Nematicidal coumarin from Ficus carica L.

Fangfang Liu,Zhongshan Yang,Xi Zheng,Shaoliu Luo,Ke Qin Zhang,Guo Hong Li 한국응용곤충학회 2011 Journal of Asia-Pacific Entomology Vol.14 No.1

The methanol extracts from 40 plant species were screened for their nematicidal activity against the nematodes Bursaphelenchus xylophilus, Panagrellus redivivus and Caenorhabditis elegans. The leaf extract of Ficus carica L. exhibited the strongest nematicidal activity, causing 74.3%, 96.2% and 98.4% mortality,respectively, within 72 h. By bioassay-guided fractionation, a coumarin was obtained. The compound was determined to be psoralen based on spectroscopic data. It showed nematicidal activity against the tested nematodes. This is the first report of the nematicidal activity of F. carica and psoralen.

High Power Switchable Dual-Wavelength Linear Polarized Yb-Dozped Fiber Laser around 1120 nm

Xiaojuan Liu,Bangcai Huang,Gongxiang Wei,Kezhen Han,Yan Huang,Fangfang Liu 한국광학회 2016 Current Optics and Photonics Vol.20 No.6

A single-and dual-wavelength switchable polarized Yb-doped double-clad fiber laser around 1120 nmbased on a pair of fiber Bragg gratings (FBGs) is demonstrated. The polarization-maintaining (PM) linearcavity is composed of a double clad PM Yb-doped fiber (YDF) and a pair of PM FBGs. The laser canoperate in stable dual-wavelength or wavelength-switching modes due to the polarization hole burning(PHB) and the spatial hole burning (SHB) enhanced by the PM linear cavity. In dual-wavelength operation,the two orthogonally polarized wavelengths are centered at 1118.912 nm and 1119.152 nm, with an intervalof 0.24 nm and a signal to noise ratio (SNR) of 35 dB. The maximum output power is 14.67 W whenthe launched LD pump is 24 W corresponding to an optical efficiency of 61.1%. The lasing lines switchovermay be realized by adjusting the polarization controller (PC) fitted in the cavity. The two single-wavelengthsare 1118.912 nm and 1119.152 nm. When the injected LD pump is 24 W, the highest output powersare 7.68 W and 8.64 W corresponding to optical efficiencies of 32% and 36% respectively. The spectrallinewidth of the lasing lines are 0.075 nm and 0.07 nm, and the average numerical values of PER are20.3 dB and 19.9 dB, respectively.

Numerical Simulation on Crater Characteristics of Different Shape of Projectiles Hypervelocity Impact on Thick Plates

Liu Xun,Gai Fangfang 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.2

Hypervelocity impact by space debris can cause direct damage to spacecraft internal subsystem, and even lead to catastrophic failure of manned spacecraft. To research the crater characteristics of different shape of projectiles hypervelocity impact on semi infinite thick aluminum alloy plates, Lagrange and SPH (smoothed particle hydrodynamics) coupling method in AUTODYN is used. By analyzing the influence on crater characteristics by different impact velocity of spherical projectile, different ratio between length and diameter and different impact velocity of cylindrical projectile, we obtain the law of crater characteristics of the semi infinite thick plates. The research results have reference value and engineering application of guiding significance to the study of spacecraft space debris shield structure design.

Energy Harvest System Research for High Precision Electronic Voltage Transformer based on Coupling Capacitance

Liu Ying,Li Bing,Song FangFang,Gao HanYu,Huang LiangDong,Chen XuXuan 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.6

High quality power is the prerequisite for high precision measurement of an electronic voltage transformer. In order to ensure a compact structure and stable operation of the transformer, this paper proposes a circuit and high voltage energy harvest of high precision electronic voltage transformer based on coupling capacitance. The energy extraction circuit is directly connected with the high voltage terminal through a capacitor, and the low DC voltage is obtained through the diode rectifier bridge. A self-holding duty cycle regulating circuit is installed on the DC side, and the power required by the load can be automatically adjusted to match the load. Because the overall load of the power extraction circuit is capacitive, there is no ferro-resonance problem. Furthermore, there is also no MCU in the device, so that the whole circuit has the advantages of small power loss, small volume, strong anti-interference ability, and can provide a stable DC power for the metering device. The proposed method is verifi ed in simulations using PSCAD/EMTDC.

Sharing and Privacy in PHRs: Efficient Policy Hiding and Update Attribute-based Encryption

( Zhenhua Liu ),( Jiaqi Ji ),( Fangfang Yin ),( Baocang Wang ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.1

Personal health records (PHRs) is an electronic medical system that enables patients to acquire, manage and share their health data. Nevertheless, data confidentiality and user privacy in PHRs have not been handled completely. As a fine-grained access control over health data, ciphertext-policy attribute-based encryption (CP-ABE) has an ability to guarantee data confidentiality. However, existing CP-ABE solutions for PHRs are facing some new challenges in access control, such as policy privacy disclosure and dynamic policy update. In terms of addressing these problems, we propose a privacy protection and dynamic share system (PPADS) based on CP-ABE for PHRs, which supports full policy hiding and flexible access control. In the system, attribute information of access policy is fully hidden by attribute bloom filter. Moreover, data user produces a transforming key for the PHRs Cloud to change access policy dynamically. Furthermore, relied on security analysis, PPADS is selectively secure under standard model. Finally, the performance comparisons and simulation results demonstrate that PPADS is suitable for PHRs.

Numerical Simulation on Characteristics of Debris Clouds Produced by Conical Projectiles Hypervelocity Impact on Thin Plates

Xun Liu,Fangfang Gai,Su Cheng 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.6

With the unceasing development of space activity, the total number of space debris is ever increasing, which greatly threatens orbiting space vehicles. To research the characteristics of debris clouds which are produced by conical projectiles hypervelocity impact on thin plates, SPH (smoothed particle hydrodynamics) methods in AUTODYN is used. Characteristics of debris cloud produced by conical projectiles with different ratio between length and diameter hypervelocity impact on thin plates are investigated with the same mass and velocity by numerical simulation. Effects of the ratio between length and diameter of the projectiles affecting on the form of debris cloud, axial location of debris clouds, radial extension of debris cloud and tip particle velocity of debris cloud are obtained. It is shown that the degree of fragmentation of the projectiles and debris cloud diffusion is changed with the velocity of the projectiles, the ratio between length and diameter and the impacting direction. The increasing ratio between length and diameter of projectiles can reduce the damage of thin plates but rise the damage of the wall of spacecraft by the debris clouds impact on with the same mass and velocity.

Effects of different amylose to amylopectin ratios on rumen fermentation and development in fattening lambs

Zhao, Fangfang,Ren, Wen,Zhang, Aizhong,Jiang, Ning,Liu, Wen,Wang, Faming Asian Australasian Association of Animal Productio 2018 Animal Bioscience Vol.31 No.10

Objective: The objective of this experiment was to examine the effects of different amylose/amylopectin ratios on rumen fermentation and development of fattening lambs. Methods: Forty-eight 7-day-old male Small-tailed Han sheep${\times}$Northeast fine wool sheep were randomly assigned to four treatments of dietary amylose/amylopectin ratios (0.12, 0.23, 0.24, and 0.48 in tapioca starch, corn starch, wheat starch and pea starch diets, respectively). Three lambs from each treatment were slaughtered at 21, 35, 56, and 77 days of age to determine the rumen fermentation and development. Results: Compared with tapioca starch diet, the pea starch diet significantly increased the concentration of ammonia nitrogen in the ruminal fluid of lambs but significantly decreased the bacterial protein content. At 56 and 77 d, the rumen propionate concentration tended to be greatest in the tapioca starch group than in other groups. The rumen butyrate concentration was the greatest in lambs fed on pea starch compared with those fed on other starch diets. Furthermore, the pea starch diet significantly stimulated rumen development by increasing the papillae height, width and surface area in the rumen ventral or dorsal locations in lambs. However, different amylose/amylopectin ratios diets did not significantly affect the feed intake, body weight, average daily gain, the relative weight and capacity of the rumen in lambs with increasing length of trial periods. Conclusion: Lambs early supplemented with a high amylose/amylopectin ratio diet had favourable morphological development of rumen epithelium, which was not conducive to bacterial protein synthesis.

Reliability Enhancement for Multimedia Delivery in Caching-Assisted MmWave HetNets

Yin, Fangfang,Wang, An,Zhang, Yu,Liu, Danpu,Jin, Libiao 한국통신학회 2023 Journal of communications and networks Vol.25 No.3

Explosive growth of bandwidth-intensive multime-dia applications may impose a heavy traffic burden on wirelesslinks of heterogeneous networks (HetNets), which also requiressubstantial energy consumption. Edge caching is emerging toreduce the service latency and relieve the huge burden on thebackhaul links in HetNets. Moreover, millimeter wave (mmWave)spectrum with huge available bandwidth has been regarded asa promising technology to satisfy the high capacity demands infuture HetNets. However, the high directionality coupled withharsh propagation environment makes mmWave communicationvulnerable to blockage, which makes link establishment andmaintenance challenging. In this paper, we propose a jointmaximum distance separable (MDS) coded caching and trans-mission problem for a mmWave HetNet, aiming at minimizingthe backhaul energy consumption while satisfying users’ qualityof service (QoS) requirements on high data rate. The formulatedmixed integer non-linear programming (MINLP) problem issolved by decomposing it into two stages of subproblems. Inthe first stage, the convex optimization technique is applied totackle the coded caching subproblem. Subsequently, we proposetwo efficient algorithms based on matching in the second stageto deal with the transmission subproblem. Simulation resultsdemonstrate that the proposed schemes can effectively maximizethe backhaul energy saving and enhance the download ratecompared with the benchmark scheme.

Content-driven Joint Allocation of Communication and Computing Resources in Vehicular Networks

Xu Zhu,Fangfang Liu,Zhimin Zeng,Caili Guo,Jiujiu Chen 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.2

With the rapid growth of computer vision applications, a large amount of video data in the Internet of Vehicles scenario are used for content analysis. Tasks based on video content understanding are usually accompanied by huge amount of calculation, which put great pressure on traditional wireless communication resource and Mobile Edge Computing (MEC) server computing resource. Furthermore, existing resource allocation schemes based on Quality of Service (QoS) or Quality of Experience (QoE) may not be the best choice for the purpose of video content understanding. In this paper, we propose a joint resource allocation scheme based on Quality of Content (QoC) to maximize the accuracy of video content understanding. Due to the real-time nature of resource allocation and the variability of the environment in autonomous driving scenarios, we design a Multi-agent Distributed Q-Learning algorithm to solve such multi-constrained nonlinear programming problems. Finally, the simulation results show that our proposed QoC-based joint resource allocation scheme has better video content understanding performance.

Self-Tuning Speed Control of Ultrasonic Motor Combined with Efficiency Optimization

Jingzhuo Shi,Fangfang Lv,Bo Liu 제어·로봇·시스템학회 2014 International Journal of Control, Automation, and Vol.12 No.1

Aiming at the nonlinear characteristics of ultrasonic motor (USM) control system, a self-tuning pole assignment speed control strategy is proposed in this paper. The parameters of motor system are identified online, and then the controller is modified online according to the identified parameters of motor. In view of the short-time working characteristic of USM, a method for determining initial values of parameters with online identification algorithms is presented. Using this method, efficient self-tuning control can be realized using a small quantity of testing data. The proposed strategy is robust and relatively simple. Experimental results indicate that the speed control performance is good.