Cooperative Approaches to Bacterial Foraging Algorithm for Clustering

Zhao Hongwei,Tian Liwei 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.4

Bacterial Foraging Optimization (BFO) is a novel optimization algorithm based on the social foraging behavior of E. coli bacteria, but it is difficult to optimize to get a high precision due to the randomness of the bacterial behavior, which belongs to intelligence algorithm. This paper presents an extended BFO algorithm, namely the Cooperative Bacterial Foraging Optimization (CBFO), which significantly improves the original BFO in solving clustering problems. A novel clustering method based on the CBFO could be used for solving clustering problems. In this work, firstly, The efficiency and performance of the CBFO algorithm was evaluated using six widely-used benchmark functions, coming up with comparative results produced by BFO, then Particle Swarm Optimization (PSO) is studied. Secondly, the algorithm with CBFO algorithms is used for data clustering on several benchmark data sets. The performance of the algorithm based on CBFO is compared with BFO algorithms on clustering problem. The simulation results show that the proposed CBFO outperforms the other three algorithms in terms of accuracy, robustness and convergence speed.

Research on Improved Firefly Optimization Algorithm Based on Cooperative for Clustering

Zhao Hongwei,Tian Liwei,Wang Dongzheng 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.3

This paper built a optimization model and proposed an improved firefly optimization algorithm called CFA, which is based on firefly Cooperative. The main idea of CFA is to extend the single population FA to the interacting multi-swarms by cooperative Models. In this work, firstly, CFA algorithm is used for optimizing six widely-used benchmark functions and the comparative results produced by, firefly optimization algorithm(FA) are studied. Secondly, CFA algorithm used in data mining, clustering analysis on several typical data sets. The performance of typical data clustering results showed that the biological heuristic algorithm based on clustering analysis algorithm with the existing success of FA compared to faster convergence, and the clustering of higher quality.

Development of a variable temperature mechanical loading device for in situ neutron scattering measurements

Yunlai Zhao,Shizhong Zhang,Hongwei Zhao,Guang’ai Sun,Yao Xu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8

Understanding the phase transformation and failure mechanism of NiTi shape memory alloys under variable environments of high and low temperatures is critical to the establishment of constitutive properties and to the realization of controllable design. Information regarding the correlation between the phase transformation and deformation can be obtained by in situ neutron scattering measurements. Therefore, a variable temperature mechanical loading device is designed, which can be used for mechanical loading and in situ neutron scattering measurements in a variable temperature environment. Specifically, the device can achieve precise temperature control with a temperature change from -55 °C to 200 °C in a protective atmosphere. The rated load in the axial direction is 6 kN, and the maximum displacement of the unilateral grip is larger than 30 mm. In situ neutron scattering measurements can be performed through neutron windows, and the strain can be measured by digital image correlation technology. Moreover, the force sensor is calibrated to improve test precision. Through an evaluation of temperature uncertainty, the temperature measurement performance is estimated. Tensile tests of the NiTi alloy at variable temperatures are carried out, and preliminary results are given. The four deformation stages of the NiTi alloy can be seen from the stressstrain curve, which corresponds to the existing results. This demonstrates that the designed variable temperature mechanical loading device can supply the testing demands. The device provides a new way to study the relationship between the phase transformation and mechanical properties of NiTi shape memory alloys at variable temperatures.

Improved mechanical properties, barrier properties and degradation behavior of poly(butylenes adipate-co-terephthalate)/poly(propylene carbonate) films

Hongwei Pan,Yanping Hao,Yan Zhao,Xianzhong Lang,Ye Zhang,Zhe Wang,Huiliang Zhang,Lisong Dong 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.5

Poly(butylene adipate-co-terephthalate) (PBAT) was blended with poly(propylene carbonate) (PPC) by a twin screw extruder and then the blends were made onto films via the blown film technique. PPC dispersed uniformly in the PBAT matrix, and the glass transition temperature (Tg) of PBAT were decreased with the increasing content of PPC. Wide angle X-ray diffraction confirmed that the crystallite dimension of PBAT was decreased after blending PBAT with the amorphous PPC. The results of mechanical tests indicated that the PBAT/PPC films showed high tensile strength and tear strength. In addition, the PBAT/PPC films showed high carbon dioxide permeability and moderate oxygen and nitrogen permeability. After embedding in soil, the weight loss and mechanical properties analysis demonstrated that the films were remarkably biodegraded. These findings contributed to application of the biodegradable materials, such as design and manufacture polymer packaging.

Advancing real-time hybrid simulation for coupled nonlinear soil-isolator-structure system

Hongwei Li,Amin Maghareh,Johnny W.C. Uribe,Herta Montoya,Shirley J. Dyke,Zhao-Dong Xu 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.1

Experiments involving soil-structure interaction are often constrained by the capacity and other limitations of the shake table. Additionally, it is usually necessary to consider different types of soil in experiments. Real-time hybrid simulation (RTHS) offers an alternative method to conduct such tests. RTHS is a cyber-physical testing technique that splits the dynamic system under investigation into numerical and physical components, and then realistically couples those components in a single test. A limited number of previous studies involving soil-structure interaction have been conducted using RTHS, with a focus on linear models and systems. The presence of isolators was not considered in these studies to the authors’ best knowledge. Herein, we aim to advance the understanding of the RTHS method by developing and demonstrating its use for nonlinear soil-isolatorstructure systems. A sliding mode controller able to deal with both system nonlinearities and wide range of potential uncertainties in such tests is designed and validated using a nonlinear shake table with a nonlinear specimen. By simply changing the numerical model and using the same controller and experimental setup, different soil types and ground motions can readily be considered with this approach. Numerical and RTHS results are compared for verification purposes.

VirtAV: an Agentless Runtime Antivirus System for Virtual Machines

( Hongwei Tang ),( Shengzhong Feng ),( Xiaofang Zhao ),( Yan Jin ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.11

Antivirus is an important issue to the security of virtual machine (VM). According to where the antivirus system resides, the existing approaches can be categorized into three classes: internal approach, external approach and hybrid approach. However, for the internal approach, it is susceptible to attacks and may cause antivirus storm and rollback vulnerability problems. On the other hand, for the external approach, the antivirus systems built upon virtual machine introspection (VMI) technology cannot find and prohibit viruses promptly. Although the hybrid approach performs virus scanning out of the virtual machine, it is still vulnerable to attacks since it completely depends on the agent and hooks to deliver events in the guest operating system. To solve the aforementioned problems, based on in-memory signature scanning, we propose an agentless runtime antivirus system VirtAV, which scans each piece of binary codes to execute in guest VMs on the VMM side to detect and prevent viruses. As an external approach, VirtAV does not rely on any hooks or agents in the guest OS, and exposes no attack surface to the outside world, so it guarantees the security of itself to the greatest extent. In addition, it solves the antivirus storm problem and the rollback vulnerability problem in virtualization environment. We implemented a prototype based on Qemu/KVM hypervisor and ClamAV antivirus engine. Experimental results demonstrate that VirtAV is able to detect both user-level and kernel-level virus programs inside Windows and Linux guest, no matter whether they are packed or not. From the performance aspect, the overhead of VirtAV on guest performance is acceptable. Especially, VirtAV has little impact on the performance of common desktop applications, such as video playing, web browsing and Microsoft Office series.

Genomics and LC-MS Reveal Diverse Active Secondary Metabolites in Bacillus amyloliquefaciens WS-8

Hongwei Liu,Yana Wang,Qingxia Yang,Wenya Zhao,Liting Cui,Buqing Wang,Liping Zhang,Huicai Cheng,Shuishan Song,Liping Zhang 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.3

Bacillus amyloliquefaciens is an important plant disease-preventing and growth-promoting microorganism. B. amyloliquefaciens WS-8 can stimulate plant growth and has strong antifungal properties. In this study, we sequenced the complete genome of B. amyloliquefaciens WS-8 by Pacific Biosciences RSII (PacBio) Single Molecule Real-Time (SMRT) sequencing. The genome consists of one chromosome (3,929,787 bp) and no additional plasmids. The main bacteriostatic substances were determined by genome, transcriptome, and mass spectrometry data. We thereby laid a theoretical foundation for the utilization of the strain. By genomic analysis, we identified 19 putative biosynthetic gene clusters for secondary metabolites, most of which are potentially involved in the biosynthesis of numerous bioactive metabolites, including difficidin, fengycin, and surfactin. Furthermore, a potential class II lanthipeptide biosynthetic gene cluster and genes that are involved in auxin biosynthesis were found. Through the analysis of transcriptome data, we found that the key bacteriostatic genes, as predicted in the genome, exhibited different levels of mRNA expression. Through metabolite isolation, purification, and exposure experiments, we found that a variety of metabolites of WS-8 exert an inhibitory effect on the necrotrophic fungus Botrytis cinerea, which causes gray mold; by mass spectrometry, we found that the main substances are mainly iturins and fengycins. Therefore, this strain has the potential to be utilized as an antifungal agent in agriculture.

Activated carbon modified by Mo-doped CQDs: An efficient method to reduce the thermal hazard in toluene adsorption

Hongwei Ren,Hongyu Dong,Tengda Zhao,Zhongqing Yan,Benzhen Jia,Liang Han,Jinfeng Zhang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.127 No.-

Activated carbon (AC) is one of the typical adsorbents for industrial treatment of VOCs, but AC itself has ahigh calorific value. When the heat generated by low-temperature oxidation cannot be released, it is easyto store heat and oxidize spontaneously, resulting in immeasurable harm. Therefore, it is important tostudy and improve the thermal stability of AC. In this study, Mo-doped carbon quantum dots (CQDs)was synthesized to enhance the safety of AC usage. The structure of AC before and after modificationwas characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy(FT-IR) and X-ray diffractometer (XRD). On the modified Mo-doped CQDs/AC, there are more crystallinestructures formed by Mo oxides on the surface, which makes the intermolecular force on the surface ofAC increase. At the same time, Mo oxide has strong oxidation resistance, which can inhibit the thermaldecomposition process of AC, and has stronger stability. The spontaneous combustion tendency and thermalhazard of AC before and after modification were greatly improved. The heat released in the tolueneadsorption by the modified AC at different temperatures was significantly lower than the heat released bythe unmodified AC. According to the Langmuir adsorption isotherm, the adsorption performance of ModopedCQDs (2.5 wt%) was 1.6 times higher than that of AC when the system was 25 C. The resultsshowed that Na2MoO4 CQDs modified AC could effectively improve the thermal stability and greatlyreduce the spontaneous combustion tendency. A relative fire safety performance evaluation model wasalso established to comprehensively evaluate the fire risk of VOCs treatment by AC.

IOMMU Para-Virtualization for Efficient and Secure DMA in Virtual Machines

( Hongwei Tang ),( Qiang Li ),( Shengzhong Feng ),( Xiaofang Zhao ),( Yan Jin ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.12

IOMMU is a hardware unit that is indispensable for DMA. Besides address translation and remapping, it also provides I/O virtual address space isolation among devices and memory access control on DMA transactions. However, currently commodity virtualization platforms lack of IOMMU virtualization, so that the virtual machines are vulnerable to DMA security threats. Previous works focus only on DMA security problem of directly assigned devices. Moreover, these solutions either introduce significant overhead or require modifications on the guest OS to optimize performance, and none can achieve high I/O efficiency and good compatibility with the guest OS simultaneously, which are both necessary for production environments. However, for simulated virtual devices the DMA security problem also exists, and previous works cannot solve this problem. The reason behind that is IOMMU circuits on the host do not work for this kind of devices as DMA operations of which are simulated by memory copy of CPU. Motivated by the above observations, we propose an IOMMU para-virtualization solution called PVIOMMU, which provides general functionalities especially DMA security guarantees for both directly assigned devices and simulated devices. The prototype of PVIOMMU is implemented in Qemu/KVM based on the virtio framework and can be dynamically loaded into guest kernel as a module, As a result, modifying and rebuilding guest kernel are not required. In addition, the device model of Qemu is revised to implement DMA access control by separating the device simulator from the address space of the guest virtual machine. Experimental evaluations on three kinds of network devices including Intel I210 (1Gbps), simulated E1000 (1Gbps) and IB ConnectX-3 (40Gbps) show that, PVIOMMU introduces little overhead on DMA transactions, and in general the network I/O performance is close to that in the native KVM implementation without IOMMU virtualization.

Renewable biomass derived hierarchically porous carbonaceous sponges and their magnetic nanocomposites for removal of organic molecules from water

Hongwei Zhou,Bo Yan,Jialiang Lai,Hanbin Liu,Aijie Ma,Weixing Chen,Xilang Jin,Weifeng Zhao,Gai Zhanga 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.58 No.-

This work describes the preparation, characterization and removal capability of a novel biomass derived carbonaceous sponges (CS) and their nanocomposites. The CS has hierarchically porous structure which is composed of lamellar structures and secondary porous structures. The pore size is on a scale from 1 nm to 200 μm. Utilizing the CS as adsorbents, rapid removal of model organic molecules, including methylene blue (MB), methyl orange (MO) and crystal violet (CV), from their aqueous solutions can be completed within 1 min with the assistance of pressure and the removal efficiency reaches up to 100%, 81% and 98%, respectively. The removal capabilities for CS towards MB, MO and CV are 0.0769 g/g, 0.2218 g/g and 1.0384 g/g, respectively and 0.0635 g/g, 0.0977 g/g and 0.8634 g/g, respectively for CS nanocomposites.