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Search Results: 1 - 10 of 157095 matches for " Lu Ma;Hsin-Yu Wei;Manuchehr Soleimani "
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Planar Magnetic Induction Tomography for 3D Near Subsurface Imaging
Lu Ma;Hsin-Yu Wei;Manuchehr Soleimani
PIER , 2013, DOI: 10.2528/PIER12110711
Abstract: Magnetic induction tomography (MIT) is a tomographic technique utilising inductive coils and eddy currents to map the passive electromagnetic properties of an object. Eddy current methods are widely used for non-destructive testing (NDT) in inspection of metallic structures. Eddy current based NDT uses a single coil or a pair of coils to scan the samples. As an emerging NDT technique, MIT scans the sample with a coil array through an eddy current based tomographic approach. In this paper, a planar array MIT system (PMIT) is proposed for 3D near subsurface imaging. This is of great importance as there are large numbers of potential applications for MIT that allow limited access to the materials under testing. The system development, practical implication, capability and limitations of PMIT are discussed. The fundamental principles are demonstrated through simulations. Experimental data are used to evaluate the capability and detectability this system has as a potential 3D subsurface imaging tool.
Pipelines Inspection Using Magnetic Induction Tomography Based on a Narrowband Pass Filtering Method
Lu Ma;Hsin-Yu Wei;Manuchehr Soleimani
PIER M , 2012, DOI: 10.2528/PIERM11111109
Abstract: Pipelines are the most common apparatus in industries; therefore, the need for inspection during the manufacturing, construction and the operation stage is inevitable and invaluable. Magnetic Induction Tomography (MIT) is a new type of tomography technique that is sensitive to the electrical conductivity of objects.~It has been shown that the MIT technique is appropriate for imaging materials with high electrical conductivity contrasts; hence, the majority of the MIT systems were designed for detecting metallic objects. In this paper, MIT technique was proposed for pipeline inspection. Structural damages of the outer surface of the pipe were considered in this study. Nonetheless, it is challenging to use the traditional MIT pixel based reconstruction method (PBRM) as a suitable pipelines inspection tool because of the limited resolution. A narrowband pass filtering method (NPFM) of imaging pipe geometry was developed as a suitable image reconstruction method.~The proposed method can overcome the resolution limitations and produce useful information of the pipe structure.~This paper shows the comparative results from the novel NPFM and from traditional PBRM. While the PBRM fails to detect damages in outer structure of the pipe the NPFM successfully indentifies these damages. The method has been verified using experimental data from very challenging test samples. It is well known that using a coil array with an imaging region of 100 mm the PBRM based MIT can retrieve information with accuracy of about 10 mm (about 10%). With proposed NPFM the information on a resolution of 2 mm (which is about 2%) can be detected using the same measurement data.
Two-Phase Low Conductivity Flow Imaging Using Magnetic Induction Tomography
Hsin-Yu Wei;Manuchehr Soleimani
PIER , 2012, DOI: 10.2528/PIER12070615
Abstract: Magnetic Induction Tomography (MIT) is a new and emerging type of tomography technique that is able to map the distribution of all three passive electromagnetic properties, however most of the current interests are focusing on the conductivity and permeability imaging. In an MIT system, coils are used as separate transmitters or sensors, which can generate the background magnetic field and detect the perturbed magnetic field respectively. Through switching technique the same coil can work as transceiver which can generate field at a time and detect the field at another time. Because magnetic field can easily penetrate through the non-conductive barrier, the sensors do not need direct contact with the imaging object. These non-invasive and contactless features make it an attractive technique for many applications compared to the traditional contact electrode based electrical impedance tomography. Recently, MIT has become a promising monitoring technique in industrial process tomography, for example MIT has been used to determine the distribution of liquidised metal and gas (high conductivity two phase flow monitoring) for metal casting applications. In this paper, a low conductivity two phase flow MIT imaging is proposed so the reconstruction of the low contrast samples (< 6 S/m) can be realised, e.g. gas/ionised liquid. An MIT system is developed to test the feasibility. The system utilises 16 coils (8 transmitters and 8 receivers) and an operating frequency of 13 MHz. Three dierent experiments were conducted to evaluate all possible situations of two phase flow imaging: 1) conducting objects inside a non-conducting background, 2) conducting objects inside a conducting ackground (low contrast) and 3) non-conducting objects inside a conducting background. Images are reconstructed using the linearised inverse method with regularisation. An experiment was designed to image the non-conductive samples inside a conducting background, which is used to represent the size varying bubbles in ionised solution. The temporal reconstruction algorithm is used in this dynamic experiment to improve the image accuracy and noise performance.
Four Dimensional Reconstruction Using Magnetic Induction Tomography: Experimental Study
Hsin-Yu Wei;Manuchehr Soleimani
PIER , 2012, DOI: 10.2528/PIER12032403
Abstract: Magnetic Induction Tomography (MIT) is a relatively new and emerging type of tomography techniques that is able to map the conductivity distribution of an object. Its non-invasive and contactless features make it an attractive technique for many applications compared to the traditional contact electrode based electrical impedance tomography. Recently, MIT has become a promising monitoring technique in industrial process tomography, and the area of the research interest has moved from 2D to 3D because of the volumetric nature of electromagnetic field. Three dimensional MIT images provide more information on the conductivity distribution, especially in the axial direction. However, it has been reported that the reconstructed 3D images can be distorted when the imaging object is located at a less sensitive region. Although this distortion can be com- pensated by adjusting the regularisation criteria, this is not practical in real life applications as the prior information about the object's location is often unavailable. This paper presents a memory ecient 4D MIT algorithm which can maintain the image quality under the same regularisation circumstances. Instead of solving each set of measurement individually, the 4D algorithm takes advantage of the correlations between the image and its neighboring data frames to reconstruct 4D of conductivity movements. The 4D algorithm improves the image qualities by increasing the temporal resolution. It also overcomes some sensitivity issues of 3D MIT algorithms and can provide a smoother and stabler result. Several experimental results are presented for validating the propose algorithms.
Three-Dimensional Magnetic Induction Tomography Imaging Using a Matrix Free Krylov Subspace Inversion Algorithm
Hsin-Yu Wei;Manuchehr Soleimani
PIER , 2012, DOI: 10.2528/PIER11091513
Abstract: Magnetic induction tomography (MIT) attempts to image the passive electromagnetic properties (PEP) of an object by measuring the mutual inductances between pairs of coils placed around its periphery. In recent years, there has been an increase in applications of non-contact magnetic induction tomography. When finite element-based reconstruction methods are used, that rely on the inversion of a derivative operator, the large size of the Jacobian matrix poses a challenge since the explicit formulation and storage of the Jacobian matrix could be in general not feasible. This problem is aggravated further in applications for example when the number of coils is increased and in three-dimension. Krylov subspace methods such as conjugate gradient (CG) methods are suitable for such large scale inverse problems. However, these methods require use of the Jacobian matrix, which can be large scale. This paper presents a matrix-free reconstruction method, that addresses the problems of large scale inversion and reduces the computational cost and memory requirements for the reconstruction. The idea behind the matrix-free method is that information about the Jacobian matrix could be available through matrix times vector products so that the creation and storage of big matrices can be avoided. Furthermore the matrix vector multiplications were performed in multiple core fashion so that the computational time can decrease even further. The method was tested for the simulated and experimental data from lab experiments, and substantial benefits in computational times and memory requirements have been observed.
應用資訊檢索技術於論文評閱者推薦模式之評估 Evaluation of Information Retrieval Based Models for Recommendation of Paper Reviewers
Shih-Chieh Wei,Hsin-Yu Luo
Journal of Educational Media & Library Sciences , 2008,
Abstract: 隨著傳統期刊逐漸採用電子形式出刊,也帶動投稿及評閱過程愈來愈多採用電子自動化之潮流。目前一般的線上投稿暨評閱系統雖然功能逐漸齊備,但仍少有推薦評閱者功能。為評估現有可推薦評閱者技術之表現,本文分別用標題、關鍵詞、摘要、全文4種不同長度的論文表示方式,搭配7種評閱者匹配法,其中包括向量空間模式下的4種相似度匹配法,及應用於OpenConf線上投稿系統中的3種主題式匹配法,交叉組合出4×7=28種推薦模式。測試結果顯示,向量空間模式匹配法優於主題式匹配法。又所有推薦模式中,以摘要為論文表示方式,搭配向量空間模式的餘弦相似度匹配法,其推薦效果最好。 As more e-journals appear and the e-review process becomes more popular, the demand for automatic recommendation of a good peer reviewer has been ever increasing. To automate the process of paper reviewer recommendation, this work evaluates four kinds of paper representations, which include full text, abstract, title, and author defined keywords. To match reviewers with papers, this work evaluates seven scoring methods including three topic-based methods from OpenConf, a popular online submission system with source, and four similarity-based methods from the vector space model of traditional information retrieval. The results of the 28 experiments show that recommendation methods based on the vector space model are better than the three topic-based methods of OpenConf in most document representations. Among them, the abstract paper representation combined with cosine similarity matching measure has the highest average precision.
Capacity Enhancement in Hybrid Wireless Relay Network with Network Coding
Hsin-Yu Chao,Chun-Yen Huang,Fan-Min Tseng,Hung-Yu Wei
Journal of Communications , 2009, DOI: 10.4304/jcm.4.11.841-848
Abstract: Network coding technique increases wireless network communication efficiency. Wireless multihop relay network has been shown to achieve capacity gain over conventional single-hop wireless networks. Hybrid wireless relay networks integrate multihop ad hoc relay and infrastructure base stations to achieve better wireless network performance. Applying the promising network coding technique to hybrid wireless relay networks could increase wireless network capacity. Capacity of multihop cellular network with network coding is derived. To enhance network throughput, data forwarding strategy is proposed to determine if a packet should be transmitted through intra-cell ad hoc relay, inter-cell ad hoc relay, or infrastructure-assisted inter-cell transmission.
The paracrine effect of exogenous growth hormone alleviates dysmorphogenesis caused by tbx5 deficiency in zebrafish (Danio rerio) embryos
Tzu-Chun Tsai, Jenn-Kan Lu, Sie-Lin Choo, Shu-Yu Yeh, Ren-Bing Tang, Hsin-Yu Lee, Jen-Her Lu
Journal of Biomedical Science , 2012, DOI: 10.1186/1423-0127-19-63
Abstract: Using an oligonucleotide-based microarray analysis to study the expression of special genes in tbx5 morphants, we demonstrated that GH and some GH-related genes were markedly downregulated. Zebrafish embryos microinjected with tbx5-morpholino (MO) antisense RNA and mismatched antisense RNA in the 1-cell stage served as controls, while zebrafish embryos co-injected with exogenous growth hormone (GH) concomitant with tbx5-MO comprised the treatment group.The attenuating effects of GH in tbx5-MO knockdown embryos were quantified and observed at 24, 30, 48, 72, and 96?h post-fertilization. Though the understanding of mechanisms involving GH in the tbx5 functioning complex is limited, exogenous GH supplied to tbx5 knockdown zebrafish embryos is able to enhance the expression of downstream mediators in the GH and insulin-like growth factor (IGF)-1 pathway, including igf1, ghra, and ghrb, and signal transductors (erk1, akt2), and eventually to correct dysmorphogenesis in various organs including the heart and pectoral fins. Supplementary GH also reduced apoptosis as determined by a TUNEL assay and decreased the expression of apoptosis-related genes and proteins (bcl2 and bad) according to semiquantitative reverse-transcription polymerase chain reaction and immunohistochemical analysis, respectively, as well as improving cell cycle-related genes (p27 and cdk2) and cardiomyogenetic genes (amhc, vmhc, and cmlc2).Based on our results, tbx5 knockdown causes a pseudo GH deficiency in zebrafish during early embryonic stages, and supplementation of exogenous GH can partially restore dysmorphogenesis, apoptosis, cell growth inhibition, and abnormal cardiomyogenesis in tbx5 knockdown zebrafish in a paracrine manner.
Cell Autonomous and Non-Autonomous Functions of IKKβ and NF-κB during the Pathogenesis of Gastrointestinal Tumors
Hsin-Yu Fang,Florian R. Greten
Cancers , 2011, DOI: 10.3390/cancers3022214
Abstract: Genetic studies describing a link between cancer and inflammation have increased recently. Activation of the transcription factor nuclear factor-κB (NF-κB) and its effector pathways has been proposed to be the missing link between these two processes. NF-κB is persistently activated in several types of tumors. However, NF-κB has a distinct role in cancer cells and in inflammatory cells. While in tumor cells NF-κB controls cell survival, in inflammatory cells NF-κB activates genes that encode pro-inflammatory cytokines which further act in a paracrine manner within the tumor microenvironment to contribute to tumorigenesis. Inactivation of NF-κB can also reduce chemoresistance and radioresistance of cancer cells. Therefore, specific NF-κB inhibition in combination with cytotoxic drugs and/or irradiation represents a very promising strategy for cancer therapy.
The Loudest Gravitational Wave Events
Hsin-Yu Chen,Daniel E. Holz
Physics , 2014,
Abstract: As first emphasized by Bernard Schutz, there exists a universal distribution of signal-to-noise ratios for gravitational wave detection. Because gravitational waves (GWs) are almost impossible to obscure via dust absorption or other astrophysical processes, the strength of the detected signal is dictated solely by the emission strength and the distance to the source. Assuming that the space density of an arbitrary population of GW sources does not evolve, we show explicitly that the distribution of detected signal-to-noise (SNR) values depends solely on the detection threshold; it is independent of the detector network (interferometer or pulsar timing array), the individual detector noise curves (initial or Advanced LIGO), the nature of the GW sources (compact binary coalescence, supernova, or some other discrete source), and the distributions of source variables (only non-spinning neutron stars of mass exactly $1.4\,M_\odot$ or a complicated distribution of masses and spins). We derive the SNR distribution for each individual detector within a network as a function of the relative detector orientations and sensitivities. While most detections will have SNR near the detection threshold, there will be a tail of events to higher SNR. We derive the SNR distribution of the loudest (highest SNR) events in any given sample of detections. We find that the median SNR of the loudest out of the first four events should have an $\mbox{SNR}=22$ (for a threshold of 12, appropriate for the Advanced LIGO/Virgo network), increasing to a median value for the loudest SNR of 47 for 40 detections. We expect these loudest events to provide particularly powerful constraints on their source parameters, and they will play an important role in extracting astrophysics from gravitational wave sources. These distributions also offer an important internal calibration of the response of the GW detector networks.
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