adequate check of the parametric Tobit model. A Cramér–Von Mises type test statistic is constructed, and its asymptotic properties under the null and alternative hypotheses are rigorously studied. The method is efective for the adequacy check of parametric regression models with a scalar or multivariate covariate. Furthermore, it avoids the nonparametric smoothing of the regression function and the choice of the smoothing parameter. Simulation studies are conducted to compare the performance of the proposed test procedure and the existing methods in the literature. A real data set of income is analyzed by applying the proposed method.
Fingerprint Liveness Detection Using Difference Co-occurrence Matrix Based Texture Features
Zhihua Xia,Chengsheng Yuan,Xingming Sun,Rui Lv,Decai Sun,Guangyong Gao 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.11
Fingerprint authentication systems have been widely deployed in both civilian and government applications, however, whether fingerprint authentication systems is security or not has been an important issue under fraudulent attempts through artificial spoof fingerprints. In this paper, inspired by popular feature descriptors such as gray level co-occurrence matrix (GLCM) and Gradient (difference matrix (DM)), we propose a novel software-based fingerprint liveness detection algorithm called difference co-occurrence matrix (DCM). In doing so, quantization operation is firstly conducted on the images. DMs are constructed by calculating difference matrices of horizontal and vertical pixel values of images; difference co-occurrence arrays are constructed from the difference matrices between adjacent pixels. To reduce the influence of abnormal pixel values, truncation is used for DMs. Then, we compute four parameters (Angular Second Moment, Entropy, Inverse Differential Moment and Correlation) used as feature vectors of fingerprint images. For the first time in the fingerprint liveness detection, we construct eight difference co-occurrence matrices and extract texture features from processed DCMs. Finally, SVM classifier is used to predict classification accuracy. The experimental results reveal that our proposed method can achieve more accurate classification compared with the best algorithms of 2013 Fingerprint Liveness Detection Competition, while being able to recognize spoofed fingerprints with a better degree of accuracy.
A Multi-keyword Ranked Search over Encrypted Cloud Data Supporting Semantic Extension
Zhihua Xia,Li Chen,Xingming Sun,Jianxiao Liu 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.8
With the emergence of cloud computing, many data owners outsource their local data to cloud server so as to enjoy high-quality data storage services. For the protection of data privacy, sensitive data has to be encrypted before outsourcing, which makes effective data utilization a challenging task. Although existing searchable encryption technologies enable data users to conduct secure search over encrypted data, the functionality of these schemes need to be further improved. In this paper, we construct a secure and efficient multi-keyword ranked search scheme which supports both the semantic extension search and the multi-keyword ranked search. The semantic extension is achieved through the mutual information statistical analysis of keywords. And the multi-keyword ranked search is achieved through a balanced binary tree whose nodes are the vectors of term frequency (TF) values. The splitting operation and secure transformation are utilized to encrypt the vectors of index and query. Note that, the encrypted vectors can be well used to calculate accurate relevance scores. Phantom terms are added to the index vector to blind the search results to resist statistical attacks. Due to the use of tree-based index structure, the proposed scheme can achieve the sub-linear search time. Finally, the experiments are conducted to demonstrate the efficiency of the proposed scheme.
Yaming Sun,Bile Li,Peng Li,Zhihua Li,Yufan Shi,Runtao Yu 한국지질과학협의회 2022 Geosciences Journal Vol.26 No.6
The spatial distribution of flow units and reductant within a sandstone uranium reservoir is very beneficial for exploring the uranium mineralization mechanism; however, such studies have been almost neglected. As such, this paper aims to provide the sedimentological interpretation and heterogeneity models of the sandstone of the Middle Jurassic Zhiluo Formation at Shiwan outcrop area, in the eastern Ordos Basin. The outcrops are sandstone-dominated subaqueous distributary channel successions, in which five distinct architectural elements are identified and interpreted: channel units (CU), downstream accretion elements (DA), lateral accretion elements (LA), sandy bedforms (SB) and no-channelized fine-grained sediments (NFS). Within the sandstone succession, six flow units are present in the middle and lower parts of CU, or the lower parts of DA and SB elements, with their geometry to be controlled by the fourth- or third-order bounding surfaces. Moreover, the carbonaceous debris-rich zones (CDZ) are places with the highest abundance of reductant and preserve exclusively upon the basal erosional surfaces of CU and DA elements. Based on those results, a prediction model is established and shows that the formation of interlayer oxidation zone is strongly selective and confined within the CU and DA elements. The favorable site of uranium mineralization is preferentially distributed in the transition zone between the front of flow unit and the CDZ.