• Title/Summary/Keyword: Uniform Current Distribution

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Numerical investigation of glass windows under near-field blast

  • Chiara Bedon;Damijan Markovic;Vasilis Karlos;Martin Larcher
    • Coupled systems mechanics
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    • v.12 no.2
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    • pp.167-181
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    • 2023
  • The determination of the blast protection level and the corresponding minimum load-bearing capacity for a laminated glass (LG) window is of crucial importance for safety and security design purposes. In this paper, the focus is given to the window response under near-field blast loading, i.e., where relatively small explosives would be activated close to the target, representative of attack scenarios using small commercial drones. In general, the assessment of the load-bearing capacity of a window is based on complex and expensive experiments, which can be conducted for a small number of configurations. On the other hand, nowadays, validated numerical simulations tools based on the Finite Element Method (FEM) are available to partially substitute the physical tests for the assessment of the performance of various LG systems, especially for the far-field blast loading. However, very little literature is available on the LG window performance under near-field blast loads, which differs from far-field situations in two points: i) the duration of the load is very short, since the blast wavelength tends to increase with the distance and ii) the load distribution is not uniform over the window surface, as opposed to the almost plane wave configuration for far-field configurations. Therefore, the current study focuses on the performance assessment and structural behaviour of LG windows under near-field blasts. Typical behavioural trends are investigated, by taking into account possible relevant damage mechanisms in the LG window components, while size effects for target LG windows are also addressed under a multitude of blast loading configurations.

Adaptive Extraction Method for Phase Foreground Region in Laser Interferometry of Gear

  • Xian Wang;Yichao Zhao;Chaoyang Ju;Chaoyong Zhang
    • Current Optics and Photonics
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    • v.7 no.4
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    • pp.387-397
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    • 2023
  • Tooth surface shape error is an important parameter in gear accuracy evaluation. When tooth surface shape error is measured by laser interferometry, the gear interferogram is highly distorted and the gray level distribution is not uniform. Therefore, it is important for gear interferometry to extract the foreground region from the gear interference fringe image directly and accurately. This paper presents an approach for foreground extraction in gear interference images by leveraging the sinusoidal variation characteristics shown by the interference fringes. A gray level mask with an adaptive threshold is established to capture the relevant features, while a local variance evaluation function is employed to analyze the fluctuation state of the interference image and derive a repair mask. By combining these masks, the foreground region is directly extracted. Comparative evaluations using qualitative and quantitative assessment methods are performed to compare the proposed algorithm with both reference results and traditional approaches. The experimental findings reveal a remarkable degree of matching between the algorithm and the reference results. As a result, this method shows great potential for widespread application in the foreground extraction of gear interference images.

Spatio-temporal Distribution Pattern of New Biotypes of Weedy Rice (Oryza sativa L.) in Selangor North-West Project, Malaysia

  • Baki, B.B.;M.M., Shakirin
    • Korean Journal of Weed Science
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    • v.30 no.2
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    • pp.68-83
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    • 2010
  • Weedy rice (Oryza sativa L.) occurred sympatrically with other weeds and the rice crop in Malaysian rice granaries. We conducted field surveys in 2006-2008 seasons in 7 farm blocks of Selangor's North West Project, Malaysia to enlist the new biotypes of weedy rice (NBWR) and assess their spatio-temporal pattern of distribution based on quantitative and dispersion indices. No less than 16 accessions of NBWR were identified based on their special traits, viz. panicle type, pericarp colour, presence or absence of awn, seed type and degree of grain shattering. The NBWR accessions exhibited a combination of morphological traits from open panicle, grain with awns, red pericarp, short grain type, and degrees of grain shattering. Others mimic commercial rices with close panicle, awnless grains, white pericarp, long or short grain-type. Invariably, the NBWRs mimic and stand as tall as cultivated rice namely MR219, MR220, or MR235 and these NBWR accessions stand among equals morphologically vis-a-vis the commercial rice varieties. Most accessions displayed varying degrees of grain shattering in excess of 50%, except Acc9 and Acc12. The seasonal dynamics of on the prevalence of dominant NBWR accessions were also displaying significant differences among farm blocks. While Bagan Terap farm block, for example, did not record any measurable changes in the dominant NBWR accessions over seasons, the Sungai Leman farm block recorded measurable season-mediated changes in the dominant NBWR accessions. Sungai Leman started with NBWR Acc3, Acc4, Acc5, Acc7, Acc8, and Acc12 in season 1 of 2006/2007, but no measurable records of Acc3 and Acc5 were shown in season 2 of 2007. In season 3 of 2007/2008, only Acc8 and Acc12 prevailed in the farm block. In Sawah Sempadan farm block, season 3 of 2007/2008 showed much reduced prevalence of NBWRs leaving only Acc8 and Acc12. Most accessions registered clump or under-dispersed spatial distribution pattern based on quantitative indices: variance-to-mean ratio (VMR) and Lloyd's patchiness values. The dynamics on the extent of infestation and prevalence of dominant NBWR accessions registered both season- and farm-block mediated differences. Most accessions showed VMR >1 thus indicative of having a clump or clustered spatial distribution, as exemplified by Acc3, Acc4, Acc7, Acc8 and Acc12 in all farm blocks throughout three seasons. Some accessions have either random or uniform distribution in a few farm blocks. The Acc8 has the highest population counts based on important value index, followed by Acc12, and both were the most dominant accession while Sawah Sempadan was the worst farm block infested by NBWR compared to other farm blocks. These results were discussed in relation with the current agronomic and weed management practices, water availability and extension services in the granary.

An Effect of Uplift Pressure Applied to Concrete Gravity Dam on the Stress Intensity Factor (중력식 콘크리트 댐에 작용하는 양압력이 응력확대계수에 미치는 영향)

  • Lee Young-Ho;Jang Hee-Suk;Kim Tae-Wan;Jin Chi-Sub
    • Journal of the Korea Concrete Institute
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    • v.16 no.6 s.84
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    • pp.841-850
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    • 2004
  • The modeling of uplift pressure within dam, on the foundation on which it was constructed, and on the interface between the dam and foundation is a critical aspect in the analysis of concrete gravity dams, i.e. crack stability in concrete dam can correctly be predicted when uplift pressures are accurately modelled. Current models consider a uniform uplift distribution, but recent experimental results show that it varies along the crack faces and the procedures for modeling uplift pressures are well established for the traditional hand-calculation methods, but this is not the case for finite element (FE) analysis. In large structures, such as dams, because of smaller size of the fracture process zone with respect to the structure size, limited errors should occur under the assumptions of linear elastic fracture mechanics (LEFM). In this paper, the fracture behaviour of concrete gravity dams mainly subjected to uplift Pressure at the crack face was studied. Triangular type, trapezoidal type and parabolic type distribution of the uplift pressure including uniform type were considered in case of evaluating stress intensity factor by surface integral method. The effects of body forces, overtopping pressures are also considered and a parametric study of gravity dams under the assumption of LEFM is performed.

Hardening Characteristics of Aluminum Alloy Surface by PTA Overlaying with Metal Powders (II) -Hardening charactersteristics and wear resistance of thicker surface alloyed layer- (플라즈마분체 오버레이법에 의한 알루미늄합금 표면의 경화특성에 관한 연구( II ) -후막 표면 합금화층의 경화특성과 내마모성-)

  • ;中田一博;;;松田福久
    • Journal of Welding and Joining
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    • v.12 no.4
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    • pp.102-109
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    • 1994
  • The thick and hard alloyed layer was formed on the surface of Aluminum Cast Alloy(AC2B) by PTA overlaying process with Cr, Cu and Ni metal powders under the condition of overlaying current 150A, overlaying speed 150mm/min and different powder feeding rate 5-20g/min. The characteristics of hardening and were resistance of alloyed layer have been investigated in relation to microstructure of alloyed layer. As a result, it was made clear that Cu powder was the most superier one in three metal powders used due to an uniform hardness distribution of Hv 250-350, good wear resistance and freedom from cracking in alloyed layer of which microstructure consisted of hypereutectic. On the contrary, irregular hardness distribution was usually obtained in Cr or Ni alloyed layers of which hardness was increased as Cr or Ni contents and reached to maximum hardness of about Hv 400-850 at about 60wt% Cr or 40wt% Ni in alloyed layer. However the cracking occurred in these alloyed layers with higher hardness than Hv 250-300 at more than 20-25wt% of Cr or Ni contents in alloyed layer. Wear rate of alloyed layer was decreased to 1/10 in Cu alloyed layer and 1/5 or 1/3 in Cr or Ni alloyed layer with same hardness of about Hv 300 in comparison with that of base metal at higher sliding speed.

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Suggestions on Future Research Directions of Autonomous Vehicles based on Information-Centric Micro-Service (정보중심 마이크로서비스 기반 자율차량 연구 방향에 대한 제언)

  • Rehman, Muhammad Atif Ur;Kim, Byung-Seo
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.21 no.2
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    • pp.7-14
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    • 2021
  • By changing the bulky monolithic services architecture to a microservices-based architecture, industries are managing the rising complexity of Autonomous Vehicles. However, the underlying communication mechanisms for the utilization and distribution of these microservices are incapable of fulfilling the requirements of the futuristic AV, because of the stringent latency requirements along with intermittent and short-lived connectivity issues. This paper proposes to tackle these challenges by employing the revolutionary information-centric networking (ICN) paradigm as an underlying communication architecture. This paper argues that a microservice approach to building autonomous vehicle systems should utilize ICN to achieve effective service utilization, efficient distribution, and uniform service discovery. This research claims that the vision of an information-centric microservices will help to focus on research that can fill in current communication gaps preventing more effective, and lightweight autonomous vehicle services and communication protocols.

A Study on the enforceability of Shrink-wrap License under the Contract Law of USA (미국(美國) 계약법(契約法)하에서 소위 "쉬링크랩라이센스" 계약(契約)에 관한 일고찰(一考察))

  • Hur, Hai-Kwan
    • THE INTERNATIONAL COMMERCE & LAW REVIEW
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    • v.20
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    • pp.129-150
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    • 2003
  • Software license agreements, to be useful in the mass market, could not be individually negotiated, and had to be standardized and concise. The software license agreement needs to be presented to the licensee-users in a fashion that would allow for mass distribution of software, also for it to enforceable, that would draw the users' attention to the terms and conditions under which the publisher allowed the use of the software. These needs have been accomplished, with or without fail, through so called the "shrink-wrap licenses" Shrink-wrap licenses purpose to transfer computer softwares to their users by defining the terms and conditions of use of the software without implicating the "first sale doctrine" of the Copyright Act. These shrink-wrap licenses have become essential to the software industry. However, in USA, the law applicable to these licenses has been unclear and unsettled. Courts have struggled to develop a coherent framework governing their enforceability. Meanwhile, the National Conference of Commissioners on Uniform State Laws ("NCCUSL") in USA promulgated the Uniform Computer Information Transaction Act ("UCITA") governing contracts for computer information transaction on July 29, 1999. One clear objective of UCITA was to settle the law governing the enforceability of shrink-wrap licenses. In these respects, this paper first introduces the various forms that shrink-wrap licenses take(at Part II. Section 1.), and explains the main advantages of them(at Part II. Section 2.) Here it shows how shrink-wrap licenses value themselves for both software publishers and users, including that shrink-wrap licenses are a valuable contracting tool because they provide vital information and rights to software users and because they permit the contracting flexibility that is essential for today's software products. Next, this paper describes the current legal framework applicable to shrink-wrap licenses in USA(at Part III). Here it shows that in USA the development of case law governing shrink-wrap licenses occurred in two distinct stages. At first stage, judicial hostility toward shrink-wrap licenses marked such that they were not enforced pursuant to Article 2 of the Uniform Commercial Code. At second stage, courts began to recognize the pervasiveness of shrink-wrap licenses, their indispensability to the rapidly expanding information technology industry, and the urgent need to enforce such licenses in order to maintain low prices for consumers of computer hardware or software, resulting in the recognition of shrink-wrap licenses. Finally, in view of the importance of UCITA, this paper examines how it will affect the enforceability of shrink-wrap licenses(at Part IV). The drafters of UCITA, as well as the scholars and practitioners who have criticized it, agree that it validates shrink-wrap licenses, provided certain procedural protections are afforded to purchasers. These procedural protections include the licensee end-user must (i) manifest his assent to the shrink-wrap license, (ii) have an opportunity to review the shrink-wrap license, (iii) have a right to return the product without costs.

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Performance Analysis of Tri-gate FinFET for Different Fin Shape and Source/Drain Structures (Tri-gate FinFET의 fin 및 소스/드레인 구조 변화에 따른 소자 성능 분석)

  • Choe, SeongSik;Kwon, Kee-Won;Kim, SoYoung
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.7
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    • pp.71-81
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    • 2014
  • In this paper, the performance variations of tri-gate FinFET are analyzed for different fin shapes and source/drain epitaxy types using a 3D device simulator(Sentaurus). If the fin shape changes from a rectangular shape to a triangular shape, the threshold voltage increases due to a non-uniform potential distribution, the off-current decreases by 72.23%, and the gate capacitance decreases by 16.01%. In order to analyze the device performance change from the structural change of the source/drain epitaxy, we compared the grown on the fin (grown-on-fin) structure and grown after the fin etch (etched-fin) structure. 3-stage ring oscillator was simulated using Sentaurus mixed-mode, and the energy-delay products are derived for the different fin and source/drain shapes. The FinFET device with triangular-shaped fin with etched-fin source/drain type shows the minimum the ring oscillator delay and energy-delay product.

Tc and Jc distribution in in situ processed MgB2 bulk superconductors with/without C doping

  • Kim, C.J.;Kim, Y.J.;Lim, C.Y.;Jun, B.H.;Park, S.D.;Choo, K.N.
    • Progress in Superconductivity and Cryogenics
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    • v.16 no.2
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    • pp.36-41
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    • 2014
  • Temperature dependence of magnetic moment (m-T) and the magnetization (M-H) at 5 K and 20 K of the in situ processed $MgB_2$ bulk pellets with/without carbon (C) doping were examined. The superconducting critical temperature ($T_c$), the superconducting transition width (${\delta}T$) and the critical current density ($J_c$) were estimated for ten test samples taken from the $MgB_2$ bulk pellets. The reliable m-T characteristics associated with the uniform $MgB_2$ formation were obtained for both $MgB_2$ pellets. The $T_cs$ and ${\delta}Ts$ of all test samples of the undoped $MgB_2$ were the same each other as 37.5 K and 1.5 K, respectively. The $T_cs$ and ${\delta}Ts$ of the C-doped $MgB_2$ were 36.5 K and 2.5 K, respectively. Unlike the m-T characteristics, there existed the difference among the M-H curves of the test samples, which might be caused by the microstructure variation. In spite of the slight $T_c$ decrease, the C doping was effective in enhancing the $J_c$ at 5 K.

Effect of Tungsten on PtRuW/C Catalysts for Promoting Methanol Electro-oxidation (메탄올 전기산화반응 증진을 위한 PtRuW/C 촉매에서 텅스텐의 효과에 관한 연구)

  • Noh, Chang Soo;Sohn, Jung Min;Park, Young-Kwon
    • Applied Chemistry for Engineering
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    • v.23 no.6
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    • pp.561-566
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    • 2012
  • PtRuW/C catalysts were prepared with the different molar ratios of Pt : Ru : W and their compositions were analyzed by energy dispersive X-ray (EDX). The uniform distribution of particles was observed using transmission electron microscopy (TEM). An average crystalline size of 3.5~5.5 nm was calculated based on x-ray diffraction (XRD) data. The electrochemical properties such as electrochemically active surface areas, current densities, specific activities and poisoning rates, were analyzed via CO stripping, linear sweep voltammetry and chronoamperometry. From the analysis, we observed that ternary alloy catalysts, except $PtRu_2W_2/C$, have higher current densities, specific activities and stabilities than those of commercial binary catalysts. Among all in-house catalysts, Pt5Ru4W/C showed the highest specific activity of $121.05mA{\cdot}m^{-2}$ and the lowest poisoning rate of $0.01%{\cdot}s^{-1}$.