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排序方式: 共有487条查询结果,搜索用时 15 毫秒
1.
Syafikah Huda Paiman Mukhlis A Rahman Khairul Hamimah Abas Azian Abd Aziz Ahmad Fauzi Ismail Mohd Hafiz Dzarfan Othman Juhana Jaafar Mohammad Noorul Anam Mohd Norddin 《化学工程与技术》2019,42(6):1321-1329
Removal by absorptive ceramic membranes can simultaneously absorb and separate metal ions from water. Alumina/yttria‐stabilized zirconia (Al2O3/YSZ) hollow‐fiber membranes, fabricated using phase inversion and sintering process, were deposited with iron oxide by an in‐situ hydrothermal process. The results showed that α‐Fe2O3 was produced and incorporated across the membranes. A reduction in flux was recorded with the deposition of α‐Fe2O3. However, it improved the adsorption capacity for heavy metal adsorption. The adsorption‐separation test demonstrated that the optimized membrane is able to completely remove Pb(II) ions after two hours. 相似文献
2.
Haliza Abdul Aziz Noor Azeerah Abas Bonnie Tay Yen Ping Zainab Idris 《Journal of surfactants and detergents》2020,23(2):251-262
The technology for transesterification reactions between methyl esters and alcohols is well established by using classical homogeneous alkaline catalysts, which provide high conversion of methyl esters to specialty or nonindigenous esters. However, in certain products where the purity of the esters is of concern, the removal of homogeneous catalysts after the completion of the reaction is a challenge in terms of production cost and water footprint. Therefore, a study to investigate the potential of heterogeneous catalysts was conducted on reactions between methyl palmitate and triethanolamine. The degree of basicity and active surface area of calcium oxide (CaO), zinc oxide (ZnO), and magnesium oxide (MgO) were first characterized by using temperature-programmed desorption (TPD-CO2) and Brunauere–Emmett–Teller (BET), respectively. Among the metal oxides investigated, the CaO catalyst showed the best catalytic activity toward the transesterification process as it gave the highest conversion of methyl palmitate and yielded fatty esteramine compositions similar to the conventional homogeneous catalyst. The optimum transesterification condition by using the CaO catalyst utilized a lower vacuum system of approximately 200 mbar, which could minimize a considerable amount of energy consumption. Furthermore, low CaO dosage of 0.1% was able to give a conversion of 94.5% methyl ester and formed esteramine at 170 °C for 2 h. Therefore, the production of esterquats from esteramine may become more economically feasible through the methyl ester route by using the CaO catalyst, which can be recycled three times. 相似文献
3.
Yehia A. Ibrahim Magdy A. Abdelhameed Taher A. Al-Sahhaf Mohamed A. Fahim 《Petroleum Science and Technology》2003,21(5):825-837
Asphaltenes obtained by precipitation from crude Kuwaiti oils have been analyzed by proton magnetic resonance (1H-NMR), carbon-13 nuclear magnetic resonance (13C-NMR) and Infrared (IR) spectral techniques. The molecular weight and elemental analysis were also determined. These combined analytical data were used for the characterization of these Kuwaiti oils. The asphaltenes molecular weights range from approximately 4200-6500 with an H/C ratio of 0.91-1.1 with an average 45-71% aromatic carbons. The average side chain length was of 4-6 carbons. It can also be concluded that the asphaltenes under investigation contain 5-9 sets of condensed aromatic rings joined together by bridges of alkyl chains or other hetero atoms and the average number of each of these sets of condensed aromatic rings is nearly 7. There are a number of alicyclic rings and condensed alicyclic rings in asphaltene. The IR spectra showed main molecular groups including OH, NH, SH, C=O and aliphatic and aromatic C-H's. 相似文献
4.
Analytical expressions are obtained for predicting the harmonic and intermodulation performance of R-LED series networks. These expressions are in terms of the ordinary Bessel functions with arguments depenedent on the modulation index. 相似文献
5.
Performance analysis of support vector machines classifiers in breast cancer mammography recognition
Support vector machine (SVM) is a supervised machine learning approach that was recognized as a statistical learning apotheosis for the small-sample database. SVM has shown its excellent learning and generalization ability and has been extensively employed in many areas. This paper presents a performance analysis of six types of SVMs for the diagnosis of the classical Wisconsin breast cancer problem from a statistical point of view. The classification performance of standard SVM (St-SVM) is analyzed and compared with those of the other modified classifiers such as proximal support vector machine (PSVM) classifiers, Lagrangian support vector machines (LSVM), finite Newton method for Lagrangian support vector machine (NSVM), Linear programming support vector machines (LPSVM), and smooth support vector machine (SSVM). The experimental results reveal that these SVM classifiers achieve very fast, simple, and efficient breast cancer diagnosis. The training results indicated that LSVM has the lowest accuracy of 95.6107 %, while St-SVM performed better than other methods for all performance indices (accuracy = 97.71 %) and is closely followed by LPSVM (accuracy = 97.3282). However, in the validation phase, the overall accuracies of LPSVM achieved 97.1429 %, which was superior to LSVM (95.4286 %), SSVM (96.5714 %), PSVM (96 %), NSVM (96.5714 %), and St-SVM (94.86 %). Value of ROC and MCC for LPSVM achieved 0.9938 and 0.9369, respectively, which outperformed other classifiers. The results strongly suggest that LPSVM can aid in the diagnosis of breast cancer. 相似文献
6.
In this paper, a new class of additive codes which is referred to as ?2 ?2[u]-additive codes is introduced. This is a generalization towards another direction of recently introduced ?2 ?4-additive codes [J. Borges, C. Fernández-Córdoba, J. Pujol, J. Rif´a, and M. Villanueva, ?2 ?4-linear codes: Generator matrices and duality, Designs Codes Cryptogr. 54(2) (2010), pp. 167–179]. ?2 ?4-additive codes have shown to provide a promising class of codes with their algebraic structure and applications such as steganography. The standard generator matrices are established and by introducing orthogonality the parity-check matrices are also obtained. A MacWilliams-type identity that relates the weight enumerator of a code with its dual is proved. Furthermore, a Gray map that maps these codes to binary codes is defined and some examples of optimal codes which are the binary Gray images of ?2 ?2[u]-additive codes are presented. 相似文献
7.
Taher Habibzadeh 《Information & Communications Technology Law》2016,25(2):150-172
In the modern world, electronic communications play a significant role in national and international electronic transactions. This issue has forced all legal systems to face up to many emerging legal problems in the context of electronic communications, such as the legal status of electronic agents in contracting electronically. Regarding the legal validity of e-contracts made through interactive websites, the legal status of electronic agents which play an important role in this process is questionable to see whether they are akin to real agents in the physical world or they are only a mere tool of communication. The current article tries to analyse this question by criticising a number of theories and some others based on the technical nature of the Internet, the traditional legal rules and principles and the UNCITRAL regulations on e-commerce and also the statues of American, English and EU laws on e-commerce to develop Iranian legal system. 相似文献
8.
David?JurgensEmail author Mohammad?Taher?Pilehvar Roberto?Navigli 《Language Resources and Evaluation》2016,50(1):5-33
Semantic similarity has typically been measured across items of approximately similar sizes. As a result, similarity measures have largely ignored the fact that different types of linguistic item can potentially have similar or even identical meanings, and therefore are designed to compare only one type of linguistic item. Furthermore, nearly all current similarity benchmarks within NLP contain pairs of approximately the same size, such as word or sentence pairs, preventing the evaluation of methods that are capable of comparing different sized items. To address this, we introduce a new semantic evaluation called cross-level semantic similarity (CLSS), which measures the degree to which the meaning of a larger linguistic item, such as a paragraph, is captured by a smaller item, such as a sentence. Our pilot CLSS task was presented as part of SemEval-2014, which attracted 19 teams who submitted 38 systems. CLSS data contains a rich mixture of pairs, spanning from paragraphs to word senses to fully evaluate similarity measures that are capable of comparing items of any type. Furthermore, data sources were drawn from diverse corpora beyond just newswire, including domain-specific texts and social media. We describe the annotation process and its challenges, including a comparison with crowdsourcing, and identify the factors that make the dataset a rigorous assessment of a method’s quality. Furthermore, we examine in detail the systems participating in the SemEval task to identify the common factors associated with high performance and which aspects proved difficult to all systems. Our findings demonstrate that CLSS poses a significant challenge for similarity methods and provides clear directions for future work on universal similarity methods that can compare any pair of items. 相似文献
9.
Al-Shehari Taher Alsowail Rakan A. 《International Journal of Information Security》2023,22(3):611-629
International Journal of Information Security - Cybersecurity threats can be perpetrated by insiders or outsiders. The threats that could be carried out by insiders are far more serious due to... 相似文献
10.
Almawgani A. H. M. Alhawari Adam R. H. Hindi Ayman Taher Al-Arashi Waled Hussein Al-Ashwal A. Y. 《Multidimensional Systems and Signal Processing》2022,33(2):561-578
Multidimensional Systems and Signal Processing - Digital images are commonly used in steganography due to the popularity of digital image transfer and exchange through the Internet. However, the... 相似文献