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Influence of sharp stiffness variations in damage evaluation using POD and GSM
Thiene, M.,Galvanetto, U.,Surace, C. Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.14 No.4
Damage detection methods based on modal analysis have been widely studied in recent years. However the calculation of mode shapes in real structures can be time consuming and often requires dedicated software programmes. In the present paper the combined application of proper orthogonal decomposition and gapped smoothing method to structural damage detection is presented. The first is used to calculate the dynamic shapes of a damaged structural element using only the time response of the system while the second is used to derive a reference baseline to which compare the data coming from the damaged structure. Experimental verification is provided for a beam case while numerical analyses are conducted on plates. The introduction of a stiffener on a plate is investigated and a method to distinguish its influence from that of a defect is presented. Results highlight that the derivatives of the proper orthogonal modes are more effective damage indices than the modes themselves and that they can be used in damage detection when only data from the damaged structure are available. Furthermore the stiffened plate case shows how the simple use of the curvature is not sufficient when analysing complex components. The combined application of the two techniques provides a possible improvement in damage detection of typical aeronautical structures.
Influence of sharp stiffness variations in damage evaluation using POD and GSM
M. Thiene,U. Galvanetto,C. Surace 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.4
Damage detection methods based on modal analysis have been widely studied in recent years. However the calculation of mode shapes in real structures can be time consuming and often requiresdedicated software programmes. In the present paper the combined application of proper orthogonaldecomposition and gapped smoothing method to structural damage detection is presented. The first is usedto calculate the dynamic shapes of a damaged structural element using only the time response of the systemwhile the second is used to derive a reference baseline to which compare the data coming from the damagedstructure. Experimental verification is provided for a beam case while numerical analyses are conducted onplates. The introduction of a stiffener on a plate is investigated and a method to distinguish its influence fromthat of a defect is presented. Results highlight that the derivatives of the proper orthogonal modes are moreeffective damage indices than the modes themselves and that they can be used in damage detection whenonly data from the damaged structure are available. Furthermore the stiffened plate case shows how thesimple use of the curvature is not sufficient when analysing complex components. The combined applicationof the two techniques provides a possible improvement in damage detection of typical aeronauticalstructures.
Thien, Huynh Thanh,Vu-Van, Hiep,Koo, Insoo The Institute of Internet 2018 International Journal of Internet, Broadcasting an Vol.10 No.1
In cognitive radio (CR), secondary users (SUs) are able to sense the absence of primary users (PUs) in the spectrum. Then, SUs use this information to opportunistically access the licensed spectrum in the PUs' absence. In this paper, we present an implementation of real-time video transmission with spectrum-sensing between two points using GNU Radio and a National Instruments 2900 Universal Software Radio Peripheral (USRP). In our project, spectrum-sensing is implemented at both transmitter and receiver. The transmitter senses the channel, and if the channel is free, a video signal (which could be a real-time signal from a video file) will be modulated and processed by GNU Radio and transmitted using a USRP. A USRP receiver also senses the channel, but in contrast, if the channel is busy, the signal is demodulated to reproduce the transmitted video signal. This project brings in several challenges, like spectrum-sensing in the devices' environment, and packets getting lost or corrupted over the air.
Thien-Hoang Ho,Kyoungho Jung,Inho Lee,Kim-Hung Huynh,Diem-Quynh Nguyen,Hyunjae Park,Sang Hee Lee,Lin-Woo Kang 한국구조생물학회 2017 Biodesign Vol.5 No.1
The emergences of multi-drug resistant bacteria such as Acinetobacter baumanni have emphasized the necessity of new antibiotics. Peptidyl deformylase (PDF) catalyzes the removal of the formyl group from the N-terminal formylated methionine residue present in all nascent polypeptides in bacteria. In this study, the PDF gene from Acinetobacter baumannii K0420859 was cloned and its protein was overexpressed in E. coli, purified, and crystallized. The purified protein was crystallized using the hanging-drop vapour-diffusion method and the crystal diffracted to 2.4 Å resolution. The crystal belonged to the trigonal space group P3 2 with unit cell parameters of a = b= 39.4 Å and c = 187.9 Å. Two protomers were presented in the asymmetric unit with a corresponding V M of 2.10 Å 3 Da -1 and a solvent content of 41.5%.
Current Perspectives on the Effects of Plant Growth-promoting Rhizobacteria
Thien Tu Huynh Le(후인르티엔투),Sang Eun Jun(전상은),Gyung-Tae Kim(김경태) 한국생명과학회 2019 생명과학회지 Vol.29 No.11
근권은 식물 뿌리와 토양 미생물이 서로의 신호를 주고 받으며 끊임없이 상호반응하는 역동적인 장소이다. 근권 주위에서 식물의 생장과 생산성에 유익한 토양 미생물을 식물생장촉진근권미생물(Plant Growth Promoting Rhizobacteria, PGPR)이라 칭하며, 이 PGPR은 식물 전 생장기간동안 생물학적 및 비생물학적 스트레스에 대한 저항성, 식물 호르몬 조절, 영양분의 흡수와 이용 등에 영향을 끼침으로써 식물의 생장과 발달, 면역, 생산력 등중요한 생명 과정에 관여한다. 그리고, PGPR은 식물 생장을 유도하는 2차 대사산물이나 휘발성 유기 화합물을 생산하고, 식물의 뿌리 역시 식물 유해한 인자 혹은 병원성 인자에 대항하여 자신을 보호하거나 토양 성질 개선을 위해, PGPR을 유인하고 정착시키기 위한 물질을 생산, 분비한다. 그러므로, 식물과 PGPR 사이의 상호작용은 필수적이면서도 상호의존적이다. 현재까지, PGPR에 대한 많은 연구는 직간접적 개념에 대하여 공통적 또는 다양한 조건들에서 여러 방식으로 PGPR의 기능을 밝히는 방향으로 전개되어 왔다. 본 총설에서는 세포분열과 팽창, 분화에 의한 식물의 생장과 발달의 촉진, 식물생장조절인자와 호르몬의 유도, 영양물질의 고정, 용해, 무기화를 촉진하기 위한 PGPR의 역할과 전략을 소개하였다. 또한 PGPR와 토양 미생물군의 효과에 대한 현재까지의 연구 정보를 요약하였다. The rhizosphere is the active zone where plant roots communicate with the soil microbiome, each responding to the other’s signals. The soil microbiome within the rhizosphere that is beneficial to plant growth and productivity is known as plant growth-promoting rhizobacteria (PGPR). PGPR take part in many pivotal plant processes, including plant growth, development, immunity, and productivity, by influencing acquisition and utilization of nutrient molecules, regulation of phytohormone biosynthesis, signaling, and response, and resistance to biotic- and abiotic-stresses. PGPR also produce secondary compounds and volatile organic compounds (VOCs) that elicit plant growth. Moreover, plant roots exude attractants that cause PGPR to aggregate in the rhizosphere zone for colonization, improving soil properties and protecting plants against pathogenic factors. The interactions between PGPR and plant roots in rhizosphere are essential and interdependent. Many studies have reported that PGPR function in multiple ways under the same or diverse conditions, directly and indirectly. This review focuses on the roles and strategies of PGPR in enhancing nutrient acquisition by nutrient fixation/solubilization/mineralization, inducing plant growth regulators/phytohormones, and promoting growth and development of root and shoot by affecting cell division, elongation, and differentiation. We also summarize the current knowledge of the effects of PGPR and the soil microbiota on plants.
Multi-material topology optimization of Reissner-Mindlin plates using MITC4
Thien Thanh Banh,이동규 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.27 No.1
In this study, a mixed-interpolated tensorial component 4 nodes method (MITC4) is treated as a numerical analysis model for topology optimization using multiple materials assigned within Reissner-Mindlin plates. Multi-material optimal topology and shape are produced as alternative plate retrofit designs to provide reasonable material assignments based on stress distributions. Element density distribution contours of mixing multiple material densities are linked to Solid Isotropic Material with Penalization (SIMP) as a design model. Mathematical formulation of multi-material topology optimization problem solving minimum compliance is an alternating active-phase algorithm with the Gauss-Seidel version as an optimization model of optimality criteria. Numerical examples illustrate the reliability and accuracy of the present design method for multi-material topology optimization with Reissner-Mindlin plates using MITC4 elements and steel materials.