• Title/Summary/Keyword: Field-in-field technique

Search Result 4,931, Processing Time 0.034 seconds

Optimal field synthesis for enhancing the modeling capabilities of reservoir/aquifer fields

  • Jang, Min-Chul;Choe, Jong-Geun
    • 한국지구물리탐사학회:학술대회논문집
    • /
    • 2003.11a
    • /
    • pp.684-689
    • /
    • 2003
  • One field identified by an inverse method is one of multiple candidate solutions those are independently obtained through a specific estimation technique. While averaging of optimized fields can provide a better description of the spatial feature of an unknown field, it deteriorates the flow and transport characteristics of the optimized fields. As a result, the averaged field is not suited for modeling aquifer performances. Based on genetic algorithm, an optimal field synthesis technique is developed, which combines diversely optimized fields into a refined group of fields. Each field in the population is paired, and a sub-region of each field is exchanged by crossover operation to create a group of synthesized fields of enhanced modeling capability. The population of the fields is evolved till the synthesized fields become sufficiently similar. Applications of the optimal field synthesis to synthetic cases indicate that the objective functions of the fields assessing the modeling capabilities are further reduced after the optimal field synthesis. The identified fields from various inverse techniques may yield a range of modeling results under varied flow situations. The uncertainty is narrowed down through the optimal field synthesis and the associated modeling results converge on that of the reference field. The developed inverse modeling facilitates the construction of a reliable simulation model and hence trustworthy predictions of the future performances.

  • PDF

A study on the appropriateness of using traditional technique in the field of Architectural heritage conservation - Through Comparing properties - (건조물 문화재 수리에 있어서 전통기술의 적합성 연구 - 기술의 속성 비교를 통하여 -)

  • Oh, Kyusung
    • Journal of architectural history
    • /
    • v.31 no.5
    • /
    • pp.7-20
    • /
    • 2022
  • Traditional building technique has been used as the main technology in the field of architectural heritage conservation in South Korea. It has remained this way with very little resistance until now. But the time has come to question the appropriateness of traditional technique as conservation technique. In this paper a study was done on the properties of the traditional technique and the architectural heritage conservation technique in order to define the appropriateness between the two techniques. As a result the traditional technique was found to be unfit for conservation technique. The reasons are as follows. First, there is a time gap between the traditional technique and the time when the heritage was first built. Second, conservation work is about retaining the values of being a heritage while the traditional technique is about safeness and practicality. Third, the use of traditional technique comes with using the tools of its time which cannot ensure the safety of the heritage. The traditional technique must be looked upon as one of an option in the field of conservation. We must develop a better conservation technology by finding balance between the traditional technique and modern science. And further more an aggressive investment must be made in order to realize this objective.

A mixed 8-node hexahedral element based on the Hu-Washizu principle and the field extrapolation technique

  • Chen, Yung-I;Wu, Guan-Yuan
    • Structural Engineering and Mechanics
    • /
    • v.17 no.1
    • /
    • pp.113-140
    • /
    • 2004
  • A mixed eight-node hexahedral element formulated via the Hu-Washizu principle as well as the field extrapolation technique is presented. The mixed element with only three translational degrees of freedom at each node can provide extremely accurate and reliable performance for popular benchmark problems such as spacial beams, plates, shells as well as general three-dimensional elasticity problems. Numerical calculations also show that when extremely skewed and coarse meshes and nearly incompressible materials are used, the proposed mixed element can still possess excellent behaviour. The mixed formulation starts with introduction of a parallelepiped domain associated with the given general eight-node hexahedral element. Then, the assumed strain field at the nodal level is constructed via the Hu-Washizu variational principle for that associated parallelepiped domain. Finally, the assumed strain field at the nodal level of the given hexahedral element is established by using the field extrapolation technique, and then by using the trilinear shape functions the assumed strain field of the whole element domain is obtained. All matrices involved in establishing the element stiffness matrix can be evaluated analytically and expressed explicitly; however, a 24 by 24 matrix has to be inverted to construct the displacement extrapolation matrix. The proposed hexahedral element satisfies the patch test as long as the element with a shape of parallelepiped.

Fabrication of Microcantilever Ultrasound Sensor and Its Application to the Scanning Laser Source Technique

  • Sohn, Young-Hoon;Krishnaswamy, Sridhar
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.25 no.6
    • /
    • pp.459-466
    • /
    • 2005
  • The scanning laser source (SLS) technique has been proposed recently as an effective way to investigate small surface-breaking defects, By monitoring the amplitude and frequency changes of the ultrasound generated as the SLS scans over a defect, the SLS technique has provided enhanced signal-to-noise performance compared to the traditional pitch-catch or pulse-echo ultrasonic methods, An extension of the SLS approach to map defects in microdevices is proposed by bringing both the generator and the receiver to the near-field scattering region of the defects, To facilitate near-field ultrasound measurement, silicon microcantilever probes are fabricated using microfabrication technique and their acoustical characteristics are investigated, Then, both the laser-generated ultrasonic source and the microcantilever probe are used to monitor near-field scattering by a surface-breaking defect.

Effect of magnetic field and gravity on thermoelastic fiber-reinforced with memory-dependent derivative

  • Mohamed I.A. Othman;Samia M. Said;Elsayed M. Abd-Elaziz
    • Advances in materials Research
    • /
    • v.12 no.2
    • /
    • pp.101-118
    • /
    • 2023
  • The purpose of this paper is to study the effects of magnetic field and gravitational field on fiber-reinforced thermoelastic medium with memory-dependent derivative. Three-phase-lag model of thermoelasticity (3PHL) is used to study the plane waves in a fiber-reinforced magneto-thermoelastic material with memory-dependent derivative. A gravitating magneto-thermoelastic two-dimensional substrate is influenced by both thermal shock and mechanical loads at the free surface. Analytical expressions of the considered variables are obtained by using Laplace-Fourier transforms technique with the eigenvalue approach technique. A numerical example is considered to illustrate graphically the effects of the magnetic field, gravitational field and two types of mechanical loads(continuous load and impact load).

Electromagnetic design study of a 7 T 320 mm high-temperature superconducting MRI magnet with multi-width technique incorporated

  • Jang, Won Seok;Kim, Geonyoung;Choi, Kibum;Park, Jeonghwan;Bang, Jeseok;Hahn, Seungyong
    • Progress in Superconductivity and Cryogenics
    • /
    • v.23 no.4
    • /
    • pp.30-34
    • /
    • 2021
  • Superconducting magnets have paved the way for opening new horizons in designing an electromagnet of a high field magnetic resonance imaging (MRI) device. In the first phase of the superconducting MRI magnet era, low-temperature superconductor (LTS) has played a key role in constructing the main magnet of an MRI device. The highest magnetic resonance (MR) field of 11.7 T was indeed reached using LTS, which is generated by the well-known Iseult project. However, as the limit of current carrying capacity and mechanical robustness under a high field environment is revealed, it is widely believed that commercial LTS wires would be challenging to manufacture a high field (>10 T) MRI magnet. As a result, high-temperature superconductor together with the conducting cooling approach has been spotlighted as a promising alternative to the conventional LTS. In 2020, the Korean government launched a national project to develop an HTS magnet for a high field MRI magnet as an extent of this interest. We have performed a design study of a 7 T 320 mm winding bore HTS MRI magnet, which may be the ultimate goal of this project. Thus, in this paper, design study results are provided. Electromagnetic design and analysis were performed considering the requirements of central magnetic field and spatial field uniformity.

A Study on Estimation Technique for Fault Location using Quadratic Interpolation in a Parallel Feeding AC Traction System (2차 보간법을 이용한 전기철도 급전계통의 고장점 산출 기법에 관한 연구)

  • Min, Myung-Hwan;An, Tae-Pung;Kwon, Sung-il;Jung, Hosung
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.66 no.3
    • /
    • pp.599-604
    • /
    • 2017
  • Nowadays reactance method is being used as a technique for fault location in parallel feeding AC traction power system. However, implementation of this method requires a large number of field tests(ground fault) which is a huge burden on the operators. This paper presents a new estimation technique using quadratic interpolation to reduce number of times for field test and improves the accuracy of fault location. To verify a new technique, we solve AT feeding circuit and model it using PSCAD/EMTDC. Finally this paper conducts a comparative analysis of usefulness between a new technique and real field data.

The Evaluation of Surface Crack in Paramagnetic Material by FEF Technique (FEF 탐상법을 이용한 상자성체 표면결함 평가)

  • Kim, Hoon
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.24 no.5
    • /
    • pp.532-537
    • /
    • 2004
  • FEF(Focused Electromagnetic Field) technique was newly developed that is based on the induction principle exciting electromagnetic field. The technique consists of an induction wire and a sensor for detecting electromagnetic field, and is applied in a non-contact mode. In this study, the technique was applied to the evaluation of EDM slits in some conductive materials - aluminum alloy, stainless steel and Inconel alloy. The voltage in the non-defect region is depended upon the measurement lift-off. The voltage signals on defects are measured with peak values, and the peak values changed with the depth of defects. The voltage distributions for all conductive materials are the same trend.

Improved Breast Irradiation Techniques Using Multistatic Fields or Three Dimensional Universal Compensators (Multistatic Field또는 3차원 공용보상체를 사용한 유방의 방사선 조사법의 평가)

  • Han Youngyih;Cho Jae Ho;Park Hee Chul;Chu Sung Sil;Suh Chang-Ok
    • Radiation Oncology Journal
    • /
    • v.20 no.1
    • /
    • pp.24-33
    • /
    • 2002
  • Purpose : In order to improve dose homogeneity and to reduce acute toxicity in tangential whole breast radiotherapy, we evaluated two treatment techniques using multiple static fields or universal compensators. Materials and Methods : 1) Multistatic field technique : Using a three dimensional radiation treatment planning system, Adac Pinnacle 4.0, we accomplished a conventional wedged tangential plan. Examining the isodose distributions, a third field which blocked overdose regions was designed and an opposing field was created by using an automatic function of RTPS. Weighting of the beams was tuned until an ideal dose distribution was obtained. Another pair of beams were added when the dose homogeneity was not satisfactory. 2) Universal compensator technique : The breast shapes and sizes were obtained from the CT images of 20 patients who received whole breast radiation therapy at our institution. The data obtained were averaged and a pair of universal physical compensators were designed for the averaged data. DII (Dose Inhomogeneity Index : percentage volume of PTV outside $95\~105\%$ of the prescribed dose) $D_{max}$ (the maximum point dose in the PTV) and isodose distributions for each technique were compared. Results : The multistatic field technique was found to be superior to the conventional technique, reducing the mean value of DII by $14.6\%$ (p value<0.000) and the $D_{max}$ by $4.7\%$ (p value<0.000). The universal compensator was not significantly superior to the conventional technique since it decreased $D_{max}$ by $0.3\%$ (p value=0.867) and reduced DII by $3.7\%$ (p value=0.260). However, it decreased the value of DII by maximum $18\%$ when patients' breast shapes fitted in with the compensator geometry. Conclusion : The multistatic field technique is effective for improving dose homogeneity for whole breast radiation therapy and is applicable to all patients, whereas the use of universal compensators is effective only in patients whose breast shapes fit inwith the universal compensator geometry, and thus has limited applicability.

Industrial Applications of PIV/PTV Velocity Field Measurement Techniques

  • Lee Sang Joon
    • 한국가시화정보학회:학술대회논문집
    • /
    • 2001.12a
    • /
    • pp.23-35
    • /
    • 2001
  • Due to advances in digital image processing, computer and optical hardware, it is possible to extract full flow information from visualized flow images. Recently, the PIV/PTV methods have been accepted as a reliable velocity field measurement technique. In my laboratory, several velocity field measurement techniques have been developed and they were applied to various thermo-fluid flow problems. In this paper, some of the industrial applications will be discussed. As a result, the PIV/PTV technique was proved to be a powerful tool for industrial fluid flow diagnosis.

  • PDF