Network Intrusion Detection Based on Stochastic Neural Networks Method

Yunfeng Yang,Fengxian Tang 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.8

With the rapid development of the Internet, especially the development of mobile Internet, network size and network infrastructure changes, especially the more random access node to detect network attacks challenges traditional detection algorithm using neural networks, so that the calculated volume increased dramatically, and will detection accuracy is not high, for this problem, we use the stochastic process theory hidden Markov chain transformation neural network, so that the convergence of a substantial decline, while improving network attack detection accuracy degree.

Logical Connectivity Prediction Models for VANET based on Nonlinear Regression and ELM : An Example of the AODV Protocol

Haiqing Liu,Licai Yang,Sijing Ding,Yunfeng Shi 보안공학연구지원센터 2014 International Journal of Future Generation Communi Vol.7 No.6

Differing from the physical connectivity of the topology structure, the logical connectivity of VANET considers both the interior network configuration and the external communication environment. Hence, the traditional mathematical analysis and modeling methods which are usually used in physical connectivity research are no longer suitable for the logical connectivity prediction. Taking the AODV protocol as an example, this paper simulates the effects of different road traffic parameters on logical connectivity probability and selects three main effect factors, roadway length, vehicle number and vehicle speed. Furthermore, the inner relation between the logical connectivity and the three road traffic parameters is studied based on data mining technique and then two logical connectivity prediction models are presented, the nonlinear regression-based model and the extreme learning machine-based model. Simulation results show that the two models are both with high accuracy in predicting the network logical connectivity under different road traffic environments.

Characterization of a Thermophilic Hemoglobin-degrading Protease from Streptomyces rutgersensis SCSIO 11720 and Its Application in Antibacterial Peptides Production

Jian Yang,Jie Li,Yunfeng Hu,Lizhen Li,Lijuan Long,Fazuo Wang,Si Zhang 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.1

High value utilization of byproduct of slaughterhousesis regarded as beneficial to both economy andenvironment. A hemoglobin degrading protease PA720was purified from fermentation broth of a Porites luteaassociated strain Streptomyces rutgersensis SCSIO 11720(SCSIO 11720) and exhibited maximal activity at 70°C,pH 10.5. The isolated strain was identified by genotypicmethod and 16 s RNA gene sequence was deposited inGenBank under accession No. KC414842. The enzymeexhibited excellent thermostability since it was stable at 70°Cwith t1/2 value of 1,386.3 min. Kinetic and thermodynamicstudy showed the activation energy (Ea), ΔG* (free energy),ΔH* (enthalpy) and ΔS* (entropy) for protease deactivationwere 62.71 kJ/mol, 74.26 kJ/mol, 59.86 kJ/mol, and-41.97 J/mol/K, respectively. Highest specific activity ofprotease PA720 was observed when using casein (9,953 U/mg)and hemoglobin (9,854 U/mg) as substrates. Hemoglobinhydrolysate prepared by protease PA720 showed significantantibacterial activity towards Escherichia coli, Staphylococcusaureus and Bacillus subtilis, indicating this protease couldbe used as an instrumental enzyme for production ofhemoglobin-based antibacterial peptides. Based on partialamino acid sequences of the enzyme PA720, the full geneencoding this protease was obtained by degenerate primerPCR and has been deposited in GenBank under accessionNo. KC414842. The deduced amino acid sequence exhibitshomology with other microbial thermophilic proteases insubtilisin family.

NiO/Ti3C2Tx MXene nanocomposites sensor for ammonia gas detection at room temperature

Jiacheng Yang,Yingang Gui,Yunfeng Wang,Shasha He 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.119 No.-

Poultry feeding will lead to a large amount of ammonia(NH3) emissions, which will seriously affect thequality of meat. Herein, we report a resistive sensor based on NiO/Ti3C2Tx sensitive nanocompositesfor NH3 detection in a natural environment. The nanocomposites were prepared by modifying twodimensional(2D) Ti3C2Tx MXene with nickel oxide (NiO) nanoparticles (NPs) by a simple ultrasonicself-assembly method. The results show that the NiO/Ti3C2Tx MXene nanocomposite sensor exhibits ahigh sensitivity of 6.13 % to 50 ppm NH3 at room temperature (RT), which is 8.7 times higher than thatof the pure Ti3C2Tx MXene sensor. In other words, the addition of NiO NPs can significantly enhance thegas-sensing response of pure Ti3C2Tx MXene to NH3 at RT. Meanwhile, the response and recovery timewere also effectively improved (63 s/19 s) due to the addition of NiO NPs. Furthermore, the responseof the nanocomposite sensor to volatile organic compounds (VOCs) was investigated, and the resultsshowed its prospective and high selectivity. On the other hand, the nanocomposite sensor exhibits goodrepeatability and long-term stability. Finally, a possible sensing mechanism is proposed to improve sensorperformance.

Image 3d Adaptive Algorithm Based on Graph Cut

Fengxian Tang,Yunfeng Yang 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.8

As a key step in the visual inspection, image to appear particularly important. Compared with the traditional algorithm, graph cut algorithm overall high precision and faster convergence speed in discontinuous area. Based on adaptive algorithm on the basis of in-depth study, this paper proposes a three-dimensional adaptation algorithm based on graph cut theory in order to realize the image matching. Experimental results show that this algorithm can well meet the requirements of high precision and high real time capability, solve the problems such as large amount of calculation in the traditional algorithm.

Controlled Synthesis of Pt–Pd Nanoparticle Chains with High Electrocatalytic Activity Based on Insulin Amyloid Fibrils

LI HOU,Yunfeng Niu,Yan Wang,YANG JIANG,Rongna Chen,Tianran Ma,FAMING GAO 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.6

Here, we present a simple and novel method based on using insulin amyloid fibrils (INSAFs) as sacrificial templates for the construction of Pt–Pd nanoparticle chains (Pt–PdNPCs) under mild conditions. By incubating INSAFs in metal salt solution and then reduction, Pt–Pd nanoparticles with an uniform particle size of around 2.5 nm nucleated and grew along the axial direction of INSAFs, and thus formed a long chain structure with length up to several micrometers. The as-prepared Pt–PdNPCs exhibit an improved catalytic activity for lowtemperature CO and methanol oxidation and possess greater CO tolerance compared with the commercial Pt/C catalyst, which makes them promising for a variety of possible catalytic applications.

Chemical Bonds-Conjugated Ag2SO3/NaNbO3 Hybrids as Efficient Photocatalysts: In-situ Fabrication, Characterization and Degradation of Rhodamine B and Methyl Orange

Yanmei Feng,Zhiqiang Wang,Yunfeng Yang,Xiang-Feng Wu,Xiaodong Gong,Yajian Liu,Yufei Li,Zuo-Lin Cao,Chao Wang,Xin Tong 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.7

The Ag2SO3/NaNbO3 hybrids have been fabricated via a facile method at room temperature. Several methods such as X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, scanning electron microscopy, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy were used to characterize the samples. Moreover, the photocatalytic activity of the samples was assessed by degradation of rhodamine B and methyl orange under the visible light illumination. Experimental results indicated the photocatalytic degradation efficiency of the as-fabricated hybrids was first increased and then decreased with increasing the dosage of NaNbO3. When the molar ratio of Ag2SO3 to NaNbO3 was 1:0.7, the as-fabricated composites had the best photodegradation efficiency of 96.4% in 30 min for rhodamine B and 97.1% in 60 min for methyl orange, respectively. These were obviously higher than that of pure samples. Furthermore, Ag2SO3 was conjugated with NaNbO3 via chemical-bonds rather than physical contact. In addition, the possible photocatalytic degradation mechanism was also provided and the main roles during the process of photocatalytic degradation were played by holes.

Modeling and experimental studies of ammonia absorption in a spray tower

Shichao Ye,Jie Zhu,Zhenhua Liu,Jie Bai,Yunfeng Yang,Qin Peng 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.1

We did an experimental study on ammonia absorption in a spray tower. The kinetic characteristics of droplets were investigated by considering the forces acting on a droplet. The gas-phase mass transfer coefficient was deduced with the Colburn analogy method. A simplified model for predicting NH3 capture with a spray tower has been presented based on mass transfer and ionic equilibrium, which was successfully validated against experimental data. The influences and the sensitivity analysis of main operating parameters on the absorption efficiency were analyzed. As the most sensitive parameter, the mean droplet diameter was obtained by fitting experimental data with an empirical correlation. The distributions of two typical process parameters along the absorber were also simulated. Decreasing the pH value of absorbent is an effective but restrictive way to strengthen the mass transfer rate on account of insufficient liquid-side resistance.